RestoRoc89

I need some ideas here.

About 6K miles ago, I replaced the tires (BFG Traction TAs on salad shooters), all suspension bushings, tie rod ends and balljoints (with PST components), shocks (with gabriel shocks unfortunately), installed a ragjoint eliminator and had my Z28 meticulously aligned to stock specs (I stood there and watched the mechanic). The car's been driving very well with very neutral steering, although it does feel somewhat jittery on roads with an inconsistent crown.

Looking at my tires last week, the very inside edge of each front tire is worn completely bald (I didn't notice sooner because the car drives well and the wear wasn't visible until I took the wheels off). I rushed back to the alignment shop and the alignment was still well within spec tolerances (hasn't changed at all). The mechanic suggested that slightly more toe out will slow the tire wear, but he was no help in determining the root cause of the problem. With slightly more toe out and a bit of a lead to keep the steering wheel straight on a crowned road, I HATE the car's steering feel now (much less 'solid' feeling). I also don't want to waste the money on two new tires only to ruin them again. What could be causing my tire wear issues? The springs are still stock and seem to have sagged quite a bit (there's a .5 to 1 inch gap in each wheel well...I have no idea what stock ride height should actually be). I also did put in cheap gabriel shocks (budget concern, I intend to change these). Will replacing the springs help at all? Should I be using alignment specs other than stock?

Any help will be greatly appreciated!

badmts

I sell tires and i think i know what happened-you went in there telling them how you put cool stuff on your car and how you wanted to watch to make sure they did it right but now your tires are wiped out-even a rookie tech can "PULL THE STRING" or pull up or down on the alignment head to make it read in spec-TOE AND BLOW! what kind of machine did they have ,did you get before and after print outs? I truly could not tell you weather newer f- bodies have adjustable caster or camber.I will know tommorow as mine is getting 4 new firehawks ,4 monroe shocks and an alignment.we have some Hunter laser alignment deal and it spits out toe caster camber ,sai ,included angle ...etc...lol.I am the #2 guy in a 19 bay shop and its my car-do NOT think for a second I will tell them HOW to align it or what specs to use-I WILL read the print out and drive the car.what are you doing with the car?racing or daily driver?if the springs are sagging and ride hight is wrong alignment is DOA.The first 2 steps to alignment are set tire pressure and CHECk RIDE HIGHt,i'll bet you can find stock ride hight figures on net somewhere and DIY right now!Is this a flat rate shop and if so are you costing the tech money by sweating his work?I will post again tommorow after i learn about f body alignments and i will try to post my alignment sheet also

RestoRoc89

I suppose that's one way to look at it, but I certainly don't think this is a mechanic's error. The car is most definitely aligned to stock specs right now and it's eating tires. Since everything else in the suspension is in good order, I'm assuming this means that the sagging springs are the culprit. If this is true, how do I determine how the car should be aligned? If the ride height being lower than stock means that an alignment is DOA, what do all the lowered cars out there do? The car is strictly street driven, by the way.

As an aside, the caster and camber are certainly adjustable (although the adjustment range is limited) on a fourth gen F-body. The mounting holes on the control arms are all slotted.

ws6transam

I really do not see how your alignment can be in specification and yet allow the inside edge of the tire to scrub that badly.

Before going back to the alignment shop, you need to check to make sure your new suspension components are nice and tight. If everything checks out okay, then you need to have that alignment verified by an independent source.

I personally dont think sagging springs are the culprit as that will only affect your ride height, not the handling (except through ride height changes). The spring rate of a sagging spring does not change with time. Ride height is easy enough to measure with a simple tape measure. (I'm still using the original 23 year old WS6 springs on my car and it handles great.)

badmts

well you are dead on with your caster camber adjustability comment,I told you I would ask some questions and I have-mine has to wait til sunday when we are SLOW-but logic says if a spring is collapsed the rate has changed right- they want to know if the remaining tread feels choppy or "KNIFE EDGED" when your palm is drawn across it,any pull and is the bad wear uniform-I wish I could get my boss on here as he loves this stuff and has formula ls1-but he is newly wed and wife hates internet as it is not "QUALITY TIME"-LOL can you post pics of tires ?I will have more questions soon

RestoRoc89

The funny thing about springs is that, although they sag, the spring rate remains the same (although I'm not speaking for progressive springs).

Anyways, the car does not pull, it's been very neutral from a handling perspective. The tire tread is worn completely SMOOTH on the inside edge of the tire, and then there is a smooth transition to the rest of the tread on the tire (which is still 98% tread depth). No knife edge at all. I wish that I had some pictures. I'll work on that.

ws6transam

If it's that worn, I still cannot see how it can get past the alignment shop. Take it to a different shop for a second opinion. I've experienced first-hand the arrogance and blind trust that shops sometimes put on their own alignment equipment, then had a second shop figure out the problem within 15 minutes. It cost me a set of tires on my minivan when I "trusted" the dealership, and attempted to live with the increased road noise caused by a bad castor and toe-in adjustment.

RestoRoc89

I think you're right. I'll have to try another alignment shop. I may wind up replacing some parts before I get it done as well. This is already the second shop I've taken the car to...and I was happy with their work up until now. Maybe I should just buy my own alignment rack...