Don’t wait for the wear sensor visually check you pads especially for uneven wear as this denotes an incorrectly fitted pad or a malfunctioning calliper. The last 4-5mm of pad material is considered to be a 'heat sink' and its used to transfer heat from the pad to the brakes, it is advisable to replace pads before this point or your breaking will be greatly affected. When you fit new pads follow the bed in procedure as it is different for each pad.
When ridges start to appear in the disc surface it is a fair assumption that the disc needs replaced. Discs are checked with a run out gauge to determine when they are used, this will denote the difference from new to the amount of material remaining this should be supplied with the disc. If you have a brake kit that uses two piece discs and are unsure or have problems obtaining new discs there are a number of companies that will make two pace discs to suit your application, they may need measurements or the mounting hat to make up new hardware, some of these companies are: Nitrac, High Spec, Reyland and Alcon.
Other Points of Note:
Make sure all surfaces are clean and flat, otherwise your brakes will not be aligned correctly. Brake callipers do require rebuilding form time to time, companies such as Big Red, Brake Calliper Refurbishment, or Autofarm and others offer a post and post back service. For smaller more specific brands like Alcon it will be worth contacting the manufacturer.
Understanding Big Brake Kits:
The idea of bigger is better is not always the case, and especially not where brakes are concerned. Choosing a brake kit is much like anything else when building a performance car there are a lot of considerations to take into account:
Piston Size: big brake kits use a wider variety of piston sizes this affects every aspect of how your brakes functions from the ability of the cars master cylinder to cope with the increase in fluid capacity to their ability to regulate heat through the brake fluid.
Brake Lines: factory lines are made of rubber and over time they start to deteriorate reducing brake performance. Most big brake kits (after market) will come with Steel braided lines which do not suffer from the issues as the OEM items, although for the standard and larger OEM kits companies such as Goodridge and HEL will either stock or make lines to your customs specification.
Number of pistons on each calliper: your OE brakes (unless fitted with Works 4 or 6 Pistons) are single piston claw action callipers, they are quick to respond to brake force as the fluid only has to work on a smaller piston surface. It is now common to find offerings of 4, 6, 8 and even 10 piston callipers for the MINI, but you may well find its the case that a larger 4 piston racing set up has exactly the same piston – disc area that 10 piston calliper has as it has made use of smaller pistons for a more progressive road set up. You should carefully look at all aspects of the design of your brakes.
Disc size: most people pay little attention to one of the more vital aspects of disc size the width of the disc, most people look at a disc and see 305, 330, 350mm and so but do not pay attention to the width of a disc which has a significant impact on cooling and disc life. Take for instance the GP MK2 discs at 330 x 26mm and the R56 Works Brembo is 316 x 22mm while the Reyland AP Racing kit is 324x30mm giving the disc a significant width advantage for more effective cooling.
Pad Choice: you must also check carefully what pad options your kit comes with, most suppliers will offer three of four choices ranging from street, street & track to full race compounds. You will also find that most big brake kits share common pad sizes and most compound manufactures will offer an option, places such as Demon Tweaks are a good place to start from as they carry an extensive range of pads for most big brake callipers. However if you can provide the original pad as a reference Carbotech will make pads to suit your needs. You should also seek advice on a suitable rear compound for the OE callipers.
Calliper Construction: cast callipers with balance weights such as the GP MK2 parts with large single piece steel discs will be at a significant disadvantage to a similarly size kit with Billet Forge Callipers and two piece discs, cast callipers such as the John Cooper works items are also weaker than their billet counterparts.
Retro Fitting: most manufactures will provide a template that you can test for wheel fitments, as in most case wheel size is only a minor concern next to spoke clearance.
Q - Can I fit OEM front brakes onto the rear of my car if I fit a big brake kit on the front?
A – As a rule no, you will lose the OE handbrake, unbalance the cars ECU controlled brake functions ASC+T and DSC and ABS will all no longer function correctly. Not to mention the additional costs of fabrication.
Q - Does anyone make a matched rear brake kit for the MINI?
A – Yes; Willwood make a rear calliper kit for the Mini designed to work with the stock handbrake and their Big Brake Conversions, we cannot stress enough that this is designed to work with Willwood front Brakes, if you have questions about this we recommend you contact TCE performance and speak to Todd.
Q – What brake fluids are the popular choices?
A – Usually a high performance DOT4 fluid such as Motul MT600, ATE Superblue, or Castrol SRF.
Q – What brake compounds do most MINI owners use?
A – On Mini Torque the favoured compounds are Performance Friction and Carbotech most users tend to opt for XP8 and above in the Carbotech range.
Q – Drilled or Slotted discs (or both)
A – It really depends on the application, slotted discs help de glaze the surface of the pad and disc but are more aggressive in relation to pad wear. On the other hand drilled discs allow for more effective escape of the hot gases generated under brake force but are more prone to crack around the holes drilled in the disc.
Q - Fixed or Floating Discs?
A – A fixed or one piece disc is the normal fitments and more common due its lower initial cost and ease of replacement at service. A floating Disc or two piece disc comprises of a steel or carbon disc with an aluminium hat that attaches it the hub, this has a number of benefits; weight reduction on un-sprung weight, more effective cooling and cheaper replacement discs as the hat is retained.
R53 Brake FAQ:
Q -What OEM kits can be retrofitted? (These kits require their OEM or upgrade specification hoses to fit the original hard lines).
A - R53 John Cooper Works callipers with 294mm discs. R56 standard Cooper S brakes with 294mm discs, JCW Brembos (4 piston calliper) with 316mm discs, BMW Performance (re branded John Cooper Works) GP MK2 6 piston callipers with 330 x 24mm discs. The rear callipers from the John Cooper Works Brembos may also be retrofitted but require an inset to be cut in the steel trailing arms (they will be a direct fit to the GP)
Q – Will I have wheel clearance issues?
A – It depends on your size and offset, as a rule very few big brake kits fit under 16’ wheels, most OEM 17’ wheels will clear the OEM brake kits however its best to assume a spacer of between 5 and 10mm will be required. The only OEM brake Kit to fit under any OEM 16’s are the R53 JCW and R56 Standard Cooper S callipers with a 294mm disc.
Q – What other issues may I face?
A – The R53 has a relatively small brake master cylinder so you may find the top of the pedal is softer once you have increased the size of the brakes. Although it is not a major effect nor does it impact on the enjoyment of the car.
Q – Can this be fixed?
A – Yes, there are a number of master cylinder upgrades on offer from aftermarket companies such as Alcon and Willwood, speak to your tuner to find the best solution for your needs.
R56 Brake FAQ:
Q - What Can be retrofitted?
A - JCW Brembo (4 piston calliper) with 316mm discs, BMW Performance (re branded John Cooper Works) GP MK2 6 piston callipers with 330 x 24mm discs. The rear callipers from the John Cooper Works Brembos may also be retrofitted.
Q – Any Considerations?
A – Mini recommends their upgraded map on the ECU for the DSC when fitting larger brakes to the R56.