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clutch adjuster nut,20 thou ???
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Posted by GRUFF (UK)   on Tuesday, October 28, 2014 at 23:38
went to change clutch cable,looked at clutch adjuster nut thought that dont look right,checked gap behind nut and its 20 thou.the book says 5 and i know some off you old boys say even less than thut.could there be some sort off mod been done that i dont know about????the bike does slip in and out off neutrel with a hot motor so what the f$%k is going on.dazed and confused i tried adjusting the nut /pullrod down to 5 thou but the tightest i could get was 20? but the clutch does work and the cable is ok other than using up all the primary cable adjuster,strange.................................
Replies   :
Sounds like it already has the washer mod fitted.
Steve HI Gruff, it sounds like the clutch plates reached it use buy date mate.
Steve. As has been discussed a thousand times before, and will no doubt be discussed a thousand times again, put a washer over the boss on the rear of the large adjuster nut so that it runs on the inner race of the bearing (in the lift arm). Then virtually zero tolerance can be used because the pull rod will be turning in both bearings. Also, virtually zero free play in cable. Instant clutch that works correctly and with a good cable is smooth in operation. This was how all the works' race bikes were set up, all the Slippery Sam replicas and Legends, and how I set up all my own and customer bikes. The washer that just happens to be of the right size is that from the rocker shaft (one at either end of each rocker arm). One or two may be required dependant upon the "lift arm". The small bearing in the lift arm isn't spec'ed for the 800lb or so load of the clutch. Having just checked it should cope with 500-600lbs, which still menas it is under specified to lift the clutch. It may well have worked OK on the race bikes but its unlikly to last all that long in a road application.
DD 250,000 miles okay which is what my T150 has done, and 35,000 on my X75 ? Also Doug Hele checked it out with the bearing manufacturers who stated that because it was not a constant load, only loading when operating the clutch, then it was acceptable. I would not call using 800lbs on a 500/600 lbs rating bearing a gross overload.
Bear (pun intended) in mind two things:
a) There is always a safety margin in setting load limits in engineering. Typically I would expect a safety margin of 100% on a bearing such as this meaning it will take 1000-1200 lbs without catastrophic failure.
b) As long as the bearing is within its catastrophic failure mode limit it is just a case of load vs life--assuming all other things (lubrication etc) are equal. Bearing (another pun--sorry!) in mind that bearing lives are measured in terms of tens of thousands of hours then I can well understand that these bearings will last for as long as we want in our clutch application.IMHO they will probably outlive us. Any more than that is I suggest overkill.
As always good engineering is about things that work in practice even if the theory points towards them being a bit questionable.
HTH Bearing in mind of course that the little fellow being discussed is very cheap and very easy to replace. As long as it doesnt fail all at once it is of small worry. Compared it to a rear tire, how much does it cost how often must you attend to it?
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