Disc brakes on a standard Mk1

[Peter Laidler]

Looks like this thread could run and run, depending on strongly held opinions of course, for ages and ages. However, there are plenty of doomsayers out there and others who want you to overspend..... Always remember, that it's a roadgoing 850cc Mini

I wouldn't let the calipers and drive flanges worry you in the least. Rebuilding a set of leaky Cooper calipers is simplicity itself and all the parts are readily available. I did a leaky set for my pal Trevor in the late 80's, even machining and grinding a set of stainless steel pistons (although they and the seals are available from the specialists - as are the industry standard size piston seals and available over the counter at hydraulic specialists) And guess what.....? They're still going strong, 40 years later. Waste not, want not as they say.

Same as the drive flanges. While there are 850 drum braked flanges still available the conversion to disc flanges is pretty straightforward. As has been shown on this very forum in illustrated form by our very own maestro engineer marvel-man, Dermott. They both started with the same casting!

Bring me your calipers and I'll do them for the cost of the parts! You CAN make mini owning cheap, reliable and fun

[Costafortune]

A servo makes a massive difference. These are only tiny discs compared to modern cars with single piston calipers. I had to drive my 1275GT without a servo for a week whilst I waited for a new one, and the brakes were horrible.

There must be a modern caliper with decent sized pads that can be fitted to Cooper brakes. The standard pads have next to bugger all heat capacity. You're probably looking at rear calipers from something made in the last 20 years.

['S'-type]

Just to add to my suggestion about starting with a cheap second hand 8.4 set up to convert to 7.5. As well as thoroughly checking them over you would also need to swap over the mk1 steering arms fom your drum brake hubs, assuming you still have a mk1 steering rack on your car.

An alternative approach to all this is to go for a complete second hand S set up, which do come up from time to time. Would probably be even more refurbing to do though. But as Spider says, parts availability will be better as and when needed down the line.

I do agree with your general philosophy Peter, trying to do things as cheaply (and properly) as possible by rebuilding and adapting stuff using your undoubted engineering nous. Cost versus end result is a tough one to call in this case. There's always more than one way to skin a Mini cat.

[timmy201]

I bought a genuine Cooper S disc brake front end. It needed a refurb and I replaced:
Caliper seals
Pistons
Wheel bearings
Drive flanges
Discs
Pads
Hoses & copper washers
Ball joints
Cv joints
Miscellaneous things like lock washers, cone washers
It also took a few weekends of cleaning and painting to get them ready

It ended up well over the cost of a new Minispares set. Just keep in mind that depending on the condition of a used set it might make more sense to buy all new (especially the kit price).

Your experience may vary

[mab01uk]

BRAKE CONVERSION TO MINISPARES 7.5" DISCS AS PER COOPER S
"Cooper S 7.5" complete brake disc kit, except for disc shields, with Mini Spares own cast standard calipers. If you want or have 10" wheels this is the kit to convert from drum brakes to discs brakes.
This kit includes every nut bolt and component necessary including hubs(uprights), bearings, ball joints, CV joints, brake discs(rotors), drive flanges, calipers, etc. All NEW parts, easy to bolt-on installation that is not built up so you can check the parts and you need to partially strip to fit.
This is a budget kit of this using Mini Spares calipers,discs, see C-AJJ4028 for kit with AP genuine calipers
If you require the brake disc shields also ,see C-AJJ4028B."
http://www.minispares.com/product/Class ... 0to%20shop

[Peter Laidler]

As a bit of an aside, the disc shields serve no thermal or mechanical purpose except to trap the occasional stone/gravel chipping. So you can safely leave them off. Unless it's concourse you're after.

[MagicWandWoody]

So you can safely leave them off. Unless it's concourse you're after.

... or if you drive in very wet weather (many Minis don't see much rain, of course). Mine was fine to use without shields in modest amounts of rain. But it was absolutely horrible to drive in heavy rain with standing water - one side or the other would randomly grab first and swerve the car for a long heart-stopping moment until the pads had wiped both disks clear of wet. After a few hundred miles of this behaviour I finally got unsafely home and immediately ordered a set of shields.

[Nathan1293]

I used to run my cooper S brakes on a daily driver without the back plates with no issues. I used the better quaility MS S-discs (with the grooves) and Mintex M1144 pads. It did have an adjustable bias valve and mintex shoes with standard S drums.

I used this car daily, sun, rain, snow etc. I am not critising the other report that experienced problems, just giving my experience. The biggest risk is also what has been reported (although I didn't personally experience) is stones getting trapped between the disc and wheel or caliper.

[mab01uk]

So you can safely leave them off. Unless it's concourse you're after.

... or if you drive in very wet weather (many Minis don't see much rain, of course). Mine was fine to use without shields in modest amounts of rain. But it was absolutely horrible to drive in heavy rain with standing water - one side or the other would randomly grab first and swerve the car for a long heart-stopping moment until the pads had wiped both disks clear of wet. After a few hundred miles of this behaviour I finally got unsafely home and immediately ordered a set of shields.

I also put shields back on when I experienced a long very wet motorway journey where you often went long periods without needing to apply the brakes...only to find there was a delay/lack of full braking effort when you most needed it. You needed to remember to regularly apply the brakes to dry off the discs as you would after driving through a flood, which is the reason the factory fitted them in the first place.....if BMC/BL/Rover could have safely deleted them to save production costs they would have along with many other car manufacturers.

[Peter Laidler]

Surely, the same wet weather water ingress problem could be said for the NON or barely shielded outer sides where the wheels have 9x 19mm or so holes around the perhipery. Water simply takes the line of least resistance. My Commando hasn't got a disc shield!

[SMOKE GREY]

I never used disc shields on my rally cars, either with S brakes or the 7” brakes, and I saw lots of water!!

[Herbert]

Deleted as duplicated

[Herbert]

I just wouldn't change to disks. Too much to change. I once put a servo with twin leading shoes and it was really a nice car to drive. The more you change, the more hassle you will get. Keep it straight and simple

[miniminor]

I'm not sure it would bring hassle, I'm just loathe to make changes to a pretty standard little car, but it would be a big safety upgrade. Then again it doesn't do a lot of miles so is it worth the effort?

[Polarsilver]

Back in the Day as an engineering apprentice with very low income ..my 997 Cooper 7inch Calipers were knackered as well as the Hubs .. solution was a trip to the scrap yard & take a set from a Van Twin Leading Shoe Brakes & put these onto my 997 Cooper .. this transformed my Brakes & solved the well worn early Cooper Front Hub issue for a few more years until i progressed in life .. Twin Leading Shoe will do the Job & do not need a Servo.. setting up TLS Brakes is straight forward task & i never found any need to be constantly adjusting them .. just make sure that the backplate brake shoe adjusters move as they can seize

[Spider]

Twin Leading Shoe Drum Brakes do work quite well, not to be sneered at, they also give a nice feel at the pedal. The down sides of them is the somewhat high maintenance and they will overheat fairly easy. Finding good hubs for them these days can be an issue too.

I'd also steer well clear of any used disc brakes. Of all the many sets I've bought over the years, the only parts I've been able to salvage from them is the calipers and the wheel studs. I don't bother with them now.

[Costafortune]

Another option is to buy an 8.4" disc set up for 50p and a Twix, buy some decent quality new discs and get them turned down to 7.5" before fitting a pair of S calipers.

I'm assured that this works.