drscrote

Hi guys. New member here.

First up a confession. I've been meaning to fix the brakes on my car for a year since I bought it, as the discs from day one had slight cracks around the drill holes. Still pulled up okay though, so put it on the back burner. The weather here has been rotten in the UK too, and this is the first warm weekend.

I promise never again to skip a safetly issue!

Here's the problem. I think it all boils down to stuck pads, caused by corrosion in the caliper behind the stainless pad guide. Help me fix it!

This is the terrible looking inner face of the disc. Pistons all move fine, but upper inner pad was very tight to the guides and pad not moving. Lower one not so tight so can't fully explain the wear pattern.



There is obvious corrosion where the upper steel pad guide meets the caliper - the paint is bubbled, and raised up. The guide looks to have been displaced downward by 1mm or so, I simply can't get the new pads in. I suppose I could but then I'd still be in the same boat with stuck pads.

Crappy phone pic after I removed the bubbled up alloy and paint.





I'm wondering if I have to remove the steel guide (what size bolt is that?) and file the caliper back to good metal, repaint etc, or if there's any other options.


In the past in other cars with sticky pads I've filed a bit off them, but the E55 ones have metal backing plates that would need removal and reshaping also so a bit more complicated.

Or am I barking up the wrong tree?

Yes I am being careful with the SBC.

drscrote

Got it all working.

Decided to file back the pad backing plates to fit the calipers.

So pulled off all the shims glued to the back of the pads, filed to suit, then replaced the shims and rebent them to fit. Had to take a couple of mm off the worst ones.

I figured better to muck about with the pads rather than mess up an expensive caliper. I fear the calipers will continue to corrode though so this may recur - I'll keep an eye on the disc wear this time.

I had a look at trying to get the stainless pad guides off the caliper. There's three small bolts with allen heads, prob 3mm or so. I don't think I'd get them off easily, so can't at this stage without a major caliper rebuild see that this is repairable.

Plugged in SBC, got through a couple of error messages, restarted, now all good and succesful test run.

Was just using OEM spec Brembo pads

pearlpower

I have seen several THOUSAND brake rotors in my life; even some completely wore down to the grooves-and they still drove with them, but none like that! Gheesh, glad you got it fixed.

drscrote

I was horrified when I saw the backs of the rotors too. The car was stopping fine, I was doing the change as there were some small cracks appearing around the drill holes on the front faces. The front faces were nice and even, thickness was ok.

I shall be keeping a close eye on this from now on!

My theory is still that corrosion of the calliper has progressively squeezed the pads so they no longer move. This is going to continue so will need a definitive cure, which will be to get the steel pad guides off, grind back the corroded ally to good metal, repaint it, replace with new guides. The guide retaining bolts are tiny and probably corroded in.

Or stump up for new callipers.

Celicasaur

Something tells me I'm going to see something similar when I replace my discs in a month or so.

drscrote

Did rears last week. No dramas, 1/2 hr per side. Fronts were a pain compared.

The UK forum guys say this is common on 911s with brembos too. The fix is (as I guessed) to take the plates off, file back the calliper, and repair. My cludge of grinding back the pads will only keep me going so long.