Bumpsteer: Correcting or Hoping?

[scoti]

Have you measured the difference? I have read that before and have measured it, very long time ago. Dont shot me cause iirc I dont think there is much of a difference if any. Some time ago a buddy of mine installed b-body spindles on a 65 a-body and that was a problem, reduced turning radius. I turned down the lower balljoints so the newer spindles would fit his 65.

I have not. I researched the B-body spindle swap back in the day & while it sounded promising, I didn't want to make changes only to make things worse. Since my car was mainly A-to-B driving it was more about ride quality & altering the look for something more along my tastes.

With each progressing g-body I worked on, I learned more & applied the knowledge (keeping the lower a-arm parallel to the road; increasing spring rate w/o over-doing it; tweaking the upper a-arm position before tall BJ's were available; using better shocks; managing alignment specs).

This round, I'm focusing more toward better parts to correct the geometry first & hopefully getting more out of a civilized combo. Better camber + correcting & minimizing bumpsteer throughout travel vs. hiding it w/a stiff suspension.

 

[scoti]

I'm fairly sure that tall stud @ the spindle steering arm end has you going the wrong way on these cars as well. * I can't qualify that because I never tried one of the kits.*

Yes I'm sure the multiple companies out there are selling them to do exactly the wrong thing. Smdh

I don't think a 'Bumpsteer Correction Kit' on a g-body does much if the problem is not addressed first. I'm pretty sure that's why the parts are sold.
Feel free to correct me if I'm wrong (no need to shake your head though)....

 

[Screwz]

This round, I'm focusing more toward better parts to correct the geometry first & hopefully getting more out of a civilized combo. Better camber + correcting & minimizing bumpsteer throughout travel vs. hiding it w/a stiff suspension.

Now this I can get behind.I have been reading old and new post and all I see is high performance mods and I just want a good modern ride . Most of the setups are 15 years old . I don’t call that modern

 

[Rt Jam]

It's common knowledge that multiple 60's-80's GM vehicle platforms suffered from bump-steer.

"what is" bumpsteer. T

Are you sure you have bumpsteer? It is relatively easy to check.

Measure the toe. Jack the car up by the front crossmember, check toe again. Compress front suspension ( ideally with front springs out ) or skip it and just push it down as much as you can. Check again. The change in toe is bumpsteer. Now you are armed with a number to know if it's worth correcting or not.

 

[scoti]

Are you sure you have bumpsteer? It is relatively easy to check.

Measure the toe. Jack the car up by the front crossmember, check toe again. Compress front suspension ( ideally with front springs out ) or skip it and just push it down as much as you can. Check again. The change in toe is bumpsteer. Now you are armed with a number to know if it's worth correcting or not.

I'm familiar w/the diag process & definition. The original question posted (& reason for the thread) was an attempt to see how many people (if any) actually check before 'fixing' the issue.

I know my car had the issue @ stock ride height. My 1st round of mods tightened up the suspension a little & lowered the car & utilized non-stock alignment so that helps band-aid the situation. These g-body cars are labeled by multiple players in the auto industry as suffering from bump-steer from GM. Certain mods like the 'B-body' spindle swap made it worse.

My next round will be focusing more on minimizing the bump-steer, increasing the Caster even more, & introducing a more aggressive Camber curve.

 

[Rt Jam]

Few people check because they do not know how. I'd be wiling to bet most drive the car, hit a bump, car does not track dead straight and order a bump steer kit.

In fact most alignment shops do not know or know how to correct for bumpsteer. Nor do they check. It takes a very determined technician to recognize it and an even more determined technician to try to correct it.

Another thing to consider is let's say you have a minor amount of bumpsteer. 1 deg in the entire range of front suspension travel. How many cars that are set up for cornering have a front suspension that cycles from full extension to full compression while driving. I had a Mustang with 0.4 deg of bumpsteer. With 12" of suspension travel but the reality was, even on a competition road course that suspension travelled 3" max.

 

[scoti]

Few people check because they do not know how. I'd be wiling to bet most drive the car, hit a bump, car does not track dead straight and order a bump steer kit.

In fact most alignment shops do not know or know how to correct for bumpsteer. Nor do they check. It takes a very determined technician to recognize it and an even more determined technician to try to correct it.

Another thing to consider is let's say you have a minor amount of bumpsteer. 1 deg in the entire range of front suspension travel. How many cars that are set up for cornering have a front suspension that cycles from full extension to full compression while driving. I had a Mustang with 0.4 deg of bumpsteer. With 12" of suspension travel but the reality was, even on a competition road course that suspension travelled 3" max.

I agree w/the statement concerning alignments & technicians. Most just go by the basics & by the book. Good enough is just that (good enough for most stuff).

I've read about the bump-steer amounts measured throughout the travel range (extreme extension/compression). One has to dial things in for their given set-up & expectations. And... each side is different. What worked on one side will not be the same answer for the other in all probability.