My Audi has developed a braking problem. The brake pedal will go to the floor intermittantly, losing brake power and weaves badly. Its not losing brake fluid. I suspect its an ABS fault ? Any pointers please ?

Cheers

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My bet would be the brake master cylinder. I have had that happen on various vehicles in the past.

 

Update.
Last Weekend I got round to having a good look at the brakes and discovered the whole problem was down to the nearside rear caliper not releasing properly ! The piston had pushed right out destroying the inner brake pad ! With this stuck right out it must have caused some kind of vacum which drew air into the system.
Stripped all calipers and serviced them then bled the whole system and brakes are good as new : ) No pedal vanishing to floor intermittently since.

Cheers

Gaz

 

Make sure that your parking brake works properly. I had similar problem with my 1991 100Q where the parking brake wouldn't release causing the pad to wear out much quicker. It is a very common problem with the rear calipers. Was it the one on the passenger side? The parking/emergency break mechanism has a tendency to accumulate water and binds from rust. It is tricky to disassemble and put back together. The problem is that there is a seal that Audi doesn't have a PN on the parts list and it doesn't come with the caliper rebuild kit, requiring you to buy a whole caliper. The fix is simple at least on my car, this seal is also used on the 1985 Audi Quattro Coupe gear selector it is 16mm X 26mm X 6.5mm. Sure beats paying $450 for a new caliper.