"if you swap front wheels, and not swap the tires, they will be mounted in the wrong direction... you better not hit any rain in that configuration..."

You are correct about that, only driving on dry pavement during the "tire retraining" period.

It does not seem like it would be a tire issue if I had the problem with both my old tires and my new tires....
-David

Any one else have a similar problem that turned out to be rear wheel bearings?

-David

Anyone?

I would think one wheel bearing going, on either end of the car, would create a "pull"...both bearings on the rear or front going at the same time? Possible, but not likely...but you did ask: "anyone else". Has this happened to you?

I'm having what may be a similar problem, My car darts left and right when I steer, the higher the speed the worse it gets, very scary to drive now. I only touch the steering a tiny bit and the car swerves as the weight transfer gets on the rear tyres, I have to opposite steer immediately to prevent leaving the road.

History: A major rebuild to my 74s - 3.2 engine and 915, Carrara axels, hubs and height adjustable arms, and new rear tyres 225/50/ZR16 goodyear eagle F1's and older 205/50/zr16 pirelli p7000s on the front. Once it was drivable I drove straight to the local alignment shop, there they punched up the Carrara specs, and I requested 1.5 neg camber front and rear. and 1 deg toe in rear. They didn't have to touch the front as it was still the same as before. The rear was way out as I suspected since I only bolted it up. They got it very close to spec.

I took it for a drive and it was as described above.
It was totally unsafe to drive fast.
I used a laser level and marked some points on the garage floor, I got 25mm (1") toe in on each side over the length of the wheelbase (2 meters) - that's 2" total !
I adjusted the arms till I roughly measured across the front and rear of the back tyres and got about 1mm toe in.

I went for a test drive and way better up to about 60mph but still bad after that.

Someone tell me if my understanding is correct, but the rear toe is so the car initiates a corner better to minimize understeer? It feels like the second I turn in the car wants to swerve in that direction, its great on a tight windy road when I throw it left and right adn keep the side loads on, but in a straight line it sux.

Seems I need less toe in?

all help welcome

summers3d, it would really help if you could post your alignment settings for us. My guess, without seeing anything is either caster or toe settings are outta whack.

In my past experience, this can be a result of several things:
1- bad front tire(s)
2- steering rack not level
3- wheels toe. This belong to the alignment job.
(3) can be the worst but (1) is not much worst.

I've seen wheel bearings do this. Usually you will notice that the car acquires a rattle or 'clunk' for every crack in the road. It could be front or rear wheel bearings.

I would expect an alignment shop to catch the front because you can just grab the wheel and feel the play in it.

If it isn't a bearing I would look at the suspension bushings, especially in the rear. Any monkey motion in the rear can be real exciting.

Does your alignment shop specialize in Porsche alignments? If not I would highly recommend finding one that does. There are a few good ones in the bay area or LA but I have no clue for Sacramento.

Has your car been lowered? If so -- how far?

As many have mentioned, Alignment is the most probable cause. Also, the question has been asked about if the car has been lowered. Are you experiencing "bump steer"?

Get to a reputable P-Car shop and have the car re-aligned and, if the car's suspension has been altered (ride hight) I would get the height set back to factory spec's and go from there.

Once your wandering is solved, you go back to a more aggressive ride height.

here is more info.
Yes lowered
(front has always been lowered and front alignment not changed or tyres)
I also have short stroke bilsteen inserts in the front struts
Rack moved up recently to minimize bump steer (8mm up)
Even spacers, so doubt rack is at an angle)

Heights (floor to fender - 40psi in each tyre)
LEFT RIGHT
23 1/2" FRONT 23 3/8"
23 7/8" REAR 23 3/16"


Alignment (before I re-did the rear by hand)
LEFT RIGHT
-1deg 50 min CAMBER FRONT -2deg 21 min
-2deg 10 min CAMBER REAR -1deg 52 min

+0deg 23 min FRONT TOE +0deg 24 min
+0deg 33 min REAR TOE +0deg 25 min

+5deg 41 min FRONT CASTOR +6deg 12 min

I don't know what the rear is exactly, but with a tape its 1mm toe in when measures front to back on the rear tyres

The camber excentric is at the same place left to right. may not mean anything, I'll get the level on it today and see if I can get a measurement for camber.

So the only change to front (is rack spacers and brakes on the front (Carrara rotors and callipers on 74 strut) so I don't really suspect the front is an issue as it ran sweet before.
Keeping in mind I had 205's all around with the original 74S suspension and narrow rear guards.

The main change is the rear arms (Carrara height adjustable), axels and hubs, shocks and Carrara rear torsion bars (im still running 19's in the front) same 7" Fuchs in rear with new 225's

Anyone have any advise with the 3.2 heavier motor/trans in the rear? seems my 60/40 will now be more like 65/35

kind regards
Brian

First of all, lower the tire pressure..... 40psi is a bit too high. What tires are you running?

new rear tyres 225/50/ZR16 goodyear eagle F1's and older 205/50/zr16 pirelli p7000s on the front

I have always run 40, I hate side wall deflection, and the goodyears have allot of side deflection cause they are 225s on a 7" wheel.

I used to get some bump steer, but now with the rack spacer it is not noticable.

The car sounds pretty low. The PO owner of my slammed the front adjusters down as low as they would go. My car was at 24.25" in the front and the ride sucked. I raised up to 25.5" (euro ride height) and the ride improved dramatically. You are 3" lower than euro ride height. Without dropped spindles it sounds like you have very little suspension travel up front.

I do have short stroke HP bilsteens (the original bilsteens did bottom out), but the travel seems fine when driving.
although when jumping on the front bumper there is less than 3/4" travel with my weight (150lbs) and appears very stiff.

in comparrison to the rear, which is much softer, and travel is 1" + perhaps this could be causing my unstable ride.

I think most of the lowered front is due to the low profile tyres, which havnt necessarily altered the suspention travel. just the body height.

Brian

bcaway---Were you having the same problem prior to replacing the rears??

Different tire manufacturers and tread patterns can lead to a wandering car.

No the previous tyres were great, all 205/50/16

but now I have a heavier motor, and changes rear suspension, its hard to isolate, Im leaning toward the rear tyres.

Quicksilver, would you mind posting a few of the good alignment shops in the Bay area?

Mine was doing the same on a set of worn Continetal Contacts and I just accepted this behaviour as a high performance tire characteristic. When I finally got a new set of tires, all that crazy behaviour disappeared.

I'll bet new rubber will solve your problem too.

Cheers,

Joe