So I started the task of replacing the rear discs and pads today. They were squeaky for the past month or so and thought it best to change.

I always noticed uneven rusting where the outer edge of the disc didn’t appear to be contacting the pad. I presumed whoever put the pads on used the wrong size. However, I noticed the pads are the right size. See the photo below of the outer radius, fully corroded, and the brake pad adjacent.

Any ideas what has caused this? Is there something wrong with my calliper assembly? With new one on, after small test drive, it appears same issue is occurring (see other photo). Close inspection of the pads makes them appear to be at slight angle with outer radius of pad further away from disc

Thanks for any help!

Car is a 2002 L322 3.0 TD6 (automatic)

EDIT: I should also mention, corrosion of the outer radius of the disc is on both sides of the discs

Thought about this the past 30 minutes; perhaps this is due to the pad not sliding on the calliper? The calliper mount which recesses the inner pad legs was severely corroded so I filed and wire brushed the sliding areas well - but of course the calliper itself is harder to take into the workshop/place in a vice! Perhaps I should throughly clean and file this sliding region better? Perhaps the pads are literally getting stuck on this part?

It is possible that the slider/pad guides are rusted and are holding onto the pads.
Check the guide pins as well for excessive wear or even a tilting of the caliper.
Maybe fit the caliper without the pads and check the calipers are parallel to the new disks.

Unless someone removed them, it appears that my early model of calliper mount didn't come with the spring-loaded guide pins to prevent tilting of the pad! But I believe they prevent tilting along the long-axis (i.e. vertically) whilst my tilt appears to be along the short axis (i.e. radially). Great tip about fitting without pads to check they're parallel! I'll do that and give the calliper a thorough wire brush and file along the guides.

Just need to work out a way of securing clamping it/mounting whilst having the guides accessible!

If in doubt, sling em out! Let us know how you get on

GladystheL322 said:

Just need to work out a way of securing clamping it/mounting whilst having the guides accessible!

Click to expand...

Remove caliper. Then remove discs. Refit caliper to the mounts. Then on most cars you can wire brush, clean, etc.

Used this method on lots of different cars. It also makes it easier to do the piston wind-back.

Thanks for the replies gents

I did do as @pwood999 suggested in the end, and cleaned up the guides - significant rust across them, it was clear they were pinned on the guide rails!

See photo below, much cleaner now and pad glides freely. It appears to have solved issue with the non-uniform wear and the full disc area is braking; brakes feel way sharper!