911 pulls to the left

[rwhaley]

I have a 1988 911 Cabriolet turbolook that pulls (most of the time) to the left. I have had a computer professional alignment by a very reputable shop and relatively new tires. They are Toyo 225/45 ZR17 on the front and 255/40 ZR17 on the rear. I have new from struts (before alignment) and everything is tight up front. Once in a while it tracks straight reasonably well then will revert back after some turns or braking. I have also had the front tires swapped from side to side with no difference.

I have new brake pads all the way around and the brakes do not seem to stick for when I jack up the car all the wheels spin very freely.

I read up on caster adjusting and tried playing with the caster some to no avail. I had scribed the aligned position first and wound up putting it back. My local Porsche mechanic said it is probably the tires but that does not make sense because I have rotated them left to right. ?????

[tonythetarga]

Did you have it corner balanced? Just doing an alignment could throw off the corner balance and distribute the weight unevenly causing the car to pull one way or another and lock up one side quicker than the other.

[rwhaley]

I have never heard of a corner balance but I had all four wheels aligned. Should any alignment shop know what a corner balance is. Do you have any more details.

[Dantilla]

Corner balance:

It is important that there is not a significant difference in weight between the left and right tires. It is possible that your left front and right rear have far more weight than the right front and left rear, or vice-versa.

When my car was aligned, 200 pounds were placed on the driver's seat to simulate me in the car. Then all four tires were placed on scales, and the suspension adjusted so that the fronts were carrying equal weight, and the rears were carrying equal weight. Only then will proper alignment settings result in the best-handling car possible.

[rwhaley]

Does that mean one could simulate the corner balancing by putting heavy weight in the passenger seat while driving?

[silver911rdb]

I had the same problem with my 1974 911S. It turned out to be the corner balance. I had 911SC adjustable rear spring plates and apparently one of them was loose and I lost the height adjustment on that corner. The weight became jacked and the car did pull pretty aggressively to one side. I could visually notice it when I lifted the rear of the car from the center using my floor jack (positioned under the engine). As I lifted the car one rear tire came off the ground. The other rear tire still had travel and kept contact with the ground. I checked the car with a level so I knew that the car was fairly level. It was pretty obvious that one of my rear wheels was holding up more of the weight than the other. This was a quick way for me to see the problem on my car. I'm not saying you'll be able to see it on yours but you never know. The proper way is to send it to a reputable Porsche shop that understands your car and have it corner balanced. An alignment is just one part of properly setting up your suspension. Corner balancing is just as important and most alignment shops usually don't have the equipment to do this or the know-how to do it to a 911.

If you would like a more in-depth discussion you can google "Mike Piera alignment". He has an excellent write-up on how to align and corner balance a 911. I did my own alignment and corner balance a few years ago and his write-up was very informative.

Hope this helps

[rwhaley]

That's three votes for corner balance so far. Sounds like I better pursue that. Thanks everyone.

[bpp944]

My money is on a front wheel bearing that's not adjusted correctly. (too tight)

[rwhaley]

bp944: Would the wheels still sping very freely if a wheel bearing was too tight?

[tonythetarga]

Originally Posted by rwhaley

Should any alignment shop know what a corner balance is. Do you have any more details

NO
You want to find a proper Porsche shop or a race shop that knows how to do alignment and corner balance.
You might post a question about shops located near you that have done good work for other members.

[fbarrett]

Start simply. After the car does this for a while, stop and check the temp at each front wheel. If the left one is much hotter than the right, you may have a wheel bearing problem or a blocked brake hose on that side. How old are your brake hoses--21 years? They can deteriorate inside and block return flow after braking, causing brake drag. If you jacked it up and spun the wheel freely later, the brake fluid pressure could have dropped.

Frank

[bpp944]

It depends on how tight the keeper nut is. Mine LF wheel felt very normal while the car was jacked up.

I previously went the same route you did, then paid the dealer to check it and they said it was fine. I added SS break lines to the car, while i was in there I repacked the bearings. Once the car was back together it pulled harder to the left, so i went back in and dbl checked the tension on the washer and found it was a little tight. I haven't had an issue since.

btw, your car is sweeeeet...

[rwhaley]

bpp944: Was it the front bearing alone that was a little tight or both front and rear?

I measured the suspension ride heights last night and a have some pecular readings. On the rear the ride heights are within 1/8 inch of each other but the wheel well heights are 2/3 inch off from one side to the other. The Lower side is the side it pulls to. I also jacked up the rear from a balanced center point and the left side appears to be heavier.

[Flieger]

The torsion bar to wheel centerline measurement of ride height is what matters. Fender heights can be all over the place. If you have ever watched the "Made by Hand" series or Jack Olsen's 911 Assembly videos (all on YouTube), you would see just how much "delicate adjustment" and hand-fitting went into these cars back in the day. Usually administered with a 5 kilo body hammer.

[rwhaley]

The center line measurement was very close (within /18 inch) but the wheel well heights were off by 3/4 inch. I talked to a Porsche mechanic today at the local dealer in Omaha, NE and they thought it could be a broken torsion bar on one side. Would that make it pull?

I think my next easiest step is to check the wheel bearings and brake lines.

[bpp944]

LF wheel bearing keeper nut was just a little too tight.