Had an alignment done on my care and I am looking at the notes from the service bill. First off I have a 2007 TT, tiptronic, w/ PASM (no mods).


In the invoice notes it reads

"performed 4 wheel alignment. Adjusted front and rear wheels as needed. Customers front caster is not within specifications however there is no adjustment provision on vehicle.

Then there is a page showing what the correct specs for the car should be and on the front left of the picture there is a hand written note pointing to the caster and it reads "Not adjustable"

I really have no idea what this means... is something wrong here or is this normal and expected? Can anyone offer any insight into decoding this "car speak" for us guys who are automotively challenged.

 

I've never heard that before, was it a porsche shop/dealer?

 

Did you buy this car used?

If you rotate the upper strut tops for more camber this would reduce your caster, if it has not been changed then it should be within the desired range.
There is also adjustable control arms with offset caster holes.

 

Perhaps one of the suspension gurus can chime in but I think you might need to add adjustable thrust arm bushings kits to the control arms to allow caster adjustment.

 

This doesn't sound like it was done at a dealer.

You may have something bent and a dealer would have told you this so they could sell you a new part to bring it back in spec.

 

1. This was done at a porsche dealership.
2. The car was purchased used.
3. If something is bent i certianly would like to know about it and have the option to replace the part..... sigh

Does anyone know for sure one way or another if the caster is adjustable on stock pasm suspension?

 

Like sparkhill mentioned, in order to adjust caster, you would need a set of adjustable thrust arm bushings, like the ones pictured below by RSS. My guess would be that something is bent unfortunately.

Did they provide you with the alignment sheet with the before/after measurements? I would be interested in seeing just how far out of spec the caster is.

 

Tom,

I checked w/ them, front left is 6.98 and front right is 6.89. I called the service manager today to ask about it and they were firm in saying that it didn't indicate any kind of problem bc the angles of both tires are close to eachother and they said "the likely hood of them being bent exactly the same amount would be very rare..." He made it sound like being .5 degress off from the recommended range isn't a big deal (which is 7.42 - 8.42). Not sure what to think.. Basically they told me it was nothing to worry about and is "normal". What do you think?

 

I recently had a 4 wheel alignment done and the range listed on the sheet is 7.25 - 8.25. Mine is 7.17 left and 7.26 right and my mechanic said it was fine.

As long as the right and left are reasonably close, and yours are very close, you are OK. Modern cars will typically range anywhere from 5 to 10 degrees of caster.

Caster is used to self center the wheels. Too much caster makes it harder to turn the wheels off center and too little can cause the wheels to wander side to side a bit.

 

Caster would decrease naturally as the car is lowered. You sure it hasn't been lowered?

Caster for a stock Turbo at 20 degrees is +7°55' +/- 30'

Caster is a very sensitive adjustment. Adding or removing a few degrees of caster can transform the steering balance of a car.

More caster aids stability, especially at high speeds. More caster generally suits large, open, high-speed tracks.

Less caster increases steering drastically. Steering feels much more direct, the car turns tighter and faster. Small amounts of caster are suitable for tight tracks.


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To my knowledge the car has not been lowered. But then again i don't know what the original specs would be for that. I measured and it's almost exactly 5 inches from the ground to the bottom of the front lip (just in front of the front tires) see picture. sorry for the poor camera phone quality.

 

What was the camber?
If they rotated the strut tops this would explain it.

If you add some camber shims this would add in some caster.

 

The current measurements sheet i got from the dealer shows my car w/ the following measurements )

Front---

Camber
L: -0.69
R: -0.80

Caster
L: 6.98
R: 6.89

Toe
L: 0.05
R: 0.05

Total Toe: 0.05
Steer Ahead: 0.02


Rear---
Camber
L: -1.90
R: -1.80

Toe
L: 0.20
R: 0.23

Total Toe: 0.43
Thrust Angle: -0.01


I don't know if a previous owner rotated the strut tops (but i have had no reason to think they did). Is there anything I can do to find out?

Any suggestions?

 

If you add some camber shims to the front you will get the caster to spec...you could use a bit more camber on the front.

Not sure of the turbos but on the GT cars at least 2deg is normal.