The following words and pictures were recently posted on the excellent UK Mk1-Forum by user NZmember. This information was news to me so I asked and received permission to post it here. I'm sure our member minijcar would be very familiar with this as he owns Howard Instruments in Melbourne but I wonder how many others know about the presence and purpose of the dot?


I had one of my speedos fixed today. I had stripped it apart to get the odometer working. The instrument tech then showed me something that I thought might be useful to other members.

To get the correct calibration and degree of tension on the speedo spring, the needle has to be fitted back onto the fine shaft so it lines up with a tiny dot under the oil pressure light (in my case). The fine needle stop is spring loaded (I didn't know that) and you simply push it in to move the needle to rest on the other side.

He then tested it at 1408 tpm and it was spot on at 30 and 60mph.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Yep...just to be sure tho (assuming you are happy with your speedo calibration)

BEFORE you remove the pointer, place the instrument on a clean bench - face up.

Carefully move the pointer past the zero stop, and let the pointer swing free until it stops.

NOTE where the pointer comes to rest and ensure you replace the pointer to the same place.

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"Show me the Mini!"

Do you mean that the tiny wire stop that holds the needle at 0 can be pushed into the dial face to allow the needle to pass over it?

Thats how i read it. You put the speedo needle back on - pointing at the dot. Push the stop in and move the needle clockwise until you go past the stop and the let the stop come back out.

Just gotta be careful not to dislodge the stop...they aren't always anchored real well...araldite and/or some sticky tape...

PS Check out how replacement/refurbished Speedos are delivered

https://www.youtube.com/watch?v=yakzUc9NAo4

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"Show me the Mini!"

Do a search for a pdf on Smiths Speedos by John Rhodes.
IIRC the dot gets a mention in this pdf.

RonR

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68 build Mk1 Cooper S
72 Clubman GT project. Total restoration required

Thanks for encouraging me to comment Doug.
I agree The spot if it is there is used for setting pointer backlash and as a starting point for linear calibration.
Often it equates to the same distance as that between the pointer stop and the first major graduation.
From there things like wear, hairspring tension, height of the speed cup and particularly magnetism come into play.
I trust the documents help people.

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1960 Morris Mini Minor

Smokin' John Rhodes is a great Mini Driver...I had a brief chat to him at Goodwood...

Andrew Rhodes did the Jaeger/Smiths thing...

http://www.lotus-europa.com/manuals/mis ... repair.pdf

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"Show me the Mini!"

Carefully chosen words there...

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"Show me the Mini!"

I was trying to encourage people to try
The reality is that I hate repairing smiths Nemag plastic odometers... so if people do them themselves there is less for me.
For the speed side of the repair we must all consider liability.
I got a ticket for 43 in a 40 zone recently And my speedo was accurate
There are so many little tricks that Would take a lifetime to explain here some more obvious than others like the spot. Many We do without consciously thinking about them. No different to any other trade.
The reality is that after 50 plus years in the game my father is still learning about how to repair an instrument every day.
I am blessed to have he and mum working with me showing me the ropes.
My trade is all but gone. They don't teach it at TAFE any more beyond a very brief mention in an Auto Elec's apprenticeship which I did at 48 years of age.

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1960 Morris Mini Minor

Please don't get me started on the ludicrous current focus on speed and only speed as the root of ALL evil on the roads (for revenue porpoises!)

Very sad to read that the Instrument Trade has gone down the gurgler (in this country at least)

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"Show me the Mini!"

When I done my auto sparky apprenticeship within the last few years there was no mention of anything related to instruments at all in the notes. But that is here in Qld.


Brad

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During the day I work on English designed cars & on my own time I work on English designed cars....