Car is pulling to the right

[brighton911]

This past winter, I lowered my 86 911 to slightly above the so-called Euro height. Rear fender lips are now at 25 1/2 and front at 26" (lowered about 1/2"). The only other change was a set of Firestone Firehawks, 205 50 17 front and 235 45 17 rear. The previous Contis were the same size. Now the car has a pull to the right (it was perfect before). Switched front tires side to side, no change. Spent a great deal of time performing a string alignment, I am very confident the measurements are within .25 mm . I tried zero front toe and then 3 mm total toe in on the front, no change. Here are the other numbers: Rear toe zero, camber -.8 Front toe 3mm in, camber -1.1 and castor is 6.1 both sides.
Disappointing to have spent so much time and care only to have the same problem. My friend JJ has a corner balance setup, that is next on the list. Meanwhile, any words of wisdom as to what might be going on ? Thanks

[nospiners]

Slight toe adjustment only would not make a difference in pulling. More of a caster/camber issue..

[Nditiz1]

Corner balance should do the trick. My 83 was a former wrecked racecar. I did the string alignment, caster, camber, everything. It still pulled. I even grossly adjusted the camber to force it the opposite way which improved it slightly. It was at this moment that I realized how important corner balancing was. It was way off, but my ride heights were in check. Due to the accident I would never have similar ride heights. The crash side sat higher, oh well. I balanced out the car and touched no caster, camber, toe and it drove perfectly straight. Don't worry about fender heights, just make sure you are balanced and it will drive straight.

[brighton911]

Thanks Nditiz1, that was exactly the type of info I was hoping for. I'll post the pre and post results after the corner balance session.

[PeteKz]

Ditto what Nditiz1 said. These cars are very sensitive to corner balance. And don't feel like you need to get the balance numerically exact. A little more bias one way or the other to compensate for your butt in the driver's seat may make it feel better too.

[proporsche]

i would suggest to you to replace the A arms bushings..it could be just a coincidence that after different tires the car pulls..you would be surprised after you change the them..

Ivan

[brighton911]

Thanks Ivan. They are Elephant polybronze, in there for some time and regularly greased.

[proporsche]

Originally Posted by brighton911

Thanks Ivan. There are Elephant polybronze in there for some time, regularly greased.

good;-)

[eastbay]

Set drivers side camber to zero and see if the pull goes away...

[brighton911]

I couldn't wait until Friday to check the corner balance. So today, using the Ray Scruggs alignment guide (fantastic), I altered the weight distribution and yes, that indeed was the problem. His instructions for a right pull were "raise the left rear and right front and lower the right rear and left front."
I guessed at the amounts to alter each wheel and low and behold, the pull is now ever so slight. Once I get the actual numbers, I may play around a bit more but it is very close to neutral now. On some roads (newer pavement) it is dead straight. And the ride height variation is certainly acceptable too. And yes, I will post the corner weight numbers once I get them.
Many thanks for the suggestions.

[brighton911]

The corner balance session was interesting and very rewarding. While we didn't get it perfect due to running out of height adjustment on the left rear (raised to the max), it is now within 50 lbs side to side on the front and 47 on the rear - with me sitting in the car. I would have to re-index the left rear to make it perfect but the car is tracking so well I may save that for next winter. Ride heights are good too. All in all, I am pleased with the results.
Attached are the before and after weights.

Before


After

[brianlay]

With a little work you can get them pretty close

[Nditiz1]

You can get them to be like brianlay with just adjusting the fronts

[PeteKz]

I adjust the rear suspension so that the rear of the car sits level. Then I adjust the fronts for balance.

[brianlay]

I use the tripod method to get the rear balanced.

Put the rear wheels on the scales and remove the front wheels and support the front in the middle of the steering rack support bar.

After you get the rear close, then it's easy to dial it in using the front adjustments.