SC follows groves, will not follow straight line
 

The car has had the problem since I bought it. I had assumed it was due to excessive tow out from the PO lowering it without an alignment. I just got it aligned the other day (at a reputable shop), and while it's better, it still won't follow a straight line. It feels like it is following groves in the road. Sometimes when I hit the brakes at a stop light, it will pull to one side or the other. Since I know it is aligned properly, I am now thinking it might be wheel berings. I jacked up the front quickly last night and gave the wheels a whobble. They have a small amount of play vertically and horrizontally. My questions are: 1. Is this the likely cause of the car unable to follow a straight line, and 2. will wheel bearings that are too loose cause any other damage? I plan on tightening them tomorrow, so is there anything else I should look for while I"m in there?

Since the car has been aligned and you say the car pulls to one side while breaking looks like you need to look at the front discs and brakes for the problem. Have you flushed out the old brake fluid and filled with new since you have owned the car? It might be possible to have air in the line to one caliper in the front causing less braking action on that caliper. Also causing the other brake to pull the car while stoping.

First of all, if the bearings are loose, then the alignment is no good. You would have thought the alignment shop would check before setting up the gauges. It does not help that there is play in the wheels. However, this also has to do with the kind of tires you have. IMO, the more cross or diagonal tread you have the better. Radial tread looks to me like it would track the grooves. That is only a theory.

Brakes are good. New pads and fluid, and calipers are in good shape. Now I wish I would have checked the bearings before I had it aligned. Not very much radial tread in the tires either. I think I made it sound worse than it is. It feels like it wants to wander a little bit, and when I brake, SOMETIMES I can feel it pull a little to one side or the other. I never pulls to the same side every time though, which is another reason I think the calipers are in good shape. I also noticed that one of the tires on front is worn on the inside, while the other tire is fairly new looking. Could this contribute as well?

CDiercks,

Both Pat and Milt bring up excellent points. If you have wheel bearing "slop", then, unless that alignment shop did your work for free, I would return there, and ask why they did an alignment on a vehicle which could not be repeatable.

You seem to have two symptoms which are related: the car "wanders" when driving in a straight line, AND it pulls to one side under braking. Alignment to road specifications (IF it is repeatable) is the place to start.

Then, as Pat suggests, there may be a front brake problem. If a pad is "hanging up" on a rotor, that could account for the straight line wander AND the braking pull. Also, to a lesser extent, if there is a brake fluid leak.

The next thing to check is corner weights. If your fronts are not relatively equal (within 8% of each other), this will also cause BOTH wander and pull.

Good luck,
Ed LoPresti
RacePro Engineering
New York

What size tires? Wider tires will have more of this tendancy.

What Alignment specs? An "aggressive" alignment for autocross or track will also have a greater tendancy to wander. The crisper turn-in means less self-centering steering feel.

Tire size= stock SC with 16" wheels. 205 front 225 rear. Alignment specs? Don't know about that one. I had it aligned by a shop here in Indy that was reccomended by Bob Farmer. He told me he trained this shop and they do several pre 89 911s a day. I told them it was for street use.

Are you sure the wheels bearing are loose? Could be play in the ball joints or tie rod.

Inside wear on one tire mean the wheels has been out of alignment for some time.

The worn tire is probably affecting the tracking of the car.

Since it a good ideal to replace the worn tire, why not replace both tires and go from there.

I don't know. First I assumed alignment because it had all the symptoms. That cured most of the problem. I haven't driven it in a week or so, so last night I jacked up the front end and whobbled the wheels. Both fronts have a little bit of play horrizontally and vertically. Not bad, but seems to have more play than my fathers old VW Beetles. I have adjusted the wheel bearings on his beetles before and I know how they are supposed to feel. Should the 911 feel the same? I haven't had time to do anything else. How do I know if the ball joints or tie rods are in need of repair?

My car follows the grooves in the road also. It also pulls at times at lights, but it pulls according to the grooves so sometimes left, sometimes right. I will be replacing my front tires soon anyways, but they do have some inside wear on them.

Two thoughts:

One. If you lowered the car did you put in rack spacers? If not, do so and re-align. This it the one of the cheapest and best way to help the handling if these cars.

Two. What brand and condition are the tires? If they are shouldered to the inside they may cause all kinds if messed up handling. Following grooves is a Yokohama trait they say. I have AVS's and that is not an issue though.

Three. Did I say two? If you have a bit of wheel bearing slop in can spread the brake caliper more on one side than the other and cause pulling under light braking that goes away under heavy braking. Adjusting wheel bearings before they get damaged. Priceless.

Alex

If your car's been lowered get a bump steer kit from our
host, your troubles will be over!!
You might take a look at the tie rods, you can replace
them with a turbo tie rod kit.
Good luck!!

When your alignment was done, was there any adjustment done to the caster?

Lot's of possibilities. Might simply be tires. If the PO drove it much with it out of alignment all sorts of wear issues could arise. Also, how much tire pressure are you running? You said your tires didn't have much tread left. I'd get new tires (front and rear) put the correct pressure in them NOT 35 psi cold... More like 29 front 36 rear and see what happens.

A note on tire pressure. The best way to find "correct" tire pressure is to do a chalk test. Run a line of chalk off of the tread onto the sidwall. Drive the car and see how the chalk is wearing off. If your wear line is at the toe of the tread your good. If your chalk line is still showing on the tread then you need less pressure. If your wearing onto the side wall then it's too low...

Care to share the specifics?

I had Pirelli P-Zeros on my '84 and they wandered and followed grooves horribly.

As I said above, I don't know what specifics were used. I called Bob Farmer here in Indy and asked him where he has his cars aligned. He reccomended one place. He told me that he trained these guys on how to align pre 89 911s. I dropped the car off and told them it was a Euro 911 that had been lowered BACK to the Euro ride heigth and the PO didn't have it aligned after doing so. They said no problem, and I picked it up at the end of the day. I took it to these guys because I didn't want to be bothered with the specifics.

I had my dad come over last night (the VW expert) and check the clearance of my bearings. He said they were probably 0.007" to 0.010" and should be at 0.005". I am assuming they should be the same as that on the old Beetles. It's funny because I always HATED those old beetles as a kid. Now all my experience helping him rebuild engines and doing suspention and brakes is paying off. I am going to adjust the bearings today and go for a spin. At the same time I will check tie rods and ball joints. Thanks for all the help and suggestions.

The rack spacer is for bump steer. It's doesn't really affect the alignment of a car going in a straight line.

Camber and toe affects the wear of a tire more than caster.

To me tires and tread patterns make the most difference in wheather the car tends to follow the depressions in the road.

Find some billiard table smooth asphalt roadway and see what happens. Vary the air pressure to get the highest amount of tread contact vs air pressure.

These cars are very light, by comparison, to other cars you may drive and you will notice the variations in road surface much more. The next thing to consider is that the width of the tires is a lot more than cars of these weights. This makes the sensitivity much higher.

The final thing is to take a look at the "toe in" and caster adjustment for the car. You alignment guys know the amount of variance that they can put into the cars to make them handle more to your preferences for local driving. My alignment buddy and I talk about this a lot. I have had him put more caster in one side than the other to get the car to run straight down a road that had more crown in it.

Good luck,
David Duffield

tramlining
 

You can read a lot on the E36 board at www.roadfly.org on "tramlining" from instaling wider tires, lowering the car, ... I hope it helps.

Just out of curiosity, did you have a two wheel alignment, or four wheel alignment? I had similar problems with my 78SC and it turned out the RR wheel was significantly toed out while the rest were largely within specs. I still have a bit of tendency to follow the grooves, but correcting the alignment made things much, much less "quirky."

This is called "tramming". Pretty common here in Chicago, usually only with larger front tire width, if there are major ruts in the road. You need to take it to some smooth pavement and try the braking again. You can easily see if the wheel bearing is good if you jack up the front wheel and get someone to hold the steering wheel steady. Now grab the outside of the tire and try to 'wobble' the wheel side-to-side. If you can feel play then the bearings are shot, otherwise they are fine.

The other thing that can influence this is bump-steer. If your car was lowered as many here have pointed out you need to get a couple of $10 spacers. As the car hits a bump the suspension travel causes a shortening of the tie rod and thus is felt on the steering wheel. This occurs because the suspension geometry has been changed by the lowering.

Tristan