5 replies to this topic

[Henry8601]

My 850 '64 Super De-luxe has just failed its MOT on a few items, the main one of which is the brakes. I have now done a lot of work on the system, and I am now moving onto the fronts. Work done so far:

New 0.70" Cooper S Master Cylinder
Braided pipes all around
New Cupronickle pipes
New 5/8" GWC1101 rear cylinders

The fronts are supposed to be single leading shoe brakes, and when I took off the drum I found this to confirm it:





Now the bit that I don't understand is that the cylinders have 3/8" bleed nipples instead of the 1/4" bleed nipples that GWC101 is supposed to have. The casting says A6 17 on it - does that give any clues?

Now I have a couple of options
1) Replace cylinders with known GWC101 for ~£60
2) Put on the 7.5" Cooper S discs that I have waiting in a corner

I am tempted to put on the Cooper S discs, but I have a few questions:
What is the difference in driveshafts?
My inner joints are like the rubber joint, but are actually brass on needle rollers - what are they??
Should I upgrade the rear pads to minisport performance spec?

Many thanks as always!!

Edited by Henry8601, 23 April 2013 - 03:45 PM.

[Guess-Works.com]

Cheapest option for better brakes is to convert to a twin leading shoe front end...

When kept in good adjustment are just as good as an average set of disks.

If you want to change to disk, go to Cooper S (7.5") disks and not Cooper 7" disks, the latter are worse than twin leading shoes.

The Drive shafts are equivalent whatever the braking mechanism, but you will need to change the outer CV for Cooper S disks.

Your inner couplings sound like a version of the Quinton Hazel QL5000 upgrades.

The main problem is, you have the wrong size master for a single leading shoe system, it should be a 0.75" (3/4") master.

If you do go cooper S brakes, then you should replace the pressure regulator valve on the rear subframe with standard "T" Piece connector and the rear cylinders with .75" GWC1102

[Vipernoir]

I've got some twin leading shoe assemblies kicking around somewhere if you go down that route.

[Ivor Badger]

The problem is that the single leading shoe system was at best marginal and wouldn't actually stop the car from 80mph without the brakes fading.

The best solution is fitting the S brakes, always was.

What engine are you using?

[Henry8601]

Thanks for the replies everyone, maybe I should reiterate that I already have a complete set of Cooper S discs that would only need fitting, but it's only an 850cc mini so is it overkill?

I just want to query about the master cylinder bore. Somerford mini state: MASTER CYLINDER ASSEMBLY, 0.70" bore, Drum braked Minis, 1962 approx. to 1975, with original style metal 60mm high reservoir, so isn't what I have correct?

On the wheel cylinders they also state:
Wheel Cylinders - Single Line System, 1963-71 (Cooper S) GWC1101 WHEEL CYLINDER, 5/8" bore 2 1963-67 (Mk I), with Type 5 1/2 servo, so again, doesn't that suggest that what I have is correct?

Thanks very much for the tip about the rear pressure regulator. I actually have one of the adjustable ones from a previous project - can I fit that instead?

Any thoughts on the performance of uprated minisport drum brake pads?

[Cooperman]

One thing you could consider if you want better brakes but want to keep the car looking original is to fit the original 7" cooper 998 discs and callipers. Then the original wheels can be fitted and with a better brake pad material it will stop a lot better than the single leading shoe brakes. Whilst those smaller discs were 'on the limit' on a 55 bhp Cooper, on a 34 bhp 850 they will work fine and won't need constant adjusting.