Norton Commando Workshop Manual

## Brakes, Weels and Tyres

# H

### SECTION H13

### NORTON LOCKHEED HYDRAULICALLY OPERATED DISC BRAKE

This brake is a very powerful and progressive unit offered from 1972 as an alternative to the drum type brake. The servicing routine is straightforward but it is absolutely essential for the components of the hydraulic system to be handled with particular care, avoiding any possible marking of the bores and pistons of the master cylinder and of the caliper since these are machined to unusually fine limits. Similarly it is vital to exclude even the finest particles of dirt and foreign matter from the hydraulic system and to avoid the use of any fluid or cleaning agent which could cause even the smallest degree of deterioration on the rubber seals. Throughout the following instructions, reference is made to the use of Lockheed Series 329 Hydraulic Fluid for Disc Brakes. This is the fluid used by the factory and recommended for use in the Commando disc brake hydraulic system in subsequent service, the fluid complying with the requirements of USA/Canada Safety Standard 116. The hydraulic system is sealed and the master cylinder and caliper with hose and pipe connected can be removed as an assembly if required without the loss of fluid and without the need for bleeding on reassembly. Providing the bellows seal is in situ in the master cylinder there will be no loss of fluid even from the breather hole in the cap.

It is not necessary to remove the caliper assembly from the fork leg during renewal of the friction pads as described below:

Caliper Friction Pad Renewal
1 | Remove the front wheel (see Section H6).
2 | Rotate the friction pads slightly and remove.
3 | Inspect the friction pads for excessive wear. uneven wear or scoring. If there is any doubt whatsoever on the condition of the pads, obtain new pads. It is important to replace the pads as a pair: never attempt to replace one pad only.
4 | Clean the friction pad recesses and exposed ends of the pistons using only a small soft brush. DO NOT utilise any solvent or wire brush for the removal of dust, dirt or scale.
5 | Smear lightly the piston faces and brake pad recesses with Disc Brake Lubricant.

6 | Remove the master cylinder cap and bellows seal to observe the level which will rise during the next operation.
7 | Press the pistons back into the caliper, observing the fluid level in the master cylinder to prevent overflowing. If necessary, excess fluid can be siphoned off.
If at this stage it is found that the pistons are locked or seized in position and not free to move, the caliper must be removed, drained and overhauled as described later in this section.
8 | On motorcycles using the cast iron disc, a rust build-up may have occurred which prevents entry of the disc between the new friction pads. Remove any such rusting by the careful use of a fine flat file. This will not occur with the stainless steel disc identified by the part number 063464 stamped into the outer rim.
9 | Ensure that the new friction pads are of the correct friction type to suit either the cast iron or stainless steel disc. It is important to consult the replacement parts catalogue and thus obtain the correct pads. Frictional and noise problems will arise if incorrect combinations of disc and pads are used. Any roughness or manufacturing flashes must be trimmed from the edges of the metal backing plate.
10 | Avoiding the friction material, smear the edges of the pad backing plates with Disc Brake Lubricant and press fully home against the pistons.

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