Hawkeye D

Hi all,

2007 STi.
Wondering if anyone can shed any light. Below is my NSR brake disc. Almost brand new genuine Brembo discs, but I can see uneven wear starting to appear. The OSR is fine and wearing evenly.
You can see from the close up that the machining grooves are virtually gone on the section of wear nearest the hub, it's almost like only half the pad is truly biting on the disc?

Is my outer pad perhaps hung up on corrosion inside the caliper? I can't see the inner side of the disc because of the stone guard, I'd have to take the caliper off to check that.

What do you reckon? Maybe the pad is pivoting on the retaining pins rather than sliding, or perhaps the piston is pushing out at an angle?

Vxr2010

subaru brakes need refreshing every so often , take the wheel off remove the pads , the pads may have got stuck and that could be your wear issue , there
are a few pads i fit that i file some of the back plate off , it’s only a few mm and sometimes it’s paint removal , so not so tight in the calliper allows the pads to move more and therefore not get stuck 👍😁

Hawkeye D

Thanks VXR, my backings have like a rubbery texture and a metal shim. Do you mean rub down the edges of the backing plates?
I did clean them recently and re-grease etc, but now maybe time has come to get the sandpaper out....

Vxr2010

you need to check the pads have free movement in the callipers , the free movement including where they contact the disc 👍😁 i’ve filed pads down before , if you are pushing the pads in to the calliper with some force then they are too tight 👍

Hawkeye D

Ok, just taken the pads out, cleaned the granny out of where they sit in the caliper.
Sanded the holes in the pads where the pins go through, sanded the edges of the backing plates down. Plenty of free movement.

Enough grease on the pins. I did see pitting and corrosion on the pins which I did my best to rub down, but they are perhaps on borrowed time, we'll see.....
Once I put the R clips through the holes in the pins, I moved them side to side to get the pins lubed in.

I can't really do any more than I've done tonight, only new pins if needed.

Hopefully that's sorted it, will report back in due course...when the.... lol

Vxr2010

were the pads stiff/tight in the calliper before you removed them ? if that does not work next thing is look at the calliper , i’ve not heard of brembo callipers being an issue , i expect they rarely fail , to test them i would create a gap between the pad and disc then push the brake pedal down to see if they are sticking , my money is on stuck pads as i’ve had that before 👍

Hawkeye D

It's looking like it was a stuck outer pad. Been out for a long spirited drive this evening, and the machine grooves are already starting to shine up and blend with the rest of the face.
I've never had this issue before, but I really hadn't used much grease when I cleaned out the pads a few months ago as it turns out. I was probably paranoid as too much grease isn't a good thing, but too little wasn't either.

I did manage to get sight of the inner side of the disc and that's wearing nice and even, but gave both pads identical treatment.
I'll probably go for 4 new pins soon as they are 15 years old, once I start not spending money on detailing products...it's an addiction, a problem, an illness!

I want to do front pads and discs soon, but I'm worried the caliper bolts will shear on me....Len Carlyon might get that job...he just doesn't know it yet

Vxr2010

sounds like the problems solved 👍😁 the front bolts tend to pull the thread of the calliper out , i’ve only had it happen once after years of servicing , i bought a helicoil kit , the calliper was left attached , i drilled then helicoiled it no issues since , mtec brakes discs are very reasonable , don’t get drilled ones more prone to cracking , yellow stuff ebc pads will have a big impact on your braking , or black diamond predator are good and cheaper , ebc appear to work better which is my preferred pad 👍

Gambit

iTrader: (6)

lack of grease isnt the cause. its a combination of the pad backing plate edges and pad guide plates on the calipers. corrosion starts behind the guide plates which in turn pushes the plates up slightly causing the pads to then start to bind - remember the pad backing plates will also expand slightly with heat.

so easy fix is to shave the backing plate edges so that it is a loose fit into the caliper - which you've done

id be very careful with your fronts if youve never had them off before - they will in all likelihood strip the threads - so either be prepared to helicoil or at least be able to take them somewhere to get a helicoil fitted for you

pic of guide plates on caliper

Vxr2010

another reason for the thread issues a steel bolt in to aluminium , metals re act , over tightening , crud getting on to the end of the bolt then get pulled through the thread , damaging the thread , helicoil kits are cheap and not that hard to do 👍😁