"A" Comet clutch slipping

greg brillus

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Just a quick one, I had issues with this Comet and it's clutch slipping.......standard 4 spring type, all components in very good condition with good friction plates that have a woven metal impregnated inserts. Springs seemed Ok at correct specs and length and so on, but on every test ride it would slip. I even had the spring adjusters done up to the point of coil binding and still would slip......... This was running with the recommended Motul 10 w 30 transoil that we have discussed on the postwar single clutches.........anyway I stripped the primary again, thoroughly cleaned the plates in thinners and blow dry with compressed air.......... I did rough up the steel plates this time for some added bite..........reassembled the whole lot, but this time only used good old ATF ..........Hey bingo........No clutch no slip no more........Happy as the cat. Whilst I had the lot apart again, I made up a cork disc with a hole in the center to clear the gearbox mainshaft, this cork disc just kisses the large ID washer that forms the inner side washer for the chain wheel bearing assembly. Not so thick so it creates drag on the mainshaft, just enough to touch with a light coat of grease.........Now the primary inner seems to be holding oil in as well.......Two birds with one stone.......... You can be lucky sometimes.
 

billirwinnz

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Good one Greg.

I use ATF in my forks and chaincases and hydraulic clutch cylinders as heat resistance is not an issue and it doesn’t corrode anything if it leaks.

My old A twin came from the UK with a clutch problem. If left for more than a day the clutch would stick solid. The previous owner had even fitted a plug so you could prise the plates apart. The chaincase was full of ATF. I tried 10/30 and now it never sticks but I did have to tighten the springs to stop it slipping.

Cheers Bill
 

Vincent Brake

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For me Harley primary chaincase oil only.
But i see ATF does the job here also.
Hows that oil doing with chains??
Cheers
 

roy the mechanic

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There is more than one type of auto oil. The one you should be using is Dexron. Made for 'boxes with slipping clutches by General Motors. Works well in vin dampers too, as recc omended by Ted Davis in m p h.
 

greg brillus

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Good points there......The only reason I twigged to it after all that was I had just done a strip and assembly of a Triumph Daytona 500 twin clutch and after using the Motul oil, I could not kick the engine over without the clutch slipping..........It appears that the clutches on them is marginal for grip (as per the pre war Vincent 4 spring clutch as well)........after a strip, thorough clean and assembly using ATF the Triumph clutch worked fine again.......this was what I figured should work for the Comet clutch, turns out it seemed to fix the problem.
 

billirwinnz

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One thing to be aware of if using a 10/30 (or any other mineral oil) in a chaincase is that it is certified JASO MA for use with wet clutches.
 
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Bill Thomas

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My "C" Comet clutch is fine, Only have slip if I have too much oil in the chain case, After a winter layup,
I always drain it off if it needs, But if the oil has got to the plates, It take a mile or two to sort itself out.
 
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