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2G Tubular adjustable suspension parts for the entire chassis. Tubular subframes

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Hey all, been a while since I did any update on this thread, after getting the T45 frame tacked up i didnt do much with it for a while as it sat in our living room for a while. During the time of designing the evo ARB brackets i then decided to use those on this bar i can upgrade it in the future if I need to.

It went on all ok and fits nicely as expected, the bar also fits very well. I had to modify the fuel filler neck lower section but i knew this and got a bit of hose ready for that so i had to trim in about 6" back to clesr the tube of the frame.

I just need to get some new smaller hose as mine was very cracked and split.

Some pics of the new one installed shall do a road test this week once i get the new small hose in to put on

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Hey just wanted to say a few things I noticed after reading your thread.

1. Great work. Overall I'd say what you've made is really sound in design and you've done a great job of avoiding a lot of the pitfalls I commonly see in the aftermarket industry. Specifically your rear upper control arm looks nearly perfect.
2. Aluminum should always be avoided with respect to threaded fasteners carrying cyclic loads. Threads are stress concentrations and aluminum is not good in fatigue. You'll never see an oem aluminum control arm with all of the load going through a threaded connection.
3. If you do use aluminum threads they should be coarse thread not fine thread. Further I would recommend using UNCR thread form standard, rolled threads if possible.
4. Frankly even steel threaded fasteners should be avoided for joints carrying a moment. This is wildly rampant in the aftermarket industry and the heim joints you use have rather large shanks so the fatigue life should be reasonable but when you have that type of loading it's a question of when not if. Specifically I would not design the front upper control arms you've done with a heim joint on the outside. Under braking or accelerating that arm is reacting those forces which translates to a moment at the root of the heim joint there. Here is an example of a design that avoids this:
You must be logged in to view this image or video.
Also the rear lower arm with the rear swaybar link has the same issue but since you put the adjustment on the inboard side instead of the outboard side the effect will be minimal.
5. I would recommend welding a spherical on your bump steer kit. The second threaded connection isn't really gaining you anything and it sounds like it's hurting you in terms of adjustment. Basically the same type of thing as what you used on your rear swaybar connection.
6. One of the things that really bothers me is anecdotal engineering. Most of what you've posted regarding roll centers falls under this category however significantly more importantly you've made everything adjustable. Frankly understanding the theory isn't terribly important of you're able to test all of the possible combinations under the sun. But things like saying the front control arm needs to be higher to reduce camber gain because it's too high just irks me haha.

It's worth noting that I do not own a 2g so you do not need to take my comments from the standpoint of a potential customer but it is worth noting that I have a degree in aerospace structures and 9 years of experience doing automotive suspension design, so I do know what I'm talking about. And like I said your work is really impressive overall. I'm assuming you don't have an engineering background and that makes what you have achieved all the more impressive. If I did have a 2g I probably would run everything you've made except maybe the front uppers (and the subframe because I'm an AWD fanboy). The workmanship quality at least over the internet comes across as top notch. Please take this post as constructive criticism!
 
Hey just wanted to say a few things I noticed after reading your thread.

1. Great work. Overall I'd say what you've made is really sound in design and you've done a great job of avoiding a lot of the pitfalls I commonly see in the aftermarket industry. Specifically your rear upper control arm looks nearly perfect. While not always perfect in design I have to account for things like cost and if machined that side of it also so I am limited and always growing to progress each part i make and no doubt will always get a revision in at a later date as I learn more,
2. Aluminum should always be avoided with respect to threaded fasteners carrying cyclic loads. Threads are stress concentrations and aluminum is not good in fatigue. You'll never see an oem aluminum control arm with all of the load going through a threaded connection. There is no Aluminum fasters as much, all the standoffs are alloy not because of loads and its weaker its because I use it as a form of stress relief / damper so it has some kind of softing effect vs if it was steel on steel,
3. If you do use aluminum threads they should be coarse thread not fine thread. Further I would recommend using UNCR thread form standard, rolled threads if possible. The only threads I have are for the rear droplink and its not an issue for loads as I did plenty of tests on it before i used alloy as my original was steel.
4. Frankly even steel threaded fasteners should be avoided for joints carrying a moment. This is wildly rampant in the aftermarket industry and the heim joints you use have rather large shanks so the fatigue life should be reasonable but when you have that type of loading it's a question of when not if. Specifically I would not design the front upper control arms you've done with a heim joint on the outside. Under braking or accelerating that arm is reacting those forces which translates to a moment at the root of the heim joint there. Here is an example of a design that avoids this:
You must be logged in to view this image or video.
Also the rear lower arm with the rear swaybar link has the same issue but since you put the adjustment on the inboard side instead of the outboard side the effect will be minimal. Rod ends are a wear item and or course most of the time faster then a bush or a poly bush even but their gain is being adjustable and if used correctly are very useful! the rod end up top is fine as the forces are mainly at the lower arm side and thats what are compression arm is there for, the force the upper arm see's vs lower arm is divided by the distance between those two so the uppers on a 2G are some way apart so the force in no way near the lower loads that are seen. the upper arm is a placement arm so while it will see some loads the main purpose of this arm is to maintain its up and down motion, the rest of the goings on are all in the lower section from things like caster, toe.much more goes on down there so thats the vital area so the uppers do way less work.

that link you sent is I dont accept, this design along with others similer is design are known to slip similer to eccentric washers, plus SPC are known to also make setups with clearance issues so not the best choice to refer to haha, another thing is there is about $100 of parts in that and they sell them for what 500 maybe more? so thats also a problem I have with these companys and also why I do what I do, I dont skimp on any part yet I still manage to make it affordable!

5. I would recommend welding a spherical on your bump steer kit. The second threaded connection isn't really gaining you anything and it sounds like it's hurting you in terms of adjustment. Basically the same type of thing as what you used on your rear swaybar connection. due to use having long inner tie rods I have no other option for this currently but am in the works for something new, but the unit I make now has the exact oem length and adjustments and I am not loosing any thread shaft length.
6. One of the things that really bothers me is anecdotal engineering. Most of what you've posted regarding roll centers falls under this category however significantly more importantly you've made everything adjustable. Frankly understanding the theory isn't terribly important of you're able to test all of the possible combinations under the sun. But things like saying the front control arm needs to be higher to reduce camber gain because it's too high just irks me haha. If you think that roll centers dont matter or not true then I dont know what else to tell you, it does matter in every way and its a thing that many struggle to get right along with every other part of the car working seamlessly well together! its not about camber gain at all. what you are doing with roll centers is controlling weight transfer and with adjusting how to control this makes a huge difference but of course there is a whole lot more to throw in to the picture so its not just about RC sure but its a decent start to balance the cornering stages. But as I said there is alot more involved to getting it all spot on. The mount of people I talk to about suspension and they have no clue is shocking so its certainly something thats not widely known nor learnt outside of the motorsport industry and thats what I am hoping to make easier to understand and help our chassis evolve over time!

It's worth noting that I do not own a 2g so you do not need to take my comments from the standpoint of a potential customer but it is worth noting that I have a degree in aerospace structures and 9 years of experience doing automotive suspension design, so I do know what I'm talking about. And like I said your work is really impressive overall. I'm assuming you don't have an engineering background and that makes what you have achieved all the more impressive. If I did have a 2g I probably would run everything you've made except maybe the front uppers (and the subframe because I'm an AWD fanboy). The workmanship quality at least over the internet comes across as top notch. Please take this post as constructive criticism! I accept all feedback, good or bad, I use the Nissan GTR as a good baseline for what can and cannot be done since its practically a lot better then a 2G in every way and it just works so damn well, so my front uppers for instance are no different then a 3k set of arms that are made for race cars, they use an outer rod end also and if they dont break them we are not going to break them either LOL and they use smaller rod ends too... if it was a lower outer joint then yes I would use a Spherical and I already have designed said spherical now for this reason and set of arms! I have in the works the other subframes (AWD and front frames) so im not just stopping at fwd parts

Im a chassis builder / Welder and fabricator, I do suspension and kit cars etc etc, so I do have a wide knowlegde base in the motor industry, learning suspension is just a hobby I got into that got out of control and now I own more equipment then most setup shops do including software to analyse data input to this software (still learning this now) so while I dont have a motorsport degree I have a good background in parts I make and development stages I go through for testing, I will be looking into small motorsport courses just because I would love to expand my knowledge base and I have wanted to do this for the last year so my plans for 2020 are to do a few courses which cover all bases and then onto some that concentrate on chassis and suspension


I certainly would not do any of this is I thought for 1 second I was not capable or putting peoples lifes at risk, Its just nice to help the community and family out and to bring new life to our long forgotten cars since no big companys are going to jump on this we the small folk have to help our group alogn with many others to keep these cars going strong.

I thank you for your post and thoughts / feedback, I am always accepting of it all good or bad.
 
Hey just wanted to say a few things I noticed after reading your thread.

1. Great work. Overall I'd say what you've made is really sound in design and you've done a great job of avoiding a lot of the pitfalls I commonly see in the aftermarket industry. Specifically your rear upper control arm looks nearly perfect.
2. Aluminum should always be avoided with respect to threaded fasteners carrying cyclic loads. Threads are stress concentrations and aluminum is not good in fatigue. You'll never see an oem aluminum control arm with all of the load going through a threaded connection.
3. If you do use aluminum threads they should be coarse thread not fine thread. Further I would recommend using UNCR thread form standard, rolled threads if possible.
4. Frankly even steel threaded fasteners should be avoided for joints carrying a moment. This is wildly rampant in the aftermarket industry and the heim joints you use have rather large shanks so the fatigue life should be reasonable but when you have that type of loading it's a question of when not if. Specifically I would not design the front upper control arms you've done with a heim joint on the outside. Under braking or accelerating that arm is reacting those forces which translates to a moment at the root of the heim joint there. Here is an example of a design that avoids this:
You must be logged in to view this image or video.
Also the rear lower arm with the rear swaybar link has the same issue but since you put the adjustment on the inboard side instead of the outboard side the effect will be minimal.
5. I would recommend welding a spherical on your bump steer kit. The second threaded connection isn't really gaining you anything and it sounds like it's hurting you in terms of adjustment. Basically the same type of thing as what you used on your rear swaybar connection.
6. One of the things that really bothers me is anecdotal engineering. Most of what you've posted regarding roll centers falls under this category however significantly more importantly you've made everything adjustable. Frankly understanding the theory isn't terribly important of you're able to test all of the possible combinations under the sun. But things like saying the front control arm needs to be higher to reduce camber gain because it's too high just irks me haha.

It's worth noting that I do not own a 2g so you do not need to take my comments from the standpoint of a potential customer but it is worth noting that I have a degree in aerospace structures and 9 years of experience doing automotive suspension design, so I do know what I'm talking about. And like I said your work is really impressive overall. I'm assuming you don't have an engineering background and that makes what you have achieved all the more impressive. If I did have a 2g I probably would run everything you've made except maybe the front uppers (and the subframe because I'm an AWD fanboy). The workmanship quality at least over the internet comes across as top notch. Please take this post as constructive criticism!
what parts have you made for your car?
 
@tstkl says I don't want to muck up this thread as I think it's more appropriate to have this discussion in your other thread I responded to the other day so I will try to keep this short, but I will say I'm rather confused as to how a suspension could be designed for no change in toe over it's full range of motion but then also not be? Lowering your car is just like always having your suspension in bump. Now I am aware that any suspension will be optimized for the factory ride height but without going into too much detail a properly designed suspension will not have bump steer induced from lowering the vehicle. If you did in fact measure bump steer on the oem suspension arms then that means the car has bump steer from the factory and even at stock ride height a bump steer kit would help. Especially if you are using +/- 1.5" of travel, you're most likely covering the travel range for the factory ride height. Basically the bump steer is not caused by lowering the car. Either it was there always or it is the result of some other change made.

Also the multi link suspension system on a 2g is a type of double wishbone suspension, regardless of where the virtual pivot lies.

The Factory always has some BS as they will likely never be able remove it all not with all the variables. when they design a car they know exactly how much the shock compresses and rebounds and know the range of the arms motion and so forth, what you are not realising is the outside range of this motion is now out of spec and not even accounted for in the stock form, while they likely do know how much it will produce its not something they worry about as to them they selling you a stock car and its good for stock only! anything out of this is not there concern (ENTER AFTERMARKET PARTS)

so lets say the car has a stock compression of 2" then someone lowers the car and thats 2" lower! within that 2" drop is likely to be zero BS change or very minimal but its now at the top end of the scale, the rebound will still be ok to a point as its now going to work backwards (downwards) rather then forwards (upwards). but now its lowered any more movement up is now into this place of (lets call this factory avoidance) as they did not want it to go here and never intended it to be here anyway, so this is where BS comes into play and lot of it too, people with lowering springs are more susceptible to this because alot of them are not even stiffer then oem springs but rather just lower, now thats not true for every spring nor brand/car but they tend to have the softest rate going as a stock type spring so of course compresses more due to its softer rates, these people see more BS overall. this can be balanced out if depending on suspension arms and tires etc if it translates this to the steering wheel or just fades out unnoticed but the guys with coilovers and stiff suspension/arms notice this alot more! I certainly know I did hence my reason to design such a thing.

also please remember alot of people are changing all there suspension arms out for others so it likely will always be a thing to alter and adjust for. I am just offering a way to help these people who do want help in this department and to help make steering feel nicer as it really does make the road feel to the steering wheel much much nicer!

so you do have the idea and know about of it but what you lack is the outside thinking of the box or (motion range of the arms) I think I have managed to explain this decently but please let me know if I have lost you somewhere and/or need to go over some parts again
 
This is going to be a long one unfortunately, I don't get too much free time to do these sort of things but I think you're doing a good thing for the community and have a genuine interest in learning which is a great sight to see.

ec17pse said:
Hey just wanted to say a few things I noticed after reading your thread.

1. Great work. Overall I'd say what you've made is really sound in design and you've done a great job of avoiding a lot of the pitfalls I commonly see in the aftermarket industry. Specifically your rear upper control arm looks nearly perfect. While not always perfect in design I have to account for things like cost and if machined that side of it also so I am limited and always growing to progress each part i make and no doubt will always get a revision in at a later date as I learn more,
2. Aluminum should always be avoided with respect to threaded fasteners carrying cyclic loads. Threads are stress concentrations and aluminum is not good in fatigue. You'll never see an oem aluminum control arm with all of the load going through a threaded connection. There is no Aluminum fasters as much, all the standoffs are alloy not because of loads and its weaker its because I use it as a form of stress relief / damper so it has some kind of softing effect vs if it was steel on steel,
3. If you do use aluminum threads they should be coarse thread not fine thread. Further I would recommend using UNCR thread form standard, rolled threads if possible. The only threads I have are for the rear droplink and its not an issue for loads as I did plenty of tests on it before i used alloy as my original was steel.
4. Frankly even steel threaded fasteners should be avoided for joints carrying a moment. This is wildly rampant in the aftermarket industry and the heim joints you use have rather large shanks so the fatigue life should be reasonable but when you have that type of loading it's a question of when not if. Specifically I would not design the front upper control arms you've done with a heim joint on the outside. Under braking or accelerating that arm is reacting those forces which translates to a moment at the root of the heim joint there. Here is an example of a design that avoids this:
Also the rear lower arm with the rear swaybar link has the same issue but since you put the adjustment on the inboard side instead of the outboard side the effect will be minimal. Rod ends are a wear item and or course most of the time faster then a bush or a poly bush even but their gain is being adjustable and if used correctly are very useful! the rod end up top is fine as the forces are mainly at the lower arm side and thats what are compression arm is there for, the force the upper arm see's vs lower arm is divided by the distance between those two so the uppers on a 2G are some way apart so the force in no way near the lower loads that are seen. the upper arm is a placement arm so while it will see some loads the main purpose of this arm is to maintain its up and down motion, the rest of the goings on are all in the lower section from things like caster, toe.much more goes on down there so thats the vital area so the uppers do way less work.

that link you sent is I dont accept, this design along with others similer is design are known to slip similer to eccentric washers, plus SPC are known to also make setups with clearance issues so not the best choice to refer to haha, another thing is there is about $100 of parts in that and they sell them for what 500 maybe more? so thats also a problem I have with these companys and also why I do what I do, I dont skimp on any part yet I still manage to make it affordable!
5. I would recommend welding a spherical on your bump steer kit. The second threaded connection isn't really gaining you anything and it sounds like it's hurting you in terms of adjustment. Basically the same type of thing as what you used on your rear swaybar connection. due to use having long inner tie rods I have no other option for this currently but am in the works for something new, but the unit I make now has the exact oem length and adjustments and I am not loosing any thread shaft length.
6. One of the things that really bothers me is anecdotal engineering. Most of what you've posted regarding roll centers falls under this category however significantly more importantly you've made everything adjustable. Frankly understanding the theory isn't terribly important of you're able to test all of the possible combinations under the sun. But things like saying the front control arm needs to be higher to reduce camber gain because it's too high just irks me haha. If you think that roll centers dont matter or not true then I dont know what else to tell you, it does matter in every way and its a thing that many struggle to get right along with every other part of the car working seamlessly well together! its not about camber gain at all. what you are doing with roll centers is controlling weight transfer and with adjusting how to control this makes a huge difference but of course there is a whole lot more to throw in to the picture so its not just about RC sure but its a decent start to balance the cornering stages. But as I said there is alot more involved to getting it all spot on. The mount of people I talk to about suspension and they have no clue is shocking so its certainly something thats not widely known nor learnt outside of the motorsport industry and thats what I am hoping to make easier to understand and help our chassis evolve over time!

It's worth noting that I do not own a 2g so you do not need to take my comments from the standpoint of a potential customer but it is worth noting that I have a degree in aerospace structures and 9 years of experience doing automotive suspension design, so I do know what I'm talking about. And like I said your work is really impressive overall. I'm assuming you don't have an engineering background and that makes what you have achieved all the more impressive. If I did have a 2g I probably would run everything you've made except maybe the front uppers (and the subframe because I'm an AWD fanboy). The workmanship quality at least over the internet comes across as top notch. Please take this post as constructive criticism! I accept all feedback, good or bad, I use the Nissan GTR as a good baseline for what can and cannot be done since its practically a lot better then a 2G in every way and it just works so damn well, so my front uppers for instance are no different then a 3k set of arms that are made for race cars, they use an outer rod end also and if they dont break them we are not going to break them either LOL and they use smaller rod ends too... if it was a lower outer joint then yes I would use a Spherical and I already have designed said spherical now for this reason and set of arms! I have in the works the other subframes (AWD and front frames) so im not just stopping at fwd parts

Im a chassis builder / Welder and fabricator, I do suspension and kit cars etc etc, so I do have a wide knowlegde base in the motor industry, learning suspension is just a hobby I got into that got out of control and now I own more equipment then most setup shops do including software to analyse data input to this software (still learning this now) so while I dont have a motorsport degree I have a good background in parts I make and development stages I go through for testing, I will be looking into small motorsport courses just because I would love to expand my knowledge base and I have wanted to do this for the last year so my plans for 2020 are to do a few courses which cover all bases and then onto some that concentrate on chassis and suspension

I certainly would not do any of this is I thought for 1 second I was not capable or putting peoples lifes at risk, Its just nice to help the community and family out and to bring new life to our long forgotten cars since no big companys are going to jump on this we the small folk have to help our group alogn with many others to keep these cars going strong.

I thank you for your post and thoughts / feedback, I am always accepting of it all good or bad.

Regarding your comment about aluminum drop links (which I'm sure will work for most people and was simply pointing out the best practices in the industry in this regard) I would avoid using aluminum as a damper, although I doubt this is actually happening. That would imply that the aluminum is seeing rather large cyclic loading. It is easy to calculate the spring rate of an aluminum rod however and compare that to the stiffness of the swaybar. The stiffness of aluminum is defined by the young's modulus and is equivalent to:

cross section * youngs modulus / length of rod (units will depend on the units you use as an input, but to stay consistent with the below I would recommend square inches, PSI, and inches respectively)

The stiffness of the swaybar can be calculated using the first equation in this link:

http://files.engineering.com/downlo...2-2b7713118bbb&file=Sway_bar_Calculations.pdf

I would say as a good rule of thumb you want your end link to be 3-10x stiffer than your swaybar, although in this case you are saying you want to dampen it so I'm not sure what you are targeting.

Regarding your comment on the forces in the upper arm being fine, there is a quote from Eleanor Roosevelt I have seen at nearly every aerospace company I have visited and it goes, "Learn from the mistakes of others. You can't live long enough to make them all yourself." As I mentioned your rod ends are fairly large and their fatigue life should be fairly high, but rod ends in bending fail at the thread root eventually where as alternative designs do not. Also you are correct that the loads on the lower arm are higher than the upper arm which is another thing helping you but it isn't quite exactly divided by the distance between them. It would be more correct to say they are a ratio of their relative distance to the contact patch. Here's a good summary of the pros and cons:

https://www.formulastudent.de/pr/news/details/article/pats-column-rod-ends-in-bending/

Regarding SPC please note that I did not say they were a good example, just that they were an example. Actually, excluding boutique companies that only make suspension components for a singular platform (think maximum motorsports etc) SPC is unfortunately the best in my experience. I would say there isn't a single company that targets "global" aftermarket support of suspension components and does a good job in the sports compact world. Some of the off road companies are OK but usually only because they absolutely do not care whatsoever about weight and their customers associate weight with strength. SPC is like, a 4 out of 10. Most of the companies I've worked with are a 1/10 or 2/10. There may be a 3 in there somewhere I'm forgetting. You'd be surprised how many aftermarket companies have zero engineers on their payroll.

Regarding adjusting roll centers, this is quite a lengthy topic that I unfortunately don't have the time to get into properly right now, but I'll try and cover a general overview. I most certainly did not say that roll centers do not matter however so please do not confuse that. What I said is that Macpherson strut cars see more benefit from the gain in camber gain than they do in the higher roll center. There are exceptions of coarse as some people like to drag the ground and their roll center ends up below ground as a result. The important thing to know about roll centers is that you want your roll center to be approximately at ground level when your car is at full compression. I have heard faint whispers of people targeting below ground roll centers but I've never found an example in the real world. Anyways, the reason why you don't want the roll center to cross the ground plane is because it inverts the horizontal position of the roll center causing some undesirable handling characteristics and has a positive feedback loop on body roll. Having the roll center as low as possible without ever crossing the ground plane minimizes the jacking forces on the tires which maximizes tire grip. If you were to have your roll center = your CG height this would be very bad because you would be constantly lifting inside wheels. Actually this is how go karts work and why go kart drivers lean out instead of into the corner. Anyways, as long as your roll center is above ground for the entirety of your usable suspension travel the factory geometry is fine. What Macpherson strut suspensions gain from roll center kits then is camber gain. Usually a double wishbone suspension has around 0.5 degrees of camber gain per degree of body roll and a Macpherson strut suspension starts out at 0.25 degrees per degree of body roll which drops to zero degrees by the time one or two degrees of body roll are achieved. Beyond that the camber gain is typically negative. This means a lowered Macpherson strut vehicle without roll center adjusters will see negative camber gain on the outside tire during cornering. This is also why Macpherson strut cars tend to run more static camber.

What software are you using? The most common in the industry is MSC Adams which is probably not something you want to spend the money on as I believe it is around 4-5k per year. I believe Optimum G has some free software or free trials. I've written my own software in MATLAB for home use but it isn't something that's easy to follow without an in person course haha. I also found a java based software when I was in college that was free and kind of cute but it was purely 2d and couldn't do multi link upper or lower wishbones.

@tstkl says I don't want to muck up this thread as I think it's more appropriate to have this discussion in your other thread I responded to the other day so I will try to keep this short, but I will say I'm rather confused as to how a suspension could be designed for no change in toe over it's full range of motion but then also not be? Lowering your car is just like always having your suspension in bump. Now I am aware that any suspension will be optimized for the factory ride height but without going into too much detail a properly designed suspension will not have bump steer induced from lowering the vehicle. If you did in fact measure bump steer on the oem suspension arms then that means the car has bump steer from the factory and even at stock ride height a bump steer kit would help. Especially if you are using +/- 1.5" of travel, you're most likely covering the travel range for the factory ride height. Basically the bump steer is not caused by lowering the car. Either it was there always or it is the result of some other change made.

Also the multi link suspension system on a 2g is a type of double wishbone suspension, regardless of where the virtual pivot lies.


The Factory always has some BS as they will likely never be able remove it all not with all the variables. when they design a car they know exactly how much the shock compresses and rebounds and know the range of the arms motion and so forth, what you are not realising is the outside range of this motion is now out of spec and not even accounted for in the stock form, while they likely do know how much it will produce its not something they worry about as to them they selling you a stock car and its good for stock only! anything out of this is not there concern (ENTER AFTERMARKET PARTS)

so lets say the car has a stock compression of 2" then someone lowers the car and thats 2" lower! within that 2" drop is likely to be zero BS change or very minimal but its now at the top end of the scale, the rebound will still be ok to a point as its now going to work backwards (downwards) rather then forwards (upwards). but now its lowered any more movement up is now into this place of (lets call this factory avoidance) as they did not want it to go here and never intended it to be here anyway, so this is where BS comes into play and lot of it too, people with lowering springs are more susceptible to this because alot of them are not even stiffer then oem springs but rather just lower, now thats not true for every spring nor brand/car but they tend to have the softest rate going as a stock type spring so of course compresses more due to its softer rates, these people see more BS overall. this can be balanced out if depending on suspension arms and tires etc if it translates this to the steering wheel or just fades out unnoticed but the guys with coilovers and stiff suspension/arms notice this alot more! I certainly know I did hence my reason to design such a thing.

also please remember alot of people are changing all there suspension arms out for others so it likely will always be a thing to alter and adjust for. I am just offering a way to help these people who do want help in this department and to help make steering feel nicer as it really does make the road feel to the steering wheel much much nicer!

so you do have the idea and know about of it but what you lack is the outside thinking of the box or (motion range of the arms) I think I have managed to explain this decently but please let me know if I have lost you somewhere and/or need to go over some parts again

I think you and Jesse are missing my point. I'm not saying that the factory does or does not have bump steer. I'm saying lowering the car does not induce bump steer. The factory suspension is incredibly soft and the suspension travel you will see with those soft springs will have more bump steer across it's travel than the travel that will be seen with stiff lowering springs. You can look up spring rates for lowering springs, I have never seen a single lowering spring that didn't have a base rate that is higher than OEM. Lowering springs are typically stiff springs with "dead coils" that are very soft. These "dead coils" collapse once the body weight of the vehicle is applied rendering them inconsequential to the spring rate of the wheel. The base rate of the spring needs to be higher otherwise the car will constantly be hitting the bump stops.

I get that the factory suspension will be optimized for the nominal ride height and the bump steer induced per unit of suspension travel will be highest at the extremes, however the factory suspension travel is going to be around 7-8 inches total. You're measuring +/- 1.5 inches, or 3 inches total. This means best case scenario you are measuring the bump steer from 1 inch of compression to 4 inches of compression, assuming you are measuring to the same location as the factory bump stop. It is possible given your coil overs you are looking at heights lower than this but I doubt it. Please remember what I'm saying is lowering the car does not induce bump steer, not that the bump steer is or is not there.

The equation that defines bump steer for a double wishbone suspension is second order. This means it has a single order first derivative which describes the rate that the bump steer would increase over the travel of the suspension. So the rate of change of bump steer across the suspension travel is a linear function with respect to suspension travel. There is no inflection point where you start to drastically see bump steer.

I'm worried that you think I'm arguing that your kit is not good or a good thing. This is not the case. An adjustable bump steer kit is useful to people who have changed control arms as you've highlighted.

Lastly, I highly encourage you to read RCVD by Milliken, as it is a great introductory text on the subject of vehicle dynamics. It's a bit pricy but worth it. You also can probably find pirated versions.
 
what parts have you made for your car?

I am going to positively assume this is not a passive aggressive question. Also I'm going to assume you are referring to suspension components explicitly as a comprehensive list would be exhausting for both of us.

For my dodge stealth: nothing, I've only had it for a year and it's at the bottom of the totem pole for suspension upgrades.

For my 1g dsm: I ran this car in STX for about 4 years. The class rules are fairly restrictive but I'm a fairly creative person if I do say so myself. I made a lot of polyurethane bushings that moved points around as best I could while staying within the rules as well as a set of front lower control arms. I am sure there is a lot more that I'm forgetting but the rule book is so tight everything had to be rather minor. I got the car to within 2 seconds of the class leading drivers in my region (one of which won the class at nationals). I was fairly impressed given the car dyno'ed at 185 wheel and was running factory evo 8 shocks (not Bilstein's) with 70k miles on them. I felt if I put more money into the car I could get it to within 0.5 seconds of the class leaders which would be rather impressive if you ask me. The 1g was re-classed to STH which I feel put me at a significant disadvantage power wise and so I stopped putting money/time into the car. I saw 1gs were being considered for DSP which is intriguing but again the budget becomes an issue given I would need to fabricate a custom center differential.

For my conquest: A few things here and there. Nothing crazy. I haven't finished the design of the multi link rear suspension I'll be converting too and decided I'd rather get the car running first and enjoy it for a while before tearing into it again. It has a 4g63 and T56 transmission.

Additionally I built/designed a couple single seater racecars in college for a competition called FSAE. I'm still happily involved in the program and have managed to convince my company to support me going to one of the US competitions every year.

Lastly, I've designed about 500 suspension components in a professional capacity in CAD, most of which were bushings but some of which were larger assemblies such as complete subframes etc. Of those about 350 would have been prototyped/tested and about 100 would have made it to production. That's about all I can say. It's incredible how much money goes into the ford mustang market by the way.
 
This is going to be a long one unfortunately, I don't get too much free time to do these sort of things but I think you're doing a good thing for the community and have a genuine interest in learning which is a great sight to see. This certainly is long and im currently on my phone so i shall do the best i can on the device as a reply, excuse the spelling. My fingers and letters dont always work well LOL,



Regarding your comment about aluminum drop links (which I'm sure will work for most people and was simply pointing out the best practices in the industry in this regard) I would avoid using aluminum as a damper, although I doubt this is actually happening. That would imply that the aluminum is seeing rather large cyclic loading. It is easy to calculate the spring rate of an aluminum rod however and compare that to the stiffness of the swaybar. The stiffness of aluminum is defined by the young's modulus and is equivalent to:

cross section * youngs modulus / length of rod (units will depend on the units you use as an input, but to stay consistent with the below I would recommend square inches, PSI, and inches respectively)

The stiffness of the swaybar can be calculated using the first equation in this link:

http://files.engineering.com/downlo...2-2b7713118bbb&file=Sway_bar_Calculations.pdf

I would say as a good rule of thumb you want your end link to be 3-10x stiffer than your swaybar, although in this case you are saying you want to dampen it so I'm not sure what you are targeting. Droplinks in oem form are always the weaklink, always will be, on oem units with thin shafts and crappy BJ's in a nylon housing are not strong at all. The 1 thing i always get annoyed about most is when its on paper its ment to be correct but for years its always been shown up by actual results and data in application usage. I made a long set for my friends daily and then turned race car M8 alloy rodends and shaft and that was 6 odd years ago, still perfect with zero threads pulled! This was also on the front ARB so alot thicker then a rear bar normally is on a FWD, so while these books and documents say 1 thing its proven to not be the case, time and time again its always being worked on and proved otherwise. May items like hubs and knuckles are now becoming alloy due to how good its getting. Get the right rodend or material and its strong for applications if worked out correctly. While I said i used alloy as a dampner i ment in the fast that its softer then steel, so less NVH compared to steel and any movement or deflection is a bunch less then rubber or a greased housed BJ which has more slop overall.

Regarding your comment on the forces in the upper arm being fine, there is a quote from Eleanor Roosevelt I have seen at nearly every aerospace company I have visited and it goes, "Learn from the mistakes of others. You can't live long enough to make them all yourself." As I mentioned your rod ends are fairly large and their fatigue life should be fairly high, but rod ends in bending fail at the thread root eventually where as alternative designs do not. Also you are correct that the loads on the lower arm are higher than the upper arm which is another thing helping you but it isn't quite exactly divided by the distance between them. It would be more correct to say they are a ratio of their relative distance to the contact patch. Here's a good summary of the pros and cons: REIB is always a concern but in certain situations, FSAE is a nice baseline but remember they akways about by the books and many if not all tend to go against it and use super small M6 rodends, my friend was part of an FSAE university and i seen the designs they did and i did not like some of it, but it worked for them but not something i would do in a road car. Plus I always take was FSAE say with a huge pinch of salt.

Another thing is to consider the suspension setup its going on, where the shock mounts to and use that data for the build of it all, and my comment on force on upper arm was given to me by a suspension person so i think i will trust them since i know them more. But i do understand your side of it though,
Also note the one that does this for the Nissan GTR is a company that races and has great race team experiance so i wouod not just pick from any old company! They have to have a good background in racing for me to even think their products are designed well.

https://www.formulastudent.de/pr/news/details/article/pats-column-rod-ends-in-bending/

Regarding SPC please note that I did not say they were a good example, just that they were an example. Actually, excluding boutique companies that only make suspension components for a singular platform (think maximum motorsports etc) SPC is unfortunately the best in my experience. I would say there isn't a single company that targets "global" aftermarket support of suspension components and does a good job in the sports compact world. Some of the off road companies are OK but usually only because they absolutely do not care whatsoever about weight and their customers associate weight with strength. SPC is like, a 4 out of 10. Most of the companies I've worked with are a 1/10 or 2/10. There may be a 3 in there somewhere I'm forgetting. You'd be surprised how many aftermarket companies have zero engineers on their payroll.

Regarding adjusting roll centers, this is quite a lengthy topic that I unfortunately don't have the time to get into properly right now, but I'll try and cover a general overview. I most certainly did not say that roll centers do not matter however so please do not confuse that. What I said is that Macpherson strut cars see more benefit from the gain in camber gain than they do in the higher roll center. There are exceptions of coarse as some people like to drag the ground and their roll center ends up below ground as a result. The important thing to know about roll centers is that you want your roll center to be approximately at ground level when your car is at full compression. I have heard faint whispers of people targeting below ground roll centers but I've never found an example in the real world. Anyways, the reason why you don't want the roll center to cross the ground plane is because it inverts the horizontal position of the roll center causing some undesirable handling characteristics and has a positive feedback loop on body roll. Having the roll center as low as possible without ever crossing the ground plane minimizes the jacking forces on the tires which maximizes tire grip. If you were to have your roll center = your CG height this would be very bad because you would be constantly lifting inside wheels. Actually this is how go karts work and why go kart drivers lean out instead of into the corner. Anyways, as long as your roll center is above ground for the entirety of your usable suspension travel the factory geometry is fine. What Macpherson strut suspensions gain from roll center kits then is camber gain. Usually a double wishbone suspension has around 0.5 degrees of camber gain per degree of body roll and a Macpherson strut suspension starts out at 0.25 degrees per degree of body roll which drops to zero degrees by the time one or two degrees of body roll are achieved. Beyond that the camber gain is typically negative. This means a lowered Macpherson strut vehicle without roll center adjusters will see negative camber gain on the outside tire during cornering. This is also why Macpherson strut cars tend to run more static camber. Without going through all details i dont know the RC on mcpherson, everyone and car has a different setup and so far i have opted to get mine close to the CofG to make the weight transfer faster, so im ourely focusing on my car currently and i aquired all the data for me to make this choice. Other cars I would have to get involved in to and see what the drive feels and wants to do,
The problem with Mcpherson is the camber range while you get camber its nice but at a certain point the camber become positive and is bad.


What software are you using? The most common in the industry is MSC Adams which is probably not something you want to spend the money on as I believe it is around 4-5k per year. I believe Optimum G has some free software or free trials. I've written my own software in MATLAB for home use but it isn't something that's easy to follow without an in person course haha. I also found a java based software when I was in college that was free and kind of cute but it was purely 2d and couldn't do multi link upper or lower wishbones.
OptimumG is my end goal and i am slowly saving for it as i like their 3D version while mine is 2D but still plenty good enough, i need to get on this alot more and learn this as i feel as if i can make more use of this as a bsseline then adjust from there in real world testing. At least i dont have to do all the calculations or drawings anymore as its all in the system.


I think you and Jesse are missing my point. I'm not saying that the factory does or does not have bump steer. I'm saying lowering the car does not induce bump steer. The factory suspension is incredibly soft and the suspension travel you will see with those soft springs will have more bump steer across it's travel than the travel that will be seen with stiff lowering springs. You can look up spring rates for lowering springs, I have never seen a single lowering spring that didn't have a base rate that is higher than OEM. Lowering springs are typically stiff springs with "dead coils" that are very soft. These "dead coils" collapse once the body weight of the vehicle is applied rendering them inconsequential to the spring rate of the wheel. The base rate of the spring needs to be higher otherwise the car will constantly be hitting the bump stops.

I get that the factory suspension will be optimized for the nominal ride height and the bump steer induced per unit of suspension travel will be highest at the extremes, however the factory suspension travel is going to be around 7-8 inches total. You're measuring +/- 1.5 inches, or 3 inches total. This means best case scenario you are measuring the bump steer from 1 inch of compression to 4 inches of compression, assuming you are measuring to the same location as the factory bump stop. It is possible given your coil overs you are looking at heights lower than this but I doubt it. Please remember what I'm saying is lowering the car does not induce bump steer, not that the bump steer is or is not there.

The equation that defines bump steer for a double wishbone suspension is second order. This means it has a single order first derivative which describes the rate that the bump steer would increase over the travel of the suspension. So the rate of change of bump steer across the suspension travel is a linear function with respect to suspension travel. There is no inflection point where you start to drastically see bump steer.

I'm worried that you think I'm arguing that your kit is not good or a good thing. This is not the case. An adjustable bump steer kit is useful to people who have changed control arms as you've highlighted.

Lastly, I highly encourage you to read RCVD by Milliken, as it is a great introductory text on the subject of vehicle dynamics. It's a bit pricy but worth it. You also can probably find pirated versions.
 
Hello again thread!

Been a while and I have a nice treat for you all! Over the last few months I have been working on the 2G tubular front subframe and trying to drum up ideas and designs for this because its not a basic subframe! No no, its going to be a subframe thats modular and upgradeable so its rather tricky Because the jig needs to also have this implimented to be able to swap bits out for the versions.

So as always i concentrate on circuit racing and cross bracing is key for strength it comes with a trade off on weight but even then its currently not heavy and sits at just over 17 Lbs and i had a projection weight of no more then 25 Lbs! So i am well within my limit and most likely will be under it still when finished.
The oem frame comes in At just over 40 Lbs.

So lets talk about the part you are asking about (modular) how and why! There are 2 main things that will be modular and 1 I am currently not sure on yet and thats still being looked into.

Well as i say many many times i am always thinking about costs and helping you all out. And this is part of this just more advanced then ever before! So the idea is the main frame will stay the same design HOWEVER with an upgrade which will be a built in 2 point under brace that ties into the factory or aftermarket cross member location.

The 2nd version of this (not yet mocked up) is a 4 point brace that ties the front lower arm mounting point to the rear mounts as an all in 1 unit and this will use a custom cross member per my design for that 4 point under brace only.

The part you will notice thats missing is the rear compression arm mounting point and this is another piece of the huge puzzle. Thats also going to be able to be swapped out to make way for my bracket similer to the front lower arm one and thats because the new compression arms will be able to adjust to the new mounting with simple bush replacements. So it all works together. This part is a tricky one as i have a few ideas i need to mock up and test the best way i like to proceed while keeping it strong.

Last part of the modular system is steering racks. Im not currently sure if it sill work well because i would have to make a system up that is a universal mount and then each rack would have its own specific sub mounting for the rack used,

So the racks are likely to be the OEM rack, EVO rack and a Woodward rack. I have to look into this more as its down to figuring out the complex mounting system and also see what costs are likey to include on this lot.

So thats the modular parts i plan to do with this subframe. I will eventually see about converting the jig to work for the 420A also as the main points are the same just a few small things differ.

The next stage once i have mocked up the 4 point brace is to test fit it on the car and see if i have worked it all out right and clears all the chassis, I have worked very closely to the oem subframe tolerances knowing my areas i can push limits more and looked at 4G63 manual, auto, FWD and AWD to take into account all of those things when designing. Which i must mention has been tricky as i have redesigned it about 3 times and made adjustments a few times over because i was out of my clearance zone or i just did not like the outcome!

So let me know what you think so far. Always nice to see peoples opinions and thoughts

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During the week i kept looking at the frame as i had doubt about 1 place hitting and more and more i thought about it the more i had to redo it as i knew from looking under the car it was a tight spot. See pic attached with the yellow circle for the place i was worried about. The piece i was and am trying to avoid is the diff cover which sits reslly close to the subframe in stock form. I made a small jig to bolt to my jig to show me my clearance area and just worked with that for guidance.
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Many other things played on from this like the under brace, so i re designed that to be 1 piece from connection points and then add supports for the crossmember. (These supports need slight adjustment due to ever so slightly touching the oem crossmember as its wide at the base) easy enough as i already mocked for the adjustment just never had time to redo it.
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Having to redesign this was another problem as i really loved my design so i had to make sure i keep it strong and support it as much as possible. So after visualizing the forces on the arms / frame i came up with this and it opens up the area for the diff cover the auto seems alot tighter then the manuals i seem to find so i can at least check mine since its auto.

Since this was all new and adjusted on the front i was having to think of how to mount the steering rack since it was a low bar to begin with, i decided to raise the front bar up giving me more room for that diff cover i mentioned above so this i have bit more freedom on rack mounting which i will look more into my idea next week. I have to make a jig to press the passenger side mounting clamp yet but thats almost resdy to make.

Other then that i have tried to keep it as triangulated as possible to keep strength up and the 4 point lower brace (yet to be done) will further add strength

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Managed to get everything off today and test fit the new one and i did have a minor clesrance issue still with the diff cover LOL it was small but still annoying. My jig helped but what i did not take into account was the section beside the part i was trying to avoid and i concentrated on the back of the part more so.

I whipped of the tube having an issue and fitted the frame and everything else fitted nicely, the driveshaft clears the lower arm mount even with a clip for the boot. Other then the issue with the tube it all bolted in ok so now i can redo the frame taking into account the issue which now makes me think of another re design so hopefully next weekend i can work on V1.7.3 LOL

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I did a video chatting about the subframe etc and its on my build thread if you want to take a look and view my youtube channel.

Onto today doing. I did not have alot of time to mess around today due to other projects and sale items going on but i did manage to get most of the modular compression arm mounting brackets mocked up and drawn / made and tacked together.

Going to test fit tomorrow and then check my final clearances for my custom bracket as its very possible i may have to revert to the 3 holed version as 4 might not be enough room up top to fit under the chassis, we shall be finding this out shortly.

The plate is just a bit of added strength as its fully tubed around the mounting points.
These are all drawn up and i shall send them to get laser cut for my sample subframe which hopefully if the metal turns up i can start in the next week or 2 after i do the small revision of the front tube area.

The area i am pointing at will have vertical tubes to connect the lateral tubes to each other.

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Whats up thread,

While i wait for some stuff to redo a new front frame i decided to work on some other bits while i had some time.

One of the items is something i have wanted to make for such a long time and its for the oem subframe but never actually got around to doing it for some reason! Guess i just got side tracked all these years LOL. When i installed the tanabe unit it certainly did help alot so i can only imagine this will make it alot better being on the front arms aswell all connected.

Before i got the tanabe under brace i wished there was a 4 point brace around as the ralliart one was nice but not that strong and would need to be modified to add cross support strength. So I made this today and its a full 4 point with added cross support for strength. For now this will work out for me well till i can complete the tubular frame and get that one on.

It currently weighs in at 4.9Lbs so its pretty light considering its CDS steel

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Whats up thread,

While i wait for some stuff to redo a new front frame i decided to work on some other bits while i had some time.

One of the items is something i have wanted to make for such a long time and its for the oem subframe but never actually got around to doing it for some reason! Guess i just got side tracked all these years LOL. When i installed the tanabe unit it certainly did help alot so i can only imagine this will make it alot better being on the front arms aswell all connected.

Before i got the tanabe under brace i wished there was a 4 point brace around as the ralliart one was nice but not that strong and would need to be modified to add cross support strength. So I made this today and its a full 4 point with added cross support for strength. For now this will work out for me well till i can complete the tubular frame and get that one on.

It currently weighs in at 4.9Lbs so its pretty light considering its CDS steel

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I would buy this from you. :applause:
 
I have been asked if the 4 point brace will clear a tubular cross member (mine is from true street when they was around) and I can confirm it sure does! With more room to spare actually then the oem cross member does.

I have had a good amount of interest for these so im currently looking into making a batch (was only ever ment to be a custom item for myself) but I cannot help whats liked. So once i have the info i need from coating and shipping etc i shall do a sale post for them.

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I whipped the oem subframe on today and confirmed fitment of the welded 4 point brace, tig welding it made it pull a bit, tig welding does this and as its in the middle of the bar it will pull, i may revert to mig welding since it wont pull no way near as much

Another thing i found out is space is different from 4G63 to 420A! Weirdly i found this shocking to see when i tested this on my 420A chassis. Its about 20mm difference and it fouls the oem cross member and oem exhaust pipe, the cross member does seem lower then my oem 4G63 cross member, could be because of the engine difference!

The rear fits fine on both as thats not an issue, just the cross member on both differs so i might have to make specific units and make them labeled to tell.

Anyone with a gsx on axle stands wanna help me out? Want to confirm clearance is ok for the transfer case, ( it should be fine since i left the same clearance as the tanabe unit and they work with the gsx )
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I decided to redesign this brace but forgot to take pics of it and I should get it back from the coaters next week.

I opted to connect to the rear mounting bush as looking at the forces this will see its a much stronger point for load spreading and left to right at the front is self supporting, this tube is very strong and does not flex like the tanabe rear unit does so its much stiffer. also welding it to the rear mounting bush means it pulls alot less which is nice. Tig welding them i much nicer then mig anyway.

keep an eye out for them soon folks
 
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