Vibration when no power

[Mark Elder]

Guys, any ideas on this:

I've just got back from a drive and for the last couple of miles I was noticing wheel speed related vibration through the whole car (fairly sure its coming from the rear passenger side wheel because I can hear, with passenger help, a slight wheel speed related noise reflecting back into car from rear if I drive past walls etc).

I can't feel the vibration when I have power on or when braking - only when coasting.

It's less noise/vibration than you get from cats-eyes, but similar.

I can't feel any slack in any of the wheels and have felt around the wheels but can't find any tyre damage/bulges etc.

I guess it could be a stone in the brake disk - but noise does not seem right for that.

Any thoughts?

Mark

 

[pse_SC]

Sounds a bit like a grumbling wheel bearing.

 

[JB 3.2]

Mark, I have a similar problem, although it has only happened a couple of times. Each time I've stopped and checked the car over but been unable to find the cause, and decided it was the type of road surface.

As Paul suggests it could be a wheel bearing on its way out, but it will be interesting to see if there are any other thoughts.

Shame the Durametric software can't assist with this one.

 

[Mark Elder]

ORIGINAL: MoC2S

Up on the lift with it !

Yes that seems a good idea, I every comment I get seems to be bearing related - will take it over to the indy tomorrow.

Only just changed the front n/s wheel bearing (said indy found play in that during the MOT)...

Thanks for comments

 

[clyde]

Might be the brake pads sticking on slightly due to corrosion under the stainless plate in the caliper causing overheating. The heat seems to do strange things to the ABS, or at least that's the conclusion that I came to after many fruitless trips to the OPC to locate the problem. The discs weren't warped at all and the car was fine under braking. For some reason if I stopped, even just for just for a minute or so, and then moved on everything was fine. Easy to check - the disc will be rather warm to the touch []

I ground a bit off the pads to help them fit better and the problem went away. I should also say that I did eventually have the plates replaced and corrosion cleaned up [8|]

 

[Johnny C]

If the problem hasn't gone away then it sounds like a bearing, a bearing makes more noise at certain speeds when it first starts to go.

Slightly OT and not the problem here, but occasionally (like once a year, about once per 15K miles) after going round a roundabout and onto a motorway when I've reached cruising speed I suddenly felt rumble and pulsing vibration as though a tyre had burst. I've pulled off and checked, but there has never been a problem. It never happens when a tyre is new, more when they're getting on. The odd thing is that as soon as I've checked them and pulled back onto the motorway the noise has completely gone. It was more frequent with my old 3.2, but still happens on the 993. I've concluded that when the wheel balances have gone a bit awry after tyres has been on for a long time, and due to the tyres rotating different amounts when you turn, occasionally the imbalance in 2 wheels (front or back) will line up. This results in the imbalance vibrations on both sides harmonising. The act of pulling off rotates the tyres enough to offset them slightly and the noise disappears.

 

[pse_SC]

I've concluded that when the wheel balances have gone a bit awry after tyres has been on for a long time, and due to the tyres rotating different amounts when you turn, occasionally the imbalance in 2 wheels (front or back) will line up. This results in the imbalance vibrations on both sides harmonising. The act of pulling off rotates the tyres enough to offset them slightly and the noise disappears.

Serious: That would make a lot of sense[]. Non-serious: Alternatively, did you have a curry the night before and your stomach was complaining[]?

 

[Mark Elder]

Turns out not to be a wheel bearing, or tyres, or balance, or ABS, on indeed anything complicated....but it has now done a lot of damage (although it could have been much worse)....more news when I work out who to blame/will pay for the repairs.

I'm feeling particularly stupid for not checking something very basic - on the other hand I would have expected my indy to have done the job properly - we shall see what he says....[&o]

 

[clyde]

ORIGINAL: Mark Elder

Turns out not to be a wheel bearing, or tyres, or balance, or ABS, on indeed anything complicated....but it has now done a lot of damage (although it could have been much worse)....more news when I work out who to blame/will pay for the repairs.

I'm feeling particularly stupid for not checking something very basic - on the other hand I would have expected my indy to have done the job properly - we shall see what he says....[&o]

Not an incorrectly tightened wheel surely Mark?

 

[Mark Elder]

OK - a follow up to this. Thanks for all the suggestions, but I'm afraid Clyde was right - doh! Wheel nuts on rear near side wheel.

Thankfully the damage was not totally disastrous - but could have been. I'd picked my car up from indy having had all four wheels off for various MOT reasons and driven it home and it sat on the drive for a week or so. Then I drove 100 miles for a weekend away and part way through the weekend went out for a 30 mile spirited blast and it was only at the end of that when I noticed the vibration. A wheel bearing (as discussed above) seemed very likely and that did not make me worry about driving 100 miles home and another 30 on to the indy next day.

I'm really angry[] with myself for not even thinking about getting out the wrench and checking the wheel nuts (I even pushed and pulled the wheels feeling for slack in the bearings) - but the degree to which the nuts were lose at that point was probably not enough to allow movement slack.

The vibration got slightly worse on the way home but the noise got much worse. I stopped a couple of times and took a look at the noisy wheel - but it was dark and I was keen to get home, I kept speed down to 40 and resolved to get a recovery truck out the next day to get to the indy.

But when home I could see to my horror the left wheel was sticking out - I'm very lucky the tyre had not rubbed on the wheel arch as I went over bumps. That caused me to get a torch out to check the arch and it was then I realised there was a gap of about 7mm between the wheel and the brake disk central drum and the wheel nuts were very lose.

Damage: Wrecked wheel (4 of the bolt holes badly worn to ovals). One of the bolts had sheared off. Threads on two of the bolts worn away. 4 cosmetically damaged wheel nuts (one lost with the sheared bolt - not the locking one) (quite impressed how the amazingly light wheel nuts stood up to the beating)...of course, if the wheel had come off....

My indy says he has procedures in place to make sure they always torque up wheels when they finish a job but, given the fact that the locking wheel nut was included in the lose ones (so it could not have been vandalism) he immediately accepted it must have been his fault and ordered up a new wheel and replaced all the damaged parts without any argument at all. Impressed by this because I had no way to prove I had not removed the wheel in the intervening couple of weeks and I know from my dealings with the local OPC that they would have denied all knowledge even if the wheel fell off on their forecourt. So I will continue to recommend him to others (although I'm ordering up a torque wrench of my own!)

So - vibration when power off = stop and check your wheel nuts!

 

[JB 3.2]

Lucky escape Mark, I will be checking mine are torqued up correctly. A number of garages recommend checking wheel nuts 100 miles after wheel removal, but how many of us actually follow this advice.

 

[pse_SC]

A number of garages recommend checking wheel nuts 100 miles after wheel removal, but how many of us actually follow this advice?

Very true. I'm glad you're OK, Mark and that you discovered things when you did [&:].

 

[clyde]

Glad it all worked out fine in the end Mark but you really were lucky there wasn't more damage to the car, or worse to you. I have a habit of undoing wheel nuts and torquing them up to 130 Nm after it's been in for a service, just to make sure because garages have a tendancy to over-tighten.

It's an expensive mistake for the indie at around £800 for a new wheel and £5 or so a nut- I bet he'll not do that again in hurry [8|]