Speedo failure

[tim wood]

So my Speedo has stopped working. I think I’ve tracked it down to the output from the gearbox drive.
The cable seems ok and if I spin the angle drive with a power drill then the speedo works ok.

This is why I think it’s a problem with the worm drive bit etc coupled to the output shaft on the gearbox. May be it’s because the spiral drive on the gearbox main shaft is spinning ? Or could a fault exist with the drive itself

I’m thinking part number c21310.
So before I rush in and start taking things apart does anyone have some thoughts?

Thanks

Tim

[mgcjag]

Hi Tim...have a read through this post....had a problem on a friends car the speedo drive was slipping on the gearbox shaft....all the best...Steve http://forum.etypeuk.com/viewtopic.php? ... ive#p12749

[tim wood]

An update.
Undid the prop shaft at both ends and lowered the rear anti roll bar. This gave me room to push the prop rearward and gain access to the companion shaft nut.
I’ve retightened this nut (it was tight but now it’s tighter).
Ever hopeful I’ve reassembled the parts without improvement.

The inner cable spins but if I hold it then it stops. If I connect my drill to the angle drive input then all works ok. So I’m left with the view that it’s the spiral drive and associated gearbox shaft that’s the problem although i can’t see why.

So before I remove the end case and explore does anyone have a view - can the drive fail?
Does the gear maybe strip or the end of the shaft lose its square section.
At the moment I’m baffled !

[mgcjag]

Hi Tim...as mentioned in a text message so just for info here on my friends ots the gear was slipping on the round shaft..there was no keyway or square section to hold it.....we dismantled to see what was wrong...found nothing...reassembled.tightened pinion and gear was then tight on shaft and not slipping...Steve

[tim wood]

Thanks Steve, I will pull the drive hopefully tomorrow and update

[MarkRado]

On my angle drive, the shaft going into the gearbox broke in two. I dismantled and resoldiered the shorter remains, but that did not work very long (I was told it has to be crimped)- in the end I bought a new one, would recommend that considering the effort of installation.

[tim wood]

To update and finish this off.

I knew that spinning the small input of the angle drive operated the speedo ok. So the fault was at the gearbox drive. Removing the drive from the gearbox revealed no problem and it fitted snugly onto the angle drive. So the fault then must be with the spiral drive on the gearbox mainshaft. Given that I had already tightened the companion shaft nut without any change I was then expecting to remove the end over with oil seal to investigate further.

Before doing this I gave it one more go and reinserted the drive into the gearbox and tested. All now seems to be working ok! With the prop disconnected I took it up to about 50mph through the gears without any issue.

So the end result is that I don’t know what the problem was or how it was fixed!

To make me feel better about this pointless waste of time I’m going to drop into Aldridge Trimming tomorrow and ask them to recover my centre console.

Tim