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#845178 04/05/21 2:46 pm
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Kevin E Offline OP
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Hi all,

I’m just in the process of removing all my gearbox components in order to give them a thorough examination and decide what needs replacing.

I’ve got everything stripped as you can see in the attached photo but how do I remove the fixed gears from the mainshaft and layshaft?

I can’t find anything in the workshop Manual that described how to do this. Is it just a matter of pressing them off, or using a puller?

Thanks.

Kev E

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Kevin E #845192 04/05/21 3:40 pm
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I mount the shaft in a vice with soft jaws, protect the end of the shaft with hard wood or piece of alloy and apply hammer to drive the gear off.

kommando #845276 04/06/21 7:16 am
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Kevin E Offline OP
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Originally Posted by kommando
I mount the shaft in a vice with soft jaws, protect the end of the shaft with hard wood or piece of alloy and apply hammer to drive the gear off.

Thanks Kommando, I thought this would be the case but asked the question just in case there was something I was missing.

I received and email this morning saying that I had received a reply to this thread from Mark Z, which was: -

'Kevin, it wouldn't appear that removing those gears from the shafts is necessary, unless the gears are worn or damaged. I think the adage about "if it ain't broke..." applies here.'

I signed on to respond but there's no message here?

I would certainly agree with Mark Z's advice and there is no point in fixing it if it ain't broke. However, I have a mainshaft with a bit of a battered keyway in it and the taper is also worn and suspect. I want to remove these gears to fit to a brand new mainshaft that I have, otherwise I would have left them as they are, as the gears themselves look fine.

Cheers,

Kev E

Kevin E #845296 04/06/21 12:24 pm
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I'd be inclined to agree also,

Check the slop in the gear on the shaft, I have some which have some rock in them, but I have probably got more spares than Auntie Wainright has tatt in her shop, so it isn't too common.

I'd replace any bushings or kickstart ratcheting gears which look worn.

Check for Burrs on the selector forks,

Check for wear on the cam-plate track, the selector tends to dig in and wear it away, whilst your at it polish the end of the selector plunger so it is much more rounded but still engages (David Drew also sells roller versions of these on ebay).

Easiest way to check the layshaft endfloat is to fit the layshaft only first, the thinnest shim (0.113-0.115) should be at the timing side end always. use a thicker shim as requried at the primary side, with only the layshaft and the trapdoor fitted you will find the layshaft endfloat quite easily and it will be easy to install and remove. then fit the main shaft.

Also line up the holes in the gears with the holes in the layshaft. Clean everything through with fine brushes and kerosene.

HTH


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Allan G #845298 04/06/21 12:47 pm
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Kevin E Offline OP
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Originally Posted by Allan G
I'd be inclined to agree also,

Check the slop in the gear on the shaft, I have some which have some rock in them, but I have probably got more spares than Auntie Wainright has tatt in her shop, so it isn't too common.

I'd replace any bushings or kickstart ratcheting gears which look worn.

Check for Burrs on the selector forks,

Check for wear on the cam-plate track, the selector tends to dig in and wear it away, whilst your at it polish the end of the selector plunger so it is much more rounded but still engages (David Drew also sells roller versions of these on ebay).

Easiest way to check the layshaft endfloat is to fit the layshaft only first, the thinnest shim (0.113-0.115) should be at the timing side end always. use a thicker shim as requried at the primary side, with only the layshaft and the trapdoor fitted you will find the layshaft endfloat quite easily and it will be easy to install and remove. then fit the main shaft.

Also line up the holes in the gears with the holes in the layshaft. Clean everything through with fine brushes and kerosene.

HTH

Hi Allan, thanks for the advice. It's much appreciated.

I have all new bearings and will be replacing any bushes that need it.

I have brand new selector forks and cam plate, along with brand new selector plunger, springs and the kickstart ratchet pinion gears.

I will take on board what you have said about checking the layshaft end float and, of course, keeping things clean.

Cheers,

Kev E

Allan G #845309 04/06/21 1:51 pm
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Kevin E Offline OP
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Originally Posted by Allan G
Check for wear on the cam-plate track, the selector tends to dig in and wear it away, whilst your at it polish the end of the selector plunger so it is much more rounded but still engages (David Drew also sells roller versions of these on ebay).

Allan, do you have any links to this David Drew's ebay listings, or can you tell me his ebay user name. I like the sound of the ball bearing selector and would like to source one.

Cheers,

Kev E

Kevin E #845315 04/06/21 2:23 pm
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Originally Posted by Kevin E
Allan, do you have any links to this David Drew's ebay listings, or can you tell me his ebay user name. I like the sound of the ball bearing selector and would like to source one.

Cheers,

Kev E
Hi Kev, no problem... See link


Cheers

Allan


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Allan G #845318 04/06/21 2:37 pm
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Kevin E Offline OP
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Thanks Allan,

I've now ordered one.

What are your thoughts on his advice about shortening the plunger spring by 10mm?

Cheers,

Kev E

Kevin E #845321 04/06/21 2:48 pm
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Originally Posted by Kevin E
Thanks Allan,

I've now ordered one.

What are your thoughts on his advice about shortening the plunger spring by 10mm?

Cheers,

Kev E


There are different opinions on this.... Ive found some of the newer springs are not as tightly wound as the "originals" that or the originals have compressed down somewhat. the the spring looks to be an original then I don't alter it. I have not found any gain by doing so. If its one that I have bought and I have found that it seems much longer and stiffer (no puns please) then I have shortened them. Personally I feel that the damage comes from the pointedness of the plunger and whilst I personally wouldn't spend the pennies to change to the ball type selector as I can round them off and polish them easily enough, I think it is quite a neat idea.

Just a thought, are your mainshaft bearings C3 clearence? not knowing where you ordered yours from? What I have found is if you order from Simply Bearings by the part number alone of the primary side ball bearing you get a bearing with a smaller ID, there must be 2 bearings that carry a similar number. The C3 one from SB' is the wrong dimension, the CN (C2) bearing is available with metal dust seals, I personally don't like this as the balls are held in place by a nylon "keeper/cage", whilst this shouldn't be an issue I wouldn't have on in my bike for an extended period.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Kevin E #845323 04/06/21 3:02 pm
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Kevin E Offline OP
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Hi Allan, thanks for that.

RE: my gearbox bearings. The drive side mainshaft bearing 68-0023 and layshaft bearing 68-0034 were supplied and fitted by SRM quite recently when they were overhauling my bottom end, balancing the crankshaft with the new 750cc pistons etc and converting the barrel studs to 3/8". I asked them to renew all the bearings and bushes apart from the drive side combined needle roller & ball bearing, as the engine had done less than 4000 miles on it since the original conversion. They left the drive side crankshaft bearing alone too as it was quite serviceable having had the same life from new as the timing side bearing.


The timing side bearings that I am fitting myself are: - SKF RLS6 for the mainshaft 24-4217 and Koyo B-1212-OH for the layshaft 42-3075.

Cheers,

Kev E

Last edited by Kevin E; 04/06/21 3:04 pm.
Kevin E #845329 04/06/21 4:28 pm
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re Shortening the index plunger spring, it was a tip passed on to me from SRM about 25 years ago, IMO its a good thing to do,neutral selection is easier. While you are in there , when you get your new cam plate spend time polishing the flat surfaces where the selector fork register along the side of the fork track, these plates were punched out , there are often high spots left over from manufacture, . A polished cam plate, short spring and well shimmed box is a transformation you will enjoy.


71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
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Allan G #845656 04/10/21 1:30 pm
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Originally Posted by Allan G
I'd be inclined to agree also,

Check the slop in the gear on the shaft, I have some which have some rock in them, but I have probably got more spares than Auntie Wainright has tatt in her shop, so it isn't too common.

I'd replace any bushings or kickstart ratcheting gears which look worn.

Check for Burrs on the selector forks,

Check for wear on the cam-plate track, the selector tends to dig in and wear it away, whilst your at it polish the end of the selector plunger so it is much more rounded but still engages (David Drew also sells roller versions of these on ebay).

Easiest way to check the layshaft endfloat is to fit the layshaft only first, the thinnest shim (0.113-0.115) should be at the timing side end always. use a thicker shim as requried at the primary side, with only the layshaft and the trapdoor fitted you will find the layshaft endfloat quite easily and it will be easy to install and remove. then fit the main shaft.

Also line up the holes in the gears with the holes in the layshaft. Clean everything through with fine brushes and kerosene.

HTH

Hi Allan,

I have just fitted the layshaft complete with all gears etc to the bottom end in order to check the end float. After tightening up the nuts on the cover plate I checked the end float with a metric D.T.I. and measured 0.59mm, which is near enough 0.023".

The spacer at the timing side of the layshaft measures 0.1145" and the one at the drive side measures 0.116".

In order to get the end float down to what I have been told is 0.004" I will need to replace the drive side spacer with one that measures 0.135".

The biggest one that they list in the parts book (42-3213) is listed as 0.127/0.129". If I take the nominal value of that spacer as 0.128", then fitting that one will give me layshaft end float of .011".

This still seems excessive to me. Do you know if there are thicker spacers available anywhere?

I’ve attached a photo of the gearbox cavity showing the area around the layshaft drive side bearing. It looks like there may be a bit of wear on there but doesn’t look to bad. What do you think?

Cheers,

Kev E

Last edited by Kevin E; 04/10/21 1:46 pm.
Kevin E #845666 04/10/21 2:31 pm
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The wear looks normal, a spacer shim can be made from a suitable over thick washer, file/ grind/ lap it down, until you end up with 2-3 thou end float.


71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
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Kevin E #845667 04/10/21 2:51 pm
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I buy thick hardened washers off ebay and they can be turned to thickness with carbide tools.

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Originally Posted by gavin eisler
The wear looks normal, a spacer shim can be made from a suitable over thick washer, file/ grind/ lap it down, until you end up with 2-3 thou end float.

I was concerned that in order to achieve the required end float I need a spacer shim that is thicker than the thickest available BSA option. I guess that it’s not that critical, as the reference end is at the timing side. It’s a brand new layshaft with new bearings and the original gears.

I can turn up my own spacer shim from stainless steel and lap it to finished size. I just wondered if thicker shims were actually available in ‘standard’ sizes.

Cheers,

Kev E

Kevin E #845701 04/10/21 7:26 pm
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I found with my Lightning the shim size needed was much bigger than what was available off the shelf. I used 2x spacers from behind the ratchet gear and that gave me the exact endfloat I needed.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

1 member likes this: Kevin E
Kevin E #845713 04/10/21 9:01 pm
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This sort of thing
https://simplybearings.co.uk/shop/B...d-Bronze-Washers/c3_4511_4772/index.html
might be better than a steel washer. Oil filled bronze , I use a diamond 400 grit stone.
Do not use stainless , its a poor bearing material, when I was a kid our local park had a slide made with Brass, it was a great slide,( we lubed it with waxed paper bread wrappers, ) then it was changed to Stainless Steel, that was a crap slide no mater what you did, even wet it was crap..Years later and having seen what happens when stainless rubs itself the wrong way I would not use it for a thrust washer.

Last edited by gavin eisler; 04/10/21 9:05 pm.

71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Kevin E #845730 04/10/21 11:44 pm
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Stainless running on the ally case is fine as a bearing.


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