front brake F1

[neat street]

Hi all the front brake is sticking 0n on my CB750 F1, moves ok forward, but can feel resistance when pulling the bike backwards? not sure where to start, front caliper or master cylinder? not a lot of resistance, but enough to fail MOT (all seals replaced on re-build).
thank you
John

[hairygit]

First of all, brakes are ONLY tested in a forward direction for the M.O.T.. Put the bike on the centre stand, and put a jack with a wooden block on it under the engine. Jack the bike up carefully (I use the oil filter housing as a jacking point) until the front wheel is clear of the ground. Spin the wheel forwards, apply the brake, then release and spin again. There should be no dragging or binding from the caliper. Then do the same spinning the wheel backwards, if it binds badly, check the tightness of the split pin that goes through the fixed pad (side nearest to the spokes) as if it is too loose it can cause the symptoms you describe, solution is split the caliper (don't pull the brake lever while the caliper is apart!) Then remove the old split pin, check the pad moves easily within the housing, if not, rub the metal on the circumference of the pad with fine sandpaper or emery cloth, and keep checking back that it then moves freely. If the inside edge of the housing it sits in is furry/corroded DO NOT use sandpaper or emery to clean it. Use a green nylon scratchy pad thingy from the kitchen to clean it out. When the pad moves freely, apply a tiny smear of copaslip around the housing, making sure you don't touch the friction area of the pad until you are sure your hands are clean of copaslip, insert a new split pin then reassemble.

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[neat street]

Thanks hairygit, I will give that a try. when collecting the bike the guy who did the MOT said it works OK forwards, but try to move backwards, and it was sticking a bit in reverse, either he got it wrong, or???
thanks again
John

[hairygit]

I can't see why it would be an issue to be honest, a motorcycle generally doesn't have a reverse gear (some big Goldwings and Russian combos excepted!) So it shouldn't make any difference to the requirements of the M.O.T possibly some might list it as an advisory, but it shouldn't be a failure point. I'm sure Bryan J on here would be able to give a definitive answer.

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[Bryanj]

The only ones I ever tested in reverse were some of the smaller ones used to show wear in the suspension if you put the brake on and pulled backwards. To me if the wheel spins free and the brake meats efficiency its a pass

[neat street]

Thank Hairygit, bang on but the opposite side (piston side ) pad had very little movement before locking, gently pulled the brake to get out, cleaned/copper greased both sides and now all good. thank you. I think that maybe he may have meant that pulling backwards was worse??? anyhow, done now thanks
John

[hairygit]

Excellent news, the reason I thought it was the fixed pad was when the moving pad is stiff/sticky the brake will bind/drag going forwards and backwards. Still, good result, good luck with the M.O.T.

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