19 replies to this topic

[positivereflect]

Since having my mini 850, and fitting some 4 pot alloy 7.9 non vented mini sport front brakes, i have had all sorts of problems with the rears failing mot every year. (front brakes were fitted so i could use 10inch wheels, not long after i purchased the car - it came with 8.4inch mini brakes fitted)

 

Car did have a tuned 1275(maybe larger - exact size unknown) engine that went well but leaked lots of oil, so much so that it was getting into clutch housing and killed the clutch... twice, so i decided to change it out for a known good 998cc engine that has a 1275 head fitted to it. (I know the brakes are overkill now, but just put this bit in to explain the reason behind the 4 pot brakes)

 

Braking system is later tandem master cylinder, split front/rear, (new master cylinder and bulkhead valve thing were fitted at last mot). Rear shoes are new, handbrake is working fine.

 

Have tried various rear wheel cylinders, and when i called minisport to see which they recommended i was told gwc1102 (which i ordered and then took to garage for them to fit so mot could be done).

 

Problem is, the rear brakes still only just pass - on the limit...... Has anyone else had experience with these brakes? does anyone have any possible solution?

 

Have asked minisport and all they advise is that brakes are bled manually instead of using an eezibleed, could anyone explain what that means?

 

[smudger068]

Well I need to use this setup for the track then as after fitting mine I still have no end of problems with locking the rear!

 

I cant help much here but by the sounds of it you are not getting enough pressure to the rear! can you think is there anyway your restricting the pressure to the rear?

 

As for eezibleed and manual differences are:

 

Manual is when you have to of you normally and one opens and closes the valve and the other pushes the pedal!

 

Easy bleed is when you use a one man kit where there is normally a ball bearing in the hose coming out the capiler and it stops any air returning back into the caliper

[positivereflect]

Hi, thanks for reply :)

Cant think of any way in which im restricting it to the rear, unless its something to do with the FAM7821 brake valve unit? this was also new on last mot.

 

Not had any problems at all on my clubman, only difference is front brakes (cooper s on clubman, 4 pots on 850). Both have same split front/rear master cylinder and fam7821 unit.

 

out of interest, what braking system do you have on your car you use on the track?

[DILLIGAF]

What year is your mini (850) and what was the original brake set up, I had a similar problem when I tried a extended pushrod in my S Master cylinder.........

 

Finally fixed by brakes by replacing the drum braked pedal with a disk braked pedal......

[positivereflect]

my mini 850 is a 1972 model, left the factory as an auto - had been converted to manual before i had it, dont know what parts of pedal box are original (brake system had been changed to later tandem type).

 

Original brake setup was drums all round (which the previous owner changed to 8.4 disk on the front).

Didnt realise there was any difference with the pedal, how can i tell which is which?

[DILLIGAF]

If it's still got the square pedals, chances are that it's still on the original drum pedal. Unless it's had the rarer cooper S pedal fitted but I'd doubt this very much.

The easiest way to find a suitable pedal is to go for one of a post '85 disk braked model. This is the difference:

Attached Files

•  MiniBrakePedals.jpg   9.17K   36 downloads

[positivereflect]

So the bottom one is from a post 85 model?

[DILLIGAF]

So the bottom one is from a post 85 model?

 

Sorry never explained it properly, the top one is a cooper S disc braked pedal thisis the type of pedal that was standardized when disc brakes where introduced on all minis. Except of course they had hexagonal pedals.

 

The bottom one is a drum braked pedal........

[positivereflect]

ahh ok, both the clutch and brake pedals are hexagonal type, same on both of my minis

[DILLIGAF]

Right I'm not actually sure if theres a difference between the later drum braked pedal and the disc braked pedal......

Never had a later drum braked pedal in my hand, but easy enough to compare with the pic......

[positivereflect]

will check the one that is on the car for angle tommorow

[DILLIGAF]

The other thing you can check before removing the pedal, is that the pushrod isn't bottoming out on the bottom of the crossmember/bulkhead box section........

[Gr4h4m]

I run a yellow tag, rear subframe valve and don't have an issue With the rears passing. The split system has a differnt circuit for the rear. I would guess is a pressure issue. I would check the conditon of the rear hoses, weaping rwc, make sure that valve thingy at the front is working.
Sometime people have said not to pressure bleed when using that valve as it moves and can effect the supply of fluid.

[Shifty]

What weight are they using for your car?  I think the autodata gives a mini weight at about 750kg?(I could be wrong).  Thats for the latest cars, I struggled to get a mk1 through the test, I found a handbook for it with the correct weight and it passed. 

[smudger068]

Hi, thanks for reply :)

Cant think of any way in which im restricting it to the rear, unless its something to do with the FAM7821 brake valve unit? this was also new on last mot.

 

Not had any problems at all on my clubman, only difference is front brakes (cooper s on clubman, 4 pots on 850). Both have same split front/rear master cylinder and fam7821 unit.

 

out of interest, what braking system do you have on your car you use on the track?

 

Sorry for the late reply

 

I have:

- Yellow Tag master cylinder

- Mini Sport 7.5" 4 pots

- Braided Lines all through  

- Wilwood Bias Adjuster

- New Rear Shoes

 

Im almost tempted to put in another bias adjuster!