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Joined: Jun 2017
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After totally overhauling the front and rear brakes, I was able to successfully bleed the rear brake circuit and the rear brakes work well. The front brakes are a diffent story - despite bleeding out the air, no brake pressure is generated to operate the pistons.

I have the original Girling tandem master cylinder type 68663 and surmise that there must be some internal leakage around the first piston. This master cylinder is now obsolete but I have been able to source a seal kit (Part No. SP2486) but wonder how difficult it will be to successfully replace the seals. My car is low mileage so I am hoping there will not be too much internal wear.
Does any one have a diagram of the internals or advice on how to do this job? Alternatively recommend an aftermarket master cylinder.
Thanks in advance

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Originally Posted By Snowteck
After totally overhauling the front and rear brakes, I was able to successfully bleed the rear brake circuit and the rear brakes work well. The front brakes are a diffent story - despite bleeding out the air, no brake pressure is generated to operate the pistons.

I have the original Girling tandem master cylinder type 68663 and surmise that there must be some internal leakage around the first piston. This master cylinder is now obsolete but I have been able to source a seal kit (Part No. SP2486) but wonder how difficult it will be to successfully replace the seals. My car is low mileage so I am hoping there will not be too much internal wear.
Does any one have a diagram of the internals or advice on how to do this job? Alternatively recommend an aftermarket master cylinder.
Thanks in advance

It's an easy enough job. There's plenty of stuff on doing it here:

http://www.gomog.com/BLAIR/tech/mbrakes/art010_1.html


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A pretty straight forward job but just double check the condition of the master cylinder bore before you put the new seals in.

The reason I say that is I've had a few tandem cylinders in with very badly rusted bored which would have ruined a new seal kit in next to no time.

Fortunately, Classicar Automotive in Cheshire put a stainless liner in it and pressure tested the cylinder for me.

Arwyn

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Give Terry Foxon at G.E.E a call
He normally has the PMA100 Master cylinder on the shelf

Simon @ SiFab.co.uk


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Originally Posted By SimonH
Give Terry Foxon at G.E.E a call
He normally has the PMA100 Master cylinder on the shelf

Simon @ SiFab.co.uk

Which way do the brake lines exit from that when viewed from the back of the car?


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Originally Posted By tmg513
Originally Posted By SimonH
Give Terry Foxon at G.E.E a call
He normally has the PMA100 Master cylinder on the shelf

Simon @ SiFab.co.uk

Which way do the brake lines exit from that when viewed from the back of the car?


Towards the centreline of the car if I recall correctly
Tandem cylinders were all the same from 1971 (ish) through to 1993 (ish)

Simon @ SiFab.co.uk


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Originally Posted By SimonH
Originally Posted By tmg513
Originally Posted By SimonH
Give Terry Foxon at G.E.E a call
He normally has the PMA100 Master cylinder on the shelf

Simon @ SiFab.co.uk

Which way do the brake lines exit from that when viewed from the back of the car?


Towards the centreline of the car if I recall correctly
Tandem cylinders were all the same from 1971 (ish) through to 1993 (ish)

Simon @ SiFab.co.uk

My '72 which uses the same seal replacement kit as Snowteck's exits the other way and I'm guessing he has the same as me. It's obviously not a big deal to re-route the pipes but it's just as well to know what you're getting into.


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Yes, my 76 4/4 is RHD and the pipes exit towards the o/s wing valance with short lengths linking to what I assume are the the brake light switch mounted on the bulkhead from the primary (front) circuit - closest to the brake pedal - and the secondary circuit links to the rear of a manifold assembly mounted on the o/s wing valance adjacent to the master cylinder. There is a link from the brake light switch to the front of the manifold assembly and I guess the dual brake switch mounted in the centre of the manifold monitors the differential pressure between the two circuits. So if I re-connect the battery I will be able see if the brake lamp on the dash illuminates to show the master cylinder fault ( with the handbrake off)
Thanks for your suggestion re. GEE - will call them in the morning.

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Thanks Arwyn - will make a start removing the master cylinder in the morning


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