30 replies to this topic

[corellian corvette]

Hello everyone!

 

New to the forum - got my first classic Mini this week - it's a 1982 LH drive Mini from Italy. It has the 998 engine and it's an automatic.

Got the car from a friend stationed overseas, he bought it in Rome and had is shipped back. Now it's mine!

 

Very excited and have been going over the car. Lots of little projects but overall appears to be a solid car. I've now encountered my first problem!

 

When I was getting the car I was aware the front drums were in OK condition, so my friend suggested we do the Cooper S disc brake conversion.

 

We ordered the kit pre-assembled from a seller in the UK, as well as new braided lines all around. Figured it was worth doing the whole system at once.

 

The install was very straight forward - installed the new front hubs, new SS lines in front, new SS lines in back. The entire system was bled - overall no issues.

 

Excited to get the car on the road and the brakes are really bad. The pedal is pretty hard - doesn't go to the floor or spongy at all - but the actual braking power is really not good. My friend installed this same system on his clubman and it works great. I can't get the brakes to lockup under even the hardest pressure. I have the correct rear drum adjustment tool and even went back over the rear drum adjustment.

 

I know "air in the lines" is a common problem but I feel like it's something else. I've restored a bunch of cars (all American), and have a well equipped shop and I'm pretty handy - spongy brakes I know what they feel like. This pedal is rock hard, but the stopping power just isn't there.

 

Is there some part of the procedure I missed? This seems to be a common swap so I must be doing something wrong..

 

Thanks in advance!

[Guess-Works.com]

Do you have the callipers the right way up.... bleed nipple at the top.

[mr cooke]

have you got the air out of all 4 brakes

is your brake master cylinder any good .

[Carlos W]

Hopefully someone will correct me if I'm wrong, but I'm not sure that drum and disc master cylinders are the same

[Steve220]

What discs and pads are you using? Have you let them bed in?

[corellian corvette]

Yes, caliper bleed screws are up, system bled fine. The pedal isn't spongy it just doesn't feel like its putting enough force.

 

There was no mention of needing another mc when I ordered the kit?

[g-dog]

It's worth remembering that the 10" Cooper s discs were always fitted with a servo when in production. Maybe that's needed. Also new brakes can feel a bit wooden and need a few 100 miles to bed in

[corellian corvette]

Perhaps. These are pretty lousy.

 

I did realize tonight that I forgot to use the crush washers on the caliper side of the hose. Not sure the purpose since they aren't leaking...

[Cooperman]

It will not be air in the system if the pedal is firm.

It could be poor quality pads, or even pads that are too hard, although if bedded in properly that should not be an issue.

The master cylinder bore is the same on the 850 and the 'S'. The 'S' master cylinder reservoir is slightly larger to allow for more fluid reserve.

First of all do a serious bit of 'bedding in'. Drive along at about 40 mph in 3rd with full power on and use your left foot on the brake pedal to hold it down to that speed for around 1/4 mile. Allow the brakes to cool, then repeat. Do this a few times. Then let it cool and try it again. That may cure it.

If not you can fit the standard Cooper 'S' servo (if you haven't already). A lot of us don't like 7.5" brakes without a servo - too much pedal pressure required.

The best pads for 7.5" are the carbon-metallic ones as sold by Mini Spares.

One other thought, did you remove all the protective grease from the discs before fitting the pads (I'm sure you did, but I thought I would ask).

[cal844]

It will not be air in the system if the pedal is firm.
It could be poor quality pads, or even pads that are too hard, although if bedded in properly that should not be an issue.
The master cylinder bore is the same on the 850 and the 'S'. The 'S' master cylinder reservoir is slightly larger to allow for more fluid reserve.
First of all do a serious bit of 'bedding in'. Drive along at about 40 mph in 3rd with full power on and use your left foot on the brake pedal to hold it down to that speed for around 1/4 mile. Allow the brakes to cool, then repeat. Do this a few times. Then let it cool and try it again. That may cure it.
If not you can fit the standard Cooper 'S' servo (if you haven't already). A lot of us don't like 7.5" brakes without a servo - too much pedal pressure required.
The best pads for 7.5" are the carbon-metallic ones as sold by Mini Spares.
One other thought, did you remove all the protective grease from the discs before fitting the pads (I'm sure you did, but I thought I would ask).

That should work :)

[Guess-Works.com]

I hated the servo on 7.5's absolutely no feel..

 

Also, don't forget, 7.5's were always installed on a single line brake system, so if you're thinking of installing a servo take this into consideration... I'm not a fan of just installing the servo on the front brakes as this means there can be situations where your back brakes are not being used...

 

You say the brakes are shocking... have you tested the brake balance... it maybe that only your rear brakes are working...

[Dr s]

They are quite hard at the pedal. I used to use ebc black stuff pads, they work pretty well. Did end up with a bend in the floor where the seat sits from hard braking though..

[Sheikh Pip]

It may be worth checking the master cylinder to brake pedal clevis pin is in situ, I had very poor brakes on a 1275 GT years ago, and it turned out a previous owner had forgotten to fit the clevis pin!!! 

[blacktulip]

have you adjusted the rear brakes properly? when i changed to the 7.5" set up over drums i found that only the fronts were working properly as i thought the same as you, then after i had adjusted the rears they work great to this day. what pads are you using?

[Wise Old Elf]

Just had the same problem with the wife's car. I adjusted the rear and she was still complaining. I fitted green stuff pads and now the moaning has stopped. :)