What would be the most likely candidates to pursue in trying to fix my situation...

the car does not pull to one side, it drifts. by that I mean when I release the steering wheel on a flat highway road, the car slowly moves to the right after about 5 seconds worth of distance at 70mph. in fact, if done from the left most lane where there is a crown in the highway, it can overcome that and drift to the right after about 10 seconds...

It does not pull on braking. It's been 4 wheel aligned, set slightly toed in. Ride height at 25.5" front, 25" back at the fender. Tie rods are good. wheels have been reverse L-R, and so has the tires. Air pressure has been checked, rechecked.

Is it remotely possible the break lines, on the right-either front, back, or both, are starting to swell/ constrict the flow just enough to cause slight unnoticeable pressure to drag the right? causing this?

Suggestions?

 

You may have to corner balance the car. I had similar experience before & also suspected sticky brakes. But my pad wear are even & after corner balanced the car, the drift went away.

 

Gino - you should not rotate the tires on these cars as they are directional tires. Did you have this problem before the tires wre switched from side to side?

 

Has the car ever been wrecked? That would cause the car to do funny things even though the alignment syas all is OK.

I've seen cars drive dog leg down the road due to the front and rear being out of alignment or wrecked.

Just a thought.

 

Bill-
The tires with the wheels were not actually rotated. My wrench dismounted- remounted the tires to change sides: L to R. He said that sometimes the diameter could be slightly different which could potentially make it drift, but it did the same before and after. But, he did not do the back tires. Could it be them that's causing this?

A930Rocket-
My Car Fax report and PPI indicated no accidents. I went further, and contacted the owner (1) and he confirmed the only 'accident' was a door ding by a parking jocky which left a 2" vertical paint scratch in the passenger door. The owner was furious about as the spot paint didn't match after 14 years!! He told me that he did not want to paint the entire door because it would stand out and I understand why, now.

So, back to tbe problem... really a corner weighting will solve this?

 

Well the tires are directional tires. Go look at them - they should have arrows pointing in the direction of rotation. If he switched the fronts then the rotation could now be reversed, which could cause handling problems.

 

Bill-
all the tires are in the proper rotation (I just checked, again). I remember when the wrench did this, and he paid attention, but I asked why not just switch the front set. He came back with rotation direction, etc., etc.

short of an actual corner balancing (which I'm not ruling out as it can't hurt, just costly), is there a way, or systematic approach to rule out other potentials like:
Tires- out
Alignment- out
Rods- out
Accident damage- out
Ride height- out
The brake line swell thing- ?
?- ?

your experience would be, as well as others in this forum....

 

Well I would imagine if the brakes were grabbing on one side you would be able to feel that. You could put the front up on jack stands to see what you can see.

Does tire wear look even?
Does rotor wear look even (I would expect there to be more wear on one side if the brakes were causing this)?

Ride height variance can cause pulling to one side, but would feel very much like a basic alignment issue. I had this issue with my 87 Carrera, which had just been 4 wheel aligned and corner balanced. I adjusted the driver's side front ride height (very simple) maybe .25 inches and the car then tracked perfectly. The driver's weight needs to be taken into account when corner balancing.

 

Well, if u jack the car up & turn the wheels, u should be able to get a feel for whether the brakes are sticking. You can also do a preliminary measurement on ride heights yourself to see how different they are from side to side. I tend to follow the factory way of measurement than fender heights.

 

I would also guess it needs to be corner-balanced

 

Hi,
I guess you should check:
1. front wheel caster (just in case, as not all alignment shops do)
2. front to rear wheel distance between the hub caps and see if they are the same on both sides
3. Recheck ride height at the torsion bars (could still be weight jacking on one side, measuring at the fender lip is not always accurate especially if the fender has been removed before)
4. Verify the torsion bars been placed the right way round (I gather they might have been removed while lowering the car)
5. Recheck alignment if still no better

 

Same problem on an 03 C4S. Inquired about this at the dealer who stated that the 911 is factory aligned with a slight drift to the right in the event the driver falls asleep at the wheel. Don't flame me, this is what I was actually told by the dealer. Perhaps someone can confirm with their dealer whether there is any truth to this statement. He further stated that if I did not like the drift, they could align the car, outside of factory recommended settings, to mitigate the drift.

Mike

 

Hi Mike,
Looking at alignment data, I don't think what the dealer said is true, alignment should be done to make the car run straight on a horizontal surface, unless I guess if the car only goes round and around on a circuit.
Running slightly to the right would be normal for the road but not for the car. Roads are designed with a slope for water drainage, if not it will be flooding.
Anyway, is there no danger if the driver falls asleep with the car running right than left?
Yes, one can align the rear toe or front camber to make the car run the other way, but then you would be fighting with the steering wheel when the slope is gone or goes the other way.

 

I have had a right drift from the time I got my 930. I have had the front calipers rebuilt, changed brake pads and even changer the front struts. I have tried having the car re-aligned 3 times. The drift is slight but always there. My next try is a corner balance. Other than that all I know to do is to try a frame machine to make sure all the wheel pick-up points are true. I'll let you know what I find.

Ken

 

Hi Ken,

I've had drift caused by tire, alignment and suspension issues, but this is the first time that a dealer has stated that it comes from the factory with a slight and subtle drift. I plan on keeping an eye on the tires to see if they exhibit any unusual wear, and if they do, I'll make sure he buys the next set.

Mike