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Car oversteers when turning left

I have a 2002 Saturn SL with about 160k miles. She’s been a great car but recently she starts to oversteer when making moderate left turns over 35 mph. It always happens when the car’s weight shifts to the right side. It is predictable but it still feels unsafe to drive. Unfortunately My mechanic couldn’t find anything wrong with it. Any ideas on what the problem could be?

Many Thanks

Did your mechanic put the car on an alignment machine? I have to assume he already looked at all the suspension components and found nothing wrong, worn, or broken. That leaves you with a possible alignment issue. Are your tires wearing evenly or are there uneven or strange wear patterns? These would also point to an alignment issue.

When I hear it feels unsafe to drive, I am concerned. What potential causes could there be, first the power steering system, then suspension components. Try a new mechanic as this could be life threatening!

It could be an alignment issue. There’s a possibility that it could also be an oddly worn ball joint, tie rod end, strut mount, or something of that nature; maybe even a goofy steering rack.
The fact that a ball joint or tie rod end is tight does not necessarily mean that it’s good. Sometimes they will develop a flat spot in the ball socket and it may tend to “catch” in a certain position. This can provide a little lurch at some point in the rotation.

Unfortunately, there is no way of determining something like that short of physical diassembly of the part. That brings up the question of if you’re going to take a high miles component apart should you go ahead and replace it? At 160k miles I would suspect some wear.

Do you actually feel like you’re sensing a weight shift? If that’s true, than it would strongly suggest that OK4450’s theory of an eccentrically worn joint component is correct. Include in the definition of “jont component” an inside CV joint.

The inside CV joint allows the axle to change length by allowing a three-pronged bearinged center to rotate with tortional load applied while also sliding within a tri=slotted housing. If there’s a detent worn into the slotted housing, when you steer and the triad assembly (my term) is pulled out of the detent, that could be affecting the steering.

Caveat: my theory in a wild one, but if true should be verifiable. You should be able to feel the detent on the ground at a dead stop. or with the suspension unloaded on a 4-point lift.

http://tijil.org/Scion_Docs/05_tC_Shop_Manuals/Repair%20Info/Repair%20Manual/Drive%20Shaft-Propeller%20Shaft/Front%20Drive%20Shaft/conponen.pdf

One other possibility that ooccurred to me is a malfunctioning spool valve in the steering rack. Again, that should be verifiable.

I have a 2002 Saturn SL as well. These have an independent rear suspension and if the upper strut mount on one side of the rear gives out, this is one of the symptoms you will get. Open the trunk and then bounce the rearend up and down a few times. If this is the case, you should hear it squeak with the trunk open.

The strut itself could be bad also and there is the remote possibility of a bad trailing arm bushing. If none of that is the problem, then have the mechanic check the rear wheel bearing. If you hear a low roar when making the left hand turn, it is a bad right rear wheel bearing.