brake disc thickness

mikegti · Post by **mikegti** » Mon Nov 22, 2004 12:30 pm

Just wondered if anyone knows whats the minimum thickness allowable on the front discs of a polo gti?

Haven't measured mine yet but the rusty edge seems quite prominent. the discs arent scored or grooved but I'm wondering if they need changing.

still waiting for haynes! ("spring 2005")

workinprogress · Post by **workinprogress** » Thu Nov 25, 2004 11:54 pm

take the wheel off and behind it in a band running round the face behind the wheel should be part number /min thickness numbers
if youve got genuine discs of course and they may need a quick clean up with a wire brush.

ttaw2 · Post by **ttaw2** » Fri Nov 26, 2004 10:51 am

If your polo is a uk car, you've got 20mm thick disks to start off with, if it's an import it'll be 23mm.

If my memory serves correctly you want to change when you get down to 90% of total thickness (please correct me if I'm wrong, it's been a while since i did my disks, and my memory is a little vague as i'm only on my second cup of coffee) but you can find the dimensions followed by the minimum percentage on the disk towards the centre as workinprogress has already said. if you can't see the writing through the rust, a spot of wire wool and wd40 will do the trick.

So working on 90% Uk spec cars want 18mm minimum, imports 20.7mm

cyhliu · Post by **cyhliu** » Fri Nov 26, 2004 4:06 pm

So whilst we are on the subject on disc brakes, when do the pads need replacing? Any ideas on that, I know that they make a metallic sound when low, is this the only way to tell?

mikegti · Post by **mikegti** » Fri Nov 26, 2004 9:28 pm

thanks for the info workinprogress and ttaw2, I'l have a look next week when i'm off work.

The cars done 60,000 miles now so i'd guess if these are originals then they might need doing.

chris - if your pads start making a metallic noise I wouldnt drive much further!
A mate with a Bora heard a squealing from his rear brakes when cornering, not many miles later he heard a grinding noise and we found the pads were so low they were 'machining' the disk!

I'd guess when they get downto a few mm they need changing, the new ones always look huge in comparison!

mikegti · Post by **mikegti** » Sat Dec 04, 2004 5:00 pm

For future reference if anyone needs to know: the thickness stamped on the gti's front discs was 22.

I measured mine to be 22.7 and 22.8. I'd guess they were 24mm new, that would fit in with your 90% ttaw2.