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Anyone do a Whitworth helicoil in the London area?

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Anyone do a Whitworth helicoil in the London area?

Posted by paul_standeven at November 13. 2018

I fitted a new extended nut to my Model 88 under the left exhaust port.  As it began to tighten, the thread stripped.  The stud has pulled from the head.  That means the head has to come off for a helicoil.  Is there anyone in the London area who can do a Whitworth helicoil?

Paul

Re: Anyone do a Whitworth helicoil in the London area?

Posted by Dan Field at November 13. 2018

Easy to do yourself, although I prefer a threaded insert. Try Tracey Tools if you fancy having a go?

Dan

Re: Anyone do a Whitworth helicoil in the London area?

Posted by paul_standeven at November 13. 2018

What distinction do you draw with a 'threaded insert' instead of a Helicoil?

BTW someone just told me that the thread below the exhaust port is BSF not Whitworth, and is a long thread.

Paul

Re: Anyone do a Whitworth helicoil in the London area?

Posted by Richard Tool at November 13. 2018

A Helicoil is essentially a spring made of diamond shaped cross section wire rather than round . The diamond cross section matches the cross section of the threads being replaced. After boring out the the damaged threads with the proper bit the new hole is tapped for the Helicoil and the Helicoil is then wound in . A threaded insert is a piece of thick walled tubing - usually brass or bronze -threaded on the inside to match original and threaded on the outside . Inserts generally require more material to be removed from original hole

Re: Anyone do a Whitworth helicoil in the London area?

Posted by howard_robinson at November 13. 2018

hello Paul - I have done repairs on those studs in the past.  One of the spares shops used to sell a new waisted stud that was 7/16 inch BSW at one end (into the head) and 3/8 inch BSC at the other (through the barrel).  The original thread in the head is 3/8 inch BSF.  It would have been Taylor Matterson or Joe Francis who supplied it - both gone now sadly.  They are easy enough to draw and then get made by Will Horgan at Stainless Classics or Clay Jones at Acme Bolt Maker.  A 7/16 BSW tap is easily got.   Good Luck , Howard

Re: Anyone do a Whitworth helicoil in the London area?

Posted by Dan Field at November 13. 2018

A stepped stud would be another solution, again Tracey tools can provide the taps if needed ( other suppliers are available!)

Re: Anyone do a Whitworth helicoil in the London area?

Posted by Paul Nicholls at November 13. 2018

I can do that for you if you want a trip out to Essex.

The thread is 3/8 bsf in the head.

Paul

Re: Anyone do a Whitworth helicoil in the London area?

Posted by Julian Wells at November 14. 2018

If you want to pay someone to do it, I recommend

JD Autoworx


Re: Anyone do a Whitworth helicoil in the London area?

Posted by paul_standeven at November 15. 2018

I had a chat with Ken White, who says that he has long 3/8" BSF helicoils for the job.  It just means two trips to Hertfordshire by train and bicycle....

It seems extremely odd to me to thread BSF into alloy, I expected it to be Whitworth.  My understanding is that alloy needs the coarse thread, and that's why these threads strip.  I'm wondering if it should be repaired Whitworth and try to source a Whit / cycle thread stud to suit.  And do both under-exhaust studs

Paul

Re: Anyone do a Whitworth helicoil in the London area?

Posted by lionel_yexley at Tuesday 16:39

Tracy Tools do "thread repair kits" (and loads of lovely taps & dies of all sizes!) but "Helicoil" is a Trade name for essentially the same thing.  Whitworth threads are best into alloy - especially castings.  It doesn't matter what the original was.  I haven't checked for years but I though they were BSF for the nuts but Whit for the stud part.

Re: Anyone do a Whitworth helicoil in the London area?

Posted by ian_cordes at Tuesday 16:49

The work can be carried out in situ, surely, to save having to remove the head?

Re: Anyone do a Whitworth helicoil in the London area?

Posted by lionel_yexley at Tuesday 16:59

This link confirms what I said about threads in alloy - http://atlanticgreen.com/nhth.htm

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