Parking brake 4000 quattro

[Huw Powell]

I think the problem is the rear caliper piston not being "unwound" back 
to the proper rest position for use.

After removing the caliper to play with rotors, pads, whatever, the 
piston is usually screwed back into the caliper to clear the "new meat" 
for reinstallation.

The proper "rest position" is when the pads are barely off the rotor, 
then the ebrake lever only has to move the pads a "barely perceptible" 
amount to grab the rotor.

This rest position is achieved by a series of reverse/forward braking, 
ie, back and forth in your parking lot/driveway until the rears wind in 
enough to make contact.  During this time the ebrake is not engaged, 
since it wouldn't work anyway.  You can usually tell when the rears are 
in the right place, because pedal motion shortens and braking 
effectiveness improves.

hope this helps...

> Ben: Not sure if it is like the 200 I just did.
> The rear caliper piston was sooooo far out bacause the pads were down to the 
> backing plate.  But the cam lever still pushed the piston outwards when 
> ratcheted out by my thumb.
> After pushing the piston back in and installing pads I couldn't "thumb" 
> ratchet (the cam) up the slack to engauge the piston to the pads.......... so the 
> rotor got rusty from the lack or "squeeze".
> The fix I found was lots of driving with HARD pedal application over 400 
> miles. ( track day too :-) ) which finally pushed the piston out to meet the pads 
> along the rotor.
> 
> I have no idea why.

>>I am in process of checking/installing calipers to fix 4000 quattro rear 
>>caliper that is not pushing the piston out when the lever is turned - either by 
>>hand or with the cable.
>>
>>I took a good caliper off a 5000 q - worked fine before taking it off.  
>>After installation and bleeding, the piston doesn't push out anymore.  Now I have 
>>scrounged up several of these, and they seem to have the same problem.  
>>Perhaps something with removing the piston and cleaning and installing good seal 
>>has  made one stop working.  
>>
>>What is causing this?  how come the parking brake portion of the caliper 
>>stops working, even though the lever moves freely?  Moving the lever results in 
>>no or barly perceptible movement of the piston.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/