Hi all,

I should have done this before I put the engine back in, but unfortunately I didn’t. I changed from a 3.76 diff to a 3.44 and now I’ve ordered some different drive gears for the gearbox end to fix it. Has anyone ever changed the speedo drive gears with the engine still in the car?

I was thinking something like:
Drain oil + coolant
Remove radiator
Hold up engine with a jack
Remove engine mount
Remove the access plate on the end of the gearbox and the part the cable screws to
Replace the gears and reassemble?

Is there anything obvious I’m missing or an easier way to tackle it?

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Only thing that might stop you is the length of the drive gear shaft. But you could jack the motor up higher if it fouls the subframe.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Interesting, I always thought the Aussie manual gearbox's all had the same ratio speedo drive gears, and that the speedo's were different to cater for different ratios.
I know the UK cars had a few different ratio drive gear sets.

Regardless, to remove the gearbox end housing, I would remove the three long studs first, so that the housing only needs to come back 10mm or so to try and get it out.

So the standard speedo is 1408tpm for a 3.76 diff
The alternative is 1280tpm for a 3.44 diff (I don’t think they made these with a silver face for an 850)

Mine is a special 140kph speedo which is 880tpk with a 3.76 diff
They didn’t make a 140kph silver faced speedo to suit a 3.44 diff (800tpk)

Seeing as the right speedo gears are available I thought that’d be simpler than trying to fix it at the speedo end

Thanks for the ideas on doing the swap - sounds like it’d be possible, maybe a bit of a pain but I’ll report back later

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