[T3] Master Brake Cylinder...

Jim Adney jadney at vwtype3.org
Tue Mar 28 08:58:11 PDT 2017

On 27 Mar 2017 at 22:43, J. Jonik wrote:

> Q.   Any way to determine best of old, out-of-car master brake
> cylinders to use to replace one that's obviously bad...leaky, etc.?  
> Awkward, messy job...don't want to just try one, then another, and so
> on. 

Yes, take each one apart. Inspect the 5 seals in each one for wear on the lip. 
Hone the bore and then feel for pits in the steel. Clean everything out and 
replace what needs to be replaced.

>    I may have 6 or more cylinders...all removed from cars ages ago
> when the cylinders worked just fine.  A couple cylinders are in thin
> plastic bags, one actually has silvery metal still on it....not just
> rusty and greasy. 

MCs which have been allowed to sit around with old brake fluid in them are 
almost never good candidates for reuse. In rare cases they can be rebuilt, 
but most of the time the exposure to air has caused excessive rust in the 
bore. You're asking to play musical chairs with MCs. This is probably a 
worse practice than the one you warn against in the paragraph below.

> PS:  Safe Driving Advice: A defunct master cylinder still stops the
> car...but nothing like it should. One is forced to keep safe distance
> from cars in front and to avoid any situation where a sudden stop
> might be needed.   This is BAD safe driving advice, but...working so
> far. 

Okay, you've been careful and lucky so far. What about tomorrow? I 
understand frugality, but at some point it becomes foolish.

If you want, you can send me several MCs. I can inspect them and rebuild 
the best one (or more than one if you like.) My terms for doing this are that I 
get to keep any parts that I've taken apart, cleaned, and inspected, but didn't 
use. Anything I didn't touch gets returned to you, along with the rebuild(s) 
you paid for.

Note that the best candidate for rebuilding is the one that's been in recent 

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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