a clutch but no clutch

[goggstrotter]

we never appreciate the benefits of a clutch until it stops working.

yesterday i rode 250km up the coast to Acapulco in the pissing rain with accompaning lightning bolts scaring the shit out of me and if that wasn´t enough the mexicans just love to put speed bumps at the end of each town and all the way in between, believe me there are many towns too....without the clutch it made for interesting riding. i was happy to get in the flea pit of a room and sleep for the night. the Taco´s i had were spot on though washed down with plenty of cold Corona...life could be worse!!!

anyway onto the fun part, i lost all feel in the clutch lever and after only rapid pumping could i only get the slightest amount of clutch dis-engagement...until that went too. i had this problem about 1 year ago and it sorted itself out.

after searching on the site today i will pull the clutch slave cylinder out, check tightness of the union bolts and bleed the system.

i can only get DOT3 fluid so that will have to do. i understand that getting access to the slave cylinder is a bitch, do i have to raise the sub-frame as the repair manual says ?

any other tips and ideas to get me up the road would be appreciated.

i raised a thread recently regarding a strange noise and clutch action...perhaps it is all connected

 

[carbold]

Hi there
if you're lucky it may just be some air in the system...I had the same problem and sorted with just replacing the fluid and bleeding. Also the clutch fluid absorbs humidity so when it gets hot due to intensive use, water becomes steam resulting in loss of pressure. Good luck

 

[goggstrotter]

CASE SOLVED : it´s shagged.

i put the bike in our hotel room yesterday and pulled off the slave cylinder. behind it was loads of crud and it´s obvious the thing has been leaking past the cylinder seal and into the cavity in the gearbox.

i stripped the slave cylinder down and there is wear on the internal bore, also the bearing that the clutch pushrod sits in is shagged too. i cleaned and rebuilt the slave cylinder and re-installed it. with clean fluid (albeit DOT3) it is working as normal again, but this morning in heavy traffic it started to lose its feel again. the only real solution is to fork out $200 and have a new one sent down from mexico city.

as i mentioned before i posted a thread about a strange noise coming from the clutch mechanism. well it seems that it was the bearing in the end of the piston becoming worn, possibly through loss of lubrication and fretting/rubbing inside the piston, upon slight application of the clutch it would seat and the noise dissappears. i´m not sure but perhaps even the bearing may have seized into the piston and then caused the piston to rotate in the cylinder...causing the wear.

does the clutch pushrod rotate, i assume it does at times ?

it was real easy to remove the slave cylinder, only the rear wheel and rear shock had to come out, i removed the silencer too but it´s not necessary. you can remove the 3 bolts holding the slave cylinder on and then loosen the input line. it´s amazing how much crud was behind it when it came out. the fluid was very dirty too, probably from the aluminium cylinder wearing out....cheap monkey metal...made by MAGURA.

looks like i will have to sit by the pool drinking cold Corona till the bits arrive !!!

 

[DrAlf]

Great site this – got exactly the same problem with the exact same cause - knackered thrust bearing and worn bores on the clutch slave cylinder. Piston nearly took my head off when I took the thing to bits Guess I’ll be ordering a new cylinder tomorrow then

Isn’t the search function great