Crankshaft End Play

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ctsbc

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I am currently rebuilding two Mk 111 850 Commandos and wish feedback on the need to shim the Crankshaft or to let the end play remain free. One assumes that the same question could be asked about the Camshaft. Any comments?

Thanks

Tom
 
Hi
Since I am sitting here recovering from knee surgery I took some time to look this up and confirm the facts for myself.
Norton Factory manual pre MKIII permissible end float is 0.005" to 0.015"
Fred Eaton call out 0.005" to 0.010" for where to start.These loosen of course when the engine warms up.
The International Norton owers tech digest calls out 0.010" to 0.024" when fitting superblends to older cranks including Atlas.
This link is from an earlier thread I found on google.
crank-end-float-t966.html

FWIW
 
The camshaft endplay will be controlled by the sprocket and timing side bushings once assembled. No shimming needed.

The crankshaft should be shimmed to obtain end play around .007 inch by using shims behind the outer races in the case. About .004 to .015 is acceptable. You can cut the shims from brass shim stock with a pair of scissors. Jim
 
Thanks Norton46

I guess there are no end of answers -- just need to know where to look.
Next question --does it matter which bearing takes the shim, timing or drive side?

Tom
 
I usually try to split it between both sides. It is not critical. Jim
 
Did that change from the 750s ? I remember (or think I do) a shim that fit between the bearing and the crank.

Greg
 
I think someone came out with the outer race shims because it was easier to heat out the outer race from the case than pull the inner race from the crank. Old Britts sells shim kits (both inner and outer I think) for $20 if you don't want to cut them out yourself.

Dave
69S
 
Tom
I would split it as much as possible.
I like fitting them between the flywheel and the inner race. This can be done a couple ways but fitting them here is more difficult , what I do if I don't know where to start is to fit some loose inner races (grind old ones) and do a test fit up and then once I have the number and size of shims fit them and install the real set of inner races. Also you may want to grind some bevels on the back side of the new inner race to allow a removal tool to be fit easier for the next removal. Mick Hemming recommends this.
I like doing this instead of putting them between the bearing and the case. One reason is you have to heat and fit, maybe multiple times and then the bearing is not set as deep in the case. Should never be an issue but just my preference.

Are the engines disassembled right now? Have you had a chance to measure the end float?
 
ctsbc said:
Thanks Norton46

I guess there are no end of answers -- just need to know where to look.
Next question --does it matter which bearing takes the shim, timing or drive side?

Tom
Click to expand...
I have heard that the timing side is easier and that is what I did. I also bought shim stock and cut out my own. Cuts with a scizzors.
 
Two reasons you don't want to shim on the crank.

First is to cut down on how many times you push the bearing on and pull it off the crankshaft. Each time takes a little metal and eventually the interference fit will no longer exist. No metal is lost in the case as you heat it until the bearing falls in or out.

Second reason applies to the drive side only. I have seen several instances where the shim got loose in between the crank and inner bearing race because there is nothing to keep the bearing snug against the shim. If the shim is hard metal it will spin freely on the shaft and cut a groove in the shaft which will lead to breaking the shaft off.

If the shim is soft metal it will wear through the shim and eventually come out and can get caught where it shouldn't be.

On the timing side the bearing is held tightly against the shim by the torque on the oil pump drive worm and I have not seen one come loose there. Jim,
 
Jim
I had not seen where the drive side comes loose. What you state makes good sense. Usually you have a heck of a time getting the inner race off.
It would seem reasonable then to employ some of both methods should one need to as long as the crank shimming is done on the timing side.
 
Heating up the timing side case involves possibly dropping out the idler spindle, then you are fumbling with extra parts that are hot instead of just the case and the race.
 
I respect the advice of shimming for "proper end float" of the previous posts. If I was to use (2) "superblend" NJ306E main bearings, I would shim for the end float the way comnoz recommends. (Someone correct me if I'm wrong, but to my "limited Norton knowledge", Norton didn't bother shimming the crankshaft end play on production bikes anyway.) Be that as it may, here is my 2-cents. I put the "superblend" NJ306E main bearing (brass cage only please) on the drive side. I then put the hi capacity ball (that Matt sells at CNW) on the timing side. Guess what ... no fartin' around with end float shimming then ! :D I've since done three Norton motors this way now, and will stick with it. If it's good enough for Matt at CNW; it's DEFINITELY good enough for me !!! Cheers.
 
I too would have used the ball on the timing side so as not to have to shim, if I knew what I do now.

Dave
69S
 
I always use superblends on both sides. They have a pretty much unlimited lifespan in a Norton. Last time I was talking to Matt he had gone to dual superblends also. Jim
 
In my experience, a bit of care is needed when shimming a MkIII 850. On earlier versions, the drive side oil seal sits against a shoulder outside of the bearing and assuming identical seal dimensions, the oil seal lip location is not variable.

On the MkIII, Nortons decided that a wire clip was needed to retain the seal. I don't have a problem with that but in their wisdom they deleted the shoulder which means that in order to keep the seal square, it is necessary to feed the clip in behind it until it just seats.

I've seen several forms of oil seal and most have quite a rounded edge which means, combined with the thin wire clip that the outer face can sit 'quite a bit' * further out than might be expected, to the extent that the lip can come very close to the drive sprocket key-way or even run onto it.

Provided I can satisfy myself that the rods are sitting central to the cylinders (not that I'm really competent to measure this sort of thing, but I feel that I ought to go through the motions and try) then my preference is to shim the timing side and therefore push the drive side crank nose as far through the seal as possible.



*technical term used by non-engineers :)
 
Hi at least somebody who is aware of the "Iso system" : the "bit" , forgot to mention the "little bit" which is a tenth of the predecessor, then the "tiny bit "which is a tenth of a tenth of its glorious father and the "quite nothing " sometimes called (little little bit) which is a thou of a "bit"............i am too with 79x100 a proud member of that confraternity, who is not affraid to approach the engineers and asking them to turn down the piece of metal " a little bit"........
 
I am doing my 69S crank now. I have installed two FAG superblends, and have .5mm or nearly .020 float. I ordered both inner and outer shim kits, and as I can't get the inner races off of the crank I'm leaning towards shimming the case side.

The kit I ordered from Old Brits only has one of each size .002", .005", .008", .010" and .015". From my calculations .010 would be me at just under 10 thousandths. Two fives, one on each side would be ideal it seems. Any recomendations on what size shims and where?

Thanks in advance, Davo
 
davomoto said:
I am doing my 69S crank now. I have installed two FAG superblends, and have .5mm or nearly .020 float. I ordered both inner and outer shim kits, and as I can't get the inner races off of the crank I'm leaning towards shimming the case side.

The kit I ordered from Old Brits only has one of each size .002", .005", .008", .010" and .015". From my calculations .010 would be me at just under 10 thousandths. Two fives, one on each side would be ideal it seems. Any recomendations on what size shims and where?

Thanks in advance, Davo
Click to expand...

More qualified people will hopefully be along any moment... but in the meantime, my own comments would be to leave it be, .020" is fine.
 
Im the guy that has the relentless small leak on the DS oil seal on the crank. This is apart now
so I can try to ascertain what the heck is going on. I put a straight edge across the face of
the crankcase and the keyway on the crank protrudes into the seal housing bore. Not enough
to clip the seal lip but it is close. In fact I have a new AN rubber sided seal and it seems to have
two lips, one on the outboard side. The keyway would definitely clip this if used. Used a
older metal edge single lip type instead.
My point is this: I shimmed the crank equal amounts on both sides never thought to check the
seal area. Maybe if you are shimming, best to shift the crank to the DS and move the keyway
away from the seal.
I still see no evidence that the seal was damaged in any way but Ive changed it out twice
(Im now on the third) and the leak remains.
Just a thought.
 
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