Wheel hop....isn't getting better either. :(

[Alex41]

I recently purchased an 81 Malibu from a friend who built it over 20 years ago. It sports a 98 LS1/T56 with a GN 8.5 3.42 rear end. He had it slammed but the problem was the rubbing of the front tires. He has stock back spaced wheels on a B body brake upgrade so it pushes the tires out. When I got it I had to lift the car up with some un cut stock front springs and add a spacer to the rear spring perch to even out the car. When this happened I was able to notice the pinion angle running positive 3-5 degrees. I figured this HAD to be the wheel hop issue.

The first thing I did was to box the upper control arms. That didn't do anything.

Next I made an instant center relocation bracket for the upper control arms. Basically it's a home made version of the anti hop bars without the wrap around the pumpkin lower section. When I did this I was able to rotate the rear end forward to create the 2.5 degrees of negative pinion angle I was looking for. This didn't help.

Today I got smart and finished boxing the what was left of the rear control arms.....you guessed it....didn't help either.


I am at my wits end here. I've owned a few G bodies before and NONE of them ever did anything like this.

Any suggestions would be great. Thanks guys. Alex.

 

[LS6 Tommy]

Did you put new bushings in the rear arms?

Tommy

 

[Alex41]

I looked at them yesterday when I welded the lowers up. The previous owner told me he did urethane bushings but I think he did just the fronts. I will look for a place to order some good rear ones when I get back from Thanksgiving. Thanks for the lead. Alex.

 

[grizwald]

I'm trying to figure out your rear upper control arm brackets. if you don't have that "wrap around the pumpkin lower section", then what's holding them in place, other than the control arm bolt?

 

[Alex41]

I used 1/8" steel and extended the control arm down.

 

[greer_racing]

I'm trying to figure out your rear upper control arm brackets. if you don't have that "wrap around the pumpkin lower section", then what's holding them in place, other than the control arm bolt?

notthing

 

[grizwald]

someone correct me if I'm wrong, but I don't think that changes your instant center at all. the "imaginary line" representing your upper control arm angle would still be from the upper control arm mounting point on the housing, to the mounting point on the frame, and forward. those arms are likely doing the same job as they would before you modified them.

 

[LS6 Tommy]

someone correct me if I'm wrong, but I don't think that changes your instant center at all. the "imaginary line" representing your upper control arm angle would still be from the upper control arm mounting point on the housing, to the mounting point on the frame, and forward. those arms are likely doing the same job as they would before you modified them.

You are 100% correct. That modification did nothing to the IC. The mounting locations on the pumpkin or the frame are what need to be relocated to change the IC...

Tommy

 

[Alex41]

So the angle of the arms intersecting, no mater where they originate, don't change the instant center? If that's the case the anti hop bars don't recreate instant center either right?

Not trying to sound like an *ss....just confused on my physics here.

A friend told me the F body springs may be too stiff for the car as well. Thoughts?

Thanks for the help so far guys. Alex.

 

[grizwald]

the relocation brackets do change the instant center by relocating the UCA mounting points to a higher location.