Author Topic: Clutch-arm hole in gearbox cover  (Read 1264 times)

Online RichardL

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Clutch-arm hole in gearbox cover
« on: 14.01. 2010 16:58 »
Has anyone repaired an out-of-round hole where the clutch arm shaft enters the gearbox?

Richard L.
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Offline rocket man

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Re: Clutch-arm hole in gearbox cover
« Reply #1 on: 14.01. 2010 18:56 »
hi Richard L. ive had my clutch arm done what you do is take the end cover off drill throue the hole the next size up so its round again
and measure your clutch arm shaft then get a bronze bush the size of the hole youve drilled then ((fit the bush )) then ream out the bush so the clutch arm
moves freely  if its got a grease nipple drill right throue  the side of bush taking care not to damage the thread so you can still grease the clutch arm shaft
job done
  

Online RichardL

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Re: Clutch-arm hole in gearbox cover
« Reply #2 on: 14.01. 2010 20:37 »
Thanks Dave.
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Online BSA_54A10

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Re: Clutch-arm hole in gearbox cover
« Reply #3 on: 15.01. 2010 09:55 »
you really should fit it first, then ream it out as the case will compress the bush slightly and make it either tight or out of round.
The most cunning  bodge (?) that I have seen was a box with a thread insert fitted into it.
The owner explained that he did not have the skills nor tooling to make a bush but he could fit the thread insert.
I expected it to leak oil every where but he greased it with very heavy non melting grease ( axle grease from a bullock dray I think ) any way, he did thousands of miles on it. It leaked no more than mine did and never gave him a spot of bother.
Bike Beesa
Trevor

Online RichardL

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Re: Clutch-arm hole in gearbox cover
« Reply #4 on: 03.02. 2010 04:10 »
Gents,

Thanks for all your suggestions, I've gone ahead with my fix on this in my own less-than-
perfect way.

First, I found a part through McMaster-Carr hardware, a very useful U.S. company online. The part is a 1/2"-to-7/16" x 1-1/8" steel shaft reducer. The ID is within about 0.004 of the clutch-arm shaft - close enough for these purposes, I think. For the O.D., I just went ahead and used a 1/2" bit in a hand drill. I probabaly should have done a better fixturing job in setting up the drill to run straight in the existing hole, but I don't think I am off enough to affect contacting the clutch rod. The ultimate fit is a tight-enough press fit, I think, but I am going to throw some epoxy in there just to be sure the sleeve doesn't go walkabout (for my friends in Oz).

The pics below show the beforehand eggshaped hole, the sleeve, then the sleeve in the hole.

For your amusement, you can see the before and after on youtube at http://www.youtube.com/watch?v=e-UWMeNDLiI (YOU CALL THIS AMUSEMENT?!)

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online muskrat

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Re: Clutch-arm hole in gearbox cover
« Reply #5 on: 03.02. 2010 06:23 »
Well done, down here necessity is the mother of invention.
Cheers
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Offline rocket man

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Re: Clutch-arm hole in gearbox cover
« Reply #6 on: 03.02. 2010 19:58 »
well done richard-l good to see youve sorted it


dave

Offline beezalex

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Re: Clutch-arm hole in gearbox cover
« Reply #7 on: 03.02. 2010 20:05 »
Nice job, Richard.  I've done a similar thing but with a bronze bush.  Unfortunately, I ended up with a little bit too much interference (I figured .002" would be OK) but in hindsight that was probably not a good idea.  I now have a bit of a crack in the cover around the bush *sad2* but it still works OK.  I think next one I do I will just make it a slip fit and use loctite sleeve adhesive.  That stuff works wonders.
Alex

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