Morris Minor Owners Club

What to get genuine master cylinder or repro that is the question

Just in case that’s not a trick question, I’ll answer by saying, a genuine one.

I ageree with Les. Be aware that some modern cylinders have a different piston where the push rod dioes not fit correctly. Compare with your original before fitting.

My understanding is that Lockheed, the original manufacturer, stopped production of master cylinders a while ago?
There may not be the choice any longer.

Thanks for your replies I will be ordering a genuine one

ManyMinors wrote: ↑Tue Oct 07, 2025 10:38 pm My understanding is that Lockheed, the original manufacturer, stopped production of master cylinders a while ago?
There may not be the choice any longer.

Yes I think you're right but ESM sell 2 different qualities of master cylinder: "original spec" and "pattern". The original spec type is compatible with original Lockheed seal kits. Original spec is about double the price of pattern.

https://www.morrisminorspares.com/brake ... ec-p829360

Given the cost of a complete new master cylinder, I would happily rebuild one with new seals subject to strict caveats. Those being, no corrosion in the bore, no lip in the bore, no scoring of the bore. In others words I would only rebuild if the problem was only worn out seals.


Stephen

Stephen - I have an old Lockheed MC that was fully operational when I removed it from a car many years ago. It might still be OK but a rebuild would be a good idea were I to ever think of using it again? I have had a MC fail when bleeding brakes, which was frustrating, as I thought the failure to achieve a firm pedal was a failure of the bleeding process and tried many times before thinking of the MC. The MC was working fine before I started bleeding the system!

myoldjalopy wrote: ↑Wed Oct 08, 2025 11:08 am Stephen - I have an old Lockheed MC that was fully operational when I removed it from a car many years ago. It might still be OK but a rebuild would be a good idea were I to ever think of using it again? I have had a MC fail when bleeding brakes, which was frustrating, as I thought the failure to achieve a firm pedal was a failure of the bleeding process and tried many times before thinking of the MC. The MC was working fine before I started bleeding the system!

Yes I have heard of the MC failing when bleeding the brakes. I believe the reason this happens is that that there is a wear ridge in the piston bore. In normal use this causes no trouble but when the pedal goes to the floor when bleeding the brakes the seal goes past the wear ridge and is damaged.

Stephen

Personally, I think given the job that a master cylinder does, even at double the price I would go for the genuine one.

You need to remember that even a small shunt could cost you ten times the price of the master cylinder, and that's if no one is injured.

Brakes are not something to compromise on.

Brake cylinders can be sleeved with brass or stainless steel. You'll have an original design with a durable surface.

They can indeed and it can be very successful. I had that done recently on another classic where a new master cylinder was not obtainable.
However, it was costly and the car was in bits and out of action for some time, so it isn't always convenient.
I would probably attempt to fit a new seal kit in my old cylinder if the bore was in good condition. If that wasn't possible I'd go for the more expensive of the 2 reproduction offerings from ESM I think.