Ultimate maybe,proper definitally, a true 2g suspension system

[Revolution]

Hello Dsm Tuners I was reading a very interesting thread not to long ago with some heavy information as to a perticulare suspension system that was being developed by one of our own dsm brothers Dennis Grant from Far North Racing.

I for some odd reason cant seem to find this thread any more ,maybe because the Modds pulled it for some trivial reason wich is fine, but it has placed me in a tight situation as a tuners member. I personally am very interested in the DG 2g suspension system because of all the R&D that has gone into them. Who knew that not every koni or any shock obsorber was not in equally matched this says alot about companies out their.

I as Dsm Tuners member would Like to see this information Posted not only for my own benifit but aswell as every other tuner in this board.

So I ask DG-FNR to please repost some information about this suspension system so we could all benefit from it whether it be a better understanding of how suspension systems work on 2g's or just good old reading material.

So To clarify I am asking DG-FNR to post all the information pertaining to this said suspension system.

 

[jtmcinder]

I have no idea if any threads have been deleted, but I can tell you why I would have at least locked a bunch of recent ones and deleted several of the posts inside.

When people use this forum to hawk their products, all sorts of grief can occur. Most of all, it creates a situation where some very knowledgable and convincing people have an interest in making you believe something. That doesn't automatically mean that they will lie to you. Maybe they are correct and you could benefit from what they are selling. But maybe they are wrong and you won't. The problem is, you can't be sure. Most of all, you can't be sure if they are using their knowledge and rhetoric to teach you or con you. In other words, if you're smart about people, you should have at least some doubt about what they are saying.

It's bad enough that we often have to wade through or bedunk the posts made by people who have no idea of what they are talking. If we also have to sort through and decode their motives, then we might as well pack it in now.

In short, I am in complete agreement with the policies of this site with regard to vendors posting advertizements in the technical forums (even if my reasons might be different from those of the management). There has been way too much advertizing in this forum lately. If threads have been deleted, it was for a very good reason.

- Jtoby

ps. if you really want to know more about the stuff that Dennis is selling, you can email him directly or click on the URL that he has posted several times ... your post came across to me as a clear attempt to stir up trouble, since anyone could figure this out in about five seconds

 

[Revolution]

I agree whole heartedly with some of your remarks jtmcinder. In retro spec to trusting people based on their knowledge and motives has and forever will be cumbersome.

I don't fully trust every single individual that is trying sell or push a product ,that's why I tend to look at their track record and see where their "expertiese" comes from.

On the topic of myself starting a thread which you so nicely stated was intended to cause some sort of trouble was very negligent. If you re-read my post you will notice that I very publicly asked for DG-FNR to re post some information on his suspension project which he will intend to sell that was deleted, I not once ever asked for a infomertial.

I was and still am a little peeved about the thread being deleted because there was very useful information which was posted. Whatever the reason for the deletion was up to managment.

Whatever issue you have with DG-FNR should be kept amungst yourselves , I have read way too many post where cheapshots where thrown at DG-FNR in the name of knowledge which I really don't condone.

I am not a wiseman nor an engineer but I do happen to race from time to time and will progressivly become more serious about my hobby as the days grow longer again.
Hence the reason for my request for product specific information.

I hope I won't have to repost as to my motives for publicly asking DG-FNR to repost this suspension specific information.

So I will leave it at this comment, I for one am not asking for an advertisment but rather suspension specific information for the rest of the public as well as myself.

Back on topic so DG-FNR what spring rate would we be looking at for a street/track setup?
Being on the same level playing field as the vettes in the suspension department would be an amazing feat indeed.

 

[DG-FNR]

I suppose it's time for a little history.

Once upon a time, the only real suspension system availible for the 2G DSM was the Ground Control Koni coilovers/. Ground Control sold you a set of off-the-shelf Konis, a set of their coilover sleeves, and for a little extra money, a set of front upper mount plates that supposedly gave you a little extra suspension travel, and a set of springs.

I bought this setup. At the time, it was the most money I had ever dropped on a car.

And after a season of racing on them, it was clear that something wasn't quite right. At the time, I was too inexperienced to really know what was right, or wrong, or how to go forward. I tried different shock settings, different spring rates, and different sway bars - but I was pretty much flailing in the dark.

Then along came Dr Mike from ShockTek. Dr Mike was a hydraulic damping specialist - he had built suspension systems for fragile electronics - and he thought racing was cool, and he wanted to get involved with it. So he started a racing shock company, and he wound up developing shocks for DSMs. He sponsored me, Fedja, and Eric Stemler, and we worked with him developing better shocks.

Then he went through some difficult personal circumstances, and the company folded.

I had ShockTeks, as did a lot of other people for a lot of different cars. They were better than the Koni stuff in some ways, but worse in others, and nobody really knew why. And with the company gone, there was no way to move forward.

So then I hooked up with another shock company... but the less said about that the better. More importantly, nothing ever came of it; there was never any product actually released.

Out of all this I learned that I couldn't just take other people's word for what was right. All the "experts" I talked to didn't actually race themselves, never mind DSMs. Dr Mike knew a TON about damping, but almost nothing about vehicle dynamics - he was depending on me and the other development drivers to give him the feedback he needed, and frankly, we were all as lost as he was.

I had an epiphany in 2002. I won the SCCA ProSolo SM Championship, plus the ProSolo Honda Street Challenge, in a 2G DSM with ShockTek components. For those of you who aren't familliar with this, it's a nationwide autocross series. The format is a little different - we have standing starts on a dragstrip tree, and two cars race side by side on mirror image courses - but the important parts are that first, it's a SERIES - you have to do well over the entire season; one race just won't cut it. Secondly, there were some big names racing against me - this was no cakewalk.

And then two days later, in the same car, on the same tires, on the same surface, we ran the amatuer National Championship race, and the car handled like utter crap. Spun out from under me twice, results way down the run order. Champion to back marker in 48 hours.

That can be a little hard on the ol' ego... I had no freakin' clue as to why that happened. I was utterly at sea.

Luckily for me, Carroll Smith happened to be attending that race, as a guest of the SCCA. I went to his Q&A session, and then I cornered him at the event and pumped him for information. And to make a long story slightly shorter, he made it very clear that as long as I was operating in the dark about not just vehicle dynamics, but also the state of my own setup, this was going to keep happening over and over. If I wanted to go fast CONSISTANTLY, I was going to have to do my homework.

So I did. The car was completely measured from top to bottom. Shocks were dynoed. Springs were rate-checked. I bought some suspension modelling software (recommended by Mr Smith) and completely modeled the suspension - giving me roll centre heights, camber compensation curves, you name it. And some stuff started to become clear.

And a whole lot more was still as confusing as ever - so I spent some serious coin, and attended a racing vehicle dynamic course, taught by a former F1 lead engineer. A whole lot more became clear - and part of that was that my current efforts still weren't going to be good enough. So I expanded my data logging efforts, adding suspension position information (which can be played back through the modelling software for some real suprises)

One of the things that became obvious was that the shock setup ShockTek had provided was good in some areas (the coaxial spring mounts were absolutely essential) but way off in others (damping forces 2X critical in bump, 3X critical in rebound) By this time, I had figured out how to convert a ShockTek into a Bilstein (ShockTek was using a mix of Bilstein parts and home-grown parts in his setup) I was building my own shocks, buying time on a shock dyno, designing my own parts, doing everything Dr Mike had done but based on actual racing dynamics theory and and actual racing experience.

When the data said I should build a set of shocks that should do X, I built shocks that did X, and then RACED ON THEM MYSELF - and they worked. When the data came back and said they might be better if they did Y, I twaked them to Y - and they worked. When the data suggested I run way WAY more front spring than ANYBODY thought was sane, and less rear spring than anybody thought was optimal, I did so - and the car got faster. WAY faster.

Fast enough that I can still keep up. Pro-level Street Modified has gotten tougher and tougher, and I'm still keeping up and winning races.

So then, part of my schtik has always been to give back to the DSM community. All you have to do is read the Talon Digest archives to see that, or even go to http://farnorthracing.com and look! There's my whole setup for anybody to copy if they want. My instructor on that vehicle dynamics course had a catchphrase "Knowledge shared is knowledge squared" and he's absolutely right. When you give back, you get back, and I've always done that.

So now I've got a pretty good setup, and more importantly, I know how to DERIVE that setup from scratch for any vehicle, so that the work can be dulplicated and verified. I helped a couple of friends do tha for their cars (Mustangs, as it happens) and THEY went faster too.

Out of all this, some things became very obvious. One is that coaxial spring hats are absolutely essential - springs cannot tolerate any amount of bending while compressed. That was the improvement that came from the ShockTeks. Another was that shocks are not interchangeable - EVERY SHOCK IS DIFFERENT, and so every single shock must be dynoed and characterized. Another was that the Konis are not all that bad as a shock, and in fact are pretty good if you do the right things and understand a few important facts.

Anyway, I tried working with a bunch of different people to bring this stuff to market. It's one thing to have all this knowledge and experience; it's another to help people actually get the stuff - but nobody was interested. Everybody is so set in their ways.. So when I left Chrysler and started working as a racing engineer for a ProSolo team, I managed to convince them to let me spend a little time developing a DSM suspension system that incorporated all the stuff that I have learned over 8 years of racing DSMs at the highest levels. If I dion't do it, nobody would.

That's how I'm giving back. Finally you'll be able to go to one place and get a good DSM setup, without all the problems that everybody has. How many times have you read IT'S SO BOUNCY HELPP!!!! on this forum?

I had to fight like hell to let them let me do this. They expect to make no money on it. If sales are good, maybe I can do more... but that's beside the point. My motivation is to have on the market a good, trustworthy setup, and to have ALL the reasons WHY this is a good setup completely documented. For example, when conventional wisdom as expressed by "wisemen" says that Konis don't cut the mustard, I posted the dyno data curves that show otherwise. You don't have to take my word for anything, even though I am the most experienced and most successful DSM autocrosser ever, because I'll back up every claim with data and third-party citiations. I've done my homework, and you get to check it if you want. And if you have technical questions, I'll answer them - as long as you're not trolling.

I'm trying to play nice with the site vendor policy, really I am. But I'm also trying to do what I always do, help and give back - it's just that now I work for the company that is providing the solution.

I'll answer any technical questions anybody has. Pricing information I cannot and will not answer here - that'll have to go on the company website, or on forums that are a little less strict about "vendor policy" I'm also on the dsm-autox Yahoo group.

DG

Learn: http://autocross.dsm.org/books.html

 

[jtmcinder]

My instructor on that vehicle dynamics course had a catchphrase "Knowledge shared is knowledge squared" and he's absolutely right. When you give back, you get back, and I've always done that.

Dennis -

This is something that we agree on 100% and I think that we should use it to move beyond our current situation. I have a very easy-to-use spreadsheet for calculating roll stiffness, weight transfer, and all those other useful things that can help everyone to really understand what they are doing. I also have many of the required input values, but only those that are relatively easy to measure. Fortunately, you have the more complicated values.

So here's my proposal: I will make my spreadsheet available to everyone while you will provide the correct values for the few things that I cannot measure without taking the car apart. This way, from now on, when you say something like "the model told me to run springrates that everyone else said was insane," everyone can plug in the values (as I have) and discover that, yes, indeed, those crazy springrates that you run do produce a weight transfer ratio that closely matches the static weight ratio.

What do you say?

- Jtoby

 

[Crawford]

I've been watching the other thread (and the more interesting parts) develop too.

In any event a quick look at the DG-FNR site shows the rates are 900lbs/in front and 450lbs/in rear. look in the car section not the tech section.

 

[jtmcinder]

Please, for a variety of reasons, (re-)read this thread to the end:

http://dsmtuners.com/forums/showthread.php?t=161603&highlight=900/400

- Jtoby

 

[Crawford]

Jtoby I read your link (and quite a few others of the ongoing jtmcinder/DG-FNR battles - which despite the....shall we say hostility?..... are some of the most informative threads I've read here). First read through your post in this thread and it looked like you didn't know them rates (which i incorrectly posted at 900/450 to boot ha ha) I now see there's a bit more of a deal going on with you two.

 

[Revolution]

I personally think both DG-FNR and jtmcinder are very knowledgable when it comes down to a suspension sytem let alone everything else that comes with anylizing the dynamics of a system to a specific car.

I agree that some times certain posts might look a bit ackward but to be honest the only reason I ever look into a suspension thread is because I notice one of their posts.

Aside from what I just posted lets keep this thread on topic not on polotics.

 

[DG-FNR]

OK, I've just finished the fitment of the prototype kits.

It turns out that there is NO suspension travel improvement between a flat-hat and a coax hat. With the front suspension fully compressed to the point that the upper control arm contacted the upper fender well, there's still over an inch of shock travel left with the coax hat.

That's worth repeating - you lose NO suspension travel with a coax upper spring hat. In fact, I was able to nudge the shock rod down a little more to gain a little more hood clearence

I also took measurements as to exactly how much misalignment there is between the centreline of the shock rod and the upper mount surface plane. You get about 3-5 degrees in the the Y axis and 1-7 degrees in the X. At NO point is the shock rod EVER square to the upper mount plate. This picture

http://www.accuratetechnologies.com/performance/Portals/2/why_coax.jpg

Is actually pretty much representative of how bad things can get. The suspension can indeed get there during normal operation.

I took pictures to prove it; they'll be posted sometime.

I also now have the locations for the coilover snap ring grooves specced out. I just have to update the drawings with a few little changes to correct some minor fitment issues here and there, and then I can get on to speccing out spring rates.

It would be helpful if I had some corner weights from some 2G DSMs that weren't full-on Championship-winning autox cars. If you've got a stock or nearly so car, and you've got corner weights (taken with real race scales) could you please post them?

DG

Learn: http://autocross.dsm.org/books.html

 

[jtmcinder]

While I hesitate to write this (since I really would like the war to end and for us to cooperate by sharing spreadsheets and raw data), I have to point out that the angle in your picture is about 20 degrees, so - as I said before - it exagerates the issue. The values that I found when testing this are smaller than yours, but that's probably because I only checked the range that seems to be used when racing.

To make up for the above, my corner-weights are 934/905 front and 608/621 rear when set up for autocrossing. Yes, I'm aware that I drive a pig, but she's cute.

- Jtoby

 

[jtmcinder]

It turns out that there is NO suspension travel improvement between a flat-hat and a coax hat. With the front suspension fully compressed to the point that the upper control arm contacted the upper fender well, there's still over an inch of shock travel left with the coax hat.

That's worth repeating - you lose NO suspension travel with a coax upper spring hat. In fact, I was able to nudge the shock rod down a little more to gain a little more hood clearence

Very cool, but by how much did you nudge it down afterwards? This is very important since it plays a huge role in determining what sort of bumpstop to use. Clearly, with less that an inch of travel, you can't use a stock bumpstop. So your plan to use Koni bumpstops makes a lot of sense. But maybe even these won't be right for people running relatively low front springrates on a lowered car. You might want to try the JIC bumpstops, instead. Or something longer but softer, so it's much more progressive.

- Jtoby

 

[ACM]

I'm not sure that's accurate JT

If one is concerned enough to run bumpstops they would need to be fully compressed by this point, and so to exhibit any progressivity(?) the bumpstops would have to have engaged at least .5" earlier, if not a full inch. Based on that there would appear to be more than enough space to fit a progressive bumpstop? The bumpstop needs to have stopped the wheel motion before the A-arm contacts the inner fender, otherwise there's not a lot of point fitting the bumpstop.

If someone is running low spring rates and a low ride height I'd have to assume they're more concerned about pulling hotties than lateral Gs ?

Charles

 

[jtmcinder]

Based on that there would appear to be more than enough space to fit a progressive bumpstop?

Maybe I wasn't being clear, but that was what I was saying. The secondary issue in the back of my head, however, was how soon did you want the bumpstop to begin to have an effect and how steep did you want the curve to be. I don't like bumpstops that come on at the last moment and suddenly stop the movement. It's extremely hard to drive a car that is set up this way unless you are incredibly good at knowing where your wheels are at all times. I would much rather a bumpstop that started sooner and gave some warning.

Keep in mind that I run springrates much lower than yours and have gone back and forth between riding the bumpstops (for camber) and not (for grip).

- Jtoby

 

[ACM]

Maybe I wasn't being clear, but that was what I was saying. The secondary issue in the back of my head, however, was how soon did you want the bumpstop to begin to have an effect and how steep did you want the curve to be. I don't like bumpstops that come on at the last moment and suddenly stop the movement. It's extremely hard to drive a car that is set up this way unless you are incredibly good at knowing where your wheels are at all times. I would much rather a bumpstop that started sooner and gave some warning.

Keep in mind that I run springrates much lower than yours and have gone back and forth between riding the bumpstops (for camber) and not (for grip).

- Jtoby

Perhaps I didn't understand your comment ? I thought you were concerned there was insufficient space available.

If there is "over an inch" of damper shaft remaining when the A-arm contacts the inner fender that's more than enough for a fully compressed, nicely progressive bumpstop. I don't think there will be any issue fitting a suitable bumpstop in there - in fact I'm betting there's enough space available to try all manner of progressive bumpstops to see what feels best.

As you note, I don't run bumpstops at all, it's extremely unlikely my car would ever bottom out. Well, unless you dropped it from a height, say like pushing it off a trailer...

Charles

 

[jtmcinder]

One the coolest, gentle-curved bumpstops that I've seen was about three inches long and had funky air pockets and cross-bridges. To compress the first whole inch required less than 50#. Another half inch required 75# more and the next half inch was around 200# more. A slammed 2G on softish springs could do worse.

- Jtoby

 

[ACM]

One the coolest, gentle-curved bumpstops that I've seen was about three inches long and had funky air pockets and cross-bridges. To compress the first whole inch required less than 50#. Another half inch required 75# more and the next half inch was around 200# more. A slammed 2G on softish springs could do worse.

- Jtoby

That should be about right then ?
"Over an inch" should translate to close to perfect for the above purposes.

BTW - I have out to tender the measurement of my car's suspension geometry. Assuming I can afford the bid, you're welcome to the data I receive (although donations would be more than welcome I am a firm believer in sharing data, though I'm not so sure I follow Fedja as far as sharing _expensive_ data !!

Oh, I also have out to tender adjustable anti roll bars; should anybody want copies I'll gladly assist. These will be hollow, and +/- the RM specs

Charles

 

[jtmcinder]

Yes, I'd be willing to chip in to get accurate suspension data. I'm willing to do quite a bit to get data out in the open where we can all play with it.

As to the sway bars, if the center setting is equal to RM bars, that would be very cool. I'd love to be able to adjust up and down for course conditions and design. If you need any information on the RM bars, just ask. Memory says the angular stiffness was around 110, linear rate around 50, and a roll resistance of about 3200. But I can check this tomorrow, if you wish.

- Jtoby

 

[aves911]

I'd chip in as well. How much of a "donation" are you looking for?


-Jacob

 

[ACM]

As far as donations are concerned it all depends how much I have to pay ! I have absolutely no idea how long such a task will take. I know of only 2 places locally that I'm confident are capable of measuring everything as accurately as I require, and neither are cheap.

My intent with the a/r bars is exactly that, RM will be approximately centre.

Charles

 

[DG-FNR]

There's no need for donations. I'm putting together a stripped-down spreadsheet that'll be posted on autocross.dsm.org once I've finished organizing it.

I say "stripped down" because the version I've been using for the last few years has every single shock valving iteration in it, plus tons of other stuff that's there for my own amusement, but really isn't all that important in the greater picture. I live with the thing, I know how to navigate it.

Mind you, if anybody really WANTS to make a donation, I won't say no.

Yes, I'd be willing to chip in to get accurate suspension data. I'm willing to do quite a bit to get data out in the open where we can all play with it.

Oh, really?

DG

Learn: http://autocross.dsm.org/books.html

 

[ACM]

That's a very generous offer DG, I really appreciate it, and I'm sure anybody else who cares about turning corners in a 2G will join me in that sentiment.

Measuring up a street car is possibly the most frustrating task I've attempted in recent memory. I doubt I was even within +/- 1/4" accuracy, and aside from building ludicrously complex jigs, I don't know how I could get closer than that - it drove me up the wall.

Charles

 

[DG-FNR]

Measuring up a street car is possibly the most frustrating task I've attempted in recent memory. I doubt I was even within +/- 1/4" accuracy, and aside from building ludicrously complex jigs, I don't know how I could get closer than that - it drove me up the wall.

There are some tricks involved that can make your life a little simpler.

One is to use software that expects its data in a reasonable reference frame. Mitchell's WinGeo's data entry screen is based around an easier measuring system, where the reference axis are in a convienient place froma measuring standpoint.

The other is to use a self-levelling laser plumb bob. Way faster than a "real" bob, and it opens up some tricks.

Digital calipers are nice too, and cheap. I also use some homemade telescoping gauges and a height finder to get the Z axis.

Dummy shocks are useful too.

Finally, I now have access to a digital CMM arm.

DG

 

[jtmcinder]

Oh, really?

Yes, really. That's what I meant earlier in this thread and in the other thread to which I linked. It is also what I meant in my private email and it was the reason for my search of the STU archives.

Admittedly, having good numbers to work with is more than half of my goal, so I will appreciate whatever you post on the other list, but it is not all of what I'd like from this.

- Jtoby

 

[Ludachris]

Just so everyone knows why the first thread about this topic was removed:

Our vendor policy clearly states that any person who sells a product that our member base might be interested in is not to promote that product in our forums. Product updates, availability, pricing and other information that is seen as marketing or promotional must be posted ONLY in our Vendor Announcement forum. Dennis has been given instructions on how to get access to post in that forum.

If you'd like to ask Dennis technical questions about suspension that does not entail availablity, pricing, and any other info about his product that would be seen as promotional by our moderating team, please do so publicly - all other info can be requested privately. We have sponsors/partners who have contributed to the operating costs of this site and they are the only vendors allowed to promote their products on our site (in the Vendor forum ONLY). If we see that this thread starts to resemble the thread that was removed, this one will share the same fate. No more product updates please - those belong in the Vendor forum.

We would like to believe that Dennis is here to share his technical experience and educate our members about suspension technology, not to help educate members about the product he's selling. We, like other sites that have forums, tend to get plenty of vendors looking for ways to advertise their products for free. We'd like to think Dennis is not here for the sole purpose of spreading the word about his product.