Misc: Everything Else 1951 Black Shadow Restoration

roy the mechanic

Well Known and Active Forum User
VOC Member
Quite correct on the selector fork pins, I had one "fall in" on my rapide. Result-smashed the double gear and the g9. filled the box with shrapnel. On the camplate, I polished the prehipery and the tracks where said pins go. Also fitted a copper washer under g55 to back-off the spring pressure slightly.
 

Bill Thomas

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VOC Member
I think all twin gearboxes feel Notchy, When you are building them,
But when they are oiled and all bolted up they feel better ?,
I like 80 or 90 oil in there.
Cam plates are another thing that are often different, Just a little ?.
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Mod done in 2007 after my spring broke at the Irish rally and the bike was changing gear willy nilly two larger holes in the chain wheel (for balance!) but it saves removing the ESA.
bananaman.
P1070553.jpg
 
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greg brillus

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VOC Member
Referring to Vic's comments about the lubrication of the output shaft bushes.......Some have drilled a small hole through the side of the shaft somewhere where the double gear slides, though this is not easy on a very hard shaft.......I generally cut a scroll into the larger G16 bush to assist "Feeding in" some oil......This can cause an oil leak as the smaller outer bush has no seal.......Sometimes I would push this bush inward a bit more and use a small "O" ring in the groove held by the small cup washer that holds the kickstart ratchet into mesh. The available end float of the input shaft will let some oil migrate in to the bushes as well.......It is quite important to check this end float before the G 2 cover door is installed, usually push the door fully home and hold in with a couple of cover screws, then pull the shaft in/out to see what you have.........A good 0.5 mm is plenty........The plunger springs are too strong........I generally squeeze them in the vice until they are coil bound, this will shorten them by about 2 mm, and this makes the shift much better........Polishing around the outer of the camplate and taking a bit off the point of the plunger helps a little. I have struck shifting issues where the bevel gear pressed into the camplate was not fully home (due to a small bur) probably as it broached it's way in.......If you spun the camplate on the G 34 spindle, it would wobble like a swash plate.......this causing a tight spot on one of the selector forks as it rotates.......As always, lots of things to check
 

Bill Thomas

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VOC Member
Yes, I cut a pair of slots in the inner end of G4 to let the oil in,
And put an O ring on the outer end,
If that lot locks up, It's 2 gears at once, Not good !!, Rear wheel locks up.
And also check for some play, As you said,
We did one some years ago and there was no play, Somebody had been in there !,
This was an engine been on the floor from the 60 s,
When I took it apart, There was a narrow ring left of the washer, Then they put another washer in
E 76, It was very hard to see the worn out washer.
As you say, I always give the shaft a little shake, Tells you a lot .
 

craig

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VOC Member
Craig, Check also the input shaft G 3 into the output shaft to check the bushes........These tend to wear a bit in service especially the larger innermost one (G 16) if the outer one shows some wear this will cause oil loss from between the 2 shafts. If the fit of the output shaft through the new bearing is too tight, put the shaft in the lathe and linish the OD of the affected area with some emery tape........A long length about 3 foot and with shaft rotating pull the tape to and fro.......this will work well so do it carefully only a bit at a time you don't want the shaft a loose fit........Cheers...... Greg.
My clearance G16 to G3 are about .012" when measured.
G3 measures o.9352"
G16 measures 0.9475"
 

greg brillus

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VOC Member
That is why you need to make sure the bushes have some play in them and that they are a proper material as well...... I was going to mention about nill end float in the input shaft........this can happen if the output bearing has shifted to the left in the case. This can happen if the shaft is too tight a fit in the bearing, and/or if the sprocket was too tight on the spline........bashing the sprocket on will in fact shift the bearing........Just got Craig's message.......so that amount of clearance is too much.........Push the bushes out and replace them.........If they are a snug fit, they generally collapse a little, so the ID may be too small, this will mean reaming them out to size. Its all worth while to get a good long lasting engine/gearbox.
 

craig

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Pushed the old G16 out, pushed a new G16 in and now have a
G16 measurement of 0.9375" ............mating with 0.9352"
Dropped a shaved washer (shown) down behind bush, used the double 3/8 extension (shown) to press out. easy press, came out smoothly
Used the G3 to press the new bush into G4....with a nut on the press end as pictured.

20210110_G16RemoveRelace1.jpg
 
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craig

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VOC Member
The large bearings in the right twin crankcase half have been staked.
I did not remove the old bearings.
New bearings ready to install.

How is this staking addressed prior to new bearing install?

20210110_RtSideBearingStakes1.jpg
 
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