OK Chuck,

Thanks.

"Hang on a minute lads....I've got a great idea."

Cable not really engaging. Just seems like it. Or,

Cable end too small for driven gear. Or,

Driven gear end splayed out.

Other possibilities get to mean a lot more work.

Pull the rad and start with the driven gear.

Yes, I've managed the cable replacement...( which explains the rad replacement... sort of). I need to know what's beyond - speedo drive gears down inside the drive unit the cable goes onto. Big mystery! (or is that misery?) If the transmission is turning but the cable isn't, and the cable won't turn independently of the gear its connected to, something's not right in there.

 Oops didn't see Chuck's reply - maybe I should sit tight until he solves his Moke's problem.

Chuck, even with the rad out, it was all I could do to squeeze my "lunch hooks" down in there and get the cable off/on.

I'm afraid I may just have to put up with terrible gas mileage until winter. (No odometer = poor mileage!)

"Hang on a minute lads....I've got a great idea."

"Can the speedo drive be rebuilt or replaced with the engine in the car?"

You shouldn't have to get to more than the driven gear to check the hollow end for damage and/or compatibility with your cable. That can be done in the car. Easiest by pulling the radiator. Others think otherwise!

"Does the transmission need to be drained?"

No, if all you do is the driven gear.

"How far into this 'project' do I need to go to replace the speedo drive? (Haynes is silent on the matter.)"

Speedometer cable removed. Cable to gearbox part (part the cable screws to) removed. Pull out the driven gear.

Sub-question re cable:

"The old cable core has a square end (in section) where it goes into the speedo drive.The new one is sort of squashed oval as if to fit into the same square hole. Do cables come like that now or is this a mis-manufactured one?  The amount  of projection out the end of the casing appears to be the same, and as noted it seems to engage the drive."

I've run into the problem of cables and driven gears not being compatible. No pattern to it that I can find, yet. In fact, when I finish responding, I'm heading to the garage to do the same thing on MOKE: pull the driven gear and match to a new cable before putting everything back together...again.

My car  (86  Mayfair with MG Metro lump) has always had an intermittent speedometer - it functioned OK until the car warmed up, then needle would drop to zero (not quite warp speed!).

I suspected a worn cable and replaced it. In the process I verified that the speedo cable would drive the speedometer itself before assembly and that the bottom end of the new cable would engage the speedometer drive. Once I got it all back together complete with a new rad, evrythign ran fine except the speedometer - not even a hint of movement on the needle, even going over bumps. I have the instument panel out now and a quick twist of the cable core inserted into the speedo causes the needle to jump, so the speedo seems fine.

I inserted the cable core back into the casing (fully seated) and the bottom end does still seem to engage the speedo drive.  The cable does not turn at all when the front wheels are rotated more over 10 revolutions.

Questions:

Can the speedo drive be rebuilt or replaced with the engine in the car?

Does the transmission need to be drained?

How far into this 'project' do I need to go to replace the speedo drive? (Haynes is silent on the matter.)

Sub-question re cable:

The old cable core has a square end (in section) where it goes into the speedo drive.The new one is sort of squashed oval as if to fit into the same square hole. Do cables come like that now or is this a mis-manufactured one?  The amount  of projection out the end of the casing appears to be the same, and as noted it seems to engage the drive. 

"Hang on a minute lads....I've got a great idea."