Upgrading Mini Brakes
Upgrading Mini Brakes
Over 5 million Minis have been made, most of them before 1985 when front disc brakes were standardized. Previously, standard Minis were fitted with drum brakes all round, adequate in light traffic but prone to fall out of adjustment, not very progressive unless recently overhauled, and not up to the quick responses needed to avoid accidents in modern high-density traffic.
More importantly, the drum brakes are not capable of safely stopping a Mini that has been fitted with a more powerful engine, if it is being driven aggressively.
Fortunately, it is easy to upgrade the brakes on your Mini to modern standards. Specifications for each braking system can be found on the Technical Data page. See all MINI Cooper brakes.
Mini brake systems
First, a summary of Mini brakes through the years (the major different versions are in bold):
The Mini's supposed successor, the Metro, was fitted with brakes that are partly compatible with Mini brakes. Turbo, Van and all later A-series Metros were fitted with vented 4-pot brakes. This compatibility was taken advantage of for the ERA Mini Turbo limited edition which featured 4-pot vented brakes and a redesigned hydraulic system.
Improving your brakes
Any old Mini braking system can be improved by moving to one from a later year - Mk1 Minis with single leading shoe brakes can be converted to twin leading shoe without sacrificing the looks of the car but the conversion most people are interested in is "Drums to Discs", the best way of dramatically improving your Mini's stopping power.
Note that all Mini disc brake hubs from the original 997cc Cooper to present are apparently the same, or at least fully compatible.
Here is a guide to brake swaps:
Metro brakes and safety notes
Metro 4-pot brake system drive flanges feature wheel locating lugs. These can obscure access to the castellated hub nut or prevent some wheels from fitting as noted in the chart above, in which case the locating lugs may be machined off, any engineering works or engine reconditioner will be able to do this. This is evidently not a major problem as the Mini Spares Center turbo conversion kit is supplied with these lugs intact.
Metro alloy wheels will fit on a Mini. However, they are offset towards the center of the car compared to Mini wheels, narrowing the wheel track and causing potential problems of fouling on suspension components or the inner wheel arches. Fitting of Metro alloy wheels is not recommended.
Many people have swapped the wheel hubs from Metro cars to Minis, as these are available very cheaply in the UK. There is a small amount of anecdotal evidence that this combination results in handing that can be very dangerous under certain circumstances.
Always use Mini Disc Brake Hubs.
The extra cost over Metro hubs is not worth risking the life of yourself and others over.
Also, many people have converted from drums to discs without any of the specified modifications to the hydraulic system. This appears to work from day to day, but the brakes will be unbalanced between front and rear, the track will be wider at the front than the rear, and the master cylinder's bore is different and it holds less fluid. What happens when you really have to rely on the car's handling, or the discs are worn causing the pistons to move out, absorbing all the brake fluid from the master cylinder?
Never attempt to save money or effort on brakes.
Your life and the life of other road users depends on the reliability of your brakes.
Apologies if the above notices sound condescending, but lives ARE at stake when doing "unauthorized" modifications to your brakes that have never been fitted to a production car.
A final note about Metro calipers - there are two types - early and late (revised to reduce the problem of stuck pistons). Either is acceptable but they use different brake pads. If possible, make a note of the year of Metro the calipers are sourced from, to help when ordering new pads.
Vented/4-Pot brakes and 10 inch wheels
Many people desire the combination of 4-pot vented Metro brakes and ten inch wheels. The Metro disc setup will not fit under ten inch wheels. It is possible to adapt the setup to fit; this involves turning down the brake discs from 8.4 in to 7.9 in, machining metal off the caliper, and re-drilling the caliper mounting holes in the hub.
The last two operations above are not safe, and the overwhelming majority of specialist advise against this option. Due to production tolerances in the caliper castings, no-one knows exactly how much metal will be left on the caliper to dissipate heat and keep the fluid in, and it takes considerable expertise to safely modify castings such as the wheel hubs. Don't take this option.
If you truly want vented 4-pot brakes under ten inch wheels, buy a set of alloy calipers from Mini Spares or Mini Sport. These calipers are very expensive but are the only way to safely achieve this braking combination.
Use the driveshafts that are fitted to your Mini, of if you prefer, upgrade to pot-joint or Hardy-Spicer driveshafts, or thicker Cooper S or Special Tuning driveshafts for mre demanding uses. Metro driveshafts are too long and will not fit.
Choosing a brake setup
There are a number of alternative brake setups, and some are more appropriate than others for certain circumstances:
Beyond Standard Brake Setups
The only car that has any degree bolt-on brake compatibility with the Mini is the Metro. Brakes from the Austin 1100/1300, MG Midget and other BMC cars will not fit - many are of the same conceptual design but the sizes, shapes and angles of the hubs, calipers and discs are wrong.
As noted in the table above, it is safe to fit Metro vented discs, flanges and calipers to Mini hubs. This is the ultimate road going setup. If you demand more, for "pose value" or for racing, the following setups are available from some Mini parts retailers at relatively great expense:
Rear braking is more than adequate on a standard Mini, so rear discs are totally unnecessary. However, it cannot be denied that nothing looks better than all-wheel discs peeking out through 3-spoke 13 inch alloys...
Mini Cooper Specials