Brake fluid leak at Master cylinder

todds112 · Post by **todds112** » Fri Jul 06, 2007 7:03 pm

I am leaking fluid between the MC and the vacuum booster. Is there a seal or a gasket there, or is this a MC rebuild situation?

todds112 · Post by **todds112** » Fri Jul 06, 2007 7:07 pm

OK found this pic, so I'm thinking the o-ring pictured might be bad?

If I pull the MC to replace this, will it require me bleeding the entire brake system afterwards?

mjnims · Post by **mjnims** » Fri Jul 06, 2007 7:18 pm

More likely the cups are giving up the ghost. A rebuild kit is available from SAV part #7103366020/ They are not all that difficult to rebuild and yes a full bleed is recommended when opening the brake system.

todds112 · Post by **todds112** » Fri Jul 06, 2007 7:42 pm

I was afraid of that.

Jim LaGuardia · Post by **Jim LaGuardia** » Fri Jul 06, 2007 7:53 pm

Scott has the complete master for $85 http://www.expedition-imports.com

todds112 · Post by **todds112** » Fri Jul 06, 2007 9:35 pm

Hmmm, $69 for a rebuild kit, or $85 for a whole new one. What a tough decision.

Profpinz · Post by **Profpinz** » Fri Jul 06, 2007 9:40 pm

The master is relatively simple to repair but when I originally rebuilt my 712, I took the effort to stainless steel line ALL the masters and slaves (6 masters, 13 slaves)

Although the component bores are hard chromed, the problem is that over the years water in the brake fluid tends to get through "pinholes" in the chroming and eat out under the surface leading to leakage etc.

Stainless steel lining (and silicon brake fluid) has alleviated these problems.

todds112 · Post by **todds112** » Fri Jul 06, 2007 11:31 pm

On a related note, do you have to have the $50 tool to bleed the front brakes?

Jim LaGuardia · Post by **Jim LaGuardia** » Fri Jul 06, 2007 11:50 pm

No, a deep socket works fine.

milesdzyn · Post by **milesdzyn** » Sat Jul 07, 2007 2:41 am

Peter....when you had the Stainless lining put in how was it done? What thickness of stainless material did you end up with for the bore. Not thinking about it right now but maybe for the next rebuilds. Got any Pics.

Miles

Profpinz · Post by **Profpinz** » Sat Jul 07, 2007 9:10 am

G'Day Miles,

I can't say I know the exact machining process as most brake shops here send them out, but they do have a 24 hour turn-around time for doing it.
Take your old slaves and masters in one day and they are usually back, sleeved the next.....you just have to repaint them and reassemble.
I guess I could have set all the parts up in the mill myself and then pressed SS sleeve's in, but it was easier (and probably cheaper) to let the pros do it .... they only cost about $35 Aus each (...but that was a few years ago!

)

The stainless steel "sleeve" itself looks about 2.5-3.00 mm thick, but of course the bore is still the same as the original diameter.

Pics....Hmmm...I don't think I've got any showing that exact detail, but I'II have a look........Unfortunately, you can't really see much