Misc: Everything Else 1951 Black Shadow Restoration

Cyborg

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Put that G3 between centres (if you can or get someone to check it) with the C20/1 nut on. Check the runout o the C20/1. You could end up with a wobbly clutch shoe assembly and drive yourself mad trying to find the source.
 

greg brillus

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Craig, the cases look in excellent condition, you are lucky there......it is nice to measure the bearing housings if you can, especially the crank mains, these are the ones that go oversize. With the old stake punch marks, have a close look at them......I generally try and leave them alone, but it does no harm to use a small dremel barrel/drum sander and just very lightly chamfer the edges where the original punch marks are......In fact it does no great harm to lightly chamfer the complete hole as this helps the bearing start in the bore........Just a quick run down.......In order of assembly you should fit the small ring of the ET 94 outer main bearing first.......Clean up the oil pump bore with a 1" parallel reamer.......Then the oil pump sleeve should be next.......Then install the 2 gearbox bearings.......then the large outer ring of the ET 92 main bearing, then do the spindles last.......I do tend to still stake the new bearings in place or else they will fall out once you flip the case half over to install the spindles.........Get the ET 94 outer race and the oil pump sleeve out of the way first, then all the other parts can be done one after another with the case half heated up in an electric oven...........Do this at 170/180 degrees Celsius and no more........If the bearings have the normal 1 to 1.5 thou interference then they should install quite easily........It is quite common for the ET 94 ring to collapse a bit too much and fitting the inner race seems too tight.......The ring will then need to be honed out by your local engine reco shop, this bearing should not be tight........I've had some that the crank had to be pressed out due to the bearing being to tight.........There is too much to list, so we will discuss as you progress along with it. Cheers.......
 

oexing

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In ideal life the outer races in an engine alu case should stiill be gripped at around 100 degrees, else they would walk and bores will be oversize in time. So with a cold engine the outer race will be clamped one or two thou and internal play in the bearing will be nil. So for assembling the engine just heat it to 50-60 degrees C and all will be loose enough for slipping in place. I don´t care about minimal tightness in bearings at cold - you cannot run an engine with a cold case for more than a few minutes, it will heat up and at normal running condition you get standard play in all bearings. This is just something you have to keep in mind when having a material mix of alu and steel and changing temperatures.
As to preload on bearings: The Velocette and some HDs have Timken bearings for mains, so in these cases you set them with a certain preload when cold. Otherwise you´d get a lot of play when the alu case expands with heat.

Vic
 

greg brillus

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I think some of the modern replacement bearings have different specs to the original brass caged ones, the outer bearing race seems to be thinner and has large radius on the outer edges.......perhaps on a small bearing like the ET 94 the interference fit is too much for the bearing........It has happened to me on several bearings so it must be a common issue........I just take the right side case with the new bearing installed and get the boys to hone the outer race until the inner slips in nice and easy. Some similar bearings have a much thicker walled outer race, but this becomes a problem when you try to fit the oil pump worm gear.......it wont pass through the ID of the new bearing........Not so good.
 

oexing

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The honing bodge can only be done with the old type bearings with plain outer race I guess, no lips types. I knew from the beginning that I would never use them so got roller bearings with PA 66 cages and rollers contained in outer races, plain inner race, one with one lip , one plain. Simple to install and on timing side I had to drop in the pump worm before fitting the inner bearing outer race with rollers as it would not pass through. But was no big thing to assemble like that. As I said, get the engine cases hot and all should be well. I´d think when you do the honing in cold state the play at running conditions will be more than it needs.

Vic
 

craig

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Looking at missing pieces at the G50 plate. This project was missing quite a few. Several have been ordered and placed for fitment. I forgot to order the studs in this G50 plate for shifting and KS spring.

20210112_MissingGPieces.jpg
 

greg brillus

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Just some points of interest whilst you have that picture on there........Those studs you mention, screw them in with some loctite.......They are in there pretty much permanently so no need to remove again.......The rear of the G59 AS near the large rivet.......You might need to linish a small amount off the end so it does not hit the G 49 lever stop housing as it sweeps past on every shift. If you use the valve stem seal type of valve lifter ferrule screwed into the rear upper corner of the timing chest, you often need to linish off a bevel at the top right corner of the G 50 plate to give the hollow tube/cable abutment room to fit without the parts clashing, about the same area as where the clutch cable hole is at the top.......from there forward, and on the inner side mostly.......another tip.......If you have all the crankcase though studs, it is a good idea to pass them through the cases to work out and label which ones go where.......The lower forward ones pass through the prop stand plates so you need to make allowances for that.......The studs can sometimes be too long, so it pays to trim them down, the excess threads overhanging the nuts looks a bit ugly. The ones that pass within the primary that hold the gearbox together, you can mark them with numbers alongside the holes and on each stud. The 2 in your pic at 7:00 o' clock are the two longest ones. The studs passing from the primary to the right side, and the 2 or 3 within the timing chest should have a generous smear of sealant under the fixed nuts that anchor into the case holes......this is very important if you want to minimize leaks, especially off the bottom front corner of the kick start cover. Oil will migrate along the studs from the primary and the same within the timing chest......oil can seep along the stud holes and show on the opposite side at some stage.........very annoying, and difficult to fix once its all together........This is where modern sealants are far superior to those available years ago..........Cheers.
 

craig

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Looking my gear box parts over, I decided that there were too many wear and fit problems.
I ordered new G3, G4, G6 , G18.
Came in today, all issues solved.
New shaft ends slide thru bearings, too much wear on G3 small end, so sloppy on new bush in G4. New G3/G4 fit is perfect.

20210113_NewG3G4G6aa.jpg
 
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