RE: Parking brake, rear caliper

["Ian J Haseltine" <Jim_Haseltine@classic.msn.com>]

Having taken apart the calipers of my Ur quattro, this is how I THINK they 
work -
The self-adjuster is a threaded rod about 2.5 inches long, threaded for about 
2 inches.  As the pads wear, the piston gradually rotates around the rod so 
that it moves towards the brake disc. Applying the handbrake makes the caliper 
handbrake lever rod rotate and a cam-shaped cutout presses a small (half inch) 
rod against the base of the self-adjust rod, forcing the self-adjust rod and 
piston unit out towards the disc. When released, the s/a rod and piston are 
returned by an internal spring. The caliper handbrake lever is aided in its 
return by the external spring.

The small (half inch) rod suffers from major wear and IMO is your problem, as 
you say that the handbrake lever is moving half an inch. If it was the lever 
or its pivot, the whole thing would be solid. The small rod is not available 
as a service part and rebuilding a caliper is a PITA and the success rate runs 
at about 10%.

Replacement calipers are 120GBP in the UK.

Jim Haseltine
88 Ur quattro


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From: 	owner-quattro@coimbra.ans.net on behalf of FMARTIN
Sent: 	12 September 1997 16:12
To: 	Q-List
Subject: 	Parking brake, rear caliper

Hi all.

The parking brakes on my 100Q haven't been working for a while, 
I've traced the problem to the right rear caliper (Girling, I 
believe). The p-cable is working on the actuating lever alright, 
but the lever moves about 1/2" and stops solid, with no effect on 
the piston at all. I've used vice grips on the lever, same 
effect.

I assume something is wrong inside the caliper assembly. Anyone 
have experience with the innards?  Can one fix it, or does one 
end up buying a new or used complete caliper assembly?  I just 
called SHOKAN, and was quoted $145 +shipping.

Thanks for any insights.

Frank M. 
'89 100Q
'88 Mazda 323 GTX