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Wheel adjuster threads in swing arm

Submitted by tony_wood on Thu, 30/05/2019
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Heavy Twins

Hi.

Today I discovered that the chain adjuster threads in the end of the swing arm have been stripped (apart from the last 1/4 inch at the bottom of the hole). That means that the adjusters are really just a sliding fit in the swing arm when the chain is fitted. As the chain adjusters have a separate nut for locking the adjuster in place, could I use that to set the position of the wheel adjuster and therefore the position of the spindle? I’m assuming that as the spindle nuts lock the spindle in place, the fact that the adjusters simply rest against the adjuster locknuts will be ok as they are simply being used to set the position of the spindle before locking it in place with the spindle nuts. I’m hoping that I don’t have to buy another swing arm.

Any views and advice gratefully accepted.

Thanks

Regards

Tony

Submitted by john_day on Thu, 30/05/2019

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shouldn't be a problem, the chain adjusters are really just locaters, as long as the spindle is tight all should be o.k.

you could always tap out the holes to take a slightly bigger bolt.

Submitted by tony_wood on Thu, 30/05/2019

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Thanks guys. That’s the reply I was hoping for. 

Robert, do you by any chance know what diameter and thread the Atlas adjusters are? If they are substantially larger diameter, there might be enough ‘meat’ in the swing arm to re-tap the holes to the larger size.

Thanks again

Regards

Tony

Submitted by robert_tuck on Fri, 31/05/2019

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Hi Tony,  The same type of swinging arm is fitted to both bikes but the Atlas is 7 years younger and built by AMC Norton  who made lots of changes .Seems likely that should be a straightforward job. You may need a longer tap and drill than usual or an extension  bar to get past the fork ends. Will look up info later.        Pre Mk3 Commando look a possibility . Thread will be 5/16th UNF (probably!)  in place of the 1/4 cycle 26tpi 

Submitted by andrew_heathwood on Fri, 31/05/2019

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As Robert says

The thread on the Pre Mk3 adjusters is 5/16" UNF (as shown in Andover Norton parts info) for the nut (14.0402) which fits the adjuster (06.0650).

According to Andover Norton the Mk3 adjuster (06.6405) has a 1/4" UNF thread.

Andy

Hi Robert - The master Parts list for the 1966 to 1968 Models shows part number 19264 for the Rear-wheel adjusters and E.3229 for the corresponding nuts.  It does not specify the size nor thread form,  sadly.  However I can confirm that my Mercury (1969) has the same adjusters as my early Dommie with the exception that the adjusters and nuts are cadmium plated and not satin chrome.  The thread form and size is most certainly 1/4 inch BSCycle.  So either your Atlas has been modified or the Mercury took a regression in this area.   There is another possibility - My Mercury may have had an earlier swinging arm fitted when it was in the Eastern Caribbean...Ho hum........ I suppose this is an almost pointless contribution?  Cheers, Howard 

Submitted by kevin_bell on Fri, 31/05/2019

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Hi Tony.

My 650SS had butchered threads for the swingarm adjustors and I resorted to the following:

[edit: re-inserted as PDF]

 

Hope it helps!

Kevin

Attachments
Swingarm adjusters.pdf

Submitted by robert_tuck on Fri, 31/05/2019

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Hi Howard, Its also possible that I did the adjuster conversion myself , a quarter century ago, memory being what it is.  Too many bangs to the head.

 


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