4 pot calipers- worth fitting?

[Plank]

I took a friend for a spin in my more mature mini recently.
He was very concerned about the fact that the car could keep up with modern stuff on B roads but probably wouldnt stop as quick as the car in front with ABS. I had never thought of that!
Is there a big avantage fitting alloy 4 pot calipers over the standard S calipers? Also whats the difference between the Mini Spares and Mini Sport offerings?

[camelotr]

Big advantage comes from the 7.9 discs, not the calipper. But of course, they will give better, more even pressure on the pads.

Soo, if You can affrd, fitt them.

[haynes]

Vast improvements can be made over the standard brake set up, 4 pots make a contribution but possibly not as much as upgrading the pads and discs.

And, minis are a lot lighter than modern cars.

[DanGT]

There is an advantge, It dos not feel a lot but a back to back test there is an impovment. I had a 1275GT with the standerd setup with green stuff pads, I then fitted the metro turbo 4 pots and disc's with green stuff. My times round Lidden circuit were better and there was a lot less heat in the rear drums.

[nick1275]

ive got minispares alloy 4 pots on mine 7.5" discs, ebc black stuff pads, single line system with bias valve, which stops very well even from cold and gets next to no fade on track. however i drove a mates mini on sat (within 10 mins of driving mine) he has the metro turbo setup with uprated pads of some sort, and the what i call the 'Xmas tree' master cyl and they felt awful. imo the std 8.4 setup with decent pads and discs and in good working order good fluid etc should stop very well

[Cooperman]

As the Mini is such a light car, 4-pot callipers are not really neessary. The key to good stopping are much better pad material and good condition discs.
I never have brake fade on my 1964 Cooper 'S' rally car, even on long twisty tarmac sections and I am only allowed the standard 7.5" discs with standard callipers. However, I use Carbon-Metallic pads (from Mini Spares), best quality discs (not the 'cheapie' ones) and AP600 racing brake fluid. What is impressive is that those pads work well from old with no 'grab', unlike the old Ferodo DS11 race pads.
The 8.4" diss are also good with standard callipers and with Mintex 1177 pad material.
The key is to have all brake system omponents in top-line order and to use the best pads and discs. I an get my 'S' discs glowing red hot and still they work superbly.

[Plank]

Thanks for the advice chaps. I have some thinking to do. The car is a 67 so I fully intend to keep 10" wheels and S discs. Steve.

[timelord]

Another thing to be aware of not all 10" wheels fit over 7.9" discs and minisport 4pots, just managed to squeeze 4.5" minilites over mine, the improvement is terrific but then I did have twin leading drums with leaking cylinders before

[Cooperman]

The only time 4-pot callipers are necessary is in long distance racing when ultra-wide and sticky soft compound slick-type racing tyres are being run. Then the 'G' available from the tyres themselves under heavy braking can be much higher than with a standard road tyre and thus higher braking loads are needed at the callipers.
So many add-ons these days are really no use on a road Mini and are just vanity and the opportunity for parts suppliers to make more profits from this vanity.
Actual competition use is another matter entirely and that's why these parts were developed in the first place, mainly for racing.

[allgearnoidea]

mini se7ens still use the S setup and they stop ok! i think the key is, good quality disk, correct pad for application and of course a well maintained braking system. my mate has just failed his MOT with poor front brakes(7.5), he got a seal kit and stainless pistons, rebuilt the calipers and he said they were 100% betterer.


Also a thing to watch out for is making sure all the conponents in the system are compatible, as there are plenty of master cylinders, wheel cylinders, break bias proportioning valves etc etc to get mixed up...

[DanGT]

The miglia cars were at one pint using 6 pot calipers (I think they were band but are not 100%). I do agree that for most road cars a good standerd set up works very well (Even the drums are not to bad if looked after). I would think (I dont know) that the 7's are not alowed to change not that they dont want to. I did find for a car that I sprinted with about 100bhp at the wheels, it was worth doing. But as sead for every day road use maybe not.

[FWDRacer]

As a Se7en racer I use the S-discs that that class rules stipulate I must use - even given choice I wouldn't use anything else. Car weighs 650kg all up with driver+ fluids. No fade issues whatsover using this set-up even at Brands/Rockingham and circuits that are traditionally tough on the brakes, and we don't bother with servo either. The amount of braking load put through hot dry tyres you won't replicate on the road.

As stated before - all about the quality of the discs and pads. I ain't saying what I use tho'

For fast road use - even accounting for the greater vehicle weight of a trimmed vehicle, the S-disc set-up is more than man enough for the job. Downsides is you can't put a mirror under the car and show them off at shows though, can you??

[rufusruffcutt]

Braking performance put to one side, there is a considerable weight reduction to be had in moving to 4 pot alloy calipers.

[Cooperman]

rufusruffcutt said:

Braking performance put to one side, there is a considerable weight reduction to be had in moving to 4 pot alloy calipers.

How much is 'considerable' in real terms? We are talking unspring weight which affects only the way the tyres stay in contact with the road. Now, a lot of those fitting 4-pots will then go and fit very wide or larger diameter wheels (i.e. much heavier) and they more than offset any weight saving from alloy callipers.
Again, they are relly only necessary for racing or for vanity, certainly not for road performance improvements. There are a lot of thing more worth spending your cash on to improve performance.

[NDT]

Are the calipers for the Cooper S setup still available?
If not then surely that's the main reason for fitting the 4-pots?

[rufusruffcutt]

Cooperman said:

rufusruffcutt said:

Braking performance put to one side, there is a considerable weight reduction to be had in moving to 4 pot alloy calipers.

How much is 'considerable' in real terms?

I believe its in the region of 2kg per corner over the cast iron equivalents.

Cooperman said:

We are talking unsprung weight which affects only the way the tyres stay in contact with the road.

Correct we are.

Cooperman said:

Now, a lot of those fitting 4-pots will then go and fit very wide or larger diameter wheels (i.e. much heavier) and they more than offset any weight saving from alloy callipers.

I concur with this, the same can be said of moving to vented discs over solid discs.

Its all horses for courses. Back to the OP's original question, a well maintained original set-up and you won't notice the difference on the road.

[PGM]

I agree, make sure the original setup is working as well as it can and that's all you need unless you are tracking or racing.

My mini is perfectly good at stopping on it's original disks and drums, incidentally as you would expect stops in exactly the same distance as my Porsche 996 and for what it's worth every other car on normal road tyres.

It's the tyres and road surface that make a difference to stopping distance.

The only difference between the normal and 4 pots is that you can do fully efficient heavy braking on multiple occasions with a more expensive setup i.e trackwork.

[GingerWizard]

This seems to be the 'ultimate' set up. cheap considering..... 200mm discs...

http://cgi.ebay.co.uk/Mini-7-9-ALLOY-4-POT-BRAKE-S...

[greggy50]

Quick question I have 4 pots and drums on the back
However peddle feel is crap at first and I have to pump the brake down and then press it again for them to work properly as without the pump they are a bit naff and with a pump they are very good
Any idea into why this may be the case air in the system or something?

[GingerWizard]

greggy50 said:

Quick question I have 4 pots and drums on the back
However peddle feel is crap at first and I have to pump the brake down and then press it again for them to work properly as without the pump they are a bit naff and with a pump they are very good
Any idea into why this may be the case air in the system or something?

master cylinder might be worth looking at.