4 replies to this topic

[Will16]

Rebuilding my brake master this afternoon, I believe it's the original 1976, 0.70" bore, single line, bean tin stylee one. Bought a Rebuild kit from minispares, but when it's come to swapping the bits over the rubber and thin metal washer parts are completely different.

The original, at the bottom, has a metal washer, then a rubber, then a plastic thing for the spring to sit in.

The bits supplied are another metal washer (wrong shape too) and a rubber, but it doesn't match at all.

Am I missing something obvious here?!

[slidehammer]

I am sure that by 1976 they were using the diagonal split master cylinders, rather than the single line master cylinder. I think I would cut my losses and buy a new master cylinder as I have had a rebuild kit fail and I have done loads over the years. Luckily it was for a dual line brake so the car still had front brakes that worked. But with a single line system it doesn't bear thinking about. Also I think most would agree the quality of new rubber components is substandard compared to old.

[tiger99]

Be sure to get a known and reputable brand of rebuild kit, and only use it if the cylinder bore is perfect. Hydraulic systems are totally unforgiving as regards scratches or corrosion, and nothing except major brands of new stock, never "new old stock", should be used. OK for some things, but not brakes.

If the car is of an age where a dual line system is required and someone has converted it to single line (it really does happen, and on this very forum) it is probable that the car is illegal under Construction and Use Regulations and the insurance is probably void too. There are inevitable consequences when mandatory safety systems are removed.

The "bean can" was only used until 1975, which would have been not long before dual circuit systems became a legal requirement. I have not found the exact date yet.

[Spider]

There were Two types of Master Cylinders being fitted around that time.

 

The way to ID them is on the Section of the Main Body below the Reservoir one type is plain, the other has a single groove machined in to it.

 

Kit Part Numbers are 50957 for the Plain type and BAU1247 for the one with a groove. You may have to go to a Brake Repair supplier for former, as I'm not sure that the Mini parts suppliers generally keep them.

[Will16]

The car is the last of the mk3's, twin bolt frame, etc, so I'd expect it to be original. I'll just buy a Cooper s style master, there goes the budget