Motorway speed cabin vibration. Again.

I posted about this last week - here's a follow-up, because I don't seem to have solved the problem yet.

To recap (apologies for repeating myself if you've read this before): my 51 plate. 55k A4 Avant TDi 130 SE tends to vibrate / judder slightly at around 80mph (ish). It's not in the steering, but throughout the whole cabin. It doesn't seem to improve with more speed. Letting the engine idle with the clutch pedal depressed makes no difference, so I guess it's not engine / transmission related (?). It's not a noise, more a low frequency vibration that you can feel through the seat and see in the luggage cover and headrests vibrating.

I had the rear wheels rebalanced last week. One was out by 10g and the other by 40g. Trouble is, the problem's still there. A long run to north Wales and back today with a passenger confirmed that I'm not imagining things ;)

It'll be going back to the dealer I bought it from 10 days ago for a more thorough investigation just as soon as I can arrange it. In the meantime, any suggestions? i did notice while I watched the wheels being balanced that one of the tyres had a noticeable radial 'hop'...

Thanks in advance...

Just an idea....

The tyre which you thought looked a bit dodgy... how about just putting the spare on to test to make sure its not tyre realted?

Cheers

Rick

Good idea, thanks Rick.

Unfortunately the spare (which I hadn't checked before) is directional and won't fit on that corner. Don't think I can be bothered to do all the switching around that checking with the spare would entail - might leave that to the dealer :)

Given that I also spotted some sidewall damage on the spare and that it appears to be at the legal limit, I should probably get that fixed too...

A tyre/wheel related problem certainly sounds like the culprit here.

Quote:

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Originally Posted by SebRogers

Good idea, thanks Rick.

Unfortunately the spare (which I hadn't checked before) is directional and won't fit on that corner. Don't think I can be bothered to do all the switching around that checking with the spare would entail - might leave that to the dealer :)

Given that I also spotted some sidewall damage on the spare and that it appears to be at the legal limit, I should probably get that fixed too...

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Even if its directional it will be ok just to test.. it will just perform like a budget tire if wet...

Let us know how you get on.

Cheers

I agree with Rick, it will be fine for a test. Also some years ago I have a problem with vibration and it was a defective tyre. All the balancing in the world did not fix it.

Pirelli had my car of the road and span the wheels and it was very bad to see.

Well, I popped on the spare and went for a test drive. Things seem improved, although not perfect... but it's beginning to drive me mad now because I'm looking for a fault and starting to wonder if I'm imagining things ;-)

So at each stage - first, rebalanced and second, swapping the wheel whose tyre had noticeable radial runout for the spare - things have got slightly better. I think. Which makes me wonder whether there might be more than one cause? Perhaps the combination of slightly unbalanced wheels and then the high spot on one tyre both contributed? So any remaining vibration is the result of... cheap tyres, perhaps? They're Events.

Worth splashing on some better tyres for peace of mind, or should I just replace the one that's got a high spot? What d'you think?

Thanks again for all the comments and advice - it's greatly appreciated :)

I'm sure everyone's sick of reading about this by now, but here's a final update: the problem seems to be cured :-)

I had an appointment to take the car back to the dealer I bought it from next week. But, well, the vibration was driving me nuts and I couldn't wait that long, so I tracked down a tyre fitter with a Hunter GSP 9700 wheel balancer - the one that can check for radial runout on the tyre and rim, amongst other things - and took it in today for all four wheels to be balanced. Seemed from the comments here and watching the previous attempt at balancing the rear wheels that a problem tyre was the likely culprit, and I figured the only way to test that - short of fitting new tyres - was to test properly for it.

Result? Three out of the four tyres - one front and both rear - showed excessive radial runout. Two were brought within spec by match mounting, but one of the rear tyres was so far out there was nothing they could do. So I stumped up for a pair of new rears and put the least worst rear in the boot as spare to replace the barely legal one.

The car drives much better at motorway speeds - the passenger seat doesn't appear to judder in the way that it used to, and the only lumpiness transmitted to the cabin is from the road surface. I'm a happy bunny :)

I've learnt a couple of lessons from the experience. First, it's worth paying for decent tyres. The Events that were fitted to the rear were on the car when I bought it and looked pretty new, but I won't be buying that brand again - two out of two duff tyres isn't a great recommendation. Second, there's wheel balancing and there's wheel balancing. I was very impressed with the way that the guys at Imperial Tyres in Swindon approached the job - they were thorough, methodical and careful in their work, right down to finishing off the wheel bolts by hand with a torque wrench.

Quote:

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Originally Posted by SebRogers

I'm sure everyone's sick of reading about this by now, but here's a final update: the problem seems to be cured :-)

I had an appointment to take the car back to the dealer I bought it from next week. But, well, the vibration was driving me nuts and I couldn't wait that long, so I tracked down a tyre fitter with a Hunter GSP 9700 wheel balancer - the one that can check for radial runout on the tyre and rim, amongst other things - and took it in today for all four wheels to be balanced. Seemed from the comments here and watching the previous attempt at balancing the rear wheels that a problem tyre was the likely culprit, and I figured the only way to test that - short of fitting new tyres - was to test properly for it.

Result? Three out of the four tyres - one front and both rear - showed excessive radial runout. Two were brought within spec by match mounting, but one of the rear tyres was so far out there was nothing they could do. So I stumped up for a pair of new rears and put the least worst rear in the boot as spare to replace the barely legal one.

The car drives much better at motorway speeds - the passenger seat doesn't appear to judder in the way that it used to, and the only lumpiness transmitted to the cabin is from the road surface. I'm a happy bunny :)

I've learnt a couple of lessons from the experience. First, it's worth paying for decent tyres. The Events that were fitted to the rear were on the car when I bought it and looked pretty new, but I won't be buying that brand again - two out of two duff tyres isn't a great recommendation. Second, there's wheel balancing and there's wheel balancing. I was very impressed with the way that the guys at Imperial Tyres in Swindon approached the job - they were thorough, methodical and careful in their work, right down to finishing off the wheel bolts by hand with a torque wrench.

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Thanks for posting an update Seb - it's been very useful. I'm seeing very, very slight vibrations at motorways speeds on my A3 and I know the front tyres aren't far off needing to be replaced, and I suspect I need to get some wheel balancing sorted out. BUT - I have NO idea where to go for this. Most of the garages near me look well dodgy. This is probably the equivalent of recommending AOL for broadband, but are there any good high street garages you can recommend for this work?

Thanks,
Dave.

Hi Dave,

I found Imperial Tyres through this site: http://www.balancemycar.co.uk/ , which lists fitters who have the Hunter machine. The only other thing I can think of is to ask around for recommendations in your area.

HTH :)