Wheel Vibration (with a twist)

[Sondar]

OK, so most of us know about the steering wheel vibration common to the TR7 at 80kph or so.

I thought I'd fixed mine by having the roll bar mounted further forward to introduce some castor. But, it now appears I was too hasty...

Having said that, there are some very strange inconsistencies. Sometimes, the wobble is quite violent, other times almost non existent. This morning, it started out really quite shockingly bad; then I went round a moderate right hand bend at an easy pace and it virtually disappeared. A km or so down the road, back again...

Doesn't make sense to me. I can only think maybe there is something worn in the suspension / steering. Having said that, all bushes are new, bolts are tight, ball joints and shocks are near new, and the bearings seem OK. The only think I would think of as a bit suspect is the steering rack, but I can't see that this would cause a wobble - possibly accentuate it, but not cause it.

Any ideas on where to look on this?

[FI Spyder]

I to have had the vibration come back. From violent when I bought the car ( had to keep it at 50 mph or below, it would come in at about 52-53 then disappear over 64 mph). In the course of getting ready for the required safety check for vehicles coming in from another country, I change the tie rod ends, ball joints (which seemed good other than torn rubbers) I got new tires (the old ones where down to the threads). Silky smooth and remained that way for years. A couple of years ago it came back in. I had the car sitting on tires over the winter (previous years the car was sitting on jack stands doing winter projects on it). I can see no play in the mechanisms, minimised wheel bearing clearance, tightened steering rack so there is just a bit of stiction, got the wheels balanced using local tire shops most advanced equipment. The only thing left is new tires. The tires are in really good shape but 11 years old now. I think sitting on them over the past few winter have wrecked them (most projects have been done, time for second go round), being too old to bounce back. I've read on some forum (or it might have been a Chevy/GM website) that if the car is going to sit on tires over the winter they should be on thick rubber/foam type stuff to help distribute the weight around the tire flat spot (not to mention higher tire pressure). This is the first time I've heard of this from an official manufacturers position. From now on, I likely won't be insuring/driving during the winter (we don't usually get snow here) and the car will be up on jack stands during the winter.

[Beans]

If the vibration appears or disappears in corners the first check is the wheel's balance.
Always use the wheels with the least amount of balancing weights on the front of the car.
And introducing more castor probably helps to highlight the problem, so reset to the factory specs.

If that doesn't cure the problem you'll have a challenge as all components seem to be new

[busheytrader]

IIRC, it's been said a few times on the forum that tyres parked up in the same position for a prolonged period, encourage the wedges wheel vibration when it's back out on the road.

I think it was Hasbeen but I'm open to correction.

[Stag76]

Have you checked the uni-joints in the steering rod.
Play in these joints can result in a wheel-wobble in the straight-ahead position which
disappears when you turn the wheel.

[John_C]

And don't forget that my steering wheel shake (with seemingly the exact same symptoms as yours) was caused by the near side half shaft in the rear axle. I suspect someone hit a curb or something following essential work when I wasn't around. I went through everything over the years to try to cure it and even found the tyres had gone a bit threepenny bit but changing them made no difference at all - zip, zero, nada, nothing!

[simontdo]

I had terrible vibrations on my 8 when I first got it on the road.

Reading forums like this, I was convinced it was wheel related; tyres/balancing/wheel centre bore not centred etc.

It turned out it was 2 things; my prop-shaft CVs were shot and the axle flange was loose on the pinion shaft.

It would be worth checking these because they gave the impression of steering wobble, when it wasn't steering related at all.