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More laydown box woes

Submitted by george_phillips on Wed, 11/04/2018
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Nortons - General

Having got the box all back together with the help of Mick Hemmings excellent DvD I now find the following;

1. With the drive sprocket locking nut pinched up I get about 80thou movement on the sprocket. Even with it tight it's around 60thou. It's as if a spacer or washer is missing but none is shown in the parts list. Any views?

2. There is massive drag in neutral between the mainshaft and the main gearwheel drive shaft(effectively the drive sprocket). Is this normal? It hints of future clutch drag.

3. It is almost impossible to change gear with the gear lever with the box in the vice. Although it changes when a spanner is applied to the camplate spindle bolt.

I'm certain all the cogs/spacers etc are back in the right order. It all went back reasonably well and the inner cover fitted fine and double and triple checked for correct camplate alignment. I did notice that the pic (plate) TN showed a washer/spacer TN12 between the mainshaft thrust washer (TN11) and the main gearwheel but does not note it as a part in the lists. Is there such a part?

I'm loathe to fit it back into the bike only to find it doesn't work so any advice would really be very greatly appreciated. I may even have to phone Mick Hemmings. Regards George

Submitted by ian_soady on Wed, 11/04/2018

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1. I think this is because the washer you mention (p/n A2/317, TN12 / N24) is missing as this sits between the bronze thrust washer and the rollers.

2. There should be minimal drag - this could be related to this washer being missing as well?

3. I suspect this is a consequence of 1 & 2 as well.

Submitted by george_phillips on Wed, 11/04/2018

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Maybe Ian. But as it's not listed it has no part number. Catch 22. BTW I found that by removing washer TN78 (again not listed but I believe it is the mainshaft bearing packing washer pt no.A2/323) the whole thing frees up and I can twist the drive sprocket against the clutch shaft in neutral. I've still got a lot of play on the drive sprocket although hardly any float on the mainshaft. Weird.

George

Submitted by george_phillips on Wed, 11/04/2018

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After a bit more research I find that for the GT108 box (Mod 7) the washer is actually noted as pt no. A2/319, now ordered. So I'll disembowel it all over again and see how it goes. Many thanks for your interest, ian. George

Submitted by george_phillips on Wed, 11/04/2018

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I'll try and answer all that Ian.

1. My sleeve gear has no hardened washer. I have now ordered one from RGM. Not sure how to "peen". Sorry, I mean - I don't know how to peen!

2. No spacer behind my drive sprocket and none show on the parts list. How would I know what to order?. Hopefully when I fi the above washer it will pull the mainshaft in a bit which should allow the sprocket nut to do up a bit better? The nut is fine.

3. Bellevue washer - I don't know. It's not shown on the parts drawing so I don't know what it looks like. It was not there before dismantling. I have a parts list for the 1950 upright and there's nothing shown there.

Once again Ian, thanks for your interest.

George

Submitted by colin_mosley on Wed, 11/04/2018

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Hi George

1. As Richard mentioned, when the sprocket nut is tightened, it should pull the sleeve gear through the bearing and remove all end float. I recall that you fitted a new sleeve gear bearing. Did you re-install the large shim immediately next to the gear before installing it through the bearing? If you are using the original sprocket, there is no hardened sleeve between it and the bearing. Try removing the sprocket, turning it round one spline to see if it makes a difference. If you are using the original gear, original sprocket and high gear shim as above, what else has changed?

An easy way to check would be to install the high gear and shim into your old bearing on the bench. Install the sprocket and nut and see what is going on.

2. With the massive drag problem, did you add the main shaft shim (Bellville washer) that Richard mentioned or was it fitted before? If it was there before and only the bearings have been replaced, one of the main shaft bearings in the casing may not be fully home. If you re-installed the "oil sealing" shim behind the high gear bearing, is it correctly fitted?

3. Finally, your shifting problem could be associated with the binding shaft because you cannot rotate the shafts independently to allow the gear dogs to line up and engage.

Hope this helps

Colin

Submitted by colin_mosley on Wed, 11/04/2018

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Just thought of one more thing. Did the inner gearbox cover have a gasket on it? If so, does it have one now?

Submitted by george_phillips on Thu, 12/04/2018

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Thanks for that detailed response, Colin.

1. Yes, large shim fitted. I will try turning the sprocket on the splines and see what results.

Original gear, new shim, original sprocket, new bearing.

2. The mainshaft shim (if you mean the washer bearing up against the rollers in the maingear) has now been ordered. It was not fitted before as it did not appear in my parts list. I believe the main bearing is fully home. The RH m/shaft bearing was left alone. The new main bearing (LHS) was already fitted with oil seals so I removed the inner and left the outer so no additional oil seal fitted (other than the large shim noted above).

3. I'll wait and see what effect the washer on the sleeve gear has.

The outer cover did have a gasket and a new one has been fitted (well greased).

George

Submitted by george_phillips on Thu, 12/04/2018

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I've now ordered a couple of 39mm OD x 22mm ID x 2mm washers so I can fit one or both between the nut and the sprocket or the sprocket and the bearing, depending how the sprocket lines up with the rear chainwheel sprocket. Shifting it round on the splines made a small but insufficient difference. I realise I'm curing the effect, not the cause but I cannot see the cause. There is insufficient thread left when the sprocket is on to tighten it to the point where the sprocket is firmly held. George

Submitted by george_phillips on Sun, 15/04/2018

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Having now received and fitted the rogue washer (TN12 on the pic) I find that it takes up so much space between the roller bearings and the thrust washer that the dogs are unable to mesh (m/shaft sliding pinion and main gearwheel) even though it fits into the recess in the main gearwheel. I've decided to leave it out. Any views? George

Submitted by george_phillips on Sun, 15/04/2018

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I think I may have an answer to this one. When I reassembled the maingear with its roller bearings it was quite tricky getting them back into their groove/recess. I'm wondering now if the retaining washer was already in there and went unnoticed by me. This would have the results I describe above. If that's the case I can leave well alone as it's the thrust washer which wears rather than the retaining washer - so I gather. G

Submitted by george_phillips on Wed, 18/04/2018

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The business of the non-tightening nut on the g/box sprocket has been resolved. I found a washer (in the wrong box) with internal castellations which fitted the splined shaft on which the g/box sprocket fits. Once that was slid onto the shaft and the sprocket fitted the nut tightened up nicely. The washer is not shown on the parts diagram nor mentioned in the parts list. typical! George

Submitted by philip_ham on Wed, 18/04/2018

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George,

The original laydown gearbox final drive sprocket has a larger shoulder that fits into the end of the gearbox housing and against the main bearing. But replacement sprockets from RGM and Norvil do not have such a long shoulder, so you need to buy a hardened steel spacer to make up the difference. I believe these replacement sprockets are suitable for newer gearboxes and it gives a greater choice for the number of teeth you have on the final drive.

I was caught out by this, but RGM were very helpful explaining the solution, and selling me the spacer.

Phil Ham.

Submitted by george_phillips on Thu, 19/04/2018

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Thanks for that Phil. I'll know in future. But it was my fault for separating the washer from the clutch box. It probably fell on the garage floor on dismantling and I didn't know where it came from - particularly as it doesn't show up on the parts list or diagram. George

Submitted by george_phillips on Fri, 20/04/2018

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For anyone still following this thread here's the crunch. Box all back together, sprockets sorted, gearbox finally back in (what faff that was), primary side all reinstalled, bike finally started (after hot air gun treatment to damp mag), lid on, gloves and boots on and off for a test run. Engine - great; g/box - crap. No first, moved off in second, then another neutral, then 3rd, then either another neutral or jumping into top. The only thing I can think of is that in trying to select gears whilst the box was in the vice I used the cam plate retaining nut to help as the gear lever didn't seem to have enough "ooomph" and I may have moved it out of sync. I really can't face taking it all out again. I think I'll try it with the box in situ. I won't be removing any bearings, just gears and - maybe - the cam plate, if I can get to the nut! Life gets tejus, don't it!

George

Submitted by george_phillips on Sat, 21/04/2018

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Yep. Standard plunger. The shorter of the two. The fact that it was difficult to select gears with it in the vice I put down to it being devoid of oil. The plunger sits directly under the camplate so - as far as I can see - can't catch anything. George

 


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