Car Drifts To The Right

[HalM]

I picked up my '99 996 a few weeks ago. I am a long time Porsche owner but this is my first 'water cooled" car. So far I love it.

When I was looking, this car met all my criteria. During the test drive I noticed a slight pull to the right. This was no big deal because I planned a complete suspension refresh. CarFax was clean and it passed a PPI at a well known east coast Porsche race shop with no signs of damage.

My suspension refresh included a nice set of used PSS9's, all new suspension bushings from Elephant Racing, a couple of new rear drop links, new (turbo) motor mounts, new front rotors, all new OEM brake pads and stainless brake lines. And of course a corner balance and alignment. The work was done by a well known shop here in Charlotte that I have used for years with my air cooled cars. The guys there used to crew professionally for a Trans Am team and are highly proficient.

On my first test drive yesterday after all the work was completed, the car continued to drift ever so slightly to the right. We took it back to the alignment rack and tweaked a setting or two but it still likes to drift right.

I am using the term "drift" because it is not a hard pull. And this "drift" is independent of the crown in the road. On a typical 4 lane highway, the drift is most noticeable in the right lane, but it will ever so slowly show itself in the left lane.

Is there an alignment step that is not obvious? Is caster none adjustable in a stock setup? My thoughts are the Bridgestone tires have radial pull. is that still common in modern tires?

Any and all thoughts are welcome.

[logray]

Do you have the alignment specs to share?

[HalM]

Thanks for the quick reply!

Front Left:

Camber -0.4

Caster 7.3

Toe Out 1/32

Front Right:

Camber -0.4

Caster 7.8

Toe Out 1/32

Left Rear:

Camber -1.2

Toe +3/32

Right Rear

Camber -1.2

Toe + 3/32 inch

The following sheet shows before and after.

[logray]

You could try a little more negative camber on the right and a little more cross caster +, there is a very small margin of adjust-ability within the mounting bolt holes for caster.

Example change to front right:

Camber -0.45 to -0.5

Caster 7.8 <---- a little more positive as well if you can do it, or a little more negative on the other side.

"For vehicles set up to drive on the "right" side of the road, the right side is aligned with a little more negative camber (about 1/4-degree) and a little more positive caster (again, about 1/4-degree) to help the vehicle resist the influence of crowned roads that would cause it to drift "downhill" to the right gutter"

[HalM]

Excellent ideas. Thanks.

When you say a "little more negative camber on the right," do you mean front, or front and rear?

[logray]

Front...

[HalM]

Thanks for clarifying. I'll pass this along to my guys.

[E Kap]

I purchased a 1999 996 about 1. 5 years ago. Had the car aligned and drove straight. About 1 year later the car drifted to the right just like you described. I also have Bridgestone front tires. The shop tested the alignment which was fine. He switched the front wheels (right to left) and that took care of the problem. Drives straight as an arrow.

Eric

[xmac]

I purchased a 1999 996 about 1. 5 years ago. Had the car aligned and drove straight. About 1 year later the car drifted to the right just like you described. I also have Bridgestone front tires. The shop tested the alignment which was fine. He switched the front wheels (right to left) and that took care of the problem. Drives straight as an arrow.

Eric

what tires do you have?

[E Kap]

Bridgestone Potenza RE6000 or RE9000