MG Car Repair: 1954 MGTF Brake Master Cylinder, brake master cylinder, chassis number

Question
Barrie. I am restoring a 54 tf fitted with front disc brakes. I have had the master cylinder, booster, front calliper's and rear cylinders fitted with stainless liners and reassembled by the brake specialists who did the stainless liners. My problem is that when pumping the brake pedal the brake fluid is seeping out through the air vents in the master cylinder filler cap under a reasonable amount of pressure. If the cap is left off a squirt of fluid will travel up to a meter high when the pedal is pumped. The pedal needs to be pumped to obtain a full pedal and appears to hold the pedal height. The car was manufactured for Australia. Any suggestions to solve this problem would be greatly appreciated. Many thanks.

Answer
Hi George.  

The master cylinder should never spurt fluid upwards.  Sounds as though it is shooting out of the return port.  If the master cylinder is correctly assembled, the return port gets covered by the main cap after it has moved about 1mm.  If you have a workshop manual, have a look at figure M2 on page M4.  You can just make out the small vertical drilling of the return port.

I am also concerned that the capacity of the front disc callipers is much greater than that of the original 7/8 cylinders.  You will need to keep a close eye on the fluid level in the master cylinder.  Personally, I would fit a remote reservoir.  Such a kit is sold by the Morris Minor Centre here in the UK.  Fitting it involves replacing the filler cap with a sealed cap, which would also fix your problem of seeping brake fluid, although I think you have an assembly problem with the master cylinder that needs to be sorted out first.

By the way, please could you tell me your TF chassis number (for my records).