I know this kind of problem turns up quite frequently here but I thought I'd run this particular one past the assembled minds to see if there might be a straightforward solution before it goes to the dealer for them to take a look at.

 

About a week ago I started to notice a grinding noise from the rear wheels as the car started moving.  At first I put it down to corrosion on the discs arising from not having been using the car much recently.  I expected it to go away after a few miles or ordinary stop/start driving.  Which it mostly did but it seems to come back from time to time while I'm driving.  Specifically,  tight right-hand turns e.g. at mini roundabouts seem to set it off, particularly (if not necessary solely) on the offside rear.  After being triggered in this way it seems to persist for a good mile or so, diminishing slowly, but becoming much more obvious if I slow down on the throttle i.e. not braking (braking does seem to make it go away, mostly).  If I manage to get up to any kind of speed (e.g. roughly above car park speed) it's no longer discernible.

 

I'm wondering if maybe I've got a sticky caliper on the offside rear that is somehow being upset by tight turns?  Or something else?

 

Grateful for any suggestions/ideas.

Hi

 

I'd be inclined to eliminate the obvious by carefully checking for a small trapped stone somewhere in a caliper or between disc and dust cover.  You may need to take the wheels off to get a good enough look.

Small trapped stones do make noises like that. Reversing a long way at slow and mediums speeds may eject such. Good luck whatever.

Rotted or fractured mountings of backplate.

I've tried the reversing trick, didn't change anything.

 

Would you expect a trapped stone to behave the way I described?  I'd have thought it would cause a continuous noise rather than being triggered by something and then diminishing over a shortish period of time.

 

Would hope it's not anything rotted on a car less than three years old!

I got a stone caught in front brake - horrendous noise like the drive shaft was falling apart. Came and went specially at low speeds and on lock. Dealer had to strip brake to get it out, a tiny piece of flint.

"I'd have thought it would cause a continuous noise"  When I had a stone in a front brake, the noise would come and go with cornering, braking and reversing.  The stone that came out had been "tumbled" to the size and shape of a small pea, with a metallic appearance.  Presumably, as it rolls around it can get sidelined for a while and then drop back down later into a position that causes mischief. I guess it all depends on the original size and shape of the stone.

Put your hand behind the wheel and try to move the backplate to rule out corrosion or fracture.

 

Stones can cause some weird noises, I have had what I am sure was one making a scraping screeching at low speed but only forwards, heard it in a French motorway services 100 miles from home, had dissapeared when I inspected the next day.

Hmm, sounds like I'll be handing it to the dealer to investigate further, then.  If it does turn out to be a stone (which is sounding increasingly likely from what you folks have described) would that necessarily require any parts to be replaced, or would it more probably just be labour time?

 

Oh, and another thing: although obviously not ideal, is it actually safe to drive until I can get it looked at?  I have a few local errands to do over the next few days that I'd rather not postpone unnecessarily.

Edited 5 August, 20205 yr by ejstubbs

Unless you're very unlucky there will just be a labour charge to remove the stone, assuming it's a stone! It cost me about £50 I think.

Again assuming it's a stone then driving a bit shouldn't be a problem. I drove back from Cornwall to North Yorkshire with the squeal and didn't do any damage - apart from my nerves!

Edited 6 August, 20205 yr by Expatman

I've come up with a theory about why sharp right-hand turns seem to make it worse.  The noise is definitely worse at low speeds (not much more than walking pace) even if I'm not braking at the time.  When turning sharp right, the offside rear wheel is going to be going quite slowly cf the nearside (that's what differentials are for) hence triggering whatever it is that makes the noise worse at low speeds.

 

Well, it's a theory...

 

Is there a straightforward way to check for stones in places they shouldn't be?  I'm not looking to start dismantling brakes and such but if there's something I could easily get at with the wheel off I might decide to have a go at it this weekend.

Edited 6 August, 20205 yr by ejstubbs

Don't think so, but everything you describe points to a trapped stone. Symptoms exactly like those I experienced, worse at low speeds and when turning. Manoevering into a parking space was awful. Get it to your dealer or local garage before you worry yourself away!!

Unfortunately the dealer can't fit me in until a week today.  On the plus side, the noise was not as bad today as it was when I first posted.  I only have a couple of shortish trips to do between now and when the dealer can look it so I'm fairly chilled about it overall...