Speedo Not Working

Post by **David53** » Sat Jul 18, 2009 6:15 am

When I origianlly ran my car 25 years ago the speedo never worked. When rebuilding I replaced the speedo cable with a new one. I had to fit a different speedo drive to the gearbox in order for this cable to fit as my original cable had a different thread.

Once back on the road the speedo worked again which was great but the miles did not tick over. Now a few miles down the track the speedo has stopped working altogether. I fitted another old speedo I found at a jumble but this does not work either.

Trouble is, I don't know if both speedos are faulty or if it a sproblem with the cable and/or drive. As the original speedo didn't tick over the miles I thought it might be worth having it overhauled and then re-fitting. If still not working then I'd know for sure it was the cable. Seems strange for a brand new cable to fail after only 40-50 miles...

Any ideas?

Post by **MarkyB** » Sat Jul 18, 2009 7:45 am

Maybe the stuck Odometer put extra strain on the cable?
Replacing the cable would be much cheaper than getting the speedo overhauled and would probably be needed anyway.

Post by **Alec** » Sat Jul 18, 2009 7:50 am

Hello David,

it looks as if you will have to go back and check what you have replaced. First step is to disconnect from the speedometer and watch the cable as you drive to see if it turns. Try and put a little load on it by holding the inner, if you can't stop it turning the drive and cable is fine, and it is the speedometer. (it could be that the cable doesn't fit the socket correctly? You just need to check things like that.)

Alec

Post by **mike.perry** » Sat Jul 18, 2009 9:42 am

To check the speedo, fit on end of a piece of broken inner cable or something the same size into a variable speed drill and the other end into the speedo. Spin the drill slowly and see if it has any effect on the speedo needle or odometer. If you remove the outer cover you will see that the odometer works on a worm drive off the cable and the speedo needle is operated by the magnetic spinning of the wheel (I think). It should be possible to identify the fault by observation
I am assuming that you have the small Series MM/II speedo serial no. X70620/7. The correct TPM should be 1000 for the Series II

Post by **David53** » Sat Jul 18, 2009 10:02 am

Looks like a cable prob, but still think the speedo could do with an overhaul to repair the Odometer. Will check cable tomorrow

Post by **bmcecosse** » Sat Jul 18, 2009 10:16 am

The electric drill has to run BACKWARDS! There is usually a little square drive in kits of drills etc. that fits nicely. Speedo overhaul is going to be VERY expensive - so if fauly - just pick up a second hand one. Always plenty on ebay - or ask here in 'wanted'. Check the 'tpm' figure on your old speedo -and get another with the same (or very close) figure. tpm = turns per mile
I don't understand why you had to fit a different drive etc to the gearbox - I suspect this is where the problem lies. Test the speedos first - if working - investigate the drive.

Post by **David53** » Sat Jul 18, 2009 10:32 am

The new cable I purchased had a different thread on the end that attached to the gearbox drive - finer than my original. Fortunately I had on old box handy which had a drive with the right thread. I have found this with lots of parts on my early Series II - threads are slightly different to later Series II and 1000.

Ditto the speedo - it is the small one in front of the driver similar to the MM, but has a different TPM than the MM one, so not easy to find.

Post by **MColes** » Sat Jul 18, 2009 2:16 pm

I have a spare speedo for a series II if it is the speedo that's the problem. PM and we'll sort out a price ;)

Post by **bmcecosse** » Sat Jul 18, 2009 2:28 pm

Ahh yes -small speedo - not so easy!

Post by **David53** » Sun Jul 19, 2009 5:35 am

Well, mystery solved.........I put a new speedo cable into the speedo and tried to turn the other end with my fingers and it is jammed solid. So it would appear that what has happened is that the speedo has locked up and this has caused the cable to snap. So it looks like have the speedo re-furbished and then fit a new cable and all should be good......I hope!