The Stovebolt Site Forums The Shop Area Driveline inner front tire wear -- GMs geometery

Hi all,
Well, Im about to poise a question that Ive been wondering about for some time regarding GM's front suspension geometry. Why is the alignment such that it promotes premature tire wear at the inner edge of the front tires?

Do I HAVE TO go to "tall" upper ball joints to correct this, or could I just hand the alignment guy special specifications to align the front end to?

Im not a fan of constantly buying new tires because of this problem.

What year vehicle are we discussing here? Obviously, it's one with independent front suspension. Normally, replacing any worn parts such as ball joints, control arm bushings, etc., followed by a good wheel alignment, should solve any tread wear problems. No need for Mickey Mouse modifications- - - -like P.T. Barnum siad, "There's a sucker born every minute!"
Jerry

Its a 69 chevy truck. I always do an alignment when installing new tires, and the last time the service guy told me it was alright, because it was only a little off.

Its both front tires, and its only on the inside edge. I could swear I read a thread somewhere about this being because of GMs geometry. Something about how that politician (Ralph Nader) went after Corvairs, which then likely caused GM to redesign the front suspension systems adversely to satisfy the legal freaks.

I've never heard of anything like that. How often are you rotating the tires? Should be doing it about every 5000-7500 miles. That goes a long way to keep the tire wear down. It also sounds like you might have a toe out or camber issue. The "alignment guy" that told you it was "alright" may not have set it, or did the quick and dirty "Toe and Go" to make a quick buck. Have the alignment checked at a different shop.

Find a real alignment shop, and have them do a full inspection. Pay particular attention to lower ball joints. If you're wearing out the inside of the tread on both sides, you've got excessive negative camber. The 69 models were notorious for bolts getting loose and shims falling out, so be sure the upper control arm bolts are well-tightened, and check them periodically.

Ralph Nader was, and still is an idiot, but he had very little to do with the Corvair getting canned. The air-cooled flat six engine couldn't meet the 1968 air quality standards, and Chevy chose not to retro-fit it with a liquid-cooled engine. it was a poor copy of a Volkswagen anyway, and Nader just helped its demise along somewhat with all his "The sky is falling!" panic.
Jerry

I had my suspicions too. Thanks.

Yeah, I discovered that about the upper control arm bolts a few years ago. It has been a while since Ive checked them. Ill definately check them again.
Theres a lot to the politics involved with the corvair that i dont know, and as youve shown, theres more than meets the eye.

Are the correct wheels on the vehicle? Correct size and offset?

The wheels are 8x16 custom ralleys in the fronts. Do you think they should adjust the alignment specs because of the non-original wheels?