At PFM we constantly invest in sourcing the best materials and up to date manufacturing techniques to produce discs that make a difference.
The information below is based around the use of PFM discs as a starting point, followed by the best practice and informed choices for optimum performance.
For the best/correct ‘brake pad friction material’ to use for optimum braking power/performance, there isn’t a ‘one size fits all’ solution. It depends on a variety of circumstances, such as:
Brake disc material and method of manufacture will always be one of the most limiting factors in terms of performance.
Unfortunately the majority if not all standard ‘Road’ bikes, are fitted with discs sourced for their price and not performance. Stock discs do have limitations when it comes to ‘dialing-in’ the required feel and performance.
The pad information here is based on the use of PFM discs.
Optimum brake performance is all about rider confidence and bike control. The higher the level of those two things, the better the lap times.
For race applications that generate a continuous high level of temperature in the brake system it is advantageous to use full race pads.
Carbon Compound pads: As manufactured by SBS / Bendix, and Carbon Organic pads as manufactured by Ferodo for example, have the ability to work consistently at elevated temperatures without a drop in coefficient of friction (braking power). These pads work equally well with either our Ductile Iron (DI) rotors or Race Stainless Steel (HP) rotors.
They have a ‘Rising Torque curve’, which means they have a progressive initial bite (feel), followed by an increase in performance as temperature builds.
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.
Sintered Pads: Good quality sintered pads, from manufacturers such as Ferodo, SBS, Brembo, Bendix, to mention a few, are best used with our (HP) rotors.
Sintered pads give a high level of initial bite followed by a ‘Flat Torque curve’, giving consistent performance throughout the ‘stop’, they also work well at lower temperatures.
Overall, in most race conditions, there is not a lot, if any difference in stopping distance, between a PFM (HP) rotor with a good sinter pad and a PFM Iron (DI) rotor with a carbon pad. However the ‘profile’ (feel) of the performance is quite different.
So it’s rider preference, high initial bite vs progressive feel.
Although it is not generally recommended that Sintered pads are used on Iron (DI) rotors, as with most guidelines, there are exceptions.
For some road applications and race applications that do not generate continuously high brake temperatures (such as the TT) high quality 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.
Under extreme conditions, one problem that can arise with sintered pads is the high heat transfer to the brake caliper, which can lead to brake fluid overheating (brake fade).
There are manufacturers who have a range of sintered pads which have a ceramic coating on the pad back plate which reduces the heat transfer to the caliper. This does help to some extent to eliminate sintered pad's issues for high temperature applications.
For road use, the majority of the information above is relevant.
The main difference as far as pad choice is concerned, is you would not want to use a carbon pad on a pure road bike, especially if you have (DI) rotors. As stated above, generally you will not get carbon pads up to optimum operating temperature in a road application.
For (DI) rotors on the road, any good quality Organic or Ceramic pad is a good choice, or if you don’t run your brakes excessively hot, any good quality sinter pad will work well.
For (HP&P) rotors, any good quality, sinter, organic, ceramic or ‘mix’ pad will work well.
The results are the same as racing as far as the rider ‘feel’ is concerned.
Sinter will always give you a higher initial bite, organic, ceramic, etc, will give a more progressive feel
At PFM we don’t make different rotors for Road use and Racing . . . We just make discs that work !!
All PFM brake discs are a performance upgrade designed to give the shortest stopping distance, whilst maintaining motorcycle control, both with equal importance.
In order to give riders the very best of performance and rider confidence, we offer the choice of two high grade brake materials. Ductile Iron (DI) and Performance Stainless Steel (HP), the latter not to be confused with the ‘budget’ product as fitted to the majority of standard motorcycles.
Overall there is little to choose between a PFM (DI) Rotor and a (HP) Rotor as far as stopping distance is concerned.
The main difference is the ‘feel’ to the rider and how they achieve the ‘stop’.
DI rotors give a very progressive feel with not a high initial ‘bite’ level. However, with the correct rotor/pad combination, DI has a ‘rising torque curve’, meaning they get better as they get hotter.
HP rotors with the correct pad/rotor combination, have a higher initial ‘bite’ level, so a more immediate feel, followed by a ‘parallel torque curve’ and a consistent stop.
Ductile Iron (DI) Rotors:
Inherently have an unrivalled coefficient of friction and an exceptional ability to disperse heat. This being the case, they don’t need sintered pads as used on stainless steel rotors. Pads such as Organic, Ceramic, or Carbon (for racing) can be used.
The main performance enhancing attributes of this combination is the progressive feel in the beginning of the ‘stop’, followed by an increase in braking power as the temperature builds up.
Stainless Steel (HP) Rotors:
Stainless (HP) rotors, will also run the carbon/Organic (progressive) pads for racing/road as above, but with the added advantage of being able to also run a good quality sintered pad, that will give more initial ‘bite’, and a more ‘parallel’ torque curve.
It also depends on how ‘hot’ you run your brakes ?
As above, the main property of the DI rotors is the ability to ‘disperse heat’, meaning, the hotter they get, the better they work where the HP Stainless rotors give a more consistent feel.
In reality, due to our unique ‘quick change’ rotor system, some racers have a set of DI and HP rotors to fit on the same centres for different circuits or conditions.
All in all, the choice is yours.
Firstly let us say that the DOT rating can be misleading, yes it’s generally true to say that a higher number should give better performance, however this is not always the case.
DOT stands for the American ‘Department of Transport’, and at best is a bit arbitrary.
For example, a high quality DOT 3 fluid can be better than a low quality DOT 4 fluid.
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 previously 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 3, 4, 5.1 or any Race Fluid (but is used on Harley Davidson's!).
Race fluids also have borate ester to handle higher temperatures and exhibit higher dry boiling point temperatures (the temperature at which the fluid will boil before it has absorbed any water) than standard 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.
A system having been drained of DOT 3, 4 or 5.1 can be refilled with any of those. Although they shouldn’t be mixed in the same system, they are compatible. As above, Never mix DOT 5 with any other fluid.
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.
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.
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
PFM discs where the clip traps the rotor in a pocket are always fitted with the circlip on the inside face of the disc with the groove angled as shown (Fig 1);
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 (Fig 2), these discs are fitted with the clip to the outside of the wheel.
Direction of rotation groove angle Rotors with a continuous radial groove are not directional.
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.
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.
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.
Always fit new pads with new discs.
Change brake fluid when fitting new brake pads.
Fit new brake caliper seals whenever you fit a new disc, they do not last forever!
If you have been unfortunate (or careless!) enough to damage a disc by setting off without removing a disc lock, then it is essential to check that you have not distorted the caliper mounting.
Follow pad manufactures instructions for bedding in procedure, if available. If not, follow West Performance guide.
Always take care when using new discs and pads, as they will not develop their full power until fully bedded.
When fitting the disc to the wheel, the mounting face of the wheel should be carefully cleaned and any corrosion or paint removed from the mounting face. If a gasket is fitted between the original disc and wheel, either replace or substitute with high temperature silicone sealant. The purpose of this is to prevent corrosion between the disc and wheel mounting surfaces. If the mounting surface is not perfectly clean and free from corrosion, excessive disc "run out" will result which cause premature disc will wear. Mounting bolts must be tightened to manufacturers recommended torque setting including use of liquid locking agent.
The disc should be fitted with the retaining clip on the back of the disc with the grooves facing in the direction shown in the picture in FAQ. Please note that from 2008 series on, the clip fits on the outside face.
Always fit new pads with a new disc and check that the caliper is functioning correctly. Check that the disc is positioned centrally in the caliper. If the disc is not central in the caliper it may be necessary to shim the caliper mounts to achieve correct alignment.
When removing the old brake hoses and calipers it is important to avoid brake fluid spilling on to any painted surfaces as this will cause damage to the paintwork.
When fitting West Performance’s PFM calipers it is necessary to use the new brake hoses supplied with the full kit.
The new brake hoses should be routed to allow free movement of the steering and full extension of the front forks.
Fit using the new banjo bolts and copper washers supplied. Use the correct pitch double banjo bolt for the master cylinder. A 10mm x 1.25mm and 1mm pitch bolt are supplied to suit original equipment and replacement master cylinders.
Fit the calipers to the fork legs using the original bolts, or in the case of radial calipers the supplied bolts (and spacers if required). Fit the hose fittings and banjo bolts using the 10mm x 1mm single banjo bolts and copper washers, torque the bolts to 14 - 24 lbf. (19 - 32 N. m), then tighten the master cylinder banjo bolt followed by the hose to banjo swivel fitting.
Important: The hose must not be under any strain in any suspension or steering position.
The caliper should then be unbolted from its mounting and secured to the brake disc with the bleed nipples vertical (a rubber band or tie wrap is useful for this). Clear plastic hose should be fitted to the bleed nipples and the free ends placed in a suitable container. The master cylinder reservoir top should be removed and the reservoir filled with new brake fluid (either DOT4, DOT5.1 or race fluid), do not replace the cap at this stage. Then each bleed nipple should be loosened by approximately ½ a turn and left until clear brake fluid with no air bubbles flows into the hose. This is done without touching the brake lever, and should be repeated for all the bleed nipples in turn. Make sure that the fluid level is topped up in the reservoir during this process and not allowed to drop and allow air into the system (if that happens, start again!). When this has been completed, tighten the bleed nipples and pump the brake lever to push pads onto the discs, then repeat the process again to ensure that there is no trapped air in the system. Once this has been completed refit the calipers to the fork legs and tighten the retaining bolts to the manufactures recommended torque settings (use liquid thread locking agent).
It is important to check that the calipers are correctly centered on the disc. Most production bike wheels are off centre by up to 0.5mm, this is normal, and our calipers are designed to accommodate this. However if it is more than 0.5mm it is recommended to take appropriate steps to rectify this once it has been established which part is causing the problem (it is usually the wheel spacers).
As your old pads have worn down, the pistons will have had a 'resting' position further out of the caliper body than when the pads were new. To install new pads you'll have to push the pistons back to their original resting place. Before doing this, the pistons MUST be cleaned to remove any brake dust that will have adhered to the protruding portion of the piston. Pushing dirty pistons back into the caliper body may cause the dirt to get trapped between the pistons and the seals, preventing the piston from retracting back into the caliper after braking. This will result in the brake pad remaining in contact with the disc after brake pressure is released, causing overheating. This will lead to the brake overheating and the disc to warp. Your calipers must be cleaned before changing your pads. The best and safest way is to take the caliper off the bike (no need to detach the brake line), remove the pads, and carefully pump the pistons out by 1-2mm to expose the clean portion of the piston. Thoroughly clean around the pistons with brake cleaner, cloth or an old toothbrush. Make sure you get into all the hard-to-reach places at the back of the pistons. After cleaning the pistons spread some silicone lubricant on their outer diameters (do not use copper slip or any other anti seize paste). The pistons must be pushed back gently and evenly into the piston bore. Push evenly with equal pressure around the diameter of the piston, so that it goes back in without scraping the sides of the piston bore.
Before inserting the pad retaining clips, make sure that the pads fit freely in the caliper, and do not feel tight when resting in the correct installation position. The caliper to pad clearance is designed to be 0.5 - 0.6mm at the ends of the pad. If there is less than 0.5mm clearance then it will be necessary to machine the ends of the pad to achieve the correct clearance. This will not be necessary with PFM pads, but must be checked with all other makes. Failure to check this can cause the pads to bind in the caliper body during heavy braking from cold as the pad temperature will cause the backing plate to expand at a greater rate than the caliper body. Once the caliper body is at operating temperature this clearance will be restored.
Bedding in is the most neglected part of brake fitting, if not carried out correctly optimum braking performance will not be achieved and could possibly damage brand new brake rotors !
Re Bedding in:
To distribute an even transfer film layer of pad material on to a bare metal disc, in the case of the rotors not being new, it is important to remove all previous transfer films. Firm use of 80 -100 grit emery till bare metal appears is best.
When using Sintered Pads on a clean/new Stainless Steel disc, they are pretty much ready to go straight out of the box. Although they would benefit from a couple of ‘heat cycles’ before full power braking.
When using Carbon/Carbon Ceramic based race pads on either Stainless Steel or Ductile Iron disc, the procedure to achieve the “even transfer film” as stated above is important.
The target being to get the pads hot as quickly as possible.
Normally achieved by applying the brake 50 – 60% whilst on the ‘out lap’, 80mph+ while keeping the throttle open so to make the brakes ‘work’ and speed up the process.
When speed decreases by around 20 – 30mph, release the brake, get speed up again and replete the process, a third time would help if track conditions allowed.
All this can normally be done within half a lap of any circuit.
It is important to make the brakes work hard to heat them up.
It is important not to ‘pump’ the brakes as this will not result in an “even” coating.
It is important not to lightly ‘trail’ the brake as pad glazing could occur.
Please also note that during these applications it is important that you do not actually come to a complete stop.
The only thing that could go wrong, normally as a result of ‘pumping’ during the bedding in procedure, or lack of temperature, is a resultant severe vibration. Should this occur, we would suggest that you clean the rotors back to bare metal using coarse emery and repeat the bedding in process.