Thread sizes gauge retaining rods

[simonlap]

Early Series 2. There are 3 rods that screw into the rear of the fuel/temp gauge mounting. All of mine are corroded away, they all had at some time a brass threaded thumb screw that held the individual gauge pods into the face of the main body. I have stripped the old gauge down for maintenance so need to replace the old rods. The diameter is 5/32 inch or 3.97 mm. My eyes are not good enough to work out the TPI using my old tpi gauge. Does anyone know the thread size I need to get hold of?

 

[lynall]

Iirc almost certainly BA thread.

 

[rob1miles]

While every bit of logic says 2BA try and M4 just in case. Lucas went metric very early for some parts.

 

[simonlap]

I have both, I will pop up the garage now!

 

[simonlap]

Lucas certainly did go metric very early! It's M4. I never even looked at metric due to it's age, every day a school day, many thanks.

 

[rob1miles]

The trouble it is "some" parts. They seemed to mix and match but my 1970 Lucas starter is metric threads and the 1970's brake servo has 10 mm cotter pin, that threw me, especially as the washers are in the parts book "7/16"

 

[Blackburn]

I have some spare instruments and noticed awhile ago that there was two different threads on the
clamp stalks depending if early or late type unit.

 

[divie]

Given that most threaded items measure slightly undersize to allow for cresting and tolerance. 3BA at 0.161 diameter could well be in the mix, late Lucas and Smiths instruments used BA threads and A/F imperial size hexagons. But if M4 fits use it, no one will ever know.......

 

[rob1miles]

If you want a mix try 10-32 UNF, its close too.