Gear Selector Mechanism

Well having reassembled the gearbox, testing it proved difficult. Its probably easy if you can install it on a bike, but in the absence of a functional LE, testing on the bench involves more than the average number of hands! You need to hold the box tightly whilst turning the output shaft (clockwise when viewed from the rear) and moving the selector shaft to try and select the gears- When you are turning the shaft directly the direction is clockwise to change up and anticlock to change down. The box functions as one-up-three-down when turning the selector shaft directly; the pedal rod mechanism will reverse this action when fitted to the bike. The trouble is all of this is quite stiff in action and having to hold the box as well means that three or 4 hands are really required.
In my case the gears would change but seemed to only allow me to select 1st and second plus neutral. After trying very hard to convince myself that this was right I decided to bite the bullet and strip the selector pawl mechanism to check that all was really OK.

Removing the box lid again revealed the selection mechanism, note edge notched selector camplate and pin driving slots in the plate itself

The central shaft is bolted on the exterior so I held that nut in a vice and unscrewed the central shaft starting with an offset screwdriver

Shaft then pulled out freeing the camplate...

Which could be removed to reveal the pawl mechanisms beneath, Note the spacer which lies beneath the plate (centre) and fits over the central shaft to raise the camplate to the correct height. The sprung and hooked "striking pawl" is on the left and the domed and sprung "indexing plunger" that engages with the grooves on the edge of the camplate is still in place in its wired housing upper left. The camplate has been inverted to show the ratchet plate into whose recesses the sprung striking pawl will hook. It is essential that this ratchet plate is not detached from the camplate rear, or if it is, it must be put back  on the same side of the camplate, the same way up and in the same orientation, the lug on the ratchet plate pointing towards the hole in the camplate as shown. In my case the discs apeared to be a unit and didn't come apart anyway. I found the whole mechanism a bit rusty which might make it too rough to rotate easily  so I cleaned all the surfaces and smoothed them with emery cloth.

The striking pawl spring had seemed weak earlier and this could be the reason- on gentle prodding it fell into two pieces! I ordered a 30mm x 5mm compression spring to replace it although this is slightly too wide (original 4.7mm- I hope the surplus 0.3mm will not prove a problem.

Domed indexing plunger had seemed seemed to be stuck in its housing and I suspect this is grooved internally, so I will smooth that out with a tight fitting drill bit rotated by hand in the socket to make sure it can move freely. Spring seemed to be in good condition and the head is still  nicely rounded. The free length of this spring should be about 0.75 inches so I'll check it and replace if necessary.

I reassembled everything and refitted the lid to the box taking care to engage the forks in the gearchange camplate. To be honest the change mechanism wasn't greatly improved although it did seem to be better- probably because of the spring replacement. The main problem remains the difficulty of bench testing the box although it you do need to turn both shafts as two gears are selected on each. If fitted then engine rotation would be doing this anyway but on the bench its pretty awkward. However I was able to engage and disengage all 4 gears! So success in my book anyway.

I have been called away by urgent Lotus requirements so I don't know when I will get back to the Velocette, but I will write more when I get around to this bike which sadly currently languishes in storage.

Gearbox Reassembly

Both the case and the gearchange mechanism cleaned up quite well, gearchange operation functioned when the splined rod was turned.

I was concerned about reassembling the gearbox, the secondary shaft slid most of the way into its rear bearing although the primary was reluctant.

Secondary shaft in,. primary introduced through the case

Both shafts in poosition but both are standing too high in the case and its not possible to fit front cover unless they are tapped farther in to their rear bearings.

Case supported on wooden blocks before tapping the shafts down

The speedo drive bushing was inserted into the speedo drive hole and checked that it seated correctly at the bottom

Front cover fitted, this was tight where the bearings bore on the  shafts and needed to be tapped firmly home before the bolts could be done up, top two holes are for the selector rods

At this point there was a mishap! Having forgotten to fit the front cover gasket (Duhhhh!) before tapping the front cover home, consequently it was now necessary to remove it again to put the gasket in! Sadly doing this meant that all the bearings remained on their shafts and pulled out of the case so reassembly was needed all over again! At this point though, with all bearings on the shafts I was able to try the second half of the alternative method of assembly- ie fitting bearings to shafts (by default mine were now fitted) and then  inserting the shafts plus bearings into a preheated case. Having now tried assembly both ways I can confirm that the second method is by far to be preferred since it means that the bearings can be pressed onto their shafts using a sleeve which should apply force only to the centre race in contact with the shaft. The outer race then fits easily into the cases when these are heated up. This method thus avoids any need to stress the bearing by tapping on an unsupported centre or heating them. I started applying heat using a hot air gun, this was OK for disassembly, but for assembly you really must use a gas torch, the bearings then slip in very easily, only gentle hand pressure was needed. However, remember to introduce the cork washer behind the primary shaft rear bearing before the shaft is mounted. As the bearing is now firmly fixed onto the shaft there will be no opportunity to insert the washer afterwards. The case was of course hot when this was done and I had to use a rod through the clutch pushrod hole, cork washer and into the primary shaft centre bore to hold it centrally as the hollow primary shaft is fitted. Fiddly but not too bad.

Finally there is no obvious shoulder or "stop" that the bearings could reach to show when they are pressed fully onto their shafts. Therefore, if you are going to try this method its probably best to mark of measure the position of the bearings before pulling them off their shafts. 

Once the shafts are in I fitted the selector forks:

The first selector rod is mounted through the first fork and 

screwed home, a lock nut then secures the gearbox

 front cover

The second rod has to be fitted simultaneously with
the second fork as it has to pass through both forks

As seen here, rod pushed home and screwed into the case wall, locknut as above.

I cleaned and oiled the collars for both shafts and fitted them over the splines. The oil seals were then lubricated and slipped over the collars and into their recesses before they were tapped home using a drift (in this case a deep impact socket).

Output shaft fitted

followed by clutch seal

Gear selection could then be checked, Front and rear gear pairs are always meshed and always turning. Neutral is achieved when none of the central gear dogs are engaged; 1st gear is when the front dogs on secondary shaft (i.e. closest to speedo drive) are engaged; Second is when the rear dogs on the secondary shaft are engaged (i.e. those nearest to the output shaft). Third is achieved by engaging the forward dogs on the primary shaft (i.e. those closest to the clutch) and fourth when the rear dogs on this shaft are engaged. I checked that all slid easily and lubricated the shafts with fresh oil.

When I took the box apart nothing was turning and it had been easy to remove the clutch centre nut (ring nut). Now that the gears turned it was necessary to engage two gears at once before the clutch centre could be tightened. I found that a clutch centre nut adaptor from a Honda was a close fit and with a little filing fitted the ring nut perfectly.

Clutch ring nut, fit this with the machine side towards the gearbox. Using a new tab washer it was easily tightened using a Honda  clutch tightening tool (see at rear attached to ratchet handle)

Tab washer folded into one of the ring nut grooves.

New gasket fitted before reattaching the selector mechanism 

in the lid, the steel pegs on the selector forks mus

engage with the grooves in the gear selector disc

In order to engage the pegs in the disc the selector disc must be set to neutral (centre of the three closely spaced notches). The pegs must then fit into the grooves but they have a fair degree of to/fro movement whilst the gearbox is still in neutral. I made a "jig" by tracing the selector disc profile using a "brass-rubbing" approach and then cut this out of cardboard. Using the gearbox ribs and studs as a guide it was possible to align the cardboard disc with the case and ensure the pegs slipped through the holes.

Tracing

Cardboard template mark alignment with stud holes, invert
 and place over the selector forks

Pegs through grooves in template

The selector fork pegs could then be inserted with minimum trouble into the grooves on the selector disc as the gearbox top was fitted. Any fine adjustments were indicated by putting a blob of grease on the pegs and then offering up the gearbox top, removing the top then showed trace grease "scars" where the pegs needed to be moved as below:

Circular mark showing the peg on this fork needs
to be moved slightly in towards the centre of the box

Finally the lid was fitted and tightened down not forgetting the shake-proof washers- several of mine had been missing. Box finished!

Gearbox part 3: Bearing renewal and Gearchange overhaul

I always worry when changing bearings- but in this case whatever I did to them they would still have to be better than the seized and rusty specimens I removed!

Whenever possible I prefer to wind in bearings using a couple of sockets and some studding (or in this case an M10 bolt. I found one socket to go outside the gearbox front cover and a second that was pretty much the same diameter as the bearing and could slip inside its mounting recess. I gripped the bolt head in a vice and  added Larger socket, Gearbox front plate, bearing, smaller socket, washers and nut for bolt in that order before tightening everything loosely and checking alignment.
Then it was possible to simply pull the bearing into the housing by winding the nut down the bolt- very satisfying! Tension on the bolt helps to keep the bearing square as it enters its housing. To make it easier I heated the housing first with a hot air gun and put the bearings in the freezer for an hour to maximise clearance- even so it was tight!

Sockets and bearing housing assembled on bolt - wind down top nut and...

Bearing safely installed

Of course you cant use this method for blind bearings- and sadly this meant there was no choice but to use a bearing drift. You can use sockets again but I have found that they can slip off the bearing leading to an ill-timed whack on the balls (if you get my gist) which can knacker the bearing once its in. Even so I don't like using the drift as there are so many opportunities for the bearing to go off centre- alignment square on to the housing is difficult but essential. Anyway I fitted the others using the drift...

Drift from a Draper bearing driver kit, bearing now fully home

job done!

Gearchange Mechanism

The gearchange mechanism contained in the box top cover wasn't working.when I got the box and when it was removed it looked pretty nasty- however its also pretty complex and I didn't want to mess with it if that's not necessary so I soaked in in WD40 before giving it a thorough clean using a can of carburettor cleaner- this blasted out a load of solidified grease and other nameless evils. I checked the two springs- one on the operating lever and the second on the pawl. Both were present and operational. I checked the box section...

This is the pedal mechanism; Screws were really tight and one was missing.

A couple of taps saw the cover coming loose

Mechanism inside was dirty but sound if rather basic.

I just cleaned this box out and applied some corrosion block grease before reassembling the lot with a new gasket to the front cover and re-oiling the rotary change mechanism. The splines on the pedal shaft are actually the same as those on the older hand gear change lever so although I don't have a pedal I was able to test it using a hand lever.- Mechanism seems to work well although I cant be sure until I get the box back together!

Rotary change mechanism (before cleaning!")

The rotating disc on beneath the cover has 5 notches- I assume these correspond to N and gears 1-4. There is a spring loaded pawl built into the column on the cover (beneath the two wire-tied nuts) that projects to engage with these cut outs in the disc rim. The odd shaped cut-outs in the disc engage with the operating heads on the gear selector forks. These can only move forwards and backwards along their selector rods, sidewise movement isn't possible so rotating the disc cause them to slid along their rods thus moving the  gears to and fro. At least that's the theory- I suspect getting the gears in with the forks in the right position will be very tricky. Not only do they need to be aligned in the correct orientation but they also need to slide into their bearings- and despite what it says in the manual this is going to be a very tight fit!

Mk3 Gearbox Continued

Bearing removal

Secondary shaft complete with rear bearing as removed

Primary shaft with front and rear bearings as removed, Shoulder piece is detached from in front of the bearing

The two shafts are shown as they were removed above. Getting the bearings off wasn't too hard, I removed the front bearing from the Primary shaft using a two-legged puller, having refitted the clutch nut to protect the threads on the shaft...

I removed the other bearings from both shafts using a bearing separator- its intended for bearings rather larger than this but it did a good job...

Assemble the two halves behind the bearing and tighten up the bolts

Screw in the side bars and fit the puller head,I used the conical tip to engage in the hole at the end of the shaft.
Then tighten the puller and the bearing pulled off neatly

The next step was to remove the bearing which had remained in the gearbox front cover- for this I used a blind bearing puller... first time I had used this bit of kit which has been knocking about for ages. How satisfying is that????

First step was to assemble the collet head in the bearing and
 tighten it down to expand it beneath the bearing

Screw in  the slide hammer

A couple of slide whacks and out popped the bearing

The last step was to remove the two oil seals still stuck in place; one in the front plate and one in the housing. A simple job using a suitably sized socket to punch the oils seal out into a larger socket beneath that is taking the weight.

using two sockets to remove oil seal, note large socket beneath

Seal removed, The seal in the case was removed in the same way.

The bearings in the gearbox case are KLNJ5/8 or 5/8 x 1 3/8 x 9/32 (also known as R10 EE5) and LJ5/8 or 5/8 x 1 9/16 x 7/16 (also known as RLS5 LS7). I ordered 2 of each from a bearing supplier. The oil seals are a little more difficult. The numbers on them specify 11907915, or 1.19 OD, 0.79 ID and 0.15 thick (dimensions in inches). These don't seem to be made any more although some specialist suppliers have them still. The closest modern size is 30, 20, 4 dimensions in mm and these are readily available. They cost about half as much so I ordered a couple to try them- will let you know whether they fit!

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.....