Brakes - Pad types & choices
I know I keep dragging this one out for an airing but it’s continually ignored by far too many folk - the only way to get the best from what you have is to be totally honest with yourself about your Min’s main usage. Delusions of grandeur cause severe disappointment, and tears before bedtime. Fitting a set of pads to your road Mini because you think you drive like Michael Schumacher, and your Mini’s built around a ‘race’ theme, with ‘race-spec’ brakes is going to get you into severe bother. Nine times out of ten they won’t work properly.
Despite a particular pad type having a high ‘Mu’ designate doesn’t mean to say it’ll give you the best braking potential. They’re generally made in a harder compound so may also give unacceptable levels of disc wear, noise output (squeal), or judder. A pad that gives excellent performance at lower temperatures may have unacceptable pad wear, and create excessive corrosive dust.
So what you need is a pad that works from cold, gives strong initial bite, gradually decreasing ‘Mu’ during the stop and through consecutive stops no matter how frequent/infrequent, no squeal or judder, minimal pad wear, maximum disc life, usable on road and track, tolerate a mile wide heat range, and last but not least, cost a fortune. Seemingly impossible - or is it?
Heat of battle
The main factor to establish then is the heat range your brakes are working in. To decide on which pads best suit this you can either rely on the experience/knowledge of your friendly Mini and /or brake specialist, or measure the temperature your brake set-up is developing. To assist in the former, I’ve jotted down my two-penny-worth in the accompanying chart. By no means the entire selection available these days - but a very broad cross-section of what's available. Achieving the latter is relatively simple. Thermal paints and stick-on tabs are available from brake specialists that are applied to the edge of the disc. They change colour when certain temperatures are achieved, indicating a certain running temperature range. Maybe excessive for road use, but an absolute must for accurate pad selection when competing to avoid loads of 'trial and error' testing…
BRAKE PAD PERFORMANCE CHART (illustration of chart to follow)
KEY TO CHART
All valuations based on a 1 to 5 scale where 1 is worst, 5 is best except the following:
Friction - Friction coefficient where 1.0 is best
Effective temperature range - 1 = 200 deg C
2 = 350 deg C
3 = 500 deg C
4 = 650 deg C
5 = 800 deg C
Area of use 1 = Street
2 = Fast road
3 = Sprint/hill climb
4 = Rally
5 = Race
Fitment C = 998 Cooper caliper
S = S/1275GT 7.5” diameter disc caliper
LM = Late Mini 8.4” diameter disc caliper
M = Metro and alloy 4-pot caliper
General notes on pad types
Carbon Metallic pads. Made in USA by Performance Industries, heralded as the latest and greatest in brake pad technology. And they were when they first arrived. Formed by combining carbon and iron particles, fused together by a special sintering process. Developed for ‘real’ race cars (the compound is the same irrespective of vehicle application) but used by one and all despite short-comings as they bettered the established marques (Ferodo, Mintex). Recommended to be used with non-drilled/grooved discs to try and maintain high operating temperatures. Pros - High friction coefficient, broad operating temperature range, no fade. Cons - savage disc wear, full potential rarely used on Mini (insufficient weight/speed), high heat transfer to caliper/fluid (causes fluid boiling), grabby in operation - especially in the wet! Can be very noisy, limited range, expensive.
Mintex M1144 pads. Part of new ‘C-Tech’ range of asbestos-free pads. Superseded the old and ‘favoured’ M171 compound, but has been struggling to achieve similar performance since the abolition of asbestos. New, superior alternatives could be sounding its death-knell with all but die hard supporters. Pros - wide range available, marginally better than OE pads, work well from cold. Cons - Prone to squeal, not as effective as old M171, limited effective temperature range.
Pagid pads. One of the ‘new kids on the block’ and are counted amongst the select few pad manufacturers that develop compounds for specific vehicle applications rather than a single compound type applied to all vehicles. Consequently their compound for Mini applications is dedicated to the type of vehicle/use. Pros - Specific compound development means no compromise for application, works well from cold, extensive effective temperature range, low disc wear, low pad wear, no ‘noise’. An excellent pad. Cons - very limited range, compound exclusivity development means higher cost.
EBC Kevlar pads. Made in England by the renowned motorbike pad manufacturers, and new in 1998. Kevlar’s a high-strength Aramid fiber, a space-age material that’s six times stronger than steel. Despite this it’s flexible, resilient, flame proof, and superlative insulation material. These combined properties make it ideal for durable, high-quality brake pads providing vast improvements over the more common high metallic non-asbestos types. Pros - Very low disc damage/wear, no ‘noise’, very high friction/anti-fade braking, extremely wide effective temperature range keeps production costs down so are cheaper than equivalent pads, enhanced pad life, extensive range. Cons - Erm.
A word about standard pads - ‘reasonable’. Sticking to Unipart pads, you’ll get pretty good results for a road car. Avoid cornflake packet lined after-market specials. They’re generally rubbish. In fact Unipart pads are pretty good for the hill climb/sprint brigade too. Obviously available for all types.
See 'Brakes - Pads, function and parameters' for further information.