Classic cars forum & vehicle restoration.

[Kleftiwallah]

Good afternoon chaps.

Does anyone know the threadform on the inside of the brass knurled connector on the speedo drive, usually round the square drive?

After peering into the problem, I think it's 24 tpi and a core measurement of .435" (if that's any help).

7/16ths U.N.F. seems to do the trick, but could the thread be tapered internally?

Looking forward to your replies. Cheers, Tony.
_________________
It may work in practice, but not necessarily in theory!

[peter scott]

Hi Tony,

I'm not sure of the size but I pretty sure it's not a tapered thread.

Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[MVPeters]

It might be easier to measure the outside of the speedometer head connection!

My Halda Speedpilot instruction sheet shows one speedometer cable with NF 5/8" x 18 connections - I think that's UNF - not tapered.
A 24-pitch thread would be 5/16 or 3/8 - quite a difference.
(The other cables are all metric M12 - M19 which I assume relates to foreign speedometers).

https://www.eaglefastener.net/technical/fine-thread.html

https://www.motalia.com/Html/Charts/unf_chart.html
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Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'

[Kleftiwallah]

Thanks for those useful answers, (even from the settlers across the pond)!

Thanks and Cheers, Tony.
_________________
It may work in practice, but not necessarily in theory!

[Kleftiwallah]

The teeny tiny screw was also missing that secures the 'bowden' cable to the speedo but with a careful threadmaking of 8BA on a piece of filler rod it fits a treat.

All I have to do now is re-thread a countersunk screw and we're away.

Cheers, Tony.
_________________
It may work in practice, but not necessarily in theory!