Tachometer

James O'Neil · Post by **James O'Neil** » Wed Jul 01, 2015 6:42 pm

Does anyone know how to get into / open up a Smiths ATRC 2320 rev counter? There is no obvious way of opening it ... I am unable to post any pictures of my own at the moment, but there is an identical one currently being offered on ebay:

http://www.ebay.co.uk/itm/321229705558? ... EBIDX%3AIT

Any/all suggestions gratefully received.

Regards,

Jams

John Murch · Post by **John Murch** » Wed Jul 01, 2015 8:05 pm

There was a discussion on AT speedometers, with a description of how to get into one, the Rev counter might be similar.
http://www.bdcl.org/forum/viewtopic.php ... peedometer
John.

James O'Neil · Post by **James O'Neil** » Sat Jul 04, 2015 11:16 am

John,

Thank you for posting that link. Unfortunately the rev counter I have doesn't have any obvious screws attaching the bezel. I have no immediate need to get inside it, but if I ever do it looks like a job for an angle grinder (or possibly Semtex).

Regards,

James

John Murch · Post by **John Murch** » Sat Jul 04, 2015 11:20 am

James,
There must be a way in, usually things of this era are put together by humans, which sort of suggests that they can be dismantled once you know how.
Good luck,
John

Robert Craven · Post by **Robert Craven** » Sat Jul 04, 2015 2:14 pm

Is any of the information on this site of use?
http://velobanjogent.blogspot.co.uk/200 ... meter.html

Stephen Blakey · Post by **Stephen Blakey** » Sat Jul 04, 2015 8:23 pm

Well my plasma cutter would definitely get it open....

That looks like an interesting bit of kit. If you're thinking of fitting it to the MKVI, you need to be aware that the distributor towers with the rev-counter take off are in short supply as few were made. Might be worth asking Jeremy Padgett? It may be possible to persuade WOSP to fit a rev-counter take off to the dynator. They certainly fit them on their other units. There would be a certain amount of groaning about asking for that in the first place.

Rather by coincidence, I was musing whilst on a rather boring drive the other day, about whether it would be possible to hack the Digital Dakota electronic-to-mechanical speedo drive to work with a mechanical tacho? It would be a project in its own right and the result may be sluggish during transients. It would save having to have the instrument butchered to electronic operation.

More questions than answers, as usual.

P.S. The ebay ones seem to have dropped in price.

James O'Neil · Post by **James O'Neil** » Sun Jul 05, 2015 2:14 pm

Robert,

Thank you for posting that link. I have sent an email asking whether they have any information about this particular model.

Stephen,

Yes, I know that fitting it would not be straightforward (but, as you have observed in the past, if something were easy we'd find something difficult to do instead). I have just tested the tacho, using an electric drill as the motive power, and it seems to be working fine. It occurred to me that it might be possible to have a new face made up, black with white numbers, and the whole thing installed upside down, to more or less match the speedo. Of course, even if I managed to do all that, I'd still have to get it to display the engine speed. I'll investigate your interesting suggestion.
The ones on ebay were reduced a couple of weeks ago, then went back to the original price and have now been reduced again - I have been watching them for some time, but this one came from a different ebay seller, for considerably less.

Regards,

James

James O'Neil · Post by **James O'Neil** » Mon Jul 06, 2015 7:09 pm

I have now had a very helpful reply from the gentleman in Australia to whom Robert posted the link. It seems that the bezel will unscrew, probably requiring the use of a vice and a strap wrench. I'll have a go and post the result.

Regards,

James

James O'Neil · Post by **James O'Neil** » Tue Mar 15, 2016 1:09 pm

I eventually found how it comes apart. It didn't unscrew, as suggested, there was a very fine rim holding the glass, which had been pressed into place. I was able to dismantle it by using a vice to press the entire mechanism, dial, glass and retaining rim out of the case, taking care not to damage the delicate mechanism. More later, when I've decided what to do next.

Regards,

James

Stephen Blakey · Post by **Stephen Blakey** » Tue Mar 15, 2016 1:41 pm

Wow, brute force applied with finesse! Who'd have thought?

I'm delighted you didn't have to resort to the Stihl saw. I look forward to the next instalment.

Stephen

John Murch · Post by **John Murch** » Wed Mar 16, 2016 4:08 am

Delighted that you suceeded with out damage.
Have you had a word with http://www.speedograph-richfield.com
They did a good job on my speedo some years ago which would appear to have a similar mechanism, however that is spot on up to 60 but does then starts to under read a bit. (Not that I get over 80 very often).

James O'Neil · Post by **James O'Neil** » Wed Mar 16, 2016 2:30 pm

Thanks again, John. I had been in touch with Speedograph Richfield and the dial has now been sent to them to be "reprinted" to match the speedo. I'll post a picture when the tacho has been reassembled, probably in a month or so.

Regards,

James

James O'Neil · Post by **James O'Neil** » Wed Apr 20, 2016 8:24 pm

As promised ...

John Murch · Post by **John Murch** » Thu Apr 21, 2016 4:50 pm

That looks nice

Christopher Carnley · Post by **Christopher Carnley** » Thu Apr 21, 2016 5:58 pm

Go compare!

Stephen Blakey · Post by **Stephen Blakey** » Fri Apr 22, 2016 9:37 am

Nice one, James,

I think it compares very favourably with the one from the Continental. This would make a nice piece for the review once it's up and running.

Stephen