Rear hub thread size for 1972 Commando?

[Cuppy]

I'll see if I can get that thread count tonight. I have a bare rear hub that I can check. By the way, it's going up for sale.

I might be interested in the hub. I am measuring 20 tpi on both hub and lockring. No visible damage on hub and tried 2 new lockrings.

 

[Fast Eddie]

So you have spare lock rings to hand.

Have you tried the thread chasing suggestion from post # 13 ?

 

[Shelby-Right]

Hub thread will be bigger with heat.

You are absolutely right , and great for bearings and bushes , but it's not the sort of thing for threaded lock ring to be a shrink fit , once that picks up , i:e galling, it will be knackered , best just to add clearance to the retaining ring threads , it's not that hard to do .

 

[johnm]

You are absolutely right , and great for bearings and bushes , but it's not the sort of thing for threaded lock ring to be a shrink fit , once that picks up , i:e galling, it will be knackered , best just to add clearance to the retaining ring threads , it's not that hard to do .

It was the physics I was questioning.

 

[Cuppy]

So you have spare lock rings to hand.

Have you tried the thread chasing suggestion from post # 13 ?

I had 2. Sent one back. I will try this in the next few days. I'm thinking maybe cutting the slots using a dremel.

 

[kommando]

I'm thinking maybe cutting the slots using a dremel.

That will work, make sure at the end that goes in first the dremel cut goes down at least to the root of the thread if not a bit more. If the hub thread is a different angle or cut undersize you need to reshape it over the full depth of the thread. Use lubrication preferably a cutting fluid but ep140 or ep90 gear oil makes a good substitute.

 

[Cuppy]

That will work, make sure at the end that goes in first the dremel cut goes down at least to the root of the thread if not a bit more. If the hub thread is a different angle or cut undersize you need to reshape it over the full depth of the thread. Use lubrication preferably a cutting fluid but ep140 or ep90 gear oil makes a good substitute.

I have thread cutting oil. Would that be preferred over the valve grinding paste?

 

[kommando]

I have thread cutting oil. Would that be preferred over the valve grinding paste?

I would use cutting fluid, the valve grind paste will act on both the hub thread and the speedo ring when you really only want to resize the hub. Once you have used the speedo ring and cutting fluid and it still feels a little stiff then use grinding paste for the final sizing.