[SORTED] WANTED GPX rear brake disc set and brake pads

[Bartpabicz]

Hi,


I'm considering replacing rear brake discs and pads in my '97 GPX. Yes, I do know about camskill, SP motors, rice rockets etc. - I don't HAVE to do that change as brakes and pads are ok, it's just that annoying scratching sound on one of the rear wheels that make me want to replace those, and I prefer not to spend 100 quid on camskill. So, if any of you have a spare set laying around and would like to free up some cash and room in the garage - let me know. Thanks!



Bart

[colm_mcm]

Far as I remember all ftos have the same rear brakes

[StewyD32]

Are the ones you have on at the moment standard ones Bart?

[Bartpabicz]

I have grooved and dimpled 3G brake discs on at the moment (rear only)

[StewyD32]

Are they in good nick?

[Bartpabicz]

they've been sanded down recently (2 months ago), but my mechanic advised me to get new ones whenever I'd have some spare cash; Nothing too urgent though. Judging from that I'd say they're only so-so.

[d_dan]

You sure the scratching noise isnt the dust shield?

[Bartpabicz]

I was told it's either the pads alone which scratch the surface of the disc or the discs. I will be seeing another mechanic on Saturday and I suppose it would be a good idea to make sure it's that indeed. In the meantime though, I'm still interested in pads/discs.

Thanks for the tip Dan.

[d_dan]

PS.. changing rear disk's is a nightmate on the FTO. I had to use a break caliper tool.

[Bartpabicz]

I just noticed today that this screeching sound disappears once I depress brake pedal or pull up hand brake lever - even if just a little bit , not even enough to make the brakes "catch" for good, but enough to hear them start working. Once I release either, back comes that annoying tone again. It seems that once the pads are being pushed against the disc and start rubbing, that scratching becomes a regular braking sound, and whatever's causing the problem, it appears when the brake pads are not in use.

As far as I know pads are not being retracted, but rather 'pushed back' by rotating disc. Thus, is it possible that the dust guard would have anything to do with that? Or perhaps an uneven surface of the brake disc collar may cause that (only the braking surface has been sanded)? The calipers work fine (checked). Ah yes, and the discs are not mirror-like finish - I don't know if it's normal for FTO's rear discs or not.

By the way, I was thinking on how to describe this sound the best and came up with this: it's as if you'd be holding a srewdriver tip against rotating surface of the disc. Impossible to hear from the inside, but once I open the passenger's window and pass any wall/building/flat surface the sound bounces off it and it's easily heard.

Any ideas?

[StewyD32]

Would it be a sticky caliper?
Try putting copper grease on it and see if the noise goes away.
Also have a look at the pads and see if they are wearing evenly, if they are not one part of the pad can be rubbing up again the disc.

[Bartpabicz]

calipers have been greased about 2 months ago - those worked flawlessly even before that. As for the pads - wearing evenly.

[StewyD32]

Worth a go. I had the same problem and it turned out the pad was not put on correctly and therefore wasn't wearing evenly. It needed to be grinder down and was perfect since

[Bartpabicz]

a small update: the noise gets a bit louder in regular intervals, depending on wheel movement speed. In other words it gets louder for a split second with every turn of the wheel. Warped disc?

[Myfeckin FTO]

a small update: the noise gets a bit louder in regular intervals, depending on wheel movement speed. In other words it gets louder for a split second with every turn of the wheel. Warped disc?

Most "warped discs" are actually not warped at all - just have deposits left on them. Maybe try a series of hard on the brakes and see if this makes any difference. I'd be more inclined to think you have a sticky caliper myself. Did you take the wheel off and have a look at the back of the disc/pads?

[Bartpabicz]

I'm pretty sure calipers have been checked two months ago - mechanic asked me to depress brake pedal several times as he held calipers to check if it works, and it did, with no problems. To retract them however he needed a tool to 'screw' them back in place, just like with the other set on right wheel which doesn't produce any sounds. I will do that hard braking test today and have another guy have a look at that wheel again on Saturday. Maybe there's indeed some residue - but then, the first time discs have been removed and polished, everything has been cleaned and checked. Ehh....

[Bartpabicz]

Just checked that hard braking - makes no difference, sound persists afterwards. I did notice though that left disc is somewhat less shiny than the right one. There's no comparison to front discs at all, but between rear ones,there is a slight difference. I'll post some pictures here:


RIGHT:




LEFT: (the one scratching)

[Myfeckin FTO]

You are getting uneven pad wear on the left - prob caused by a sticky caliper.
Is there much heat in the hub/wheel on the left after a drive in comparison to the right?

[Bartpabicz]

just got new brake discs and pads. Replaced the rear ones and will send them abroad to be reconditioned. I'll put them up for sale if they're in good condition after the process. Thanks for all the help and advice!