Morris Minor Owners Club

I wonder if anyone could possibly help.

I have a 1967 minor with front disk conversion. It needs a new master cylinder so I purchased a B&B replacement off eBay.

On the origial (see photos), there is a bolt at the back which (I believe) connects to the back brakes. There is a blanking bolt on the replacement where this bolt can be inserted. The problem is that the bolts are different sizes/threads.

Any ideas on what may be the problem?
Maybe the B&B is not a direct replacement (but it is supposed to be).
Maybe the 'original' on the car is incorrect.

Thanks for help/ideas.

Mark

The bolt you refer to is the take off for a master cylinder remote brake fluid reservoir and which is not original. An original master cylinder has the plain blanking plug same as the new master cylinder.

It does not connect to the rear brakes.

The connection for the rear (and front brakes) is the lower hole in the rear of the master cylinder.

If you do not have a remote reservoir fitted just use the new master cylinder as supplied.

If you want to use an existing remote reservoir and bypass the difference in threads - just drill the new plug and solder in a piece of pipe of the same dia as the original plug.

The remote reservoir feed is only under gravity pressure so the flexible pipe can be secured with a suitable clip

Dear Phil,

thank you for your fast and positive help. I really appreciate it and it has helped a great deal.

Thank,

Mark

Be warned also that a "B&B" master cylinder is just a poor quality cheap foreign "pattern" part. My Minor 1000 had recently had a new one fitted when I bought the car some years ago. I had problems with it and threw it in the bin eventually and bought an original quality one......

As a matter of interest, does your car have disk brakes fitted? The remote reservoir is a common mod when fitting discs. It is also possible that the original rear feed has been removed and re-routed so that both front and rear are fed from the outlet to the side of the master cylinder.

The OP does say that his car is fitted with disc brakes
The other important thing is for him to remember to remove the top hat seal from the new cylinder. Otherwise he'll experience some brake dragging

what to do..... as far as i know....
take care when working on brake system
check that the old (installed) filler plug fits to the new master cylinder. In your case, It should be one without a hole. If no external reservoir is fitted, the filler plug has a little hole.
for example Charles Ware is selling it
https://www.morrisminor.org.uk/parts/35 ... -of-master

find a suitable plug with bore and connection for the hose of the external brake fluid reservoir.
for example Charles Ware is selling it
https://www.morrisminor.org.uk/parts/35 ... r-cylinder
additional adapter needed

disassemble master cylinder, remove the valve cup from the master cylinder to prevent the disc pads from binding due to retained pressure in the system. Removal of this valve has no other effect on the braking system but will cause binding if not removed. Reassemble master cylinder.

fit the connection brass banjo and the banjo bolt with new copper washers to the master cylinder.

The replacement has a filler plug fitted, this should have been supplied for a standard system, I would fit the new master cylinder after removing the top hat seal, bleed the brakes and use the vehicle.
You don't need the remote reservoir for disks if you check your master cylinder level regularly. I have had midget disks and a remote fitted for the last year but the fluid level has yet to drop.