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1G DSM front k-member and tubular control arms

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C'mon man you came too far to give up on this!
I've sent you an email and a pm with no response, I'm dying for an update, good bad or indifferent don't leave us hanging...
 
I am completely supportive of these K-Members and will be buying 2 when/if they actually come to life as a real product. I am a fan of the work that Vassil does, bought Cross members and mustache bars. His website has pics of progress he has made so far, but hasn't been updated in awhile. I am guessing he is saturated with work since he does his fabrication in his spare time. I wish I had the fabrication ability and equipment to put this together myself. I like the idea of having greater adjustability.
 
his web site is down and he is not returning PM's, the project is complete until someone else tries to do it. People need to make parts for us, not to get rich but to expand the community. If the community is expanded then there will be money to be made down the road. Make parts because you enjoy it and the rest will work out.
 
He has been busy filling orders and making passes at the track well trying.

He made 859whp with a 6266 and went 10.06@15x with the car and issues came up, I'm hoping this off season this gets made, especially since he might want one now.
 
The project is not dead in the water as many may think. Life happens sometimes that put things on hold. They say patience is a virtue. I have been checking the site and looking for updates on this project in particular to see if there were and are any signs of life. I think that it just needs a shock with an automated external defibrillator (AED). Vassil puts out great fabbed products. Need to keep guys like him around in our community. Merry Christmas!
 
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After more than a year I am back in K-member mode. I got married and became a dad. Between my regular job as a Network Engineer, family, racing my car and constantly breaking it, making crossmembers & mustache bars, the k-member went on the back burner. I got some free time over the last couple of weeks and spent a bunch of time in the shop. Big thanks to Alex Westerholm for helping me jumpstart this project back up.

Here is the quick update:

1. The K-member itself got a major redesign. I did not like my initial design.
2. I changed the control arm mounting points for that they match the stock locations
3. Finally figured out a way to mount the rack and it works much better than last time
4. I got one made and mostly welded
5. Everything is made out of 1.25" 0.083 4130 Chromoly
6. Figured out a way to tie the 3-piece crossmember to the K-Member. Look at the red arrows on the forth picture
7. The weight savings are pretty significant. It weighs a hair over 16lbs.

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What I have left are the control arms. My old solutiuon was to use the the AFCO tie rold end instead of ball joints. They are the same ones that we use to make our rear control arms: AFCO Racing Tie Rod Ends 30211 - SummitRacing.com

It works and the taper fits the front hub, but I really want to use uniball/monoball cups with spherical bearings and a stud that matches the taper of our front hub. It is nicer, stronger and it will also allow for roll center changes. Like this:

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I have been looking all over and I found the tons of monoball cups and sperical bearings and studs. I have no idea what's the taper of our hubs and where to find one. Do you guys have any suggestions on that?

On the other hand, if I don't find one. I am thinking to cut up a factory ball joint and take it to a machine shop and have them machine a stud for me that will fit perfect and use a 1" spherical bearing from Aurora of FK and a matching cup and call it good.

What are your guys thoughts on the whole control arm situation? Any input is very welcome

--Vassil
 
I'd love to see it work with stock control arms, there's no significant weight to be saved there and it would keep the cost down. I'd also want to see it retain the sway bar. Great to see you're back into it though!
 
Yup, I'm back at it. Thanks for the comments. I'm sorry but I don't intend on making a K-Member that fits the factory control arms. They are actually very heavy. I don't have the numbers yet, but I will weigh them this week and let you guys know. Also they do not provide any adjustability.

I am planning on finishing up the motor mount and the crossmember tie-in this week and I'll post pics of the progress as I get them done.

Any thoughts on the spherical bearings?
 
Will the geometry be the same as the factory in terms of movement of the control arms? My only concern with changing it from the stock design is that you'd be in uncharted territory with the suspension design. It's one thing to add in adjustability and stiffen the bushings, but to change the motion and pivot points, I don't know. Vassil, how much work have you done on race car suspension design? That's really the main reason I've been pushing for a k-member that uses the stock control arm.

I really want to replace my front k-member and control arms with something lighter, stronger, and more adjustable (camber, caster, toe, and roll center adjustments). But since I'll be running this thing on a road course like Sears Point, I'd need to have complete confidence in the design. I like the idea of the spherical bearings to replace the ball joints, that will really help with roll center adjustment.
 
A threaded height adjuster on one of the control arm pickups would be nice for tuning anti-dive. Other than that, I'd just like to see the mounting points as high up as possible to minimize the necessary length of the outer balljoint stud. I have a set of 355x32mm rotors and they'll definitely be a tight fit.
 
So I got some more work done on the k-member tonight. It is now fully welded and the rear motor mount is finished also. The jig is almost 100% finalized. I might have to move the control arm mounting points a little bit, but I will figure this out over the weekend.

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The front mounting point of the control arm is at the stock location. The rear one is about 2-3 degrees outward. Here is a picture that show that:

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I plotted the a line going through the middle of the mounting points and intersected it at the center of the ball joint. Like this:

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This way, I stayed within the confines of the factory control arm. The actual pivot points on both locations are roughly .75in higher, but that was to compensate for the distance between the bottom of the hub where the ball joint slides in and top of the actual ball joint. There is about a 3/4" gap there stock and it won't be there with a spherical bearing unless a spacer is added. That way the control arm sits as close as possible to the factory level.

Now finally the control arm dilemma. The factory control arm weighs in at 9.4lbs and mine should weigh roughly 4.6. If I modified the jig and made the k-member fit the factory control arms, it will be heavier by about 9.6 lbs.

So here is the scoop:

Tubular K-Member + Tubular arms = 17.9 + 4.6 +4.6 = 27.1 lbs
Tubular K-Member + Stock arms = 17.9 + 9.4 + 9.4 = 36.7 lbs
Stock K-Member + Stock arms = 61 lbs

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One way we loose 34-35 lbs and the other way we loose 24-25 lbs. The million dollar question is: Are the 10lbs and lack of adjustability worth the cost savings? It will certainly be less headache for me once I redo the jig for the eleventeenth time.

I can also have new tabs laser cut that will have multiple mounting points so that the arm could be moved up and down a certain height, but I am not that savvy in vehicle suspension design. I am open to suggestions to make this a better product for everyone.

Lowell, can you elaborate on the threaded height adjuster or post some pictures of it? I am having a hard time imagining it.

What are your guy's thoughts on all this?
 
I would definitely offer this with the ability to utilize the factory control arms. With the cost savings you will cater to a bigger crowd thus selling more units for you.
 
If you could give an idea of the cost for both options, I think it would help people decide if it's worth it. Can you answer my previous question regarding whether it will retain the sway bar mounting points? Also, I believe the rear mount may be different for stick and auto cars, if so will you be making both versions? Last, will you be adding any support to the steering rack mounts? And will it work with both power and manual racks?
 
Steve, I have not messed around with the sway bar yet. I will see if there is a viable way to attach it without adding too much complexity. Currently the K-Member is provisioned to fit the manual rack. The power rack is huge in diameter compared to manual rack and it also has lines coming in and going out of it, which makes the top loop fabrication very challenging. I will address the power rack once the manual rack version is 100% complete.

As far as added cost for tubular control arms, you need to figure out the price of good spherical bearings like Aurora, uniball cups, c-clips, tube adapters and clevises and some PFTE (teflon lined) rod ends and a few feet of tubing, plus bending it. It all adds up in a hurry. I would guess easily 350-400 ish extra.
 
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If you haven't messed with the swaybar yet you're not making accurate weight difference calculations then. You weighed the factory control arm with the end link and compared it to a custom control arm with no swaybar attachment solution. That's not apples to apples. If your argument is that drag racers won't need it then you'd have to consider cutting off the steel mounting tab on the OEM control arm and toss the end link then weigh it... that might only shave a few pounds, but at least it would be more accurate. Some of us who want the k-member will be using it on road race cars so the swaybar is critical. If it's too difficult to to make swaybar provisions, I'd beg you to reconsider using factory control arms so us road racers can use this k-member too.
 
I would definitely offer this with the ability to utilize the factory control arms. With the cost savings you will cater to a bigger crowd thus selling more units for you.

This for sure. As stated by many before, the ~$400 savings will be huge for a high percentage of people. Plus factoring in the current uncertainty of the sway bar, I think you should strongly consider fabbing for stockers. offering the adjustable arms as an OPTION is key if you're going to have this be profitable for yourself.

aside from the above, kudos to you for jumping back on this project. my car is apart right now, and i have been prepping to build a jig but haven't had any time since the car is over an hour away from me and i've been working like a madman. PM incoming
 
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