Rear Wheel axle position adjustment

[GraemeLangley]

Good morning

I have a 1934 NH frame and the thread on one of the rear wheel position adjusters is stripped.
I haven't stripped this yet and so not measured the thread, does anyone know offhand what the thread and diameter is and has anyone tried to use a Heli coil in this part of the bike?
If not, and the collected wisdom is not to do that, what is the best way to repair this? Weld up the hole, redrill and re-tap? (which is obviously a lot more work!)

Many thanks for any advice

Graeme

[nevhunter]

Oversize the thread and make a suitable replacement adjuster. 26 TPI British Cycle thread. Doing it that way will give the strongest result . Being on the chain side you don't want it to fail. Nev

[Roger Gwynn]

I wouldn't weld it, rather difficult to drill afterwards, never mind tapping it. It may be the thread on the adjuster, take it apart and find out! original thread is 5/16 x 26 Whitworth but CEI is close enough!

[Mick D]

Hi

If the damage is to the frame thread then in my opinion the best and least intrusive method of repair is by wire thread insert, ('Helicoil'). This will remove the minimum of material from the frame and retain the original design adjuster components.

Regards Mick

[GraemeLangley]

Thanks for everyone's replies, a bit of dismantling and further investigation is needed I think, nobody likes the idea of welding so I will cross that off the list. Thanks for the thread information.

I will let everyone know how it goes - my suspicions were aroused when I realised the back wheel pointed off to one side!

[GraemeLangley]

Hi All
Thanks for all the help so far, having removed the adjuster and measured it, the outside diameter across the thread is .297 inch (5/16 equates to 0.3125) and the head of the adjuster and locknut fits a 3/16 Whitworth spanner! The TPI is 26, so I assume it is a cycle thread. Have I got this completely wrong or do i assume that the adjuster too small a diameter?


It seems that the adjuster thread is damaged and that has probably damaged the thread in the frame, I think I will try to get a 5/16 26TPI bolt and a suitable tap and then tap out the hole and try the slightly larger diameter bolt arrangement.

If this fails, or the thread is still not holding, i will fit a 5/16 helicoil.

Regards

Graeme

[Mick D]

Hi

Roger has said the thread should be 5/16" Whitworth, this has a 55 degree thread angle as opposed to that of 60 degrees which BSCY has. My first move would be to get a correctly threaded adjuster and try it for fit, you may find that this will resolve your problem.

Regards Mick

[paul.jameson]

I have a NOS adjuster available if you want one.

In my experience, these threads eventually suffer from rust and seize up. Freeing off from this may well be the cause of your problem. So make sure that the thread is suitably protected with copper grease or similar when you re-assemble.