Girling master cylinder leaking, advice desired!

[Cueball1]

George Hillards old Birkin has a Girling .75 master cylinder leaking.  I've disassembled it and the bore looks clear and unmarked.  I am planning to rebuild it.

 

The question is...

 

This car has 3 of these same units.  Front brakes, rear brakes and clutch.  The car has only 8k miles but is right at 20 years old.  Should I go ahead and rebuild the other two that are still good, figuring it was maybe age that caused the failure?  Or would I be making unnecessary work for myself?  

[CarlB]

I would rebuild them, and the calipers. 

[IamScotticus]

If the master is a TRW PMC146 (GMC226TRW) buy new and replace

Edited April 26, 2024 by IamScotticus

[Cueball1]

They are genuine Girling remote reservior units.  The girling part number looks to be 64067620.  Took one off and disassembled.  Bore and piston looked good.  I think it's just deterioration of the 20 year old rubber gaskets.  Have the parts to rebuild in hand.  Fingers crossed it works!  

Same unit as this...

 

https://www.merlinmotorsport.co.uk/p/girling-master-cylinder-remote-3-4-inch-bore-64067620-gmc-12-r

[jbcollier]

IF:

- the bore is clean, smooth, free of any signs of scoring, and;

- the piston is perfect, no marks whatsoever, and no measurable out-of-round;

then, by all means, rebuild the cylinders.

 

If the rubbers in one went, then all three are due.  Any signs of wear on the bores or pistons, replace them instead.