A10 layshaft bushes

[Jules]

Hi Swarfy, thanks for the explanation, I've just had a closer look and assembled it into the housings...
First point is really end float, is there a max and min? obviously its worn but it seems a lot, yet to measure it..how/where do you shim it out to reduce the end float, because I'm sure that wherever you bias the shaft could affect the gearshift performance, I'm not replacing the blind bush, so maybe put a shim in there?? The hardened washer doesn't have a chamfered side either, does that mean its worn down? whats the best way to fix the end float please? cheers

[berger]

there is only one hardened washer that fits on the layshaft and should have a slight relief in it that sits against the shaft and the full flat side against the first gear cog. you don't have to be fussy with shims at the blind bush end, once the sandwich plate and gasket is on it normally is anything between 10 and 20 thou

[Swarfcut]

Jules, bergs has given you the answer, here's the how and why.

 The layshaft has a circlip, in a groove at the blind bush end. This circlip acts as a stop to position the layshaft pinion on the layshaft such that the pinion flat base is level with, or more usually, slightly proud of the layshaft end.  This is the datum that positions the layshaft in relation to everything else. This pinion face runs against the top hat face of the blind bush.  You can see now that layshaft and loose first gear need a spacer to keep everything within bounds. The spacer is the washer that goes between the layshaft shoulder and first gear cog. No shim or washer is fitted at the blind bush end. Adjusting the thickness of this washer (Part no. 67-3251) controls the layshaft endfloat when the inner cover is replaced.  With new bushes, etc a new standard washer should be good enough. Depending on what you have, it may be easier to make one.

 The layshaft has a very slight radius where the diameter changes. The correct washer has the inner edge relieved to clear this radius. Maybe your washer is not original. It should be hardened.

 Endfloat on the layshaft will depend on the position of the fixed pinion on the layshaft, the amount of wear on the top hat faces of the layshaft bushes, face wear on the first gear cog, the thickness of the washer and also the thickness of the gasket between the inner cover and the gearbox casing. We assume the basic castings are standard.

 With old machines that have been through  mis -guided hands there is plenty of scope for things to be not quite right.

 Plunger and swing arm layshafts are different.  Plunger layshaft has a plain blind bush end. S/A has a scroll. Circlip groove is nearer the end of the shaft on plunger, the pinion gears have the corresponding location step deep in the pinion (plunger) or at the dog tips (S/A) 
   Both shafts are dimensionally the same, so sometimes get mixed up. Check you have the right parts.

 Check the pinion is on up to the circlip on the layshaft. If all in order, leave the pinion in place, but if it has to come off, removing the pinion requires a lot of force. Knocking the pinion off the shaft with a steel tube is how the drive dogs get broken off, so use a proper press. One root of the pinion gear teeth has an oil hole, this corresponds with an oilway to the centre of the layshaft.

 Swarfy.

 Additional. Looking at the second picture I reckon I can see the circlip, at the tip of the pinion dogs, so that should be a S/A layshaft. Even the oil holes line up! Pinion looks to have the later type of round profile drive dogs.

[Jules]

all clear now, and I found the bevel/chamfer on the washer too, its not much! thanks Swarfy….
I've been going through bits and pieces I bought years back in prep. for this restore and found these new bearings, 2 are for the gearbox and the other is x4 for the wheels ('56 A10 s/a, which has Ariel type full width hubs, I believe), they are all "sealed" type bearings...I'm pretty sure they are the right sizes, but what about the fact they are sealed, is that an issue for the gearbox? I believe they will be fine for the wheels, but do I need to change anything when I fit them, assuming they are correct/ok to use??
see pic..cheers

[berger]

you can pop the seals out if you want, on the out put big gearbox ball race I take one side of the seal out to help keep the oil in the box, on the wheels you can leave them sealed, the smaller ball race on the main shaft take them both out if you wish

[Jules]

thanks Berger, I did consider that, then thought "well if they are sealed for life, why not leave them alone", is there any reason to remove them in this enclosed environment, do you know? if they don't need the splash lubrication, is it actually detrimental to leave them sealed? cheers
PS I measured the layshaft endfloat the other day without sealer/gasket fitted, and its about 15 thou, so figure with the gasket/sealer, it'll end up around 20 thou, which seems a lot of float actually (physically). I've found an old shim that fits the shaft and am thinking it would work well between the floating (1st?) gear and the bush, and will help locate the gear and reduce its potential to "wobble" - what do you think? any reason not to?? cheers

[berger]

I remove one side of the big bearing just for it to get oil, they are sealed so muck doesn't get in so there's no harm in letting the gearbox oil fully lubricate the small bearing, as for the float you could try that if you wish but my box ran perfectly with 20thou. to make the bush less wobble it needs bushing to the worn shaft as near as one can be made unless you have the shaft ground true and a perfect bush fitted. the shim might get chewed up. my experience is these boxes run with loads of bush play as mine did for years

[Swarfcut]

Jules. A single thicker washer is the best way. Moving the fixed layshaft pinion towards the blind bush is another option but would be difficult without a press.  If you go down the extra washer route put it between the original washer and the loose first gear. Putting it outboard between gear and bush will alter the gear teeth axial relationship between the first gear and the mainshaft pinion gear.

 The large gearbox bearing is effectively in its own poorly lubricated compartment, so could be left sealed. Probably a dab of grease needed to lubricate the oilseal, which will still need to be retained to locate against the bearing and the big circlip. Halfway house is to remove inner bearing shield, as bergs does but leave outer in place as an extra oilseal.

 Swarfy.