Bumpsteer Problems

[breeves002]

I read a few other threads but none of them really covered 100% what I'm wondering.

I'm having a lot of problems with bump steer on and off the track. Its really frustrating. Takes a lot of small steering corrections sometimes and it makes it difficult to handle on parts of the track. I've noticed it moves around a lot based on the way the car settles and weight transfers.

Here's the mods to the front end:
-Eibach sportline springs
-350R reps +45 offset 19x10
-25mm spacer
-stock everything else in the front end

I do my own alignments and the cross toe is within 0.05º. Camber is -1.8º on both sides. I have camber bolts I'll use during the winter but then I spun them around for more camber for the track. Not that it should matter but rear toe is .0 to .1 and rear camber -2.0º even.

Just trying to figure out what I need to do to fix this. Its really frustrating. I didn't seem to have much of a problem before I switched wheels and tires and added the camber back in. Previously I was running 255 pilot super sports on the stock pp front wheels with 25mm spacers.

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[BmacIL]

I read a few other threads but none of them really covered 100% what I'm wondering.

I'm having a lot of problems with bump steer on and off the track. Its really frustrating. Takes a lot of small steering corrections sometimes and it makes it difficult to handle on parts of the track. I've noticed it moves around a lot based on the way the car settles and weight transfers.

Here's the mods to the front end:
-Eibach sportline springs
-350R reps +45 offset 19x10
-25mm spacer
-stock everything else in the front end

I do my own alignments and the cross toe is within 0.05º. Camber is -1.8º on both sides. I have camber bolts I'll use during the winter but then I spun them around for more camber for the track. Not that it should matter but rear toe is .0 to .1 and rear camber -2.0º even.

Just trying to figure out what I need to do to fix this. Its really frustrating. I didn't seem to have much of a problem before I switched wheels and tires and added the camber back in. Previously I was running 255 pilot super sports on the stock pp front wheels with 25mm spacers.

First thing: use a 5 mm spacer instead of a 25 mm. Adding that big of a spacer increases your scrub radius significantly.

Second, your sportlines. The drop ruins the geometry. Stick under 1" drop. It improves many things.

 

[Roadway 5.0]

I read a few other threads but none of them really covered 100% what I'm wondering.

I'm having a lot of problems with bump steer on and off the track. Its really frustrating. Takes a lot of small steering corrections sometimes and it makes it difficult to handle on parts of the track. I've noticed it moves around a lot based on the way the car settles and weight transfers.

Here's the mods to the front end:
-Eibach sportline springs
-350R reps +45 offset 19x10
-25mm spacer
-stock everything else in the front end

I do my own alignments and the cross toe is within 0.05º. Camber is -1.8º on both sides. I have camber bolts I'll use during the winter but then I spun them around for more camber for the track. Not that it should matter but rear toe is .0 to .1 and rear camber -2.0º even.

Just trying to figure out what I need to do to fix this. Its really frustrating. I didn't seem to have much of a problem before I switched wheels and tires and added the camber back in. Previously I was running 255 pilot super sports on the stock pp front wheels with 25mm spacers.

What are your front toe specs for each wheel? Also, 19x10s +45 on the front along with 25mm spacers seems like an issue in itself...how did you fit that much width under the fender? Perhaps you have rubbing issues that seem like bumpsteer.

 

[breeves002]

Yeah I was thinking too positive scrub radius may be a problem but with the 19x9's same offset I was thinking it couldn't be THAT different. I could be wrong though. I may try putting the oem wheels back on with the smaller tires and see what happens. I need a spacer to fit 275's with a +45 10" wheel but it doesn't need to be 25mm. I just happened to have those already.

I have no rubbing problems at all as far as I can tell...

I don't know what the exact specs are I just know the cross toe is 0.05º so they're pretty darn close. Thats within measurement error is it not?

Is there a way to fix it with the increased drop from the sportlines? Or even just make it better. Will the steeda bump steer tie rod ends help?

 

[BmacIL]

Yeah I was thinking too positive scrub radius may be a problem but with the 19x9's same offset I was thinking it couldn't be THAT different. I could be wrong though. I may try putting the oem wheels back on with the smaller tires and see what happens. I need a spacer to fit 275's with a +45 10" wheel but it doesn't need to be 25mm. I just happened to have those already.

I have no rubbing problems at all as far as I can tell...

I don't know what the exact specs are I just know the cross toe is 0.05º so they're pretty darn close. Thats within measurement error is it not?

Is there a way to fix it with the increased drop from the sportlines? Or even just make it better. Will the steeda bump steer tie rod ends help?

Yes the bump steer kit does help. I would target +/- 0.01 for toe. It's more sensitive than you'd think, particularly with firmer suspension. You only need a +40 effective offset on a 10" wheel to clear, so the 5 mm will work and will definitely reduce tramlining.

 

[breeves002]

I'll probably go with a 10mm spacer to be safe. Now that I think about it. I had these same wheels with 255 tires and no spacer and didn't have the problems I have now. The 275/25mm spacer combo is what screwed it all up.

I will probably try the spacer and if I need to I'll then order the bump steer kit. Next time at the track is 5 weeks away so I have time to fix this.

I'll also try to get the toe perfect but that seems hard to do. I'm going to put my rear toe to 0 too. I have toe links, rear LCA bearing, and vertical links on the way now. The last track day put my toe out by 0.5º in the rear on both sides!

 

[BmacIL]

I'll probably go with a 10mm spacer to be safe. Now that I think about it. I had these same wheels with 255 tires and no spacer and didn't have the problems I have now. The 275/25mm spacer combo is what screwed it all up.

I will probably try the spacer and if I need to I'll then order the bump steer kit. Next time at the track is 5 weeks away so I have time to fix this.

I'll also try to get the toe perfect but that seems hard to do. I'm going to put my rear toe to 0 too. I have toe links, rear LCA bearing, and vertical links on the way now. The last track day put my toe out by 0.5º in the rear on both sides!

Can't use a 10 mm without it being a bolt through spacer (not adapter) and extended studs. There's not enough thread engaged otherwise. +40 gets you plenty, particularly with only 275s.

 

[breeves002]

Ok I will trust you with the 5mm then it just seemed really close with the 255's and no spacer - I will be going with 275's. Where's the best place to get them?

Could also do 10mm and extended studs? Guess thats extra work.

 

[BmacIL]

It'll be close. You'll probably have just ~5mm, but there's not enough deflection to worry about it.

 

[breeves002]

Where to get 5mm spacers?

 

[breeves002]

I ordered a hubcentric set off of Amazon. They were less expensive then I expected.

 

[Grintch]

Those the wrong offset for the front (again) AM wheels?

Like most others, I would be thinking big spacer and too much lowering are likely causes.

Doesn't Steeda offer a bump steer kit?

 

[breeves002]

I wanted to update this.

I actually really only had minor bumpsteer. I thought it was much worse then it really was. Spacer removal mostly fixed this. I have to run a +40 to run 275's so I left in a 5mm spacer. The real issue I was having was my camber arm was loose where it goes into the knuckle. I used steeda's (OEM) torque spec with blue loctite and it came loose on both sides. This caused the entire alignment to shift as the suspension compressed causing serious movement of the car which I interpreted as bumpsteer. I overtorqued these and haven't had issues sense. I probably should replace the bolts.

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