[200q20v] Re: Need some advice with rear caliper

[Bernie Benz]

Kneale,  I'm glad to see that there is someone else that is willing to go
the last mile to understand the caliper design and solve a problem.  Your
discription of the PB internals jogged my memory, that years ago I had done
so on a 5KQT.

Maybe some of our profesional wrenches have, but I have never seen a caliper
leaking brake fluid around the PB activation lever rod. Thus, this rod seal
is not prone to leak and, if it did, the leakage would be outward, not
inward. Therefore, any rust and krud within must have been caused by dirt
and moisture in the brake fluid, not by external influences.

IMO, an internally clean caliper (and total brake hydraulic system) that is
flushed with new brake fluid at least biannually will last indefinately.
BTDT, disassembly after 8 years showed internals still spotless and fully
operational.  Thus, my MO with any "new" used car is a full brake hydraulics
overhaul, after which it is good for the life of the car, with fluid
changes.

Regards.

Bernie  

> From: Kneale Brownson <knotnook at traverse.com>
> Date: Mon, 26 Feb 2001 15:45:54 -0500
> To: Bernie Benz <b.m.benz at prodigy.net>, Peter Schulz <peschulz at cisco.com>,
> <cahki at lav.boehringer-ingelheim.com>
> Cc: audi-20v <audi20v at rennlist.org>, 200q20V mailing list
> <200q20v at audifans.com>
> Subject: Re: [200q20v] Re: Need some advice with rear caliper
> 
> I took one of my old 200q20v rear calipers apart after I bought new ones to
> solve the half-a-year-long problem I had with the caliper hanging up
> despite all the routine services.   There is an internal C-clip at the base
> of the rod the piston screws onto that, if removed, permits removal of the
> threaded rod.  Beneath that you'll find a small peanut-like rod that fits
> into a cavity machined in the rod to which the parking brake activation
> lever is afixed.  You need to get the peanut out in order to remove the
> parking brake activation lever and its rod.  If the internals there are
> rusty, you probably need a new rubber seal that goes around the parking
> brake activation lever rod where it fits into the caliper body.  You'll
> also need to clean up the rust in the rod and the cavity part of it, as
> well as in the housing in the caliper.  A 5Ktq caliper I took apart to try
> to figure out how to get the 200's caliper apart had a very rusty
> chamber.  That car's parking cable had been cut off years before.  My 200
> didn't have any rust on the peanut/parking brake activator rod area, and
> the parking brake lever moved relatively freely, but the brake piston
> didn't draw back into its cylinder.  The inside of that cylinder had some
> small rust spots in several locations, and I suspect that it's that rust
> that kept the caliper from working properly.
> 
> 
> 
> At 09:33 AM 02/26/2001 -0800, Bernie Benz wrote:
> 
>> I have never had to remove the parking brake piston advance screw from the
>> caliper, so don't know if it is possible.  But, with the piston out of the
>> caliper and everything cleaned up, one can work the cam to be sure that it
>> is free and easily returned by the return spring, after adding external
>> lube.  I would not attempt to remove the cam and advance screw just for fun,
>> unless they could not be freed by the above method.  If this internal
>> cleaning of the caliper does not free up the PB release problem, more likely
>> it is in the cable system.
>> 
>> Bernie
>> 
>>> From: Peter Schulz <peschulz at cisco.com>
>>> Date: Mon, 26 Feb 2001 10:44:25 -0500
>>> To: cahki at lav.Boehringer-Ingelheim.com
>>> Cc: b.m.benz at prodigy.net
>>> Subject: Re: Need some advise with rear galiper
>>> 
>>> At 03:07 PM 2/23/2001 -0500, you wrote:
>>>> 
>>>> Dear Peter C. Schulz,
>>>> 
>>>> I saw you posted a message on how to fix the VW Rear Caliper sticking  in
>>>> web page 20v.org/20v/brakprob.
>>>> My rear Caliper is sticking, the shaft axle is rusted and I want to
>> take it
>>>> out to remove the rust.
>>>> I take out the piston but I still can take the shaft out. Do you have any
>>>> idea how to take(remove) the shaft out?
>>>> 
>>>> I would appreciate greatly if you could help me out about this matter.
>>>> Claude
>>> 
>>> Claude:
>>> 
>>> Based upon your description, I cannot tell whether you are having an issue
>>> with the caliper guide pins sticking, or the parking brake.
>>> 
>>> If the caliper guide pins are sticking, you need to remove them from the
>>> caliper, carefully remove the rubber boots, and polish the pins on a bench
>>> grinder/polisher.  If they are too rusted, you may need to replace them.
>>> 
>>> If the issues is tied to the parking brake, I removed the cable on the cam
>>> which connects to shaft which is indexed to the caliper piston, I turned
>>> the piston all of the way into the caliper, then used a screwdriver to help
>>> pry the shaft/cam away from the caliper body -about 1 -1.5 cm.  I then
>>> polished the shaft with some emory (sand paper) sprayed it liberally with
>>> rust remover and let it dry.  Before putting it back to together, I applied
>>> heavy duty brake grease to the shaft before working the cam back and forth
>>> to its limits and reinstalling the parking brake cable.
>>> 
>>> I've included Bernie Benz in this email, because he has taken this one step
>>> further by completely rebuilding his brake calipers, therefore he has a
>>> much better understanding of the internal workings of the caliper.  Bernie,
>>> can you comment?
>>> 
>>> Hope this helps!
>>> 
>>> 
>>> Peter Schulz
>>> 1990 CQ
>>> 1991 200 20v TQW
>>> Chelmsford, MA USA
>>> peschulz at cisco.com
>>> 
>> 
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>