Speedometer disassembly

[snowyelan]

Hi All,

Something has jammed in my speedometer. I suspect a bit of debris is stuck in the odometer gears as I can rotate the cable to a certain point then it stops. What I am stuck on is how to remove the mechanism from the housing. The reset shaft and the cable entry threaded post prevent it from being removed. I could remove the needle and faceplate but I doubt they were installed after the mechanism was put in the housing originally.

Any tips? The only mention I could find for this issue was a youtube video where they had elongated the cable entry point.

Thanks,

[ericbushby]

Hi Scott
The reset shaft is in two parts.
The outer part is fixed to the part which goes through the case by a small cross pin. You need to press that out in order to shorten the shaft enough to remove the mechanism from the case. I think yow will have to remove the dial and hand also. One small lever either side of the hand to gently prise it off. protect the dial from scratching.
Best of luck
Eric in Burnley
1967 S3SE DHC

[h20hamelan]

There is a good YouTube, guy doing a Europa.
Same same

[snowyelan]

Hi All,

I managed to get it apart, had to remove the needle and faceplate. The trip reset is loo long on the version I have, and can't be removed while in the case. I found the issue and its a split gear that is molded onto a steel spindle.

Next question is who I can get parts from, preferably in Canada or the US. Most places seem to list repair and restoration, but not parts. Nisonger is unfortunately no longer supplying spares.

[pharriso]

You could try https://www.westvalleyinstruments.com/contact/

[tonyabacus]

Scott
No contacts your side of the water but you might try these people in the UK if you are stuck, they supply a repair service and new instruments for Lotus models
https://www.smiths-instruments.co.uk/lotus/elan

Tony

[snowyelan]

Thanks for the replies. I found, what I think, is the correct replacement/remanufactured part. I have one on order and will report back if it is a good solution.

https://www.ebay.com/itm/175185608872?h ... SwvY5iMv7d

[ericbushby]

Hi Scott,
Well done finding that source of parts.
Just a small detail in case you don`t know:-
Look for a small white calibration dot on the dial plate at about minus 7 MPH. This is where the pointer must be fitted at rest. Then gently prise it over the springy zero stop.
Just to save you having to do it twice.
Best of luck, let us know how it goes.
Eric in Burnley
1967 S3SE DHC

[snowyelan]

Thanks for the tip. I was aware of it, so tested where the needle landed before I removed it out of curiosity. It was midway between the dot and the stop pin. Crap. Now I get to decide whether its natural settling point is what I set it to when I re-assemble, or the dot.

If I were a cat I would have been killed a long time ago...

[ericbushby]

Hi Scott.
Now you have to decide if your speedo was a few MPH slow all the way up the scale or was it fast. Any error brought about by putting the pointer on in a different position would be a constant error not a percentage error.
If you were happy with it before then put it back there.
Best of luck, keep going.
Eric

[tonyabacus]

Besides the Youtube links, here is a written article with lots of photographs in a stage by stage process to repair of a Smiths speedo. Whilst it is talking about that from an MGB the principles are the same
Tony

[tonyabacus]

Scott
I just realised I did not include the link to the article on rebuilding a speedo, so here it is
Tony

https://obswww.unige.ch/~wildif/cars/do ... repair.pdf

[snowyelan]

Thanks Tony,

The part I ordered (linked above) seems to be working. It's called a worm gear in the article. I have yet to test it on the road. Some notes and cautions on this.

My speedometer was a bit erratic, pulsing low. I suspected cable bind. The small cable stub in the gearbox angle drive failed, and at this point I was about to start a full rebuild so I added it to my list of things to replace. Fast forward to this year, new angle drive, new cable. I decided to see if the speedometer was still working before installing it so spun it up using the cable and my fingers. It would only spin so far an then it hit a stop. I figured there was a piece of debris stuck in it somewhere so dis-assembled. What I found was the worm gear was split and as the split section of the gear started to engage the teeth collided. Dead stop.

I suspect that the split gear was the initial cause of the pulsing and that it caused the gearbox angle drive to fail.

The replacement part I ordered is only the gear, no shaft. The old gear is easy to remove from the shaft due to the split. The new gear is very tight to press on. I chamfered the gear bore slightly to aid in the process. Keep it square when pressing. I used a piece of bar stock with a slip fit hole to support the shaft and keep it square.