Help With Rear Wheel Caster..? |

Hey guys, i've noticed this mainly the other day when i broke my tires loose in some 360's. Tread wear....in a bad spot.

I have a sub box, along with 2 12's and 3 amps...all on the box, grand total weight is no joke 58lbs. Ever since i had that in there, i've noticed that my rear wheels are alittle negative in caster, meaning the top of the tire is in towards the body...basically the rear wheels look / \...but not to that extreme. Enough to wear out the edges of each tire and not as a whole. Now i went to firestone, and they said something about shims..? Doesn't my tbird have caster +/- adjustments..? And isnt it relatively easy to do..? $$ etc is the main thing here, how much does that cost..?

BTW, when i take out my sub box, the rear wheels are perfect, just like | |... Is that normal..?

95 4.6L bird btw...

I'm having second thoughts about having a place make both rear wheels straight with the sub box back there, #1 cause alot of people i speak to say that alittle - caster in the back is normal in a rwd...? #2 the whole tire is to the ground, i keep my rear tires at 30psi also, so all tread is to the ground....but it's just something that bugs me.

BTW, the / \ is from looking at my car from behind, like a good 20 feet away....but it's very slight.

Oops...i mean CAMBER, not caster.

haha, i was about to say? rear wheel caster???? I'm not too familiar with your car. For both wheels to be in like that, you have full independent suspension? I would suggest changing your springs. They could have lost some of their elastic properties...

I'm not too familiar with your car. For both wheels to be in like that, you have full independent suspension?
Yes, those T-birds had IRS.
Most front and rear independent suspension systems with unequal upper and lower control arms (not the strut-type systems) are designed to have a camber change as they move through their suspension travel. It compensates for chassis lean and roll in hard cornering, among other things.

However, at rest, they should not have a noticible camber.
So, try taking it to an alignment shop and have a 4 wheel alignment with the stereo equipment in the car.

Also, a good alignment shop will align it with someone in the drivers seat, at about your weight, to make sure it is aligned properly when you are driving the car.

Finally have the shop take a good look at the rear suspension, to be sure there is nothing worn out or broken.