Fitting Guide

Warning: Due to the safety critical nature of brake systems it is essential for brake components to be fitted by qualified, professionally trained mechanics.

The following is intended as a guide to specific requirements of West Performance’s PFM Brake Systems to aid fitting and assembly. The general information contained is not intended as a definitive guide to fitment that would enable an unqualified person to install brake components safely.

General Points

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 manufacturers 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.

Fitting Discs

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.

Fitting Calipers

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 centred 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).

Replacing your Brake Pads

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

Bedding in is the most neglected part of brake fitting, and if not carried out correctly can destroy brand new brake rotors in a matter of minutes!

View correct bedding in instructions.