Rear brakes not good enough

[tomkidd]

Just a thought while searching the world wide web. My pedal box came off a car with drums all the way round, will this make any difference that I am now running discs? I've just read somewhere that the pedals are different...?

[gr4h4m]

So did mine. I now run a yellow tag MC, 1275 gt rwc and fiesta front brakes a the pedal is right there.

IMO is air, or the rears aren't adjusted all the way up.

I adjust them until they have resistance when turning on the jack, then take it for a spin. I have never found ths two flats off stuff any good.

[gr4h4m]

The ezibleed kit is very good IMO

[Lord Croker]

Just a thought while searching the world wide web. My pedal box came off a car with drums all the way round, will this make any difference that I am now running discs? I've just read somewhere that the pedals are different...?

Pedal boxes are no different, disc or drum (except Autos!) the only change was the fitting of a larger pedal pads from 1976.

[mk1coopers]

There is a difference in the angle of the brake pedal on the Cooper S, the pedal sits higher compared to a 'normal' pedal

Knew I'd find a picture somewhere, although this shouldn't make a difference to the pedal feel

http://forum.minicooper.org/showthread.php?t=10145

[Tim]

I used a Gunson's Easibleed for the first time recently. For the price, it was very good. I hate bleeding brakes, lying on the cold floor with brake fluid running down your arms and dripping off your elbows... This thing made it almost a pleasure...well nearly.

Tim

[tomkidd]

The rears are adjusted so that they are binding 'just' so I don't think it is adjustment.

How long do you think I bleed it for with an eazibleed?

[Tim]

Until the bubbles stop coming out. A nice trick is to use different brands of fluids which have different colours (making sure they're compatible) when the stuff coming out turns from green to blue you know you've flushed it right through.

Tim

[tomkidd]

Until the bubbles stop coming out. A nice trick is to use different brands of fluids which have different colours (making sure they're compatible) when the stuff coming out turns from green to blue you know you've flushed it right through.

Tim

What if there are no bubbles... like it is now anyway?

[gr4h4m]

Well the ezibleed bottle takes a fair amount.

[gr4h4m]

Rear brakes AND handbrake effort low doesn't sound like a hydraulic problem.

Are your shoes in correctly? Have you re-adjusted once the shoes have had chance to centre themselves? Where are the shoes from - I've had issues with Unipart ones before now being poorly sized.

I have had the same as above where the shoes were the wrong width, in the box and wore a grove in the lining. Iirc the front drum shoes are a different width to the back.

[Lord Croker]

There is a difference in the angle of the brake pedal on the Cooper S, the pedal sits higher compared to a 'normal' pedal

Knew I'd find a picture somewhere, although this shouldn't make a difference to the pedal feel

http://forum.minicooper.org/showthread.php?t=10145

My apologies, gentlemen, I had forgotten about that Cooper S brake pedal, I had one in my 'S' but I preferred the standard one for 'heel & toe' down shifts. Can't do that any more since I snapped a tendon in my right ankle

[Tim]

If there is no air in the system bleeding won't gain anything.

Tim

[sclemow]

This is obviously a really old thread, but I was wondering if you found the problem?
I am having similar problems with my S. The handbrake is ok, brakes are adjusted with new cylinders etc, and are bled correctly.
The shoes have been on for a couple of years. It has always been marginal on the rear brake effort on the footbrake, and is below what it needs to be.
I have the standard rear bias valve, S discs on the front, with no servo and the smaller early GT wheel cylinders.
The brakes feel fine on the road, but I don't think you'd notice underperforming brakes on the rear.
I tried warming the brakes thoroughly and putting it back on the rollers, but this evened the brakes from side to side but didn't affect the efficiency.

Any ideas?

[abs]

The smaller the slave cylinders piston the least braking power it will give so the early GT cylinders will not give a lot of braking as they are 1/2" bore size so they are the lowest power available. You should be using 5/8" cylinders with an S regulator valve.

Personally I always use the cheap 3/4" bore cylinders on everything and fine tune the rears with an adjustable valve ( MS72 ) but you can fine tune with a standard valve but it`s a lot of messing about. I tune it so it won`t lock the rear wheels under very heavy braking when the rear of the car is very light.

It`s worth remembering that minis don`t want a lot of braking power at the rear as if they lock up during heavy braking the car is likely to swap ends which is where an inertia valve gives the best of both worlds.

[Spider]

I just read through most of this, my suggestions would be;-

Low Pedal - many of the new Calipers seem to lack lubrication of the rubber seals and so the pistons in them really stick not allowing them to properly self adjust. One by one, a disc pad need to be removed, one of the pistons chocked and the other pumped out about 6 mm, them pressed back and move on to the next piston. That will lubricate them.

Rear Brake Performance - While Tom never said what size rear cylinder he went to, he needed to go to a bigger size, not smaller.
Adjustable Rear Bias - Sadly, we didn't find out what type that was but it may well not had enough low end setting, few do.
It also appeared the rear shoes needed bedding in, but it would have been nice to find out some history of the drums too.

[sclemow]

Thanks guys. I’ve tried both minifins and good used standard drums.
It looks like I’m heading towards bigger space cylinders and an adjustable bias valve

[Peter Laidler]

I'm glad that this rear brake problem raised its head again. All too often we hear the the brakes have been bled and are free of air......., but they're still spongy and weak and ineffective. I don't want to teach my granny how to suck eggs so listen in close......

Getting rid of the air back to the rear wheel cylinders is a bit of an art, taught to me ages ago. It's a two man job and not one for ABV's (auto bleed valves). You've got to press really hard on the brake pedal and in doing so, compress any air that is within the system. It has migrated to the highest point....., that's the problem with air., It doesn't do what you want it to do.

When you are foot down hard on the pedal, with the air compressed to buggery and the system pressurised, now ask the brake bleeder at the rear to unscrew he nipple. The compressed air aided by your foot pressure will literally blast the fluid AND AIR rearwards - to be replaced by some more new fluid as per usual. If brake fluid is running down your arm or all over the garage floor, you're doing it wrong!

Do this again and any residual air will be blasted and pressurised clear. End of. Time taken, 10 minutes or 30 minutes if you rush!.

As for ABV's. Don't forget that these spring loaded valve thinggies are constantly full of brake fluid that\s open to the elements. That just rusts them out. Just my opinion based on my limited experience.....

[Polarsilver]

Very Good Rear Brakes is not what a Mini wants or needs .. for the reason "if" the Rears Lock Up the car will very quickly try to swap ends.
my solution is to fit adjustable rear bias valve on anything other than a car with oe standard brakes

[gr4h4m]

Calver many years ago wrote a good article on mini brakes.

The RWC Size is inversely proportional to the mc. So a larger cylinder has less pressure.
Either way I found the yellow tag, 1275gt Mintex rear shoes and I’ve now got kad four pots in the front and the brakes are good for an old car…
The other thing is to make sure the tester is using the correct weight for the car as the more modern minis were heavier IIRC.