Author Topic: Final Drive Long Bolt Dimensions  (Read 540 times)

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Offline Peter Sampson

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Final Drive Long Bolt Dimensions
« on: 15 Oct 2016 at 20:53 »
Hello All,

I am looking for the dimensions of the final drive long bolt for a MK 4 Sports.

I have had a problem with excessive end float on the final drive if I tighten the nut on the long bolt to allow the split pin to engage with the castellated nut and pass through the hole in the bolt. In fact the engine will pull the shock absorber over the cam lobes in this position.

I have dismantled the final drive and it looks like a previous owner has 'bodged' the long bolt by welding a nut at the kickstart end on a piece of studding. I therefore am not certain if the split pin hole is in the right place.

Can anyone tell me the correct length of the long bolt in the final drive and the distance of the split pin hole from the threaded end of the bolt?

Many thanks

Peter

Offline eddie

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Re: Final Drive Long Bolt Dimensions
« Reply #1 on: 15 Oct 2016 at 21:38 »
Peter,
         I can't help with the length of the bolt , but the one you have described sounds like an original - Mr Douglas made them from a stud with a welded on nut!! If your shock absorber is riding, it is probably down to a missing spacer or incorrect one. If you dismantle the shock absorber, the sprocket should turn on the splined sleeve and lift the cam past the end of the sleeve. If it doesn't lift that far, the cam/sprocket lobes are excessively worn. The cam should be capable of lifting beyond the end of the sleeve and there should be a spacer about 1/2" long between the end of the sleeve and the spring end plate - the spacer prevents the shock absorber from riding over the top.
  Hope this helps,
                         Regards,
                                      Eddie.

Offline eddie

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Re: Final Drive Long Bolt Dimensions
« Reply #2 on: 16 Oct 2016 at 06:56 »
Peter,
         Further to my previous posting, if the shock absorber lobes are worn, you can effect a temporary repair by fitting a thin washer over the end of the splined sleeve. This will restrict the movement of the shock absorber, but will prevent it riding over the top.
  Also, the 1/2" long spacer should be about the same diameter as the end of the shock absorber cam. The nut then needs to be fully tightened so that the splined sleeve is securely clamped against the end of the gearbox output shaft - Mr Douglas did not intend there to be any means of adjustment for the shock absorber.

  Regards,
               Eddie.