Which brake pads should I use?
What are the benefits of Dectile Iron Discs?
What brake fluid should I use?
What difference in performance is there between sport discs and the full race kit?
Wave Discs?
How do I bed in Brake Pads and Discs?
Which way round do the discs fit?
How long should a brake disc last?
Do you have to fit discs as a pair?
What is the correct way to bleed a PFM brake caliper?
Fitting Guide

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Which brake pads should I use?

The best type of brake pad to use depends on the type of use. For race applications that generate a continuously high level of temperature in the brake system it is advantageous to use full race pads such as Carbon Compound pads as manufactured by SBS / Bendix. They have the ability to work consistently at elevated temperatures without a drop in coefficient of friction (braking power) that would occur with Organic pads. Performance Friction Corporation (PFC)  and Ferodo also produce a range of pads which are excellent for pure race applications. Care must be taken, as with all race pads when being used on the road, as if they are not run at elevated temperatures they can display a very high pad and disc wear rate. There are now some excellent pads available from all these companies that offer most of the performance benefits of full race material, but without the high pad and disc wear rates at lower temperatures. This allows use for fast road as well as track use.

For road applications and race applications that do not generate continuously high brake temperatures (such as the TT) sintered pads offer a number of benefits, the main one being its ability to give very high friction (braking power) at low temperature. Organic and Ceramic compounds are also suitable for this type of application.

Care must be taken when choosing the sintered pads for your particular application, as the huge variance between different manufacturer's products means that not all sintered pads are suitable for use with Iron rotors as excessive wear may occur.
The main disadvantage of sintered pads is the high heat transfer to the brake caliper, which can lead to brake fluid overheating.

Dunlopad (DP) manufacture a range of sintered pads which have a ceramic coating on the pad back plate which reduces the heat transfer to the caliper. This almost eliminates sintered pad's main disadvantage for high temperature applications.

What are the benefits of Ductile Iron Discs?

Almost all motorcycles now use Stainless Steel brake discs. This is for two reasons: 1. They are cheap to manufacture, 2. They look nice and shiny even when used in the wet!

Ductile Iron (DI) discs will always give better performance than a Stainless Steel disc because of its superior frictional and heat transfer properties but cost more to manufacture and don't look shiny for long if left in the rain! So if excellent brake performance is your prime objective then the only choice is a Ductile Iron disc. The PFM Brake System combines the high performance of a DI rotor with an innovative system for connecting the rotor to the carrier.

What brake fluid should I use?

Most brake systems are filled with DOT 4 fluid (and usually state on the reservoir to only fill with DOT 4). This is slightly misleading as DOT 5.1 can be used in a system that has already had DOT 4 fluid used in it, with a useful increase in temperature resistance. The warning on the reservoir would be more useful if it said 'Do Not Use DOT 5 Fluid' as this is a silicon based fluid that does not mix with DOT 4, 5.1 or any Race Fluid (but is used on Harley Davidsons!).

Race fluids exhibit higher dry boiling point temperatures (the temperature at which the fluid will boil before it has absorbed any water) than DOT 4 and 5.1, but usually show a marked reduction in wet boiling point. This means that race fluids have to be changed frequently to be of any advantage over normal fluid, but can be beneficial for high temperature applications

What difference in performance is there between sport discs and the full race kit?

The PFM Brake Systems Sport discs are a direct replacement disc and are designed to work with standard calipers. They will improve the brake performance because of the higher coefficient of friction and heat transfer properties over stainless steel discs, which is sufficient for motorcycles fitted with a good quality well maintained OE calipers.

The race kit replaces the standard disc with a 320mm diameter narrow pad track disc that gives the same effective operating radius as a conventional depth 330mm diameter disc (without the increase in gyroscopic force that a 330mm disc would produce). A 6 piston 'machined from solid' caliper with a narrow pad depth developed for the narrow pad track disc provides the minimum deflection within the envelope available, along with the lowest residual drag possible. This provides the highest level of performance available from a ferrous (non carbon) brake system.

Wave Discs?

In the main we have not made a ‘wave’ disc because of the high pad wear rates they cause. To some degree, advances in pad compound technology, driven by the popular demand for the aesthetics of profiled rotors have made improvements in this area. In our opinion they should primarily be used for their originally intended purpose; that is, off road use in muddy conditions where, when made as per the original patent application, with a continuous disc band, they offer excellent pad cleaning properties. All our products are designed with the aim of producing the best performance that can be obtained without using exotic (very expensive!) materials. Braking performance is relative to the friction created between pad and rotor surfaces. To this end West Performance did not jump on the bandwagon of Stainless Steel ‘wave’ discs as we do not believe they offer any benefits for road or race use, therefore we do not manufacture them.

We have however been working on a material which will allow us to fulfill the more fashion conscious market with a profiled (wave type) rotor, whilst retaining our company’s aim of producing High Performance Discs. This material will out perform OE type stainless steel discs, with a performance level which is approaching that of (DI) Iron.

How do I bed in Brake Pads and Discs?

The process of bedding in pads and discs varies depending on the type of friction material being used, but there are some basic principles that apply to all pads and discs.

Never fit used pads with a new disc. Even if the pads are not excessively worn they will not have a flat surface and will cause localised overheating of the disc, which will result in disc distortion.

If fitting new pads to a used disc, clean the friction surfaces of the disc with an abrasive material (emery cloth or wet and dry, about 120 grit) then clean with brake cleaner

Which way round do the discs fit?

PFM discs are always fitted with the circlip on the inside face of the disc with the groove angled as shown;

From 2007 our design which now offers a ‘quick change’ facility will become our standard. Identified by the fact that the clip now fits into a slot in the centre of the rotor spigot, these discs are fitted with the clip to the outside of the wheel.

Direction of rotation groove angle

How long should a brake disc last?

It is impossible to put a definite life on a brake disc of any sort, there are too many variables that can have a dramatic effect on the life of a brake disc, but it should be noted that a ductile iron disc will last approximately 50% longer than a stainless steel disc if used to generate the same level of performance. However, as ductile iron discs offer higher levels of friction, it is almost always the case that the rider will make use of this and reduce the life of the disc to that of a stainless steel disc. So whatever your riding style, a ductile iron disc will offer advantages; either longer disc (and pad) life, improved performance, or a combination of these two benefits.

Do you have to fit discs as a pair?

The simple answer is No! The reason for this is that, unlike cars, the steering of a motorcycle is unaffected by different friction levels between two discs on one wheel.

What is the correct way to bleed a PFM brake caliper?

A great deal of thought and design led to us producing a caliper with two bleed nipples. This design allows a free path for any air or fluid to exit the caliper with the bleed nipples vertical. The easiest way to fill the calipers with fluid for the first time is to mount them on the discs in a upright position (hold them onto the discs with elastic bands) then connect clear plastic hose onto both bleed nipples of the caliper being bled, that is long enough to clip onto the handlebar. With the reservoir filled but the top not fitted, undo the inner bleed nipple. No pumping of the lever is necessary, as the fluid will feed by gravity into the caliper. When only clear fluid is coming into the clear plastic hose from the bleed nipple, close it and repeat with the outer bleed nipple. Repeat this process for other caliper, and then mount the calipers to the fork leg. If a firm lever cannot be obtained immediately it may be necessary to repeat the process.

Fitting Guide - Click here