Hi all, hoping someone can point me in the right direction before I have to start rolling around on the ground under MrsC's 2000 20VT Plus.

I was driving it last weekend, exited a main road via a slip road, and halfway up the sliproad the steering wheel suddenly started juddering from side to side really violently - I'd say probably 3" of movement in either direction. I was right by a petrol station so I pulled in, checked everything I could do a visual on, and found nothing, so I drove along the road slowly and it all seemed fine again. I put it down to something on the road surface. Got home from there, about 40 miles, without it happening again.

However, she was driving it today and has told me that the same thing happened, twice. I drove it about 50 miles this morning with no problem. She then did a similar distance and got within 3 miles of home when this happened.

Are there any known/obvious reasons for this? All I can really think of is a knackered inner or outer track rod end, but it passed the MOT first time in December with no advisories, so it would be strange if that's happened so quickly.

All suggestions most welcome, thanks!

Could a Viscos Diff playing up cause this?

Check the wheel bolts

Checked the wheel bolts the first time it happened, that was my immediate thought.

Re the diff, this has only occurred three times in approx 200 miles - I assume if that was playing up it would be more frequent? Also each time it has stopped after a short time/distance.

Here's my thought: each time it happened was after braking, twice coming off a motorway/A road, so, reasonably hard braking. I'm wondering whether one of the front calipers is binding after hard braking, and if it's grabbing the disc then that will shake the steering wheel. Once it cools down a little it releases and the wobbling stops. Make any sense?

Check tyre pressures and top mounts are the correct way round, bump forward as they're handed.

I was thinking about a caliper/pad binding after heavy braking and it's possible when you speed up again it throws the piston back into position.
But if it's binding after the braking it then really it should be getting hotter not cooler when moving off again,if still binding.

It could be on the cusp of giving a total lock up on that caliper. If of course that is the problem.

I'd hope the top mounts are the right way around, last time they were off was about 5 years ago, and the problem only started a week ago!



Yes, I see where you're coming from there. My thoughts were that one of the pistons is just a bit slow to retract and that's what's binding. Could be wrong though. I just can't think what else would come on suddenly, only do it three times in about 200 miles (with perfectly normal driving in between) and only do it when braking for a roundabout each time it happened. Hmmm....

I wouild agree that the track rod ends, drop links or other front suspension fittings could be to blame. Maybe a ball joint is on the way out and causing the steering to "jump" like that? But I suppose it could always be the rack istself or PAS pump?

Wheel balancing or tyre deformation/damage?

Have you checked the level of the fluid in the power steering reservoir?

Sounds like the issue was when the car was pointed up hill?

Regards

MM

I haven't, but on the three occasions it happened (approaching a roundabout coming off a motorway or main road), one was uphill, one was fairly steep downhill and one was completely flat.

Each time it has done it for about 2-3 seconds max and then stopped. So it's happened three times, for that short duration, in around 200 miles. The rest of that distance it has behaved perfectly and as expected. To me this rules out something broken or damaged.

I've arranged to have it on a ramp tomorrow, initially for a visual on all the suspension & steering components.

Just a comment about steering fluid. I have boiled my fluid plenty of times on track without any judders etc. mind you I know it can boil so I Allways make sure there is plenty in there.

Sticky piston. I had massive judder under heavy braking, or braking from speed. Swapped calipers with another set, no more judder.

I had similar from a loose wishbone bolt.

Well just to update. It went into a local garage today (a proper repair garage, not a "remove this whole item from the car and replace with a new item"), a garage which I have used, albeit mostly for MOTs, for at least 30 years, so they know me quite well.

They've driven it and been all over the front end and can't find anything more than a broken ABS/brake wear holding bracket and a few extra PSI in the front tyres. Driveshafts and CV joints all OK and holding grease.

The only thing they didn't dive into was the calipers but they don't think that could be the culprit. That said I might overhaul them at the weekend anyway, if only to rule them out.

So I'm properly stuck now.

I heard of a similar problem a long time ago, which was eventually diagnosed as a damaged tyre. The damage was such that a bubble of rubber was sometimes being pushed out from the surface of the tyre without bursting, then being pushed back in again.

Would be worth at least swapping wheels front to back just to see if it makes any difference, might also help if it's some weird wheel balancing issue.

Thanks yes, potential quick win there, I'll try that.