Adjust comet front brakes
- Thread starter alscomet
- Start date
My Comet was recently tested on MOT brake test rollers. It returned 38% for the front brake. I winced thinking this was low but the tester said many modern bikes with discs only show 28%. As he commented, it doesn't matter if the lever is spongy on a static bike so long as the wheel is being effectively braked and may well lock before the lever reaches the handlebar.
My A twin recorded over 90% on the front brakes, the tester said it was the best he'd seen - but also said that most Vincents out-perform mdern bikes on the rollers !!
Spongy brakes have to be caused by flexure somewhere. Have you looked at the cable. I make my own up using stronger than standard industrial cabling. Look at the brake plates and are they bending when the brake is applied hard? If so then either you have to weld gussets on the steel originals or buy some of the new machined from solid ones. Flexing of the brake plates could be caused by the shoes not coming on together or their pivots being loose. Have a look. Are the handlebar levers flexing on the handlebars? How about the pivots on the handlebar levers? If all those items are found to be ok then you can start and worry about adustment. Are the lower brake arms at 90 degrees to the cables? Do the brakes come on together? Is the front balance beam flexing either its pivot or its mounting plate? Patience and reading the book will sort out most of this problem. Good luck.
Hi A-BCD,
not having to have had a brake test on a bike yet (living in Germany) what exactly are the testers measuring to get the percentage? (can´t possibly be braking effort up to wheel locking?)
Thanks.
not having to have had a brake test on a bike yet (living in Germany) what exactly are the testers measuring to get the percentage? (can´t possibly be braking effort up to wheel locking?)
Thanks.
http://www.ukmot.com/bike_3-3.asp#Text_top Vince 998 have a look at the following from the MOT testing manual. Alan
The procedure is not very clear in the book but the procedure is as follows, put the bike on the front stand, or just chock it up to let the wheel clear the ground. Lay in the front and push both operating levers up to engage the drums. Now these MUST be paralell IN THE ON position,
if not you can adjust the angle by moving the arms around and if this dosent do it the serrated washers the the arms are attached to can be moved round 90 degrees to alter
the position until the correct alignment is obtained. Before starting this operation slacken the cable adjustment right off when correctly aligned adjust the cables so the shoes start to make contact, then slacken off a bit to suit. Your brakes will not work as PCV
intended. To all the critics reading this try it before picking holes it works!!. Always a good test of a strange bike see how the front brake works!. Try it gently when you've done it as it will work well!!.
Dave G6XNC (alias Dave GS from another world)
if not you can adjust the angle by moving the arms around and if this dosent do it the serrated washers the the arms are attached to can be moved round 90 degrees to alter
the position until the correct alignment is obtained. Before starting this operation slacken the cable adjustment right off when correctly aligned adjust the cables so the shoes start to make contact, then slacken off a bit to suit. Your brakes will not work as PCV
intended. To all the critics reading this try it before picking holes it works!!. Always a good test of a strange bike see how the front brake works!. Try it gently when you've done it as it will work well!!.
Dave G6XNC (alias Dave GS from another world)
Yes they do have to be parallel with each other. If you think about it, the reason for the ninety degrees between the cables and the arms is that it is at that angle that one can apply the maximum torque. This 90 degree angle is when the brakes are fully applied The angle will be slightly less that that when the brakes are not being operated.