Replaced the rear brakes on my Fabia VRS a couple of days ago. Used Mintex discs and pads for £37 from the local factors.

Anyway, today I had a close look at the old discs to find out what the corroded lip was all about, and found out some fairly interesting facts. Old brakes were grinding something chronic, so it was worth the money to fix that alone.

New discs are 9mm thick with a wear limit of 7mm. The discs I removed measured 8.4mm thick (35,000 miles) yet had a horrendous lip at the edge. This lip measured 12mm thick! The lip chipped off with gentle taps from a toffee hammer and sanded down well to leave a fairly new looking disc.

Conclusion. Modern pads use some metal particles mixed in with the non asbestos linings. I believe it is these metal particles which cause a lip to build up, as opposed to actual disc face wear. Not helped by the fact, the pads don't sweep the full disc area.

I reckon the way to avoid this, is to strip the rear brakes down and clean down the outer edge of the discs every 10,000 miles.

I also ran into one seized 8mm hex bolt that holds the caliper frame to the rear axle. Heated it, froze it, soaked it in plus gas, it wasn't for coming out and eventually the hex rounded off. Had to break out the angle grinder and grind down the bolt. Strangely my local dealer didn't have the bolt on stock, but local VW dealer did

interesting moggytech, are you saying the lip build up is pad dust being thrown onto the outside edge of the disc, if so how does it stick the disc?

interesting moggytech, are you saying the lip build up is pad dust being thrown onto the outside edge of the disc, if so how does it stick the disc?

I would say combination of magnetic forces and road crud, especially salt. Obviously my old discs had a 0.6mm genuine wear lip, but that nothing on a disc that is designed to wear by 2mm.

its just rust build up, i have been saying for ages its worthwhile knocking it off every now and again, stops the grinding and sometimes the squeak that can occur as the pads touch the disc

my rear discs are the originals at nearly 80k

so your saying the pads dont contact the disc fully ? (centre to outer edge)

thanks for that nugget of info as its been bothering me ever since i bought my car but ive never stripped it down to have a look

so your saying the pads dont contact the disc fully ? (centre to outer edge)

thanks for that nugget of info as its been bothering me ever since i bought my car but ive never stripped it down to have a look

Width of the pad is about 4mm smaller than the face of the disc. The pad does need to be slightly smaller than the disc to avoid brake snatching, but the VRS pad setup looks to be a bit too small at the outer edge.

its just rust build up, i have been saying for ages its worthwhile knocking it off every now and again, stops the grinding and sometimes the squeak that can occur as the pads touch the disc

my rear discs are the originals at nearly 80k

You are meant to find this task very satisying - as long as you wear protective googles, or feel really lucky! I agree a good clean up every 6 or 12 months stops a lot of brake problems.

If you have a mate with a lathe, it's a 2 minute job to skim the edge flat. I did all 4 on mine and they're like new now

Rick