Speedometer died

[robinlarry]

My speedometer stopped working on Saturday while I was driving. I have an S1 with mechanical unit. Before I go to the trouble of putting the car up on the lift, I was wondering if there might be anything other than disconnected or broken speedometer cable causing the problem. Thoughts?

[Le TVR]

It is just a simple mechanical system so if its not the cable it can only be the takeoff drive from the gearbox or the speedo itself.

[v8s4me]

it may just need a new cable. The square ends round off over time.

[greymrj]

I also run an S1. It does sound as if the cable has gone.
It isnt particularly difficult to unscrew the speedo drive from the back of the speedo and I had no great trouble getting it to move far enough to get hold of the inner. If the inner doesnt rotate it looks like the speedo unit has failed, so that would be off to a specialist for repair. If the inner does rotate it is either broken cable, cable rounded off or failed speedo drive unit. If it rotates you might as well draw it out from the cab and see what state the cable is in....it will be oily so take care.
I have heard of a speedo drive becoming disconnected at the gearbox end (not on an S) so if the cable actually looks OK then check the outer is attached correctly.

[magpies]

have a speedo for sale if it isn't the cable

You can borrow it to prove the system if you wish

where are you?

[TVRees]

As far as I remember, robinlarry is on the other side of the "pond".

[greymrj]

Just one further thought. If someone has been over zealous in oiling/greasing the cable then oil can enter the speedo and effectively stop the delicate mechanism from working. If you take the cable off the back of the speedo and find it pretty wet or sticky then take the speedo out and check it. Put the tang end of a file or similar in the drive socket and see if anything happens when you spin it. A good speedo will jump a little and fall straight back. Cleaning out an oily speedo is a bit dodgy and I haven't done it for years but I seem to remember we used paraffin to save any damage to the working or dial. We sort of part immersed it, back down, and left it for a bit and then VERY gently swirled it around. If the parafin turns black you have found the culprit!
These speedo heads should be quite dry afterwards, not even WD40!
Good luck!

[robinlarry]

Thank you for all of your advice.

I pulled out the cable and both square ends are intact. CHECK

Inserted one end into the speedometer and turned and speedometer 'jumped.' CHECK

That leaves the possibility/probability that the difficult to get to end has come disconnected.
Tomorrow's project.