1990 80 G54 rear emergency brake mechanism

[Kneale Brownson]

If the hydraulics aren't shining up the rotor, you have a couple of 
issues with the caliper.  First, the piston isn't pushing the brake pads 
against the rotor when you're braking.  Most likely, the pins the 
caliper ride on are too corroded to let it function.  These need to be 
cleaned and relubed or replaced.

Second, you have a leaking seal around the parking brake actuator lever 
(#4 in the illustration in this link: http://www.20v.org/brakere.htm ).  
That lets the lever (#3) and the inside of its housing become corroded 
as in the photo at the bottom of the link.

If you're really into it, the best approach is a rebuild, as in: 
http://forums.audiworld.com/showthread.php?t=2770104

The slacker approach to the parking brake issue is to disconnect the 
cable from the lever arm, remove the spring, spray the seal area 
repeatedly with penetrating oil and work the heck out of the lever until 
it moves smoothly.  A month later you may be doing the same thing 
again.  As you can see from the links, the whole lever arm becomes 
corroded on both sides of the seal.  The chamber into which the actuator 
goes is filled with a high temperature paste.  I've seen that paste, 
which is sort of a clear-white like petroleum jelly, turn rusty red.

On 7/14/2013 1:25 AM, Al wrote:
> Hi guys/gals,
> I have noticed that one of my rotors on the rear is not shiny, at least not a shiny as the other side. I use the parking/emerg handle when I park the car. I lay behind the rear wheels and watched the parking brake being activated. One moved a lot the other very little and when released the good one opened or unclamped quickly, not the other.
> I have looked in the Bentley but nothing about that section of the caliper.
> Is there a way to grease or lube the pin that goes into that parking brake assy?  Is there a bearing involved?
>
> Any BTDT or directions to a manual?
>
> Regards,
> Al
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