Norton crankshaft flange squaring

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As I understand it to increase the mass of the flywheel in the areas required (bob weights where I come from) as the engine capacity increased they became wider.
 
A standard 750 crankshaft cannot be ground while assembled, the flywheel is in the way on all standard Commandos and I beleve any 750 engine whether Atas, P11, N15.
 
After my anti wet-sumping valve failure and subsequent big end seize, I had the big ends ground on my 750 with it all bolted up including the flywheel. The grinding wheel did remove metal from the edge of the flywheel (not much) but I do have the 0.090" radius. I did not want to go through the splitting crank issue again with the cost of another crank fixing kit. The bottom end had only done 3000miles since the previous build so sludge build up was not an issue. Copious flushing after grinding was good enough for me.
 
Okay, sounds like the crankshaft components were turned and ground prior to assembly.
Three components, four faces, eighteen holes, six bolts, aligning four journals.
Multiple setups, fixtures to achieve concentricity, machined with clapped out equipment.
Doesn't sound very promising, IMHO.

Back to Madass's question: "Skip, maybe your crankshaft man can enlighten us on how much Norton cranks run untrue".

Anybody else spent quality time with a stock crankshaft (not reground or split), a pair of knife edges and some accurate dial indicators?

Stephen Hill
 
Is it possible that the rod journals were ground, then the crank was assembled and then the bearing journals were ground at the factory. That way at least the crank was straight through the cases and the misalingment, if any, was in the rods? Not saying this was a good system but probably better than having the entire crank out of wack.
 
The question is, do billet cranks, which should be machined accurately, smoother?

If not, what's the problem?
 
Stephen Hill said:
Anybody else spent quality time with a stock crankshaft (not reground or split), a pair of knife edges and some accurate dial indicators?

Stephen Hill
Click to expand...

I can offer some data, but not a lot. I've checked a couple of stock Norton crankshafts, and some aftermarket cranks for mainshaft runout with this setup

Norton crankshaft flange squaring


The stock crankshafts and a Falicon billet crank were all .001" or less runout on both drive and timing sides. A new Maney crank was a little under .002" out.

I've used this setup to measure rod journal indexing, and a similar arrangement for checking stroke variations.

Norton crankshaft flange squaring


Unfortunately, I've not done that for a stock crankshaft, so can't give you any numbers. On the billet cranks I've measured, they are typically within .001" or less variation.

Ken
 
SkipSchloss said:
I now realize that the tradition on the forum is to list one's bikes below the sig line.
Click to expand...

Mine would be too long to fit on one screen. Maybe just the (6) Nortons...

...Nah.
 
lcrken said:
Stephen Hill said:
Anybody else spent quality time with a stock crankshaft (not reground or split), a pair of knife edges and some accurate dial indicators?

Stephen Hill
Click to expand...

I can offer some data, but not a lot. I've checked a couple of stock Norton crankshafts, and some aftermarket cranks for mainshaft runout with this setup

Norton crankshaft flange squaring


The stock crankshafts and a Falicon billet crank were all .001" or less runout on both drive and timing sides. A new Maney crank was a little under .002" out.

I've used this setup to measure rod journal indexing, and a similar arrangement for checking stroke variations.

Norton crankshaft flange squaring


Unfortunately, I've not done that for a stock crankshaft, so can't give you any numbers. On the billet cranks I've measured, they are typically within .001" or less variation.

Ken
Click to expand...
Ken what were your findings on the journals between each pair? I am curious for stock setups. My P11 crank shows 0.0025" thou difference between the pair @ TDC. My setup is very similar to your surface plate/123 block dial indicator.
Cheers,
Tom
CNN
 
CanukNortonNut said:
[Ken what were your findings on the journals between each pair? I am curious for stock setups. My P11 crank shows 0.0025" thou difference between the pair @ TDC. My setup is very similar to your surface plate/123 block dial indicator.
Cheers,
Tom
CNN
Click to expand...

Unfortunately, I've not done that for a stock crankshaft, so can't give you any numbers. On the billet cranks I've measured, they are typically within .001" or less variation.

Ken
 
Thanks Ken,
How about anyone else???? There is a lot of engine re builders out there in Access Norton Land. Does anyone else care to check?
Cheers,
Tom
CNN
 
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