I had a strange (not too strong) left-right shake of the steering wheel, especially noticeable when the engine was cold, even at low speeds. The shaking would significantly be reduced after the engine has warmed up but some would still be there. Not continuous but occasional and it would be fairly smooth on the highway but, when the wheels hit a small irregularity on the road, it would induce a brief small left-right shake.

I have brand new wheels and tyres and I balanced the wheels well (twice within a month actually) but it did not cure the described shake. All front suspension bushes and ball joints, as well as the bearings, are good and tight. Then I decided to go for a wheel alignment check as I suspected incorrect toe-in. True enough, the machine showed that I had no toe-in but the wheels were practically dead-straight with actually a tiny bit of toe-out. After setting the toe-in to the correct figure, the left-right steering shake disappeared. Looks like the absence of toe-in (that keeps the wheels "wedged-in" and stable) allowed the wheels to wobble somewhat left-right in certain conditions.

I speculate that, if there is insufficient or no toe-in, the reason why the steering shake is noticeable when cold but reduces when the engine warms up is because, when the steering rack picks up some heat from the engine, it will lengthen somewhat and this will add a small amount of toe-in which will reduce the steering left-right shake caused by the wheels being "too straight".

I hope this will help someone fighting a similar problem.

 

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That is interesting, I can easily see how neutral toe-in/out would allow the front wheels to shimmy, literally not being able to make up their minds whether to toe-in a little, or toe out a little, producing a shall we-shan't we condition. I'm surprised that with little or no toe in that you hadn't experienced "wander", whereby the car would wander at speed, especially with a crosswind, or have a tendency to "tram-line" and follow every undulation and ripple in the road.

Good that you discovered the cause, if not for the fact that you had already done so much front suspension work you could have had a hard time tracking that one down (no pun intended)!

I wonder if the rack does indeed expand with heat sufficiently to affect steering geometry, I have to admit I can't think of a better suggestion!


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Ditto on CK's comments. Could the addition of the rack fluid heating up, the tyres getting warm etc also contribute? Your findings are something well worth noting for the future, I have done all the same work to the suspension both front and back, I seems I was lucky that I took mine to get the steering geometry done straight after I finished the suspension! Excellent piece of detective work in resolving the issue M Stojanovic :-)
Paul