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Adjustable Rear Control Arms?

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Does anyone have any experience with fitting adjustable rear control arms (top) on their 996s to solve the too negative rear camber problem and resulting inner rear tire wear on lowered C2s?

I just put on a new set of 285/30/18s on my stock 10Jx18 rear wheels on my 2003 C2 with M030 and H&R springs that lower it by 30mm after finding extreme inner tire wear. My alignment guy could not get the camber into spec (too negative) , but said that if I got a set of adjustable rear control arms (top) he could get it into spec and the uneven wear pattern would be reduced or eliminated. I know this effect is common on lowered 996s, and with the price of tires, I would like to solve this problem.

I found sets of these adjustable rear control arms (top) for ca. $350-550 and wondered if there is any collective knowledge on this forum of how well they work. Any problems with tire rubbing? (I tried a search, but did not find anything really relevant.)


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  • Admin

The negative camber is there for a reason - too help you corner flatter and faster.

Changing the rear camber outside of factory specs could have dangerous handling results - we urge to to be careful with any changes especially if you go outside the factory specs. It is set the way it is for YOUR safety.

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I guess I did not make myself very clear. I presently cannot get my car adjusted to the factory specs with the lowered suspension my car has. My query has to do with whether or not using adjustable rear control arms in place of the stock non-adjustable ones will enable me to get to the factory specs without any additional problems.


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  • 2 weeks later...

I solved the problem with adjustable rear toe control arms - and upper control arms. It's expensive but holds alignment even at very low ride heights (track only at 108mm). There are high quality vendors aout there making excellent parts. An easy install for a quality alignment shop (home install isn't bad, but you'll still need a full alignment). There are tons of threads on alignment specs. Loren is right, sa you go lower, be careful. Some unpleasant things can happen as you begin to mess with the factory specs, especially at high speeds (loss of straight line stability isn't fun). Make sure your alignment shop knows what they are doing. Good luck.

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Thanks for letting me know that this can be done. My 2003 C2 with factory US M030 has been lowered ca. 30mm by replacement of the original springs with a set of H&R sport springs. With this setup, the rear camber still is too negative at the best set point and there is excessive inner tread wear on the rear tires. I have replaced the upper control arms with a set of adjustable ones, but still have the original lower track control arms. I have a full alignment scheduled for tomorrow by an excellent indie shop. I hope they will be able to solve the alignment problems with this setup. I will report back after the alignment as this must be a common problem for anyone wishing to lower a 996 without using Bilstein PSSx or GT3 suspension part$.

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You could always go with a set of Pilot Sport Cups or something similar that will love all that extra camber!!! ;) Lowering the USA M030 ride height shouldn't put you beyond the adjustable upper control arms capability. I think lowering the USA M030 puts you at about the ROW M030 ride height which lots of folks have successfully done. You definitely won't need the adjustable lower control arms with that set up, something else is going on. My car is ridiculously low (don't ask about what my oil pan looks like). What camber are they able to get dialed in? Are you running factory wheels and tires? Spacers? Again, IMHO seems to be something we are missing. Did you go with adjustable drop links on the car when you lowered it? Perhpas something is binding? I guess it is woth asking, apart from the tire wear, does it handle OK?

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OK, time for an update on this subject. I got back from a morning session on the alignment machine. Too negative rear camber problem solved! Car handles beautifully! After installing a set of adjustable upper control arms on the rear, my indie suspension shop was able to attain the proper factory alignment specs. I hope this means that I will not see the excessive inner tread wear on the rear tires that I was experiencing before. As noted, these adjustable control arems are not cheap, ranging from ca. $1000 to $350. After investigating all of the sets I could, and finding that most of the differences are related to cosmetics rather than quality of materials, I opted for the least expensive set. Time will tell if this was a good choice, but everything seems a great improvement at the moment.

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