The threads in my 650 swinging arm are stripped . I think they are 1/4 cycle . I ordered new adjusters and happily they have turned up larger !. Perhaps my luck is changing . When did they increase the thread size and what is it ?. AF i am guessing .
Hi Bob - You're correct but…
- Log in to post comments
Looks like a trickey job…
Looks like a trickey job needing a long adaptor and both taper and bottoming taps . I have a 30 year old memory of doing this on the Atlas . Have to look for the taps . is 5/16 unf compatible with cycle or bsf ?. Might have to leave this job till after the bike run in , Another nut on the old adjusters will at least make them a locking device !. Wheel bearings and speedo drive next as barely turn .
- Log in to post comments
SWINGING ARM ADJUSTERS
All of the Featherbed Frames (Wideline & Slimline) from 1955 onwards, used the same 1/4" Cycle thread wheel position adjusters. Including the Mercury which was produced alongside the Commando. The Commando used a good many UNF threads and this included 5/16" UNF thread wheel position adjusters. See photo below......
OPTIONS: Basically there are 4 ways to fix the problem of stripped threads in the swinging arm.
1) Drill and tap the existing holes to extend them by about 12mm and then get some longer adjusters made up. It is quite easy to get long bolts and grind metal from the heads to form a hexagon and stud end.
2) Retap the S/A holes to take the Commando 5/16" UNF adjusters.
3) Try and fill the S/A holes with something that could be retapped. JB Weld possibly???
4) Does anybody offer a Helicoil kit for this problem???
- Log in to post comments
Robert - A word of warning…
Robert - A word of warning. Dommie adjusters have a reduced hex for the head of the bolt that rests against the spindle bolt and nut. The reduced hex stops the adjuster fouling on the swinging arm. Usually the Commando ones do not have a reduced hex because there is more room. So you will need to reduce the hexagon on the Commando adjuster to make the repair, The 5/16 inch unf thread form will have a nut spanner size of 1/2 inch AF and this will foul the Dommie s/a. 1/4 unf is 28 tpi. Good luck, Howard
- Log in to post comments
And another way...
Another way to fix the problem. Improving the situation but ignoring originality is to fit snail cams.
The snail fits on the rear axle very easy. The only issue is fitting a high tensile screw into the swinging arm as a stop. Its position is very crucial. But subsequent rear wheel adjustment becomes a doddle and the original issue of bent bolt adjusters is gone.
- Log in to post comments
And another....
... rather than tap UNF, tap 5/16" Cycle then you can make up new adjusters using long setscrews and reducing the head size by judicious filing. You can get reduced hexagon nuts from Nooky's Nuts (probably amongst others).
- Log in to post comments
Now I really do have a…
Now I really do have a headache !!, I can't make my mind up if given 2 options !, Strangely i can remember no issues with the Atlas after fitting the Commando adjusters , perhaps the very late Atlas had more room or perhaps the Commando ones have a reduced hex ?.. A trip to son Phils garage needed to check. Sadly i have no engineering facilities at present ,not even a decent vice. Sometimes the wife lets me use the top of HER washing machine ,as long as its cleaned after. Not keen on having to carry odd spanners either. Its not proper Nortonning. Although did those AMC heretics fit much UNF threaded and AF stuff to the 63 Plumstead built 650? ,not found any yet, though I have replaced a few metric ( yuk) .
- Log in to post comments
slimline chain adjusters
Snail cam adjuster as fitted to my Dommi in 1978, still working well.
This is a 1970s Yamaha part although Royal Enfield made similar ones, so much easier to adjust chain, but, as Al said, they do need to be accurate. My left adjuster is one notch ahead of the right hand adjuster.
- Log in to post comments
Recoil....
....makes a 1/4"x26 kit. Expensive for a one time use but maybe a local engineer shop keeps one. We had one where I worked but then I'm in California.
Mike
- Log in to post comments
The Snail cam looks…
The Snail cam looks surprisingly doable, however the orriginality freaks would not be happy. I have several Recoil kits , but they would pose a few more issues with the access being so awkward. As I have done this job before ( in a different century!) ,I must still have the necessary bits ( if not the energy) to do it again with the thicker 5/16 adjusters that will be stronger and not really notice as non standard .
- Log in to post comments
Might it be possible?
The Manx has different adjusters than other featherbed frames. Pulling backwards.
Could it be possible to make something similar?
- Log in to post comments
Hi Bob - You're correct but Commando are 5/16 inch unf........... Cheers, howard