1990 80 G54 rear emergency brake mechanism

[Kneale Brownson]

I think the parking brake system actually applies a mechanical pressure on the caliper piston, bypassing the hydraulics.  When the hand lever pulls the cable, the cable pulls the actuator lever that turns the rod on its other end, where a football-shaped object rides in a concavity and gets pushed outward to apply pressure on the rod onto which the piston is screwed.

Sent from my iPhone

On Jul 15, 2013, at 7:58 AM, "urq" <urq at pacbell.net> wrote:

> While I agree that changing fluid may have little to do with it, I will
> disagree with the statement that the e-brake has nothing to do with the
> hydraulics.  In effect the piston for the e-brake forms the back of the
> brake cylinder, and is very much involved with hydraulics.  The rear piston
> has a seal that can become sticky, and in effect the back side of the
> caliper is a piston (without a dust cover) for which the bore it slides
> through can get contaminated.  
> 
> I thought Kneale hit the nail pretty firmly on the head.  
> 
> Used to think that the fact that so many people don't use their parking
> brake leads to the mechanism seizing, but even out here in temperate
> California, over time the mechanism can get dodgy ...
> 
> Steve Buchholz
> 
> -----Original Message-----
> From: Cody Forbes
> Sent: Sunday, July 14, 2013 9:20 AM
> To: Project Pat
> Subject: Re: 1990 80 G54 rear emergency brake mechanism
> 
> Unfortunately changing the brake fluid gas nothing at all to do with the
> parking brake. The parking brake side of the caliper is insulated from the
> hydraulic side and has no brake fluid in it.
> 
> -Cody Forbes (mobile)
> 
> On Jul 14, 2013, at 12:02 PM, "Project Pat" wrote:
> 
>> 
>> I have seen many VAG products from this vintage with all kinds of 
>> crap(rust) in the caliper bores.
>> Most people don't change brake fluid every 2-3 years, and this happens.
> 
> _______________________________________________
> quattro mailing list
> http://www.audifans.com/mailman/listinfo/quattro
> http://www.audifans.com/kb/List_information