worntorn wrote:Hi Brent
I actually started on it in mid January but went away for holidays in the first half of February then got talked into a complete Bathroom Reno here at home, that killed most of March.
First up was to deal with the problem of sealing the mainshaft. Original Vincents did not have a seal between the crankcase and the primary housing. They have four mainbearings in total, two per side. The outside bearing on the drive side is a ball bearing. It's outer race is held in place by two heavy circlips and by the interference fit in the case. The inside bearing is a roller bearing an butts tight up to the flywheel. There is about a 5/8" gap between the two bearings and this is take up by a scroll which runs inside of a hardened outer distance piece. The scroll runs with about a half thouclearance to its outer,so it holds some of the oil back, and worms most of the rest back. A little gets thru to lube the ballbearing and this oil then carries on out to the primary.
After awhile the primary gets over full and needs to be drained. This also makes for a high level of oil consumption. By the midfifties Paul Richardson had come up with an after the fact seal housing and seal to deal with the issue. On standard cases the seal carrier gets mounted on the outside face of the ballbearing housing. Hole are drilled and tapped into the face.
In my cse, with much larger than standard mainshafts and bearings, even though these cases are greatly thickened around the mainbearings there wasn't quite enough meat to do this.
I spent quite awhile agonizing over this issue. Finally I came up with something that was quite simple and should work fine.
Here is the area where the seal needs to be
These Molnar cases are about three pounds heavier than original cases. Most of that weight is increased thickness around bearings. With this dim. bearing in a standard case, there would be no wall remaining!
Below the area where the webs are the cases are solid and about 1.25" thick. The cast webs were milled down to get a uniform flat support area for the seal holder. A flange was formed on the holder so that it could attach directly to this thickened up area of the crankcase.
A light tap fit over the housing. This will give backing to the ballbearing which is maybe not necessary, but won't hurt.
The ball bearing locates the crank axially, the rollers take the thrust. The rollers sit in material which is thick and solid right out to the case perimeter.
worntorn wrote:Eddie, thanks for the warning, I'll have a good look at the alternator pulley position when setting up the primary.
This was a first for Bob New by in that he made the primary ratio the same as standard Vincent. In the past he has worked to standard belt lengths which only allowed a ratio somewhat lower than standard Vincent. This time he made up the drive, fitted the components to an old damaged set of Vincent cases he uses for this. The cases are fitted with dummy shafts. With the pulleys mounted he measured the belt length needed and ordered accordingly. He also charged me extra for doing all of that, but the result should be a proper fitting belt and an easier load on the gearbox. I decided to get a spare belt as these will not be something that is readily available.
Next off was to drill and tap screw holes for staking the inner mainbearings to prevent rotation of the outer races. The screws used are coutersunk head type. After the bearing is shrunk into place a Dremel tool was used to grind a very small recess for the edge of the screw head where it protrudes into the bearing race. Pattern blueing is used for this as the recess should be just enough to let the screw tighten down fully without actually touching the bearing. If it binds on the bearing at all it will squeeze the outer race out of round.
Nice attention to detail Glen. More evidence that this will be a cracker when its done! Please do keep us all posted. And I mean step by step, don't just wait till its done. We want the nitty-gritty, step-by-step detail!!
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