Overclocker

The subject says it all. Since my wheels are 8" wide I’m wondering if it’s wider tires on stock suspension causing ware, or if it’s the saggy suspension theory.

Also, do you think I should post this in the wheel forum for more exposure?

Overclocker

PERRYinLA

It can't hurt to try the wheels forum, since they like them wide ones, anyway. Also the Maintenance forum.

I am gonna check my camber settings myself soon. It does not appear to be hard, and I don't need to be ultra-precise. The basic steps are:
1) Park car on a flat, level surface
2) make sure rims are true (spin them and measure any runout)
3) Span a flat, straight rod/bar/stick across the rim
4) using a level and/or plumb bob, measure any deviation from straight vertical (pull out them cosine tables, geometry buffs!)

If I find myself to have negative camber, I'll try to adjust it myself, or have it done when I soon put on my newer tires. I'll be sure to have it adjusted with the gas tank full, so as it empties, the camber will become more positive.

IMO, I don't think our stock springs sag significantly to the point where alignment can't be properly set. If they did, we'd be hearing about them on this forum, just like we all know about leaking steering pumps, window sill cracks and burnt out gauge needles (on those issues, my car is 2 for 3!).

London Bill

Some interesting theories on inside tyre wear, excessive -camber will eat the insides but you say it has been setup correctly by a reputable shop. I have seen many sets of tyres ruined on 91-94 cars the cause was worn lower front arm bushes.

When you have the geometry set it is done when the car has static loading on the suspension, any wear in the bushes allows the arms to "float" under dynamic forces, so save your tyres and improve your steering/handling and get the lower arm bushes sorted out.

DoubleWhoosh

A few issues, but not the actual causes of your problems...

225/40 is too short, that car actually takes a 245/40 sized tire. This will not be the cause of your tire wear problem however...just looks a little funny

Alignments can be done with whatever tires you have on the car, as the equipment is bolted to the wheels. There is a tiny bit of play involved if you are using severely worn tires, but it's usually not enough to ruin the whole process. You can get it pretty damn close even with screwed up tires on the car.

*********************************

The real problem...

Virtually ALL tire wear problems with these cars are with the lower front control arm bushings, as even when the car is properly aligned, the second you go driving the arms are floating around all over the place and causing irregular tire wear due to constantly changing toe conditions. We do have a bushing kit that can permanently fix this, but it's somewhat labor intensive. Kind of a necessary evil though. Plan on quite a few hours of work or a labor bill anywhere from 300-500 bucks, but well worth it. The only alternative is new arms, which will end up close to $1500 and the problem will occur again sooner than you think. I am sure that this is the cause of your tire wear problems.

The control arm setup on this car is very innovative and advanced as far as the shape and location of the arms, but the bushing design was not up to par at the time this chassis was engineered. Things have changed since then, but unfortunately us SC owners will need to address the issue one way or another if we want to keep our cars in good running condition (and without changing tires every 6 months!)

Todd Matsubara
TM Engineering LLC
www.tmengineering.net

Hermosa

I bet alot of these shops just use some factory guideline and don't really put any work into the alignment. They are set for 16" stock rims. I worry about getting an alignment.

London Bill

Mongoose from the ALSC spent several months and hundreds of pounds on his geometry settings, he had 17" +38mm offset rims and took some advice on "settings", he persued this for 6 months without ever getting the steering correct, eventually he bought a set of standard 16" +50mm offset rims and the steering was still not right.

Eventually he decided to get the geometry put back to the factory settings, lo & behold everything went fine, no more tramlining or "darty" steering, knowing the car was perfect (it was, I drove it), he re-instated the 17" rims and found they performed just fine with more kickback and slightly heavier steering as would be expected from the increased track width (scrub radius).

With his now extensive knowledge of geometry settings he has made the following determinations,

1, Dont **** with the factory geometry settings unless you know what you are doing.

2, He would add 1degree of castor to improve the steering feel on standard 16" rims.

Keith13b

iTrader: (3)

London Bill- Great post. It seems that most things on our cars just seem to be fine w/ the stock settings.

A lot of time was put into the design of the car, why change years of research.

pcmw

Hmmm...

I had the car lowered, put on 18" rims, etc.. Took it to my alignment shop and never have had an issue with tire wear.

However, my alignment shop has no "factory settings" book, no computer, no BS clamp on wheel stuff. They have aligned all my cars, friends cars, and family's cars since I my father was a teenager with a 57chevy. Never a problem. I think the biggest issue are these computer driven machines with the factory settings built in. When the read the larger rim they see something that isn't there and so the mechanic pushes the car out of alignment instead of in.

Just my .02

MW

London Bill

Here is one I dont know the answer to;

You have stock rims (16"x7"/+50mm Offset) on stock tyres (225/55/16) but the car has been lowered 1" front and 1.5" rear, how should the geometry now be set, use the standard factory settings at the new ride height or compensate for the difference in ride height or, jack the car up to the original ride height to have the factory setings applied before letting it back down to the modified height??

Answers on a postcard to, London Bill.

pcmw

Well, the general idea is to get the wheels square to the ground. So I would think that you would have to bring the camber in to compensate for the axis of the suspension being at a different level. So if aligning it at the new height...the wheels should have the same or near same geometry that it did at rest at the stock height. Meaning... The wheel camber at new height = wheel camber of stock height.

MW

VQT

Todd,

What about rear tires wear fast yet pretty evenly. I think my cars have the same problem as 928owner. You keep talking about the front control arms brushing. Do you have the rear brushing also? Do I need to replace all brushings, front and rear? I have two 93 SC400, how much for the parts.

Thanks