Velocette LE Mk 3 Gearbox

Well I have now acquired a 1956 Velocette LE mk2:

A few obvious bits missing- oil filter for instance, all hoses and although it doesnt show, both cylinder heads are cracked

Loose exhaust- it wasnt supposed to be an extra so one obvious job there!

I dont think the colour is original but the transfers on it might suggest that. Anyway its a job I am really looking forward to, BUT it will need to wait for the Lotus. In the meantime I am starting to collect anything obvious that's missing- to that end I bought a job lot of parts for replacement heads and oil filter... these also came with a Mk3 engine in pieces and I thought I would practice on that  lot before I get stuck into the Mk2... also if there's anything decent there then I can try and recoup some of my (too extensive) outlay!

So a Brief aside- Velocette LE Mk 3 gearbox!!!

The gearbox appears complete- no clutch components and the hand start crank is missing but the box itself is still sealed. Nothing turns though so I suspect its been stored without oil! Best to strip it and see whats what... so...

Here is the box,  viewed from behind. The clutch lever is centre at the bottom with the secondary shaft to left. 

The Mark 3 LE had a four speed box so it wont be any use as spares for my mk2. Clutch basket (or "bell" as they call it) is on the far side. The manual recommends selecting neutral before stripping but this wasn't possible in my case as everything was pretty solid and I have no idea what gear the box might be set in.

I removed the 10 2BA nuts (1/8 W) nuts and shake-proof washers from the top cover. The cover is very stiff so I had to use a mallet to loosen it and fit wooden slips to keep it open as I worked my way around- take care not to scratch of dent the mating surfaces.

Here is the top cover coming up

Once the cover came off the horrible truth was revealed...

Gear shafts inside, lack of oil! 

Speedo drive gear at top right in this picture,
the drive itself is recessed inside the
 threaded sleeve.

The speedo gear should unwind as the secondary gear shaft is turned but this wasn't possible as nothing turned in this box!

Gearbox top cover

The gear selector mechanism is contained in the top cover- this was also pretty nasty- The manual doesn't even detail what to do with this mechanism so it must be tricky to service- It will need some attention but for the time being I left it soaking in WD40 to try and get some movement.

Clutch lever

There were no thrust rods inside the clutch shaft so it was a simple matter to remove the lever itself.

Clutch basket (bell) removed

The gears would usually need to be locked before the clutch can be removed... no need for that here as they didn't turn anyway! I simply bent back the tab washer and tapped the special nut (ringnut?) round before lifting off the basket.

Behind the clutch- Gearbox front plate revealed, speedo drive unit projecting upwards . I have already removed the  nuts and shakeproof washers from the front plate

It was impossible to remove the speedo drive gear by "unwinding" it from the secondary shaft; luckily a W/W box spanner fitted nicely over the tube and unscrewed the drive housing

Speedo drive tube removed, drive gear spigot projecting

Once the drive housing was off the stem of the speedo drive unit was accessible; it was easily wiggled and sprayed with WD40 until it twisted out.

Removing speedo drive gear

Selector fork rods, note clutch lever removed, hole for clutch thrust rod is visible.

The box has 2 selector rods on which the two forks are mounted. These are screwed into the case, I loosened them with an offset driver before...

Removing them with a normal screwdriver, as they pull forwards the selector forks come loose.

Gear shafts revealed when selector rods and forks removed.

I bagged up both forks with their respective shafts to keep them together.

The gearbox front plate is retained by 6 nuts, these were already undone- see picture above removing speedo gear. The gear shafts are pressed into their bearings and the bearings are pressed into the case at the rear of the box and removable cover on the front. Although at this stage I could rotate the gears I couldn't remove the gearbox front plate. The trick is ...

Heating the gearbox front plate

to use a hot air gun to warm the front plate, thus loosening the pressed in bearings. The plate can  then be driven off with a wooden drift from inside the gearbox...

Wooden drift used to free gearbox front plate

Gearbox front cover viewed from Gearbox side
The loose cover contains a secondary shaft bearing and an oil seal; Primary
shaft bearing remains attached to primary shaft.

Note bearing and seal inside the released front cover, both will need replacing

Gearbox front cover removed, Primary shaft to left, secondaryshaft on right. Note bearing retained on primary shaft and the way that the front gear on the secondary shaft cannot clear this bearing

I was following a Mk2 manual- this recommends doing it this way, but at this point I had expected the gear shafts to pull forwards out of the box. However they were firmly held by their bearings inside the crankcase. I'm not sure that this is right so I will need to check them for burrs and rust- I think they should slide out, but in my case definitely not! It was possible to tap on the end of secondary shaft from behind the gearbox to move this forwards by driving out the shaft with its bearing, but this could only move a small way before its gear  fouled the bearing retained on the front of the primary shaft. Bit puzzled! However as the bearings are all in need of replacement I tapped the primary shaft forward using a screwdriver on thefront bearing alternating this with a tap on the secondary shaft to drive both forward without them touching. Again using the hot air gun to loosen the bearings in the rear of the gearbox case helped a lot. Both shafts then came lose, both with their rear bearings still firmly attached. The mark 3 manual suggests doing this operation in reverse- i.e. tap shafts out of the back and then remove the front cover; luckily despite doing this operation backwards it seemed to work! 

Starter lever mount

The starter mechanism wasn't inside the box, I will need to research how this works and whether I have the rocker gear section in another box, but for the time being I decided to remove the shaft. Undo the 3 nuts from the starter flange and remove the three shakeproof washers beneath. Tap the flange to release it...

Starter lever

... and remove the starter lever from its bush inside the case.

Finally its time for a really thorough clean and ordering some parts before reassembly. In case you need them too the parts I've ordered are:

Part Number	Description	No. Req'd
B22/3	GEARBOX HOUSING BEARING	2
LE385	GEARBOX END COVER BEARING	2
LE394/2	GEARBOX TOP COVER GASKET	1
LE393/2	GEARBOX END COVER GASKET	1
LE431	PRIMARY/SECONDARY SHAFT OIL SEAL	2
LE665	GEARCHANGE COVER GASKET	1
LE376	GEARCHANGE COVER BUSH	1
BK36/2	GEARCHANGE TOP COVER BUSH
LE374	STARTER AND STARTER LEVER SHAFT BUSH	2
LE667	GEARCHANGE COVER SCREW
LE375	STARTER FLANGE BUSH	1
LE398	GEARBOX CORK WASHER	1

I may not need all these items but I certainly will need all 4 bearings, both oil seals and both gaskets. Items from LE665 on are really in anticipation of things I might need for the gear change mechanism, and the two starter lever bushes might not be needed at all but were cheap enough anyway!

So clean everything, check for wear and smooth any burrs, pull off the bearings and remove any bushes before and reassembling- sounds deceptively simple eh??? However, I think I'm going to need a variety of pullers and possibly a press!

To Be Continued.....