Bump steer correction
Bump steer correction
Has anyone attempted to correct bump steer on their car? I've noticed that my SC4 suffers from this a bit with the new suspension. I'm sure the 245 width front tires on 8.5" rims are also promoting the cars desire to wander. Would the Daizen camber kit I have installed on the upper control arms (set at full 2 degrees) be the culprit, throwing the tie rod out of the new arc created by the upper and lower control arms? Can the factory tie rods be adjusted to work within this new arc? If not, are the JIC hard tie rods designed to allow greater bump steer adjustment? Anyone have any experience adjusting this?
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Joined: Apr 2003
Posts: 672
Likes: 2
From: South Carolina
I believe bumpsteer is the steerings tendency to wander left and right with changes in the vertical geometry of the steering. Translation, when you hit bumps, the car tends to steer a little crazy. Anyone feel free to correct me if I'm wrong
Yes, bump steer refers to the effect of bumps and grooves in the road surface essentially steering the car without your input. It causes the car to wander, and is a rather nervous feeling. Here's a link which explains the geometry between the upper and lower control arms, and tie rods; and how they impact bump steer:
http://www.rebcoperformance.com/arti...rt.asp?ARTID=6
Other causes for wandering are worn power steering rack bushings allowing the entire rack to shift , as well as wider tires. Wider rubber gives you better traction, but also works the other way for those imperfections in the road trying to steer your car for you. 4x4 trucks often experience wandering when oversized tires are installed. A steering stabilizer usually helps this (essentially a horizontally mounted shock absorber for your power steering system.)
I only really notice this affect under hard braking on uneven roads. So, you have the bumps in the road as well as nose-dive under braking causing the front suspension to compress. I'm assuming that since the Daizen camber adjusters installed in the front upper control arms, in essence, lengthen the arms; the new geometry created between the upper and lower arms is not perfectly compliant in relationship to the tie rod. After all of the suspension components were installed, the car was aligned and the toe angle was adjusted. However, that was while the car was at rest. I'm thinking that as the suspension compresses, the tie rod begins to stray outside of the proper arc and the toe angle is increasing to an inappropriate level. If you have too much toe-out, the car will have a greater tendency to wander. I know that the Stillen adjustable tie rods for Nissans are supposed to cure this, however, I haven't been able to find an answer as to whether the JIC hard tie rods for the Supra and SC do as well. HorsepowerFreaks has them in stock and on clearance, so I'm going to go ahead and order them tomorrow.
p.s. To those of you who I've responded with about the Do-Luck rear cross bar for the Supra, HPFreaks has them in stock and on sale, so I'm ordering one of those as well. I'll post on that thread about fitment on the SC and impressions once it arrives.
http://www.rebcoperformance.com/arti...rt.asp?ARTID=6
Other causes for wandering are worn power steering rack bushings allowing the entire rack to shift , as well as wider tires. Wider rubber gives you better traction, but also works the other way for those imperfections in the road trying to steer your car for you. 4x4 trucks often experience wandering when oversized tires are installed. A steering stabilizer usually helps this (essentially a horizontally mounted shock absorber for your power steering system.)
I only really notice this affect under hard braking on uneven roads. So, you have the bumps in the road as well as nose-dive under braking causing the front suspension to compress. I'm assuming that since the Daizen camber adjusters installed in the front upper control arms, in essence, lengthen the arms; the new geometry created between the upper and lower arms is not perfectly compliant in relationship to the tie rod. After all of the suspension components were installed, the car was aligned and the toe angle was adjusted. However, that was while the car was at rest. I'm thinking that as the suspension compresses, the tie rod begins to stray outside of the proper arc and the toe angle is increasing to an inappropriate level. If you have too much toe-out, the car will have a greater tendency to wander. I know that the Stillen adjustable tie rods for Nissans are supposed to cure this, however, I haven't been able to find an answer as to whether the JIC hard tie rods for the Supra and SC do as well. HorsepowerFreaks has them in stock and on clearance, so I'm going to go ahead and order them tomorrow.
p.s. To those of you who I've responded with about the Do-Luck rear cross bar for the Supra, HPFreaks has them in stock and on sale, so I'm ordering one of those as well. I'll post on that thread about fitment on the SC and impressions once it arrives.
Last edited by P.Williams; Jun 24, 2004 at 11:17 PM.
Instructor
Joined: Jun 2001
Posts: 1,135
Likes: 1
From: Seattle
I've actually pitched the car out of shape at speed from this; good thing the car handles as good as it does.
I've played with the toe settings to try and help, but not much improvement, I have 245/45-17 on 8" rims on the front,.
I was hoping to get my Supra brakes installed and see if that helps, adding four piston calipers helped on another car I had that suffered from the same problem.
I've played with the toe settings to try and help, but not much improvement, I have 245/45-17 on 8" rims on the front,.
I was hoping to get my Supra brakes installed and see if that helps, adding four piston calipers helped on another car I had that suffered from the same problem.
Instructor
Joined: Jun 2001
Posts: 1,135
Likes: 1
From: Seattle
I've actually pitched the car out of shape at speed from this; good thing the car handles as good as it does.
I've played with the toe settings to try and help, but not much improvement, I have 245/45-17 on 8" rims on the front,.
I was hoping to get my Supra brakes installed and see if that helps, adding four piston calipers helped on another car I had that suffered from the same problem.
Maybe just bleeding the old, nasty brake fluid out from the calipers where it gets fried from the heat/moisture would help too.
I've played with the toe settings to try and help, but not much improvement, I have 245/45-17 on 8" rims on the front,.
I was hoping to get my Supra brakes installed and see if that helps, adding four piston calipers helped on another car I had that suffered from the same problem.
Maybe just bleeding the old, nasty brake fluid out from the calipers where it gets fried from the heat/moisture would help too.
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