SOHC.co.uk Forums > CB750
Dragging clutch
Scottvincent:
Hi
I’ve checked the plates for flatness, all seemed ok. I am happy that the clutch lifting mechanism is working fine, the problem seems to be in the separation of the plates. Looking back I think that I can see what may have happened.
I believe that the F1 sat for many years after money had been spent on renewing numerous parts, I would imagine that the p.o. ran out of energy (or money). It was then traded in as an unfinished project to a local bike dealer in Norfolk who wanted to move it on quickly - this is where I came in as there is nothing I like more that an orphaned bike ( I have more in my shed)
I got it up and running but never touched the clutch. The bike had no oil in the tank when I got it and a stripped sump plug and I would imagine that the clutch was dried out. I assumed that new plates and springs would sort matters out, but thinking back, I don’t think that I soaked the new plates in oil and so just duplicated the problem. Things were definitely better after I soaked the clutch for a couple of days recently. Unfortunately I just changed the oil for fully synthetic, compounding the problem.
I will clean the plates and change the oil for mineral. Hopefully this will resolve the problem.
Thank you to everyone who contributed to the (hopeful) resolution of the problem.
JezzaPeach:
Good job. Your case a useful learning curve for me as I nearly ruined mine by letting a leak cause the oil to get too low and had a similar issue.
philward:
--- Quote from: Scottvincent on January 07, 2021, 09:24:16 PM ---Hi
I’ve checked the plates for flatness, all seemed ok. I am happy that the clutch lifting mechanism is working fine, the problem seems to be in the separation of the plates. Looking back I think that I can see what may have happened.
I believe that the F1 sat for many years after money had been spent on renewing numerous parts, I would imagine that the p.o. ran out of energy (or money). It was then traded in as an unfinished project to a local bike dealer in Norfolk who wanted to move it on quickly - this is where I came in as there is nothing I like more that an orphaned bike ( I have more in my shed)
I got it up and running but never touched the clutch. The bike had no oil in the tank when I got it and a stripped sump plug and I would imagine that the clutch was dried out. I assumed that new plates and springs would sort matters out, but thinking back, I don’t think that I soaked the new plates in oil and so just duplicated the problem. Things were definitely better after I soaked the clutch for a couple of days recently. Unfortunately I just changed the oil for fully synthetic, compounding the problem.
I will clean the plates and change the oil for mineral. Hopefully this will resolve the problem.
Thank you to everyone who contributed to the (hopeful) resolution of the problem.
--- End quote ---
I hope you are right Scott but I have built 3 x 750's in recent years, changing the plates on all 3 and have never pre soaked the friction plates (just smeared with oil) - hope you sort it!
Scottvincent:
Now you tell me!!
However, I’m not just basing my optimism on chance but on the fact that after I soaked the plates, the clutch felt considerably better than before. Hopefully the change to mineral oil will also incrementally improve matters. I am looking for for all the small detail adjustments that will add up to a larger improvement, as I cannot see anything fundamentally wrong with the clutch.
Thanks for the advice.
K2-K6:
I'm not sure if I've followed the logic correctly on this one.
The general claim is that "synthetic" engine oil is considered (not by me) to make wet clutches MORE likely to slip. Ergo, it follows that "mineral" engine oil will provide MORE grip from the plates, which is the problem you are attempting to avoid.
It seems counterintuitive in logic terms.
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