Norton Commando Workshop Manual

## Brakes, Weels and Tyres

# H

11 | Replace the front wheel as in Section H6, support the motorcycle so that the front wheel spins freely and apply the front brake lever at the handlebar several times to restore the fluid in the caliper and locate the pads correctly.
12 | Restore the master cylinder level as in Fig. K8 using Lockheed Series 329 fluid and replace the bellows seal and cap.
CAUTION: It is dangerous to ride the motorcycle after pad and hydraulic system attention without first applying the brake a number of times to restore pressure and locate the pads to the disc. To avoid glazing of the friction surfaces, the brake must be applied gently if possible over the first 50 miles of use.
Caliper Overhaul
It is unnecessary to remove the front wheel but the hose support bracket must be released from the central fork mudguard bridge mounting studs and the hose to bracket clamp nut slackened to facilitate separation of the hose and pipe from the fork leg. Proceed as follows:
1 | Prior to releasing the caliper from the fork leg, ease the fit of the caliper end plug which will be very tight. This will require the use of peg spanner tool 063965. Do not yet remove the plug.
2 | Remove the two caliper bolts and washers and swing the caliper clear of the fork leg, taking the weight to avoid straining the brake hose.
3 | Lift the two friction pads from the caliper.
4 | Brush clean the exposed ends of the pistons and the outer surfaces of the caliper body, using methyl alcohol (methylated spirit) if required.
5 | Lubricate the exposed ends of the pistons to ease their passage through the seals.
6 | Place a clean receptacle below the caliper to receive displaced brake fluid and remove the inner piston. The outboard piston can be removed easily at a later stage if necessary. For this reason we recommend the use of a clamp to restrain the outboard piston. Apply the handlebar brake lever and the inner piston will be ejected into the friction pad cavity, and fluid released. Do not use any tool or airline to remove the piston nor use excessive pressure at the handlebar if the piston is seized.

NOTE THAT THE ONLY SATISFACTORY REMEDY FOR A SEIZED PISTON IS RENEWAL OF THE COMPLETE CALIPER ASSEMBLY.
7 | Remove the clamp restraining the outer piston.
8 | Slacken the lower brake pipe union nut and separate the pipe from the caliper.
9 | Remove the caliper end plug, drain the remaining fluid into the receptacle.
10 | Remove the piston from the caliper. If there is any difficulty, push the piston towards the centre of the caliper and clean carefully the outer working surfaces of the piston, removing any traces of dirt, dust or scale with methyl alcohol and/or metal polish before pressing the piston back into the caliper body and withdrawing through the end plug aperature.
11 | Using a blunt nosed tool and taking the greatest possible care not to damage the seal grooves in any way whatsoever, remove the pressure seal from the outer bore.
12 | Remove the inner piston through the outer cylinder bore then with the same care remove the pressure seal from the groove in the inner bore.
13 | Pencil mark "Inner" and "Outer" on the friction material of the pads as applicable for future reference.
Caliper Component Inspection
Clean the pistons, caliper bores and seal grooves with ethyl alcohol or clean brake fluid.
1 | Examine the pistons and renew if there are any signs of wear, damage or corrosion. No attempt must be made to rectify damage wear or "out of square" thrust faces by machining, filing or polishing. It is permissible only to restore pistons by the ultimate use of a fine metal polish.
2 | Examine the caliper bores for abrasion, scratches and corrosion, or damage to the seal grooves. The caliper bores are not normally subject to premature failure or wear but irreparable damage can be caused during removal of damaged or corroded pistons or careless removal of seals with a sharp instrument.
After examination clean all the parts thoroughly in methyl alcohol or clean brake fluid.

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