New 8.8 rear end added understeer...?

MSC58 · 09-14-2009

So about a month ago I swapped out my little 7.5 rear end for an 8.8 into my 87 notch(4 cyl). The rear end came out of a 90 gt so it has the sway bar on it and I'm thinking thats why my car has been understeering so much..? Because the stock 7.5 rear end never had a sway bar on it. So my question is would upgrading the front sway bar to a thicker one cure my problem..? or is this common with 8.8's? I don't have the quad shocks hooked up either so that may be contributing to it also.

NavySVO · 09-15-2009

Did you make sure that the rearend was loaded when tightening the lower and upper control arms?

MSC58 · 09-15-2009

What do you mean loaded?

NavySVO · 09-16-2009

The weight of the car on the suspension. It is easiest to do by putting the rear on jackstands once everything is in place and you are ready for the final tightening down of all the fasteners.

If this is not done, then the rear end will bind up and act just as you are describing

MSC58 · 09-16-2009

When I put the rear end in the car was on a lift and the rear end was on the ground so it was not under load when i tightened everything up. Im not sure I understand what your saying though because with the rear end of the car taken out you would need to suspend the car anyway. Are you saying I would need to put all the studs through the a-arms and then tighten the bolts after I sit the car on the ground..?

93stangfutr5.0 · 09-16-2009

yes that is what he is saying

lilcobra 93lx · 09-22-2009

if it still has understeer after this get the alinement checked the rear axle could bent I've seen a lot of v8 car's with bent axles
from miner wrecks or from sliding into a curb it dosn't take much
just a couple of degree's will cause problems
Jim

MSC58 · 09-23-2009

So today I got a chance to loosen it up, drop it to the ground, and tighten the bolts back up. Also got to change the thermostat while I was in the shop. My understeer problem is completely fixed now and it handles 100x's better.Thankfully it wasn't a bent axle.. that would suck. Thank you guys for all your help!!

NavySVO · 09-24-2009

Hey good deal.

Just FYI for others, you can let the the weight of the car rest with the rearend on jackstands. This will "simulate" the the car sitting on the ground and give you a lot more room to get under the car to tighten things up.