Driven round bend bywobbly wheels

14 November 2011 - 22:33 By Gerrit Burger
subscribe Just R20 for the first month. Support independent journalism by subscribing to our digital news package.
Subscribe now

I have a problem with my Nissan Almera automatic of 2006. It has 76000km on the clock. When I get up to about 100km/h, there is a distinct vibration on the steering wheel.

The tyres are pretty new and I have had everything checked more than once - wheel balance, alignment, etc. I did discover that there was a drive-shaft that was wrongly fitted, but that has been corrected. What can I do about the problem? - Chris

Of all the baffling problems a motor car can throw at you, a vibration on the steering wheel has to be the most aggravating, Chris. I assume by vibration you mean a rapid oscillation - left-right-left-right jerking, also loosely referred to as shimmy, although a true shimmy is a much more violent phenomenon, mostly confined to vehicles with non-independent front suspension, like older 4x4 bakkies, Jeeps and Land Rovers.

If the vibration is speed-related it would normally indicate a dynamic imbalance in a rotating assembly (wheel-hub-brake disc) on the front of the car. If the imbalance is in the wheel, a good balancing machine should factor it into its readings. But not all balancing machines are regularly calibrated, and not all operators are skillful, observant and meticulous.

The owner of a small, specialist wheel alignment and balancing workshop told me recently that it's not unusual to get customers coming to them straight from big-name fitment centres where their tyres had just been balanced, only to find significant imbalances when they were checked on their own machine.

So the first thing to do is make sure the front tyres are balanced, as accurately as possible. Stand by while they do it, and check for lateral run-out (side-to side wobble) when the tyre is spun on the machine.

Anything more than the faintest twitch can initiate a vibration at certain speeds when the rpm of the wheel coincides with the natural frequency of the front suspension/steering system. Run-out would indicate a problem with either the tyre or the rim.

If the vibration persists once the tyres have been balanced and are running true, check the discs for warping and the drive flanges of the hubs for run-out. If you are still none the wiser at this point, I'd be inclined to go for on-car balancing of the front wheels.

There are still places that can do this, although you might have to ask around at tyre dealers to find one.

If that also does not help, it becomes a matter of clutching at straws. Some of the more esoteric causes of steering wheel wobble are worn CV joints, worn wheel bearings and worn shocks. I take it the alignment shop did check the front suspension and steering linkage for excessive play in ball joints and bushes before setting the alignment.

Wear in the suspension and steering linkage is unlikely to initiate the wobble, but it can cause the wobble to escalate instead of being damped out quickly.

subscribe Just R20 for the first month. Support independent journalism by subscribing to our digital news package.
Subscribe now