Norton Commando Workshop Manual

## Brakes, Weels and Tyres

# H

Caliper Re-Assembly
1 | Coat the new pressure seals with Lockheed Series 329 Hydraulic Fluid and ease the first pressure seal into the groove in the inner bore with the fingers, taking care to bed it correctly. It will be noted that the diameter of the seal is larger than that of the seal groove, in order to provide an interference fit. In addition, the seal groove and seal are different in section so that when bedded, the seal feels proud to the touch at the edge furthest from the bore. This is normal.
2 | Coat the inner piston (the pistons are identical) with Lockheed Series 329 Fluid, insert it squarely right through the outer cylinder into the bore of the inner cylinder, closed end into the bore. Leave the piston protruding approximately 5/16 in. (8 mm) from the mouth of the inner bore.
3 | Fit a new pressure seal to the caliper outer bore groove, again bedding it correctly.
4 | Coat the second piston with Lockheed Series 329 fluid and insert it open end first into the bore with the fingers. Avoid tilting the piston and continue inserting it gently through the bore until approximately 5/16 in. (8 mm) of the open end protrudes from the inner mouth of the bore.
5 | Replace the end plug using a new '0' ring seal and tighten into position. For final tightening, the caliper must be secured to the fork leg.
6 | Wipe the caliper clean, removing excess fluid which may subsequently contaminate the brake friction pads, taking care not to allow any rag particles to pass anywhere near the brake pipe feed union.
7 | Fit the two friction pads and ensure that they seat correctly.
8 | Assemble the caliper assembly over the wheel disc and offer the caliper to the fork leg, securing with two bolts and washers.
9 | Tighten the caliper end plug using peg spanner tool to 26 Ib./ft. torque.
10 | Refit the fluid feed hose bracket to the mudguard bridge stud.

IMPORTANT
Before connecting the lower end of the brake pipe to the caliper, note that the pipe olive is specially formed to provide an effective high pressure oil seal against the caliper union seating. The olive is very susceptible to overtightening and if it is severely distorted by overtightening it may be impossible to remove thus rendering the caliper scrap.
11 | Examine the union olive of the metal brake pipe for symptoms of previous overtightening such as distortion, damage and cracks and if necessary renew the pipe.
12 | Offer the olive of the brake pipe to the caliper, hold the pipe in the required position and run the union screw fully down the thread until the pipe is just "nipped" on to its seating. Tighten the union nut with a spanner one flat only, i.e. 60°.
13 | Slacken the bleed nipple one full turn and connect with a suitable bleed tube to a clean container (see Fig. HI 7).
14 | Fill the master cylinder reservoir with Lockheed Series 329 brake fluid.

15

Operate the brake lever until fluid begins to flow through the bleed tube. During this operation, guard against the master cylinder fluid level becoming too low, otherwise air will be drawn into the system. The master cylinder bellows seal must be removed to observe the fluid level.
If replenishment is necessary during this operation, hold the lever to the handlebar whilst the reservoir is topped up. Similarly, when fluid free of bubbles flows from the bleed pipe, tighten the caliper bleed nipple, whilst the brake lever is held against the handlebar.

16 | With the bleed nipple tightened up, remove the bleed hose, apply the brake lever a number of times to check for sponginess (indicating air still in the system and a need for further bleeding) and examine the system for leaks.
17 | Finally recheck the fluid level in the master cylinder reservoir, topping up as necessary, then road test the motorcycle.

<< | < | rocbo.net | >