Final Drive Sprocket

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Final Drive Sprocket

Post by Ubert767 » Thu Jul 11, 2019 10:19 pm

b44icon
In pursuit of a leak free bike I'm inspecting the final drive oil seals etc.
Does anyone know the torque setting for the final drive sprocket 1 ½" AF nut on a B44/B50, please?

Rob

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Re: Final Drive Sprocket

Post by JB » Fri Jul 12, 2019 8:12 am

According to the manual it's a 1" 3/16 (30.16mm) Whitworth Form thread and the torque setting is 100 lb/ft (13.8Kg/m).

Having said all of that, I've never bothered with a torque wrench and simply done it up "tight as ***k"...if you know what I mean :laugh

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Re: Final Drive Sprocket

Post by Ubert767 » Fri Jul 12, 2019 9:37 am

:thumb Thanks JB, much obliged.
Rob

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Re: Final Drive Sprocket

Post by Ubert767 » Tue Jul 16, 2019 8:06 pm

I've just purchased a cheap 38mm A/F socket with 3/4" drive in order to fabricate a spanner for the final drive sprocket nut, but I don't know the reach required.
Please can anyone tell me the length of projection (X) of the drive shaft from the clutch end to the outer face of the sprocket?

Grateful if you can.
Rob
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Re: Final Drive Sprocket

Post by skippy » Wed Jul 17, 2019 12:26 am

I got a cheap truck wheel spanner and cut the end off about 1 1/4" long and welded a larger spark plug socket on to that and it works fine.
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Re: Final Drive Sprocket

Post by mlb50 » Fri Jul 19, 2019 5:31 am

For a number of British bikes, I have a big 3/4" socket that fits over the gear sprocket nut, but as you mentioned the mainshaft is too long to allow a extension bar. So what I did was to cut 2 flats on the socket end so that I can fit an open ended spanner and tighten it.
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Re: Final Drive Sprocket

Post by Ubert767 » Fri Jul 19, 2019 9:33 am

:thumb Thanks for the two replies from Oz.

I, too, intend to weld an old socket onto the 38mm socket so that I can use it with a torque wrench. To be prepared for the strip-down I need the length of the drive shaft extension to determine the reach required (x). My engine is assembled at present.
Thanks again,
Rob

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Re: Final Drive Sprocket

Post by skippy » Sat Jul 20, 2019 12:26 am

Locks like no one has one apart.
To add to what I did, to get a good grip, I ground the socket end flat as it has some rounding on it. That nut is very thin.
Doug
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Re: Final Drive Sprocket

Post by koncretekid » Sat Jul 20, 2019 10:57 am

I simply purchased a deep socket, 1-1/2" I think, cut it in half, and welded a piece of steel pipe about 2" long in the middle. It is shown here along with some other interesting tools.

download/file.php?id=8404&mode=view

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Re: Final Drive Sprocket

Post by Ubert767 » Mon Aug 19, 2019 7:25 pm

Screen Shot 2019-07-16 at 19.54.28.png
I've had my Victor primary side apart again because I couldn't bear the small oil leak from the final drive sprocket any longer.

To answer my own question and in case it is of use to others, the amount of required reach for a socket for the final drive sprocket nut (dimension " X " in the drawing) is 60mm.

Reassemble and test tomorrow, fingers crossed!

Rob

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Re: Final Drive Sprocket

Post by minetymenace » Mon Aug 19, 2019 10:04 pm

:thumb
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Re: Final Drive Sprocket

Post by ghislain » Wed Aug 21, 2019 8:25 am

Check the depth of the oil seal , I've been sold seals with a protruding lip which was just at the level of the chamfer of sprocket ....Very nice leaks :grin:
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Re: Final Drive Sprocket

Post by Ubert767 » Wed Aug 21, 2019 4:52 pm

Double seal gearbox bearing, sprocket boss in good order, no wear groove in sleeve bush projection, final drive sprocket nut (with a smear of silicone) torqued up using newly fabricated socket, new primary backplate oil seal and gasket, Locktite 5188 on on the primary cover jointing faces, cover screws torqued to 5ft/lbs ..................and the bar steward is still weeping! So am I. <218

Next time it's apart I'll look for a case crack.
Rob

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Re: Final Drive Sprocket

Post by Ian Hingley » Wed Aug 21, 2019 7:33 pm

Is it leaking engine oil, gearbox oil or primary oil?

Ian
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Re: Final Drive Sprocket

Post by Ubert767 » Wed Aug 21, 2019 7:52 pm

Hello Ian,

I'm pretty certain that it is primary oil, being thin and containing what looks like clutch plate debris ( blackish). It only weeps down the back of the casing directly after a run. All is OK during storage on prop stand, with no further leakage.

Rob

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Re: Final Drive Sprocket

Post by minetymenace » Wed Aug 21, 2019 8:33 pm

The bush on the end of the cog (the one that runs in the seal) was originally a split affair, PES do a full circle bush that they ream to fit the mainshaft, got to be a better job....no doubt others do too
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Re: Final Drive Sprocket

Post by skippy » Thu Aug 22, 2019 12:12 am

I have replaced the bush and primary seal and i still have a chain oiler.
Doug
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Re: Final Drive Sprocket

Post by Canberra » Sat Aug 24, 2019 9:09 am

The handy sprocket nut socket! Has been used a few times now and only way you can torque up the nut properly.
B50 Gearbox Drive sprocket socket.JPG
Had to weld a couple of sockets together but need to be careful you clear all the shaft
John

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Re: Final Drive Sprocket

Post by Ubert767 » Sat Aug 24, 2019 9:55 pm

I've been going over a fix for this persistent oil leak in my mind. I am now wondering if it could be caused by the primary backplate oil seal (40-0243) being distorted by the felt washer. Could it be that an excessively proud felt washer ( i.e. too thick) is making the oil seal lip flare outward, as the backplate is secured, therefore allowing primary oil to pass?
Has anyone found the need to reduce the thickness of these washers?
I'm clutching at straws here!

Rob

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Re: Final Drive Sprocket

Post by Canberra » Sun Aug 25, 2019 1:22 am

I'm assuming the seal is in the right way round? Sprung lip to the inside.

If there is a burr on the split bush it can cut the seal.

Some replacement seals are rubber on outside and can move due to pressure of the felt washer if it is too thick. That is why I went with a metal case seal.

John

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Re: Final Drive Sprocket

Post by Ubert767 » Mon Aug 26, 2019 9:15 am

Hello John, thanks for your thoughts.

The metal-bodied seal was the correct way round and a snug fit in the backplate, there were no burrs on the sleeve bush projection.

I was wondering if this could be happening;

Screen Shot 2019-08-26 at 08.55.16.png
I'll strip it again soon to have another look!

Rob

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Re: Final Drive Sprocket

Post by Ian Hingley » Tue Aug 27, 2019 9:48 pm

The felt washer in the gasket set is mean to be 'parted' rather than put in at full thickness. It should only just bear against the backplate rather than be compressed. I don't think the mechanism you're proposing is feasible/what the issue is anyway.

Cheers

Ian
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