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"Bump steer is an undesirable condition where the wheels of a vehicle steer themselves in response to bumps in the road, without any input from the driver. It occurs when the suspension geometry interacts with the steering linkage, causing the wheels to change toe (the angle of the tires relative to each other) as the suspension compresses and extends. This can result in the steering wheel changing direction unexpectedly, making the car feel unstable or darting on uneven surfaces."
How does one resolve this issue? Buy dampers that are adjustable on the rebound side?
I have this same problem/question. I'm hoping switching from Kumho PS91 to Continential DWS06 will help some.
Diff bushings and front/rear power bars (bracing) made a noticeable difference for me. These upgrades combined with lowering, spacing, coupe alignment specs and mad sticky tires makes my car feel very neutral, and I am trying to find body roll and cannot detect any.
The one think I do notice is when I am driving around 70mphish on flat, yet uneven road, there are times when the rebound feels like it wants to pull me in another direction like the toe is changing. I think this is referred to as "Bump Steer"
AI provided description:
"Bump steer is an undesirable condition where the wheels of a vehicle steer themselves in response to bumps in the road, without any input from the driver. It occurs when the suspension geometry interacts with the steering linkage, causing the wheels to change toe (the angle of the tires relative to each other) as the suspension compresses and extends. This can result in the steering wheel changing direction unexpectedly, making the car feel unstable or darting on uneven surfaces."
How does one resolve this issue? Buy dampers that are adjustable on the rebound side?
There are several companies out there that sell bump-steer "correction kits" for our cars. Some of these kits are quite expensive and go as far as relocate the steering rack and even allow you to change/adjust the ackermann steering angle/geometry. When I had this same issue years and years ago I just went the simple route and used SPL's tie-rod ends that are designed to help reduce bump-steer by "relocating" the tie-rod connection point to the steering knuckle using spacers. The kit comes with several different size spacers so it took a little bit of work getting everything dialed in, but overall these virtually eliminated the bump-steer for me. Ideally, if you try to do this yourself you should have the proper equipment to readjust the front toe yourself, or at least to be able to get it close before taking it in for a proper alignment once you find the ideal set-up.
The last pages of sections FSU and RSU of the OEM FSM provide alignment specs. Just go to NICOClub, navigate to your year/ type car and download away.
Are you saying you do not have a copy of the OEM FSM for these cars?
I don't. Those links don't work for me. Maybe I'm just a rock.
Last edited by socketz67; Jul 17, 2025 at 09:39 AM.
I don’t. Those links don’t work for me. Maybe I’m just a rock.
That's odd. Granted those links have a history of "going down" they usually get back up in decent time. I have more copies downloaded on more devices than I can count.
You do know you have to open each section first then click the "download a copy" button?
That's odd. Granted those links have a history of "going down" they usually get back up in decent time. I have more copies downloaded on more devices than I can count.
You do know you have to open each section first then click the "download a copy" button?
Bring up each individual PDF in your browser, then use the "download" control to save the PDF locally. It might take you a few minutes to collect all the sections, but once you do you have it and you're done.
Best to "open link in new tab", because clicking "back" in your browser will reset the page back to the top, and you'll have to go through the selection process all over again.
There are several companies out there that sell bump-steer "correction kits" for our cars. Some of these kits are quite expensive and go as far as relocate the steering rack and even allow you to change/adjust the ackermann steering angle/geometry. When I had this same issue years and years ago I just went the simple route and used SPL's tie-rod ends that are designed to help reduce bump-steer by "relocating" the tie-rod connection point to the steering knuckle using spacers. The kit comes with several different size spacers so it took a little bit of work getting everything dialed in, but overall these virtually eliminated the bump-steer for me. Ideally, if you try to do this yourself you should have the proper equipment to readjust the front toe yourself, or at least to be able to get it close before taking it in for a proper alignment once you find the ideal set-up.
This is gold @2GoRNot2G. Are these straightforward to install, connecting between the steering knuckle and inner tie rod ? Which spacer did you end up using?
I've read about the "correction kits", but those seemed a bit extreme for a daily driver. Had no idea there was a simpler solution.
In this trunk is a set of red Z1 big brakes and rotors, oem dust shields, oem hubs, 10mm Z1 spacers, GTR brake fluid, new axel bolts, washers etc and new wheel hub bolts.
This is the second to last project for this car. I truly don’t want to add up how much I’ve spent on this car to get it where I want it and where I think it deserves to be. With only 62k miles on it, I’d like for it to last me to 160k so I can feel as though I’ve gotten my money out of it. If it craos out before then, this will be the first big mistake I’ve ever made with a used car…
Trusted shop to do the work + I put the torque specs from the factory manuals on every bolt bc you can’t even trust a trusted shop😁, although these guys have been very good with everything else so far.
Last project is to replace all of the weatherstripping and chrome around the windows, chrome will get professionally painted black (thank god for Amayama for these parts/prices). The previous owner clearly had the drivers side of the car facing the sun because the window weather stripping is in bad shape/disintegrating. Doing the whole nine yards, even the weatherseals for the doors themselves.
Coupe camber specs are slightly more aggressive (.5 degree or so) than the sedan. With toe zeroed out, tire wear is minimal.[/
Just checked my alignment specs and was pretty surprised to see my camber as negative as it is (although I am admittedly not an alignment expert). What do you guys think of these after specs? Do we have stock front camber adjustment? Should I not be this negative?These are the specs after getting my new steering rack and NVA tie rods installed. At least it is all green…
This is the second to last project for this car. I truly don’t want to add up how much I’ve spent on this car to get it where I want it and where I think it deserves to be. With only 62k miles on it, I’d like for it to last me to 160k so I can feel as though I’ve gotten my money out of it. If
I feel you on the “gotta get my miles worth out of these mods” sentiment.
Although I’ve invested in mods at a glacial pace. Scooped my car at 35 miles, now at 56k miles (12ish years later). Now just getting to figuring out what to do suspension-wise.
Once I had the revelation that I’d own this car for a long time, my frame shifted to “upgrade things as they show sign of wear.”
We’ve all got our own approaches, schedules, grand plans, etc
This is gold @2GoRNot2G. Are these straightforward to install, connecting between the steering knuckle and inner tie rod ? Which spacer did you end up using?
I've read about the "correction kits", but those seemed a bit extreme for a daily driver. Had no idea there was a simpler solution.
Yes, that's exactly where these get installed. Other than getting the alignment corrected afterwards, it's a very straight forward installation process. I installed these so many years ago that I can't remember which spacer I ended up with. I know I there are probably still some old posts on here of all of my suspension work, but the below picture that I just took might help (looks like its probably the largest spacer, but not multiple spacers). Your ultimate goal is to try and keep the tie-rods as parallel to the control arms as possible to try an eliminate any arc that will cause bump steer as the suspension moves.
I also just realized that I'm actually using SPL's "Titanium Series" Tie Rod Ends, which have a slight dogleg in them to make sure they clear the wheel when turned at full lock when used with wider wheels and tires.
Yes, that's exactly where these get installed. Other than getting the alignment corrected afterwards, it's a very straight forward installation process. I installed these so many years ago that I can't remember which spacer I ended up with. I know I there are probably still some old posts on here of all of my suspension work, but the below picture that I just took might help (looks like its probably the largest spacer, but not multiple spacers). Your ultimate goal is to try and keep the tie-rods as parallel to the control arms as possible to try an eliminate any arc that will cause bump steer as the suspension moves.
I also just realized that I'm actually using SPL's "Titanium Series" Tie Rod Ends, which have a slight dogleg in them to make sure they clear the wheel when turned at full lock when used with wider wheels and tires.
I called SPL this morning and they confirmed that you only need the Titanium series ($400ish) if running much larger wheels and tires. For folks like me, the standard Z34 series ($269ish) works fine: https://conceptzperformance.com/spl-...09_p_20516.php
They also reiterated that the goal of the spacers are to make sure the tie rods remain parallel to the lower control arms. I sort of see that in the pic you posted. I am amazed that so few have made this change as a majority of our members are lowered and the bump steer has to be noticeable. In all fairness, I just figured out what this is myself reading posts on the Bimmer forum. The problem is unless you know the technical name, googling the problem produces all sorts of unrelated results.
Last edited by socketz67; Jun 4, 2025 at 02:51 PM.
Is this a DIY project, or do you have a shop you trust for the work?
