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Smiths clock thumb nuts


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I have a rectangular Smiths Clock in my 4A, I think originally in 2000's and 2.5's ?

In my wisdom....  I decided to take it out to fix it, and in re-fitting, trying to put the back plate on, i dropped both the thumb nuts for it. Couldn't find them, so took the H frame out as I thought they had dropped down one of the "legs".

Found one, but the 2nd had vanished completely. Anyone know where I can get these from? They are a smaller inner diameter than the thumb nuts on the rest of the gauges, not sure what thread? 3BA, 4BA?

Any advice welcome.

I have some standard nuts to use if I cant get the thumb nut, but theyre not so easy to do up/undo from behind the dash.

Thanks

 

john

Edited by johnwill
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Bad luck John, these thumb nuts are a fiddle - whenever I remove the instruments I invariably manage to drop one of them but have always managed to find it. They are 3BA and readily available on Ebay.

Tim

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1 minute ago, RogerH said:

Hi John,

I believe they are all an odd size - 3BA

 

Roger

Roger

The thumb nuts on the instruments gauges, fuel, water etc are bigger I/D than the ones on my clock. (they slide straight down the threaded "bolt") The clock nuts are smaller. Are the guages 3ba? or bigger

thanks

John

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15 minutes ago, RogerH said:

Hi John,

I thought they were all 3BA but your comment has jiggled something in my head. The speedo and Tacho may be 2 and or 3 BA I'm sure I've come across both.

 

Roger

 

I think theyre the same thread, just larger O/D. The clock is smaller I/D... weird.

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16 hours ago, wish i could drive it said:

i have just bought new aluminium thumb nuts for all my instruments on my car(1973 tr6)

they fit on the speedo and rev counter but will not fit any of the small gauges.

i have been told they are 3ba so that is what i ordered, so what is the thread on the small gauges?

the studs are 4mm diameter.

ian

Have you tried M4?
here are plastic M4 thumb nuts.   They should not ruin the metal stud thread!

https://www.ebay.co.uk/itm/Black-M4-Plastic-Nylon-Knurled-Thumb-Nuts-With-Collar-14mm-Diameter/192180245758?_trkparms=ispr%3D1&hash=item2cbed5d4fe:g:NcIAAOSw7GRZDv6W&amdata=enc%3AAQAFAAACcBaobrjLl8XobRIiIML1V4Imu%2Fn%2BzU5L90Z278x5ickkfKe2vUidqHRg3XM2X2xOVOMFbwmsCcNl11KtuUI6NfxrixCG86L4S7qht5T3nJQ%2BHO6GZPCdJKnh5h4SXhL59Xnz4mI6gJIunGGgDHFC9u69PJh9neUXzMa9RDOOeA2wspDxm9FYEicy1pmxO6ApAZKbkBMamLhVxvrjwXIl8%2BuMyfb8dhKzOnM%2FZFD6vidyaejO2r%2BwkkgfKAfn3h4ZuXWLiQyWzNSgRYqX9W0fZLFw6FvWiR0aqqGmNQtWHvE9kq033l%2FyKkcEDcKsPNl63zW1fOsJ44h1vH6ixwHVOd7%2Fb4dQ2iOEABo67v65IXxcAkOge9Frfn3xXOI4bK%2BASfz%2Bq%2Fx8D3qOfol3v5zh1b5ViAWdwCweLkMOJkEItPjj%2Fb6cZ%2FvOmibFDUvnVqvGF0BkXNNHTuPlmvA4OElFWHgLkFuHntgKAlzZhSUyszjcQ4wXOJF6895bSXsPdcWYDZ21v9rd0KPVlwyE4HunXRwUZIRWUvYiK9sMWXMixXM9xATfaaNajEchCHi7ATtTu8ZKzsUSAW8NwHNmtjKgs8qciXqj20eVZ%2BVEafiPMU5ASwIfW1cETiQ1XxzB1hjWGutZT1i%2B45Fzefqi6HkJswmpgSYr8m7RK1ISvGNRJAeIyK6ohp2ETVvOYUCHUPqlA1lHJMiycuUuK7n0RD8KNXO8qBQAeSMSxEccsNWATYB9W2optUK2Y1JiFV5L85Uhfhmc5ElP8eZCtc5odaFRmhOSoaiK5P8qqNBHptH9LkPkCjoG5X49hEMTWY5NdgquVg%3D%3D|cksum%3A1921802457589ce99ea9f8b64fa4a4d948a8c25ca8df|ampid%3APL_CLK|clp%3A2334524

 

 

cheers

Peter W

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16 hours ago, wish i could drive it said:

i have just bought new aluminium thumb nuts for all my instruments on my car(1973 tr6)

they fit on the speedo and rev counter but will not fit any of the small gauges.

i have been told they are 3ba so that is what i ordered, so what is the thread on the small gauges?

the studs are 4mm diameter.

ian

Hi Ian,

that is interesting.

The Moss WebCat shows all the gauges using the same nut on the TR6

On the TR4/4A it shows the same nut for the big gauges as the TR6 but they refer to 'small' nut for the smaller gauges.

The OD is certainly smaller but I would have thought the ID was the same.

 

Roger

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  • 2 weeks later...
On 12/4/2020 at 9:35 AM, RogerH said:

Hi Ian,

that is interesting.

The Moss WebCat shows all the gauges using the same nut on the TR6

On the TR4/4A it shows the same nut for the big gauges as the TR6 but they refer to 'small' nut for the smaller gauges.

The OD is certainly smaller but I would have thought the ID was the same.

 

Roger

My guages thumb nuts are the same ID and thread as the Speedo & tacho, but as you say, the OD is larger on the Speedo & Tacho.

 

Looks like i'll have to use normal nuts on my clock, will be more fiddly than the thumb nuts, but only solution I think.

Edited by johnwill
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I think the 2 inch gauges nuts are tapped 8-32, the tacho and speedo nuts are 3BA, which is a few thousandths larger than 8-32, and 34-8 threads per inch.  

Edited by DaveN
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just to add to the confusion?

evidently smiths instruments, sometime in the early seventies switches to metric threads,in their wisdom they kept the same part numbers.

so you could get a mixture, in my case the speedo and rev counter are m4 threads, but all the small gauges are 3ba. clear as mud.

so you had better check your nuts carefully?????

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