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 Mini’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, maximumdisc 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 color 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.
|EBC||Mintex||Ferodo||Pagid||EBC||EBC||Performance Industries||Performance Industries|
|Street Kevlar 'Black'||1144||4003F||Fastroad||Roadsport 'Green'||Competition 'Red'||CM5183||CM5193|
|Effective temp range||2||2||2||3||3||5||5||5|
|Area of use||1, 2||1, 2, 3||1, 2, 3||1, 2, 3, 4||1, 2, 3, 4, 5||5||5||5|
|Fitment||C, S, LM, M||C, S, LM, M||S, M||LM||C, S, LM, M||C, S, M||S, M||S, M|
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||
|Area of use||
General notes on pad types
CarbonMetallic 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.
MintexM1144 pads. Part of new ‘C-Tech’ range of asbestos-free pads. Superseded the old and ‘favoured’ M171 compound, but hasbeen struggling to achieve similar performance since the abolition of asbestos.New, superior alternatives could be sounding its death-knell with all but diehard 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.
Pagidpads. 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.
EBCKevlar 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 overthe 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.
Aword about standard pads - ‘reasonable’. Sticking to Unipart pads, you’ll get pretty good results for a road car. Avoid corn flake 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.
|GBP102AF||7" 998 Cooper disc pads, standard Unipart|
|C-AHT223||Mintex C-Tech M1144 pads for above|
|C-AHT223KEVLAR||EBC 'Greenstuff' pads for above|
|GBP103AF||7.5" S/1275GT disc pads, standard Unipart|
|GBP103KEVLAR||EBC 'Blackstuff' pads for above|
|C-8G8995KEVLAR||EBC 'Greenstuff' pads for above|
|C-8G8995||Mintex C-Tech M1144 pads for above|
|C-8G8993||Carbon Metallic pads for above|
|GBP281AF||8.4" Post 1985 Mini disc pads, standard Unipart|
|GBP281KEVALR||EBC 'Blackstuff' pads for above|
|C-AHT16KEVLAR||EBC 'Greenstuff' pads for above|
|C-AHT16||Mintex C-Tech M1144 pads for above|
|C-STR986||Pagid pads for above|
|GBP258AF||8.4" Metro-type 4-pot caliper pads ('A' type with 70mm pad-pin hole centres for retaining pins) vented and non-vented, standard Unipart|
|GBP258KEVLAR||EBC 'Blackstuff' pads for above|
|C-8G8994KEVLAR||EBC 'Greenstuff' pads for above|
|C-8G8994||Mintex C-Tech M1144 pads for above|
|C-STR987||Carbon Metallic pads for above|
|C-17H2460||Stick-on anti-squeal pads (car set)|
All other service items are available separately; see relevant section on site.
Appliance of science How brakes actually work isn’t too difficult at all (see 'Brakes - How they work' for further information). The braking system simply turns kinetic energy (motion) into thermal energy (heat) - more commonly known as friction. The greater the friction generated, the greater the stopping power. Nice and easy. So what we want is a brake pad that creates copious quantities of friction, right? Well, no. The trick is to generate just the right amount of friction to suit certain applications. Consequently just banging in a set of ‘race’ pads for your racer, or ‘fast road pads’ for your road car may not give the best result if the brake set up fitted is already over the top. A controlled stop is desired, not screeching to a halt amid a plume of tyre smoke. Getting to grips with brake terminology is a step in the right direction, so walk this way....
Friction - we now know what it is and how it’s produced. The industry give pads a numeric tag that describes their friction coefficient (referred to as ‘Mu’ hereafter) where 0 is worst and 1.0 is best. The highest a pad would be expected to achieve is approx. 0.50. Higher than this and any control would go out the window as a pad designed to just give maximum friction isn’t the answer. Too much friction for any given application will over-come the tyres ability to grip the road (traction). The result is the aforementioned tyre-smoke shrouded, howling stop. Eventually. Wheels locked-up under braking are grossly inefficient, and negate any steering input. Basically you’re out of control. A situation that gets very much worse in the wet as traction is more easily broken. So a pad has to be designed to give maximum friction in a controlled manor for any given application. Just picking a pad that has a high ‘Mu’ will get you in trouble, as this doesn’t describe the whole story.
Bite - the initial friction experienced at the start of a stop. That feeling you get when you first press the pedal. We already know that brakes need heat to work. Generally higher performance pads take longer to get up to working temperature, so initial bite is low - that ‘o my god, the brakes aren’t working’ feeling, making you press harder, then all of a sudden the temperature rises sufficiently to work, and you lock the wheels up. Formula one pilots left foot brake most of the way around the warm-up lap to put heat in their car’s brakes to avoid disappointment at the first bend - going either sailing into the kitty litter (if they’re lucky) or someone else (if they’re not). This practice is all well and good for racing, but on the road you can’t be doing this all the time, so a pad that gives good initial bite must be high on the priority list. Having a pad for racing that can do this and give maximum ‘hot’ performance verges on ecstasy!
Cold friction - the pad’s performance for a heavy application from ambient temperature - such as experienced from braking to a standstill from motorway cruising speed. Many standard road spec pads seem barely adequate at this. A race-type pad may be better at the end, but heart stopping nothingness when you first hit the pedal can cause panic, and an impromptu interface with another vehicle/armco! Most undesirable. A pad with a very stable compound will give the best performance in this instance.
Fade - the drop off in ‘Mu’ from stop to stop. One of those much-abused terms. Although heat is necessary for good braking, excessive heat can cause a pad to become inefficient, even stop working, because the compound has been ‘cooked’. This happens when frequent and successive hard braking stops occur. A rare problem on the road, but one experienced often on the racetrack. A pad that tolerates a broad heat spectrum dilutes these problems.
Friction consistency - how consistent the pads perform during a stop from cold to hot, and from stop to stop - the pads ‘characteristics’. Important points to remember here are that a locked-up wheel is nowhere near as efficient at stopping the car as one that’s rotating under braking, and the slower the car is going, the lesser the braking effect needed. Consistent characteristics are essential as they greatly influence your confidence. Pads that perform erratically will have you worried, predictable pads have you subscribing to the ‘last of the late breakers’ club! There are three basic transient situations for pad performance in the stop, and in repeated applications. One that starts with a low initial ‘bite’, ‘Mu’ increasing with heat build up is hard to control - necessitating skillful driver input (‘feel’) as the pedal pressure will need to be gently eased off through the stop to avoid wheel lock-up. Not user friendly, but preferred by some racers as the type of compound used generally has high ‘Mu’ levels and fade resistance. One that maintains its ‘Mu’ throughout the stop is tricky to use. The compounds used generally give better than average initial bite, reasonable ‘Mu’, but can fade in arduous situations. Diligence is required from the driver to get the best use of these. One that has a strong initial bite with ‘Mu’ gradually decreasing through the stop is the most desirable - most user friendly. And these features need to duplicate themselves whenever the pedal's pressed!
Pad wear - how quickly a pad wears in use. The compound used needs to be sufficiently sustaining to endure an acceptable service life. One for road use that only lasts a few hundred miles is as unacceptable as a race pad that barely manages a race. However, some mid ground needs to be accepted when superlative braking is sought.
Disc life - how abrasive the pads are in use, giving rise to increased disc wear. Of great importance on a road car, and a consideration in racing where budgets aren’t in the formula one league! A pad that provides high ‘Mu’ levels with minimal abrasion is obviously preferred.
Effective temperature range - strangely enough, the temperature range where the pad gives its best performance. Operational temperatures vary from zero to 800-degrees Celsius. These are greatly affected by the overall brake set-up and how they’re cooled. Generally the greater the disc mass and the greater the airflow around the disc/caliper, the cooler they run. Road cars generally operate in the region of 0-250-deg C, fast road/competition 0-450-deg C, and all out race 300-800-deg C. Few Minis would reach the upper end of the race scale as they’re neither heavy enough or quick enough to generate such temperatures. Pads that transgress these boundaries give a greater performance envelope than more dedicated ones.
Area of use - the most suitable arena of use for a given pad type - usually designated by road, rally, or race. But as pointed out earlier, this is not a parameter that should be considered carved in stone. The actual application is entirely dependent on what temperature the brakes work at.
Noise/comfort - the amount of squeal/judder generated, and pedal effort needed. Obviously both are completely undesirable on a road car. Squeal on a race-only car is immaterial if the stopping power is what’s wanted. Judder on a race-only car can be tolerated but generally needs to be avoided as it can be confidence destroying for the driver, and may upset your Mini’s handling under severe braking on bumpy surfaces. Excessive effort may tire you, and eventually give you a sore foot! See 'Brakes - Pad types & choices' for brake pad options/applications.