Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: mickwinf on May 02, 2012, 09:03:33 PM
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Got a problem with the master cyl rebuild, the circlip that holds the piston in has broken, one of the ends with a hole has snapped off.Any ideas welcome!
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You could try using a pair of long/fine nosed pliers to pull the remaining hole in the clip away from the wall of the m/cyl, then slide something thin (old feeler gauge?)behind it so the clip can't go back in the groove, then try pulling the feeler gauge round to dislodge the rest of the clip from the groove, has worked for me in the past. Then it should be fairly easy to remove ???
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Hmmm, is it the old one or the new?
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Les its the spare one i got to replace the broken original, i will try hairygits method, will get the bugger out one way or another, its all part of the fun (or so i tell the wife!)
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I used one of those precision screwdrivers to lever the old one out, you could use a fine punch or scribe.
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got it out! used a couple of thin screwdrivers and worked it out bit by bit, thanks for encouragement guys,
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another query about the master cyl, the little holes that lead from the main resovoir to the tube, only one of these is a through hole, the other is a blind hole (not blocked with debris)is this correct?
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NO NO NO, Both have holes BUT the one you think hasn't is VERY tiny and cleans out with a pin, easiest way to check if its clear is put one of thos tidgy torches (turned on of course) over the indentation in the reservoir and see if you can see light looking down the main bore.
Blockage of this hole is the most common cause of the front brake "Hanging On"
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thanks Bryan will check it out
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Bryan you are right again, the hole is tiny, even a pin was too fat to go through, i used a modelling drill bit size 0.3 mm. Now reassembled and painted, on to the next job!
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this brake is starting to anoy me now! Master cyl has been rebuilt, caliper has been refurbished with new piston and seal and bleed nipple.So i thought i would bleed the brakes, should be a simple job.....I pumped fluid through until no bubbles appeared, then tightened up. Result, no brakes, no pressure on the lever at all.Tried several times but no success.so i have left the lever tied up overnight. What anoys me most is why can i fix a cars brake system which is much more complicated but not this simple bike with one caliper! ah well at least there are others out there with similar problems as many posts seem to be about brakes.
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What i have had to do in the past is put a gloved finger over the threaded oulet hole in the master (pipe disconnected of course) and using the finger like a bleed nipple get the master pushing fluid (finger closing hole, pull in and hold lever, release and replace finger---keep repeating till pressure is felt and fluid squirts not just dribbles).
Then whilst holding the lever in get your trained spider to re-connect teh flaxi pipe an bleed away as normal.
NOTE WELL THE GLOVE IS MOST IMPORTANT UNLESS YOU REALLY WANT TO SUFFER FROM CONTACT DERMATITIS!!!!!! Plus its a good idea to cover over everything that might get squirted.
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...and might I say, avoid those 'self bleed' things. They attempt to save time but usually end up wasting time. There is no substitute for the laborious process of opening the bleed nipple, pulling lever, hold, tighten bleed nipple, then repeat and repeat etc. Takes ages but always works...
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Mickwinf,
Had the same with my 750.What I did was using a pair of grips with rag in the jaws not to damage pipe was to pinch the pipe at the master end and pump the lever until you feel force on the lever then release grips repeating until fluid reaches the bleed nipple.
CAREFUL FLUID BUBBLES OUT OF THE MASTER CYLINDER!!!!!!!
Mine is great this way.
Hope this helps
Bitsa
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Hi Mickwinf, Not sure if this will help but I always use a syringe and pull the fluid through very quick and no mess. last used when fitting complete new system with no problems. Good luck.
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thanks will try these methods, on inspection there seems to be fluid leaking from near the lever so i am suspecting a bad seal, they are all new but pattern items and i was not impressed as a couple of parts didn't fit and i used the old ones. Fluid is being pumped out the nipple so master cyl is working to a certain extent
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If you have fluid leaking out by the lever, the seals ARE NOT doing what they should ??? Mixing old parts and new is a recipe for disaster. From where I see it your options are (1) Dismantle again, get the bore of the cylinder lightly honed, and fit a new genuine seal kit (2) Buy a new pattern master cylinder from DSS (less than a genuine seal kit) After all, 90% of your braking needs are suppied by the front brake on a dry road, and if something lets go when you really need it :'( You only have one life, don't compromise with brakes, PLEASE
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Hairygit i agree safety is first priority, the parts i reused was the circlip and washer that hold the piston in, the ones supplied were the wrong size, the bore was honed out and cleaned so at a loss until i dismantle it and check.Thanks for advice everyone, it gets lonely in the shed when things are going wrong!
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hmmm, tried again tonight, the leak was actually coming from the resovoir top as i had not tightened it properly there seems to be quite a build up of pressure in there when pumping. Tried the syringe method ( sounds like some sort of birth control!) but no better, also tried Bitsa's idea and clamped the hose, this gave a solid lever so it seems to suggest the mastercyl is working. Checked for leaks at all joints, also changed the bleed nipple.Brake does work but lever comes back to the handlebars.Now need more fluid so will leave it for a day or two
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I recently had a problem where I had used pads in my caliper that had worn unevenly, so when pulling the lever the brake worked but only just coz it took up all the lever travel just to straighten the pads up, then when letting go of the lever the pads would push the piston way back in. New pads made a huge difference.
Another bleed method I've used when struggling to bleed coz of air stuck at the bottom yoke mounted ali brake light switch/joining piece, crack the banjo bolts to bleed the air out. Its bloody messy so protect paint and as said, your fingers, but it works ::)
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you can always try a reverse fill/prime,
detach caliper,remove piston,fill caliper with fluid,then insert piston,press in,and watch the bubbles appear on the mastercylinder,.
this may be a drastic last resort.
sometimes,if you use just one pad in the caliper,and pump it full,then push the piston all the way in,this also helps to dislodge air .
John