A Lock Down Project

from Erik Benson in France

Here is the tale of the little project I gave myself in the garage during lock-down.

I have owned, restored and raced TDs since my first one in 1960, and am pretty au fait with everything about these great little cars.  The gearbox however is a territory I have never strayed into.   It is known to be weaker than the previous TC one however. (In my full-race TD I had converted it to the unbreakable TC ‘box).

Here in France, there is much less chance to find parts or people who can fix, so I was lucky enough to obtain a ‘box locally from my friend Mike, who had just swopped out a TD ‘box for a Ford conversion before selling the car.  This ‘box had been jumping out of 3rd gear, which seems to be the first sign of trouble.   (My ‘box has done it a couple of times, so this fix should give me a spare for that dreaded day!

I was in no hurry, so could take lots of time considering before making any moves.  But first I contacted a couple of people out there in ‘online’, in Canada and Australia, who were MG experts and who passed on to me their knowledge of the job.  Without them I could never have dared tackle the task and I had dreaded the vision of little springs, ball bearings, shims, gears etc all rolling about in the ‘box, or on the floor.  (Thanks Hugh, and Bob!).

If you feel the same ….  courage!   as the French say … “ tout est possible!! “.

  – – – – – – – – The JOB – – – – – – – – – –

The job is to insert a spacer shim on the main shaft between the front of the rear bearing and its circlip.  The reason for this is to prevent the gear slipping back under load and jumping out.

So, to begin….

I was lucky to find the gearbox support which I had made up decades ago, which was a great beginning.  In fact, it is ESSENTIAL.

First job . . . . . . CLEAN EVERYTHING! –  this took quite a while!

Next, I removed the bell housing and the extension, followed by the top cover . . .  being very careful to extract the three springs and their balls. I used a fine magnet to pull the balls out – then kept those parts in a sealed container, also here remove the speedo drive gear.

The shim will be going down the middle spring hole.

I was trying to access the insides of the box without extracting all the gears and shafts if possible.

Next thing was to remove the rear casing.   Remove the three selector brackets from their shafts, putting the three tapered lock screws safely into the container with the springs and balls. You can slide the casing back a bit to let them slide off.   By the way, the drive flange did not need a puller and slips off easily. 

The shaft is still well supported by the bearings. . . again … clean everything.

Now we come to the shim. Hugh recommended one at 18 gauge, or 1mm, but …where was I going to find such a thing?    By amazing luck, I discovered several of them of differing thicknesses in my spares!!  I honestly cannot remember where they come from, but the sizes are shown, and they must be available.

I was warned that I should make sure that the main shaft would stay in place when I removed the rear bearing to avoid internal parts falling into the bottom of the ‘box, so I devised four cords to the flange ….and, using a screwdriver from the inside tapped the bearing backwards … it slid fairly easily. 

So, using two large screwdrivers I prised the bearing out …

To remove, I had to untie the drive flange, but because I was not pushing anything back, the shaft and gears all stayed in place … shim in and slide bearing back in.

To replace the rear casing is straightforward – BUT … you have to fit the new rear felt seal, which can be (is) tricky (mine was completely missing).  It has to fit over the end of the flange and NOT get any felt caught between flange and bearing guard washer. This means that you have to fit the rear casing with the flange already in place – i.e. drive out the bearing and washer …  fit the felt and replace the flange … then replace the bearing, getting a metal-to-metal contact.

Here is the internal view:

… and here we are back where we started.  I did not replace bearings or other parts as this was a first, and they all seemed reasonable enough for a “spare” ‘box. I locked the flange nut up to 65 lbs torque.  and the paint?…  sourced in France, may, or may not be the exact shade for an early TD.

All of this will seem a bit amateur to some folks…  but here in France, “amateur” probably means someone who loves what they are doing … voilà!!        ERIK