wheelhopper Posted December 2, 2012 Share Posted December 2, 2012 I am running a 1990 GT that I installed an IRS into for my track fun. When I installed the IRS it instilled some extreme oversteer. To counteract this I installed the Steeda HD front sway bar, the stiffest I could find. Which is still only 15% stiffer than the stock one. It worked pretty well. In hindsight I am wondering if it would have been simpler to remove the rear sway bar instead. Has anyone here done this with any success? Currently I am trying to reduce some weight on the car so I have ordered the Steeda light weight tubular sway bar, which is softer than stock, and am planning to remove the rear. I am hoping that the car will remain balanced, maybe a bit improved, while losing about 25lbs. Maybe this will unclutter the rear a bit also. and make servicing the IRS easier with less parts in the way. Any feedback with those who have some IRS experience is appreciated. Quote Link to comment Share on other sites More sharing options...
Dizmm Posted December 2, 2012 Share Posted December 2, 2012 I'm not a mustang pro but didnt i hear rear bump steer as a common issue the should be addressed with IRS? Quote Link to comment Share on other sites More sharing options...
UBR Posted December 2, 2012 Share Posted December 2, 2012 I run a 90 Mustang in AI. It does not have the IRS rear suspension, but it is/was an over steering beast. I prefer a loose car, but this was ridiculous when we bought it. Some basics, if you are running a rear sway bar, disconnect it and see how it behaves. I also suspect you may be running too hard of springs on the rear, or at least too hard compared to the fronts. Also, shocks can go a long way to helping tame the rear end. Get some good double adjustables and learn how to set them. Our car came with a Griggs torque arm rear setup. It was never right and we took it off and put a custom 3-link setup on the car. I know people are running the Griggs setup and doing well. Ours was never right. The 3 link is simple and cheap. It has allowed us to go harder on the rear springs and I now run an adjustable Maximum Motorsports rear sway bar to balance everything. The car rarely pushes now, but is very drivably loose. I like it that way and could probably make it push if I unhooked the rear bar. j Quote Link to comment Share on other sites More sharing options...
Mystic_Cobra Posted December 2, 2012 Share Posted December 2, 2012 Have any of the IRS upgrades been done? Call Maximum Motorsports. They have a bunch of parts for it and great tech support. http://www.maximummotorsports.com/store/index.php?main_page=index&cPath=514_88 Quote Link to comment Share on other sites More sharing options...
snakebit Posted December 2, 2012 Share Posted December 2, 2012 I have an IRS in my 2000 GT. After the stock 4 link came out, I installed a torque arm/watts link which worked very well. I put the iRS in last year and its the best thing yet (in my opinion) for our cars. It puts weight right where you need it, and the grip on corner exit is amazing...but I had to re-learn the car. But setup is critical, if the bump steer or toe is out, the car can be un-drivable. PM me a list of mods on your car (springs, shocks, other suspension components etc.) and I'll see if I can offer some advice. John Quote Link to comment Share on other sites More sharing options...
DHarsay Posted December 3, 2012 Share Posted December 3, 2012 I removed the rear sway bar from the IRS in the process of tuning the suspension to my liking. Currently have 400# CO's in front with 550# CO in the back... but there are a lot of factors to consider. Just don't throw it away like I did, now I wish I had it for a stickier tire combination. Quote Link to comment Share on other sites More sharing options...
wheelhopper Posted December 5, 2012 Author Share Posted December 5, 2012 Glad to find some other IRS users out there. I have been on several forums and not had a lot of success with info. My car handles well, so I am not really trying to fix anything, more of a moving forward effort. Other than coil overs there is not a lot left for me to do to the IRS. I went ahead and purchased a light weight Steeda front bar, while they had 20% off and free shipping. If I simply disconect an endlink on the rear sway bar will that essentially be the same as not having one? That way if my experiment with the front bar is way off I can simply install the endling and swap the front bar back on. John, I'll put my suspension list here, in case someone else has any advice. Front H&R Super Race springs SN95 control arms with Delrin bushings Koni DA struts Steeda HD sway bar w/ poly bushings and endlinks MM steering rack bushings MM Camber plates Rear H&R Race springs Bilstein HD shocks Delrin control arm bushings MM adj. endlinks MM HD toe links Poly diff. bushings Poly IRS mount bushings Quote Link to comment Share on other sites More sharing options...
Striker-7 Posted December 5, 2012 Share Posted December 5, 2012 If I simply disconect an endlink on the rear sway bar will that essentially be the same as not having one? That way if my experiment with the front bar is way off I can simply install the endling and swap the front bar back on. It's a very common technique for autocrossers that drive to the event. Disconnect one endlink, and as long as the bushings holding the bar are fairly free, the bar is effectively just dead weight. Quote Link to comment Share on other sites More sharing options...
D Algozine Posted December 5, 2012 Share Posted December 5, 2012 If I simply disconect an endlink on the rear sway bar will that essentially be the same as not having one? That way if my experiment with the front bar is way off I can simply install the endling and swap the front bar back on. It's a very common technique for autocrossers that drive to the event. Disconnect one endlink, and as long as the bushings holding the bar are fairly free, the bar is effectively just dead weight. Be sure the sway bar doesn't rub against the half shaft when disconnected. And..........Rear Bump steer and toe are very critical. My advice Bump steer as close to zero as possible, if not zero, then slight toe in during compression Toe - 1/8" total toe in Quote Link to comment Share on other sites More sharing options...
snakebit Posted December 6, 2012 Share Posted December 6, 2012 The first thing that I see is that you're probably over-sprung and under-dampened in the rear. The springs that you listed provide about the same wheel rate front and rear. It's been my experience that our chassis w/IRS like a rear wheel rate about 70-75% of what you run in the front. You might be ok going with the H&R super sport rear spring (about 10% softer), with the rear shock that you have....otherwise you're doing all that you can do with sway bar tuning. Next step would be coilovers ...and yes, zero bumpsteer in both compression and rebound. I also run 1/8" total toe in, and 1 1/2 negative camber. John Quote Link to comment Share on other sites More sharing options...
99cobra2881 Posted December 6, 2012 Share Posted December 6, 2012 Does the IRS allow the outside wheel/tire to roll over that much like the front end does during cornering? Quote Link to comment Share on other sites More sharing options...
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