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Barrel repair

Submitted by dave_mooney on Thu, 04/08/2022
Forums
Commando

I have a stripped thread on my Commando barrel. Specifically the 3/8 stud between the barrels.

Is it possible to drill and tap for a helicoil? Will the cast iron require any special precautions or tools?

If its not a "diy" fix, what needs done to repair it.

Thanks in advance

Dave

Submitted by ian_soady on Thu, 04/08/2022

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... he was talking about the one between the pushrod tunnels. The one you need a slim 3/8" drive socket to get at. There isn't a lot of meat at the bottom here and it often breaks through into one or other tunnel but a helicoil should have enough at the top end to hold. The main issue would be getting it true with the existing hole.

Thanks, it is the one at the top. Drilling and tapping shouldn't be a problem as I can set it up in my bench drill. I was more concerned about the cast not being able to be tapped.

 

 

 

 

 

 

 

 

Submitted by john_holmes on Thu, 04/08/2022

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Cast iron is easy to drill and tap, the high carbon content acts as a lubricant (but still use one on the tap) and the swarf is a fine powder so a good vacuum after the thread is cut is a good idea. 

Thanks all.

I didn't realise that the thread was BSC. I was just going by the exploded-parts list on the Norton site.

I haven't pulled the barrels yet and would have checked when I did. But its good to have a sanity check.

Submitted by paul_nicholls on Sat, 06/08/2022

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Helicoil is the way to go. I have done this before no problem.

Paul

Submitted by robert_tuck on Sun, 07/08/2022

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About 30 years ago I fitted a Recoil insert  for one of the cylinder base studs on my 99 ,  Still working perfectly , still have the kit, probably never use again. What size is it? Where are you based Dave.?.

 


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