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Front hub bearing lock ring

Submitted by tony_wood on Fri, 28/08/2020
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Heavy Twins

Hi, 

I’m rebuilding both wheels of my Dommie 99 project.
Today I stripped the front wheel. The bearing lock ring has been well and truly butchered and was a pain to get out - it’s well past usable or repairable. I’d already bought a new lock ring from Andover Norton - the web site says that it’s for all pre- Featherbed and Featherbed bikes. The only trouble is, it won’t screw into my hub - well, it goes in about half a turn then gets tight. With a lot more leverage on the pin spanner it goes in about two turns then locks solid. The original lock ring spins into the hub with light finger pressure. Both the old ring and the new one are 26TPI but I’m not sure about the pitch angles of either one .
Has anyone else come across this problem? If so, how did you solve it?

All of the replacement rings from all the usual suppliers seem to be the same part number so I’m really scratching my head on why the new one won’t fit.

Thanks

Regards

Tony

The original Bearing Lockring had part number E6888. This had a Right Hand Thread of 26tpi.

The later version was given part number 067615.  Again 26tpi Right Hand Thread.

The Commando Front Wheel Bearing Lockring has part number 060363.  This looks very similar to the other two but crucially has a Right Hand Thread of just 20tpi.

tom.

as philip has said the commando hub has differant thread,my dommie hub was damaged so i bought a new one 35yrs ago and found the 750 hubs were differant.tpi.

Submitted by tony_wood on Fri, 28/08/2020

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Hi Robert. The thread direction isn’t the problem - both original and new are right hand thread. The problem seems to be either that the diameter of the new one is microscopically too big or the thread teeth angle is different - possibly 60 degree versus 50 degree.

Tony

Submitted by george_farenden on Fri, 28/08/2020

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Measured the  OD of both old and new rings to see how they compare? If they are the same  then inspect the thread closely.  If it isn't deep enough, there will be small flats on top of the thread. Had a similar issue years ago with the fork damper top caps not screwing on.

Regards, George. 

Submitted by andrew_heathwood on Sun, 30/08/2020

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Tony

I have no specific expertise on Dominators - I'm a Commando owner - but it seems to me there are two 'reference points' for confirming that any replacement lock ring has the correct thread form.  As the original lock ring and the new one are both 26 tpi it can only be that the thread forms or some other dimension are different.  All this is assuming that the wheel has a standard original hub.

The reference points are: i) The known original thread form, e.g. (afaik) BSCy (60 degree thread angle) or Whitworth (55 degree thread angle) are the usual suspects for 26 tpi but does anyone have the definitive answer?  ii) The old lockring which clearly fits best.

In any event I'd contact Andover Norton.  They are usually correct on thread forms in my experience but anyone, including supplier's suppliers, can make mistakes.

I'm just trying to help here.  Happy to be corrected!

Andy

Submitted by paul_nicholls on Wed, 02/09/2020

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I too have had this problem with the lock ring. It should be 26tpi as you have bought. I found it was too big to thread in. I did tell AN but it sort of fell on deaf ears.

Try and find a new old stock one that does fit.

Paul

Submitted by tony_wood on Wed, 02/09/2020

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Hi Paul. Interesting that you had the same problem. I’ve ordered a new ring from Norvil (after checking that they don’t buy them from AN). I’ll post the results on the Forum. I contacted AN about the ring not fitting and they said that when they order a new batch of lock rings, they send an original hub to the engineering company so that they can test fit the first few rings made before going into mass production. I wonder if their hub is so worn that the threaded area for the lock ring is worn down a bit.

Did you find a new old stock ring? If so, where did you get it? I’ve tried hunting one down but have had no success so far.

Thanks

Regards

Tony

 



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