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navigator mainshaft and clutch spider

Submitted by terence_canning1 on Sunday, 19 April, 2020 - 14:41
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Light Twins

hi ,i have a early 1961 navigator with the old type gearbox and the  main shaft and clutch spider are worn , there are clutch spiders for sale on ebay for dominators does anybody know if the splines are the same or are there any other way of fixing this problem

  thanks terry

 

Submitted by andy_sochanik on Sunday, 19 April, 2020 - 15:34

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Sadly, the 1961 mainshaft & spider splines are not the same as Dominator. The Dominator shafts are inevitably larger diameter.

Beware when buying replacements on eBay (or Autojumble). There are at least 3 mainshafts in use.

First one was Jubilee only, with a smaller spline. (Mainshaft stepped down)

Second, up to 1963, Mainshaft without a step-down. For the Navigator, Norton removed the stepped shaft, deeming it a weak point.

Third - after 1963, entirely different gearbox, non-interchangeable, fatter mainshaft.

Your main source of supply is either NOC Spares, or Russell Motors in London. Also, when life returns to 'normal', autojumbles are the place to head for...

There is a possible way forward for you (that I cannot recommend). The NOC Spares have the 1959 Mainshaft & spider (PNo 21468) in stock. The mainshaft should fit your Gearbox (I'm not entirely sure if the spider will fit your clutch, however - as there were changes early on. Its a bit of trial & error. AND you will need to drive more gently.

Again - I stress that I cannot recommend this adaptation. Norton changed the shaft for a reason.

Lightweight mainshafts
 

 

Submitted by terence_canning1 on Sunday, 19 April, 2020 - 17:11

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hi andy ,Thank you for the info it has been a great help and i now know what to look  for , the smaller shaft is not a option as it would be in the back of your mind and i plan to use this bike as much as i can and not just for shows . most of the wear is in the spider and i was thinking if you could build up the splines on the shaft to compensate for the wear in the spider but i'm scared it could warp the shaft , have you heard of anybody doing this before , this would be a last resort if i can't get a replacement  . 

thanks Terry  

Submitted by robert_tuck on Monday, 20 April, 2020 - 10:36

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I have had trouble with weak spider details on a  Dommy and I was considering making up a special thrust washer to reinforce the stop detail  in the center .Happily I found an improved detail on a new spider that is working fine. If the spider detail is poor that may be a solution.

Submitted by peter_holland1 on Tuesday, 23 July, 2024 - 23:17

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Just brought this up because of the interest recently in lightweight clutch spiders. Andy Sochanic clearly explains above and dimensions the three mainshafts. Three spider types match these mainshafts. Jubilee 1959 had 5/8 spline. Jubilee and Navigator 1960 to 1963 had larger 11/16 shaft. Electra 1963 and late Jubilee and Navigator had 3/4 shaft. Visually, all three spiders look similar and  often confuse the unwary. Best to measure with digital calipers the spider spline maximum diameter which will be one of the three sizes mentioned. 

All sound advice and Andy's picture of the 3 variants of mainshaft really clarifies things. Sadly my own Navigator gearbox has been fiddled with at some point in the past and it has the incorrect Jubilee 5/8" mainshaft fitted.

Anyone out there got a decent 11/16" mainshaft I can purchase?  At least I'm ok for spiders now!!

Nick

 



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