wiinky

I have never diagnosed or repaired brakes on my 1999.5 Avant. I heard a constant squeal with my foot off the break pedal, so I thought it might be an audible wear indicator.

The front pads look fat so I pulled the right rears and noticed that the remaining frictional material thickness on each pad was noticeably different. The inside pad ( in direct contact with piston ) was 3/8" thick and outer pad was only 2/8" thick. Pad's OEM # 4D0615415.

If I place the pads together so that their frictional material is touching, I can see light shining between them. The surfaces feel rough and appear pock-marked.


Is this unusual wear and could it be causing the "squeal"?

wiinky

The parts (set of rear pads & Audi/VW piston compressor tool) arrived. So I went into action to replace both sets of rear pads. Image on left is of the left rear pads. The pad in direct contact with the piston had worn all the way down to the audible wear indicator(shiny metal), yet the other pad still had 2/8" of "material".

Upon further inspection I noticed that the bottom "guide pin" in the brake carrier carrier was frozen (See Bentley, A4, pg. R46-5). It would not move in or out(float), nor would its 15mm nut turn. This may have accounted for the extreme uneven wear in the pads. When the brake was applied the only thing that moved was the piston driven pad.

Image on right is the left, rear caliper carrier (bracket. The "free" pin just pulled right out. The only thing holding it in is the rubber boot, which was craked & degraded. The pin is coated with red powder that used to be grease. The other pin is seized.

I might try to get away with new boots, pins & grease. The pins are hard to find online.
Stay tuned.

~ ~ ~ References, front & rear brakes ~ ~ ~
https://www.audiworld.com/tech/wheel24.shtml
http://www.s2-audi.co.uk/tech_articles/rear_pads.htm
http://www.johnvey.com/features/a4brakes/
http://www.audiforums.com/forum/showthread.php?t=7865
http://wiki.rockauto.com/2001%20AUDI...20-%20Rear_0_0

~ ~ ~ Some previous posts on this problem ~ ~ ~
https://www.audiworld.com/forums/sho...php?p=18797402
http://www.s-cars.org/postnuke/modul...rder=0&thold=0

Just Me

i'm baffled - your next post is from 2005?

Pls confirm what you need.

wiinky

The first post within this current thread started off asking what was acceptable/normal for "uneven" brake pad wear. My second post describes what I've discovered about the causes of uneven pad wear and invites comments/advice from other members about their experience with the same problem.

Update Feb 17 2010

I splurged and also got new rotors & caliper brackets (pins are included).
After all, it should be good for another eleven years of neglect.