Gearbox rebuild
 

Is there any tricks to put back the lower and upper shafts in the M40 gearbox?
I found the way to disassemble it but cannot put them back in the box. Thank you in advance:tongwink:

I notice there are a few Videos on tube about rebuilds for these M40 boxes if that helps.

Follow the dismantle process and do it in reverse to reassemble 😎👍

Hello, I tried to put them back in place with the disassemble process inverted but I can't put the lower shaft in place once the upper one is installed! It seems that the upper shaft takes too much place and I can't place lower axle through the lower shaft and through the holes in the gearbox. Then I tried to place the lower shaft first and then the upper one, same result! Any ideas? Thank you

Look on David Bello's videos on YouTube or read through this. There are tricks with holding the shafts in with string and using thick grease for the needle bearings. http://vclassics.com/archive/tranreb.htm

This is a “M40/41 Transmission Rebuild 101” question…
Correct procedure described in factory manuals, Haynes, etc, etc.

You need a wooden dowel of identical diameter (~3/4”) to the layshaft gear cluster center rod, just long enough to fit inside the cluster without protruding. This will allow the needle bearings to remain in place during installation.

Lay the cluster with it’s shortened dowel shaft and bearings in the bottom of the case and completely assemble the mainshaft cluster above it.

Turn the case upside down allowing the layshaft cluster to engage the mainshaft cluster and use the steel layshaft rod to drive out and ultimately replace the wooden dowel.

Nothing tricky here, just good clean fun.
Good luck.

Hello, I just want to say that it's quite easy to transform a M40 gearbox to M41 with overdrive! I just did it on mine and the major problem was the oil level to be changed because instead of 0,75L of oil you need 1,6 liter. If any body interested I can tell you how to do it and with pictures!

Jack the car up at the front as high as you can. Please use jackstands and appropriate safety measures. Then fill, gravity will allow more lube to go to the OD. And don’t wait for the lube to completely drain from the fill port while filling, put the plug in as soon as you see overflow.

I always remove the gear lever and fill from the top,much easier that way.

Fit the filler plug tight. Pour 1.6 litres in through shifter hole as suggested. Then you know the oil quantity is correct.