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Trapped stone in front disc assembly. - oldgit
After having negotiated a newly laid car park, with very fine stone, I seem to have picked up a stone (or two) between the disc and the protective backplate, on my front off-side wheel's disc brake assembly.

Most of the time I don't notice it, but then suddenly it seems to get picked up and then makes some temporary grinding noises and then suddenly stops. Will it eventually fall out as I don't want to just take off the wheel, which in any case might not enable its removal.

Edited by Pugugly on 26/05/2008 at 15:37

Trapped stone in front disc assembly. - maltrap
If the noise is not permanent are you sure it's a stone? Try reversing then apply the brakes hard. (exercise caution).
Trapped stone in front disc assembly. - oldgit
If the noise is not permanent are you sure it's a stone? Try reversing then
apply the brakes hard. (exercise caution).

It's not permanent and when it occurs it is only for a few revolutions and then stops and the type of noise is variable. I did have this problem many years ago on my Austin Healey Sprites (those with front discs, of course). Then I used to have the front wheel off in seconds and could spring back the rather flimsy backplate and release offending object.
Trapped stone in front disc assembly. - grumpyscot
It takes less than 5 minutes and costs nowt to remove a wheel in order to remove a trapped stone. It takes longer - and much more money - to replace a damaged disc caused by not removing said stone.

If you put the car on full lock, you can usually get into the affected area and using a small screwdriver to remove the offending article.

Trapped stone in front disc assembly. - pet
Happen twice to me in an Audi A3. Must be the geometry of the caliper. The Audi assist took apart the assembly to remove. Can to remember the stone, if limestone it wont do much damage, if flint it could ruin your disc