Picking up stones in the brakes

[Ferg]

Took the car out for a blast yesterday which was awesome, but pretty much everytime I hit a road with little sones on it I end up with that aweful screaching as one lodges between the brake disk and the guard. Sometimes you can get rid of it by reversing, but mostly have to drive until it goes away which is really grinding on my mechanical sympathy.

Does this happen to all? Or might my guards be a little bent? They didn't look adversely wrong when I last had the wheels off. Just interested in what poeples experiences of this are and any solutions..although probably not many.

Cheers
Ferg

[Rich H]

Do you have a solid pedal? Grooved discs?
If you have had a lot of them check the leading edges of the pads make sure they are still square and the pad faces check they aren't damaged.

[Ferg]

Standard discs and pads and the pedal could be described as a little hard. Good shout on the pad leading edges, I'll take a look.

[tut]

When you say guards Ferg, do you mean the steel plates that were bolted on to try and get MMC disks working in the wet?

If so I just took mine off, made no difference to braking performance.

tut

[Ferg]

It's a thin bit of metal sheilding that covers the inboard side of the disk. I don't think they are MMC specific as I've seen the same thing on most other cars I've owned. It's just everytime I come across a bit of gravel covered road I pretty much expect to pick one up and sound like a screaming banshee for the next few miles. I wondered whther they may be bent open a little making them more susseptable to picking up stones.

[tut]

I would take them off if they are proving a problem. Mine used to get bent and scrape on both N1 and N3, so I did away with them.

I did not realise that they had continued with them after the MMC's ran out, probably just wanted to use them up. However I can not see that they have any relevance on steel disks, they were purely installed for the MMC's.

tut

[r10crw]

I had the same prob on sat and as you say had to reverse to get them out. I also have the guards in place so probably worth trying to remove.
Craig

[Ferg]

Having had a think, are the guards not there to stop stones etc getting into the inside vanes of the vented disks?.. and therefore reducing braking performance and disk lifetime..

[Kelvin]

I would take them off if they are proving a problem. Mine used to get bent and scrape on both N1 and N3, so I did away with them.

I did not realise that they had continued with them after the MMC's ran out, probably just wanted to use them up. However I can not see that they have any relevance on steel disks, they were purely installed for the MMC's.

tut

tut as I recall they were never fitted to MMC cars as standard. They were introduced in later cars and then retrofitted to the earlier cars. The vin they were introduced from will be in the parts manual . I've taken them off my car and added to my collection of Elise bits removed/dropped off box but they do get fairly damaged on their leading edge presumably from getting whacked by stones.

[campbell]

Ferg,

Been happening to me for some time. I think even slightly mis-shapen guards are susceptible, and both of mine are less than perfect after various animalisations during wheel bearing and ball-joint changes etc!

I'd taken the decision not to remove them, as I perceive (but can't prove) that they help protect the disks' inner surfaces from larger stones, water spray, etc.

Whilst the grinding stones thing can be annoying, it's heightened just now because of the cheeap grit used in the latter part of our arctic winter this year. You'll notice this stuff is actually wee stones, not the rocksalt and sand combo which breaks down a lot better under traffic. Therefore, the problem will drop off a bit when more of the cheapo stuff is washed to the side of the road and/or swept up by street cleaners (fat chance).

HTH!

Campbell