Misc: Everything Else 1951 Black Shadow Restoration

Michael Vane-Hunt

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SMITH puts a seal here.
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greg brillus

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To answer Vic's question, I believe the chainwheel bushes are not generally a snug fit, running clearance a good 3 thou or more, and oilite material on the thin outer bush.......The scroll on the inner bush would help to feed oil to some extent. I don't believe this arrangement works as well with a multiplate clutch because the clutch assembly is mounted out from the chainwheel, thus any play in the bushes makes the clutch wobble around too much.......this would not help with the clutch "freeing off" So Vic's bearing mod is good, if not a bit difficult, certainly for anyone else without the ability to machine up parts.
 

craig

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This is a lip seal same dimensions as bushing ID/OD?
What is this smeared number?

I thought an oring was discussed for sealing this.


DanSmithSeal.jpg
 
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greg brillus

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Craig, I use "O" rings there.......To fit a seal the outer end of the shaft needs to be machined to take a very small section seal.........Obviously the bronze bush would need to be slightly shortened to do this. You have to exercise a lot of care when passing the G 3 shaft through this seal as the spline for the kick start ratchet gear will damage the seal very easily, plus the circlip groove as well. A smear is a a light coating that covers the inner face of the C 20 nut, around the outer edge so that it forms a seal on the mating face of the C 3........Like I said, if the C 3 is a nice fit on the mainshaft, with no back and forth play, then this seams to work well..........If the bushes in the G 4 are good without excessive play, the gearbox should not leak badly from there.......The factory spec of oil quantity was 2 pints (1200 ml's) ......I generally put one litre in and add about another 100 ml's until the oil just shows on the tip of the dip stick........Using the full 1200 ml's can result in the box leaking........One litre is actually plenty enough anyway........I use 80 w 90 gear oil in all the gearboxes.
 

craig

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Do you know the secret about countersunk fastener length dimensions?
Did you know that Vincent parts suppliers/manufacturers do not know this?


CskVsStdLength.jpg
 

timetraveller

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I think that that somehow things have got confused. Considering only the clutch side of the gear box. My suggestion about the 'o' ring, inside and at the inside end of the C3 shaft is intended to stop oil getting inside that tube and passing through the C3 around the gearbox main shaft. If there is any doubt about what I am referring to it is where the early Vincent recommendation was sealing compound and later a modified C3 and modified C20 together with an 'o' ring. Oil passing along the main shaft by this route will emerge inside the clutch drum and cause slipping. Any oil passing through the inside of the clutch sprocket will emerge behind the clutch drum and will get flung outwards and unlikely to get onto the linings. Lubricating the bushes and seal inside the sprocket probably requires that a small amount of oil gets in there.
A small section 'o' ring at the output side of the gear box only requires the bush to be tapped in about a mm so I did not machine the bush itself. I will find out eventually whether that was a mistake or not, The 'o' ring mod at the clutch side of the gear box has worked without problems for, probably, 55 years.
 
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