Author Topic: M21 gearbox  (Read 1218 times)

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nige63

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M21 gearbox
« on: 24 May, 2024, 15:24:05 »
Hi There is obviously something missing.  I have the mainshaft bearing oil retaining washer 65-3509 you can see in-situ but it is lose. Inside there should be a mainshaft bearing oil retaining washer 24-4225 but if put in it just rattles around on the mainshaft.

Pete C

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Re: M21 gearbox
« Reply #1 on: 24 May, 2024, 17:06:23 »
the outer washer should rest in a recess in the casing and, while free to move a little, it is held there by the bearing outer race. It looks to me as though the bearing may not be fully home in the case and so allowing the washer to float outside of it's recess.

nige63

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Re: M21 gearbox
« Reply #2 on: 24 May, 2024, 17:19:19 »
Thats what I was thinking Pete C . Didn't want to bang in to hard as I have already damaged an inner case bearing holder. Not sure how the inner washer stays in place.

GLENN

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Re: M21 gearbox
« Reply #3 on: 24 May, 2024, 18:03:40 »
Surely the oil retaining washer will fit on the sleeve gear? 

Glenn

nige63

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Re: M21 gearbox
« Reply #4 on: 24 May, 2024, 18:35:15 »
Not unless I have the wrong one Glenn. The hole in the washer is to big.

Steve.S

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Re: M21 gearbox
« Reply #5 on: 24 May, 2024, 19:21:29 »
You will need to remove the bearing again. Heat the case first.
There are 2 oil retaining washers, one either side of the bearing. The outer one sits centrally in a recess in the casing and is held firmly in place by the bearing. Yours is loose because the bearing has not been seated properly. When fully seated, the bearing will trap the washer. Although it doesn't matter too much with a seal fitted, this outer Oil Retaining Washer should be fitted with the recessed inner to the outside. The inner washer should be fitted the other way round. The oil seal runs on the sleeve gear which you have yet to fit.
It would be worth checking the end floats once assembled, and remember that the mainshaft kickstart nut should not be done up tight, as per the M20 Manual.

Steve.S

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Re: M21 gearbox
« Reply #6 on: 24 May, 2024, 20:59:13 »
Sorry, the oil seal runs on the boss of the sprocket.

nige63

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Re: M21 gearbox
« Reply #7 on: 25 May, 2024, 11:15:07 »
Thanks Steve.S . Have done all that but the inner case will not fit on snug. It is about 3mm away. Looks like the main shaft bearing will not seat properly

Steve.S

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Re: M21 gearbox
« Reply #8 on: 26 May, 2024, 13:59:55 »
Nige,
 So I take it that you have refitted the bearing and that the oil retaining washer is being held centrally. (It will finally be trapped hard against the bearing when you fit the sprocket and tighten the ring nut).
It is often the case that you have to rotate the mainshaft and jiggle the gear change quadrant when fitting the inner cover.
From memory, the bearing should be about flush with the casing, maybe just proud.
One way to see if the bearing looks seated is to grind the OD of the old bearing so it's a drop fit in the casing and make a comparison.
However, if you heated the casing up enough, the bearing should just drop in with a satisfying plop, when it will be obvious it has seated.
You might want to do a trial assembly without the layshaft and selector rod, to confirm that the mainshaft is causing the problem?
You could also remove the mainshaft and make sure it is fully entering the small bearing in the inner cover.
Let us know how you get on.

Steve.S

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Re: M21 gearbox
« Reply #9 on: 26 May, 2024, 14:06:12 »
Glenn,
Yes, the Oil Retaining Washers fit either side of the bearing, so when the sleeve gear is fitted, you could say the washers are on the sleeve gear.


nige63

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Re: M21 gearbox
« Reply #10 on: 26 May, 2024, 14:06:51 »
Thanks Steve Will give that a go.

Mark Cook

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Re: M21 gearbox
« Reply #11 on: 29 May, 2024, 12:46:08 »
The notes with this should help.

https://pesltd.uk/?product=24-4225

Mark

nige63

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Re: M21 gearbox
« Reply #12 on: 29 May, 2024, 13:01:24 »
Thanks Mark. Still waiting for some parts.

nige63

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Re: M21 gearbox
« Reply #13 on: 05 June, 2024, 12:59:57 »
Ok so I have got all the parts in the correct order but still the inner cover will not fit without causing problems. If I do up the three screws the gear selector is very hard to move, but if I loosen them it all works fine :-\

neil1964

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Re: M21 gearbox
« Reply #14 on: 06 June, 2024, 22:20:23 »
So now you have your original main casing and are using a replacement inner casing?
Are the part numbers the same?
Are they the same thickness?
I ask because Iím building up a s/a box and have three different outer covers and two casings, all superficially the same they all need different combinations thickness shims/thrust washers to get the required endfloat for the layshaft even allowing for decent thickness gaskets between the main casing and inner.
I presume you have proper gaskets (not the really thin pale brown paper ones?