Lotus Elan

Odometer not working but speedometer ok

PostPost by: Mike2drummond » Thu Dec 02, 2021 7:17 pm

I have a 1968 elan plus 2 in which the speedometer works but the odometer does not.

I believe that this will be due to the plastic gear wheel that drives the odometer and before taking it out of the car I would like to have bought a new gear.

Does anyone know the number of teeth on this gear and the best place to get it. I am keen to try repairing this myself as I don’t want the car to be off the road all the time that it is away being repaired.

Thanks in advance

Mike
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PostPost by: ericbushby » Thu Dec 02, 2021 7:41 pm

Hi Mike,
While my speedo was away for several weeks being repaired I marked the rev counter at 30, 50 and 70 MPH in top gear and continued driving it.
A passenger read out the speed from a GPS on a phone and noted the revs that I called out.
Three white dots were put on the glass back at base.
I still have those marks on as confirmation.
Eric in Burnley
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PostPost by: Mike2drummond » Thu Dec 02, 2021 7:48 pm

Thanks. I was assuming that I would have the dash in bits and did not want to build it up again to repeat the process again when the Speedo came back but maybe I will have to.

Mike
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PostPost by: ericbushby » Thu Dec 02, 2021 8:02 pm

Hi Mike,
Ah, Plus 2.
On the Elan the speedo comes out without disturbing any thing else. It is not easy but it does.
I know nothing about the Plus 2.
Eric
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PostPost by: mbell » Thu Dec 02, 2021 8:05 pm

They can be removed individually without touching the rest of the dash. Remove the trim under the dash, then there two thumb screws and the connections to remove and it should slide out the front.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Mike2drummond » Thu Dec 02, 2021 8:30 pm

Removing it out the front sounds much better to me. I had read that it had to come out the back after removing a voltage regulator. I will give it a go at the weekend.

Does anyone know about the odometer drive gear?

Mike
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PostPost by: john.p.clegg » Thu Dec 02, 2021 9:48 pm

If you can post the TPM number on the dial I can give you that ...but I think it may be just a locking shim that has made its bid for freedom..

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PostPost by: john.p.clegg » Thu Dec 02, 2021 9:52 pm

Part 7

speedo.jpg and


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PostPost by: Mike2drummond » Fri Dec 03, 2021 2:45 pm

John

There is a number on the speedo. See photo below.

sn-6153/101a

Regards

Mike
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PostPost by: john.p.clegg » Fri Dec 03, 2021 4:21 pm

The number is 940 , which means a 47 odometer tooth gear and a 20 tooth worm gear.

http://www.mgb-stuff.org.uk/speedorep.htm

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PostPost by: Mike2drummond » Mon Dec 06, 2021 1:06 am

John and others. Thanks a lot for all your help. I will try to get some parts to repair the odometer.

Regards

Mike
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PostPost by: ericbushby » Mon Dec 06, 2021 8:21 am

Hi Mike,
It might be worth checking it over first.
In my case it was a small ratchet and pawl type mechanism where the pawl was not engaging with the tooth on the wheel This indexes the first wheel of the count mechanism. Cleaning and lubrication nearly fixed it, but I also made a small spring which is fitted on some types and not on others.
That is a few years ago and with encouragement from John Clegg and others.
Good morning John.
Eric in Burnley
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PostPost by: john.p.clegg » Mon Dec 06, 2021 8:25 am

Good Morning Eric...

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PostPost by: jk952 » Thu Dec 09, 2021 12:52 pm

I had a 78 Caterham with the same problem, turned out all the parts were fine, but the worm gear on the main input shaft was no longer bonded to the shaft. Figured I would likely cause more damage trying to fix it, so just ticked the tumblers over a few thousand miles forward to approximately represent my driving time and put it back in. Was honest with buyer “TMU” but was obvious not out by thousands as was evident by condition of the very low mileage car.
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