10 replies to this topic

[bluemini1979]

Hi all.
I've fitted a pair of minispares 4 pot calipers for 7.5" discs. Bled them using an easy bleed and then using the pedal. Started bleeding them with the pistons part way out as was advised on the forum by Keith calver. Brakes are working and do stop the car but not as I would expect. I had standard 2 pot cooper s calipers and although they would stop the car (1310 turbo 130wbhp) they didn't give any confidence or have anything extra. Was advised to fit 4 pots for better efficiency.

Problem is I have a lot of pedal travel which it didn't with the standard 's' calipers fitted. Is this normal when fitting 4 pots? Also when driving along the drive (dirt track) the brakes would lock up with standard calipers but with the 4 pots I can't lock them up which I expected to be able to do.

Braking system is as follows.
Minispares 4pots
11/16 rear wheel cylinders
Yellow tag master cylinder
No servo
Front rear split with valve on bulkhead

TIA.
David

[nicklouse]

Presuming you have bled them and the air is out. You should not really have that much pedal travel.

But as you bed the brakes in and the Pistons settle in to their position travel will reduce and grip will improve.

The same as any new brakes and pads. Will take longer if the the discs are worn.

[bluemini1979]

Not getting any air out when bleeding. Have bled the whole system as the Haynes Manual describes. As I say they do stop just don't have the confidence due to the pedal travel

[dean]

i have the same calipers on my mk1 but running on a single line system no servo, but with 3/4 rear cylinders and a rear brake adjuster.

 

they work well, and yes if i push hard i can easy lock my front tyres up. i would not say they give a massive improvement over standard S calipers, i bought them more to give better clearance for my wheels, not to improve my braking, 

 

i do find i bleed them twice a year, more to keep the fluid new, but also i do fine that the bleed nipples being steel in a alley hosing do start to corrode, so i like to make sure they free off every so often. 

 

i must say that my car is not a daily, it covers about 1000 miles a year, so spends more time sitting in the garage, i took it out yesterday for its first ( spirited)  drive since novemeber last year, the brakes were fine , but i did feel a bit of air as my pedal got harder on the second press with in a second of two, but it was not effecting the braking, just the pedal on the first stroke when down a little further. 

 

maybe if you want more effective brakes fit a servo. i know a lot of people don't want there engine bay blocked up with one, 

[bluemini1979]

I'll rebelled them and see how I get on. They were new pads onto a 500 mile old disc so may need time to bed into them.

[Spider]

I have a set on one of my Minis. I did find they gave a little extra pedal travel - not unexpected - and do need more pedal effort.

 

However, and I can't recall off hand what pads I have in them, they are among the best brakes of any car I've driven. Other Minis and Mokes I've driven that have them I'd make the same comment for though, I should also point out that these have all been on an 8.4" Disc.

 

Did you also fit new discs or have yours skimmed at the time?  And then allow the pads to bed in? If you stomped the brakes before allowing them to bed in, then the discs will likely be glazed and the brakes, hopeless.

[bluemini1979]

I didn't change the discs but I do have a lathe so I will give them a skim in the morning and try them again

[Cooperman]

With new seals in the pistons it can happen that the seals are trying to pull the pistons back very slightly when pressure is released. I had that with an Innocenti on which new pistons/seals had been fitted. Some hard braking over a week or so saw them working fine. I had thought that there was still air in the system, but that was not the case.

I've never seen much advantage with 4-pots over the original 2-pot 'S' callipers. It is the quality of the pads, discs and fluid which determines the braking efficiency. For normal driving bigger pads can fail to get warm enough to work properly.

You could try bedding in the pads a bit more by driving in 3rd at about 45 mph and gently pressing the brakes on with your left foot until they get hot, then repeating this once they have cooled again.

[olly33]

Sounds a bit like air in system for pedal to travel so far. Could also back bleed the system with a large syringe and a bit of pipe on the nipple.

[Carlos W]

I'd push the pistons back in, then leave it over night with the pedal slightly pressed.

 

Are the rears adjusted properly?

[dyshipfakta]

Don't know if They are similar to the metro calipers but are they on the correct sides?
Often just simple stuff