Brake grinding noise

TB2 · Post by **TB2** » Mon Mar 15, 2010 3:38 pm

Hello everyone.

Everything going well at the moment, generally speaking, after my BX hat a major leak a few weeks ago which was promptly fixed by my stealer because I was quite busy at the time (just a blown off pipe at the front height corrector). Spring is coming up (finally...) and I'd like to put on my shiny refurbished Swift2 rims which I've spent so much work on. The problem remains that the rim offset is different to the regular (GTI) rims for some unspeakable reason. I'll either need to get distance plates (which are illegal) or sell the current 195/65 tyres, which is pretty stupid as they're new, and get smaller ones.

In any case, I still have the problem that the rear right brake makes a grinding noise each revolution. (As in, if I drive faster, it's there more often), and I've taken the wheel off today and found the following. On this picture you can see a dark spot on the brake disc. That's the part that makes the grinding noise every time it passes through the brake pads.

Has anyone seen something like this before, could I fix it myself (by just grinding it off or something), or should I be replacing the brake disk?

Thanks!

Post by **Tim Leech** » Mon Mar 15, 2010 6:20 pm

I would just clean it up, use some emery cloth and brake cleaner and that should cure it.

ken newbold · Post by **ken newbold** » Mon Mar 15, 2010 6:56 pm

Yes you could clean it up as a bodge, but if you're keeping the car I want to replace those rear discs, assuming the other side is in the same condition as this one.

Have you checked the inward face of the disc, they're usually worse than the outward face.

You are loosing a third of your braking surface on this side alone, if the other side is the same and the inward sides are the same, your braking efficiency is well down.

MULLEY · Post by **MULLEY** » Mon Mar 15, 2010 7:05 pm

Could there possibly be some air in the rear brakes, hence why the discs look well shot & don't appear to have much of the brake contact patch touching the disc?

TB2 · Post by **TB2** » Mon Mar 15, 2010 8:57 pm

Mhh, I see. After reading some stuff about break discs and how they look like after different types of damage, mistreatment or similar, I'm guessing that mine might look like this because the car stood for a very long time (possibly as long as 10 years) in which time the discs caught rust and upon reusing the car, the rust particles have grinded these groves into them. In any case, it seems like I should replace them. I'll look into how to do that. Hope I find the time. Is it very difficult?

MULLEY · Post by **MULLEY** » Mon Mar 15, 2010 9:09 pm

I've managed it, so i'd say no

The biggest problem is probably having to replace the rear pads (getting them out is a problem as everything is probably seized up), if they have gotten uneven wear on them because of the rusty discs, then you'd probably be best replacing them as well. An alternative would be if there is plenty of meat on the pads, you could always sand them down flat & re-use them with your new discs.

I also had really rusty rear discs, i chose to take them off, take a hammer to them to get all the rust off, bit of sanding & then i popped them back on. I'll replace them for the next mot, or if they pass i'll do them in the summer when conditions are nicer for outdoor work.

Post by **Defender110** » Mon Mar 15, 2010 11:24 pm

Looking at that I would check your rear caliper isn't siezed, a brake that is working properly would soon clean the disc up.