Norton crankshaft flange squaring

toppy · Dec 31, 2015

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.

dave M · Dec 31, 2015

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.

gripper · Jan 1, 2016

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.

Stephen Hill · Jan 1, 2016

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

Deets55 · Jan 1, 2016

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.

Fullauto · Jan 1, 2016

The question is, do billet cranks, which should be machined accurately, smoother?

If not, what's the problem?

lcrken · Jan 1, 2016

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

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

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.

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

grandpaul · Jan 2, 2016

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

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

...Nah.

CanukNortonNut · Jan 2, 2016

http://i626.photobucket.com/albums/tt34 ... pfbhf.jpeg
A Stock 750 flywheel crank assembly front view from another post but shows there is no room for the grinding wheel. 750's had the bolt nut arrangement. 850's had Studs and nut arrangement.
Cheers,
Tom
CNN

CanukNortonNut · Jan 2, 2016

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

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.

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

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

lcrken · Jan 2, 2016

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

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

CanukNortonNut · Jan 2, 2016

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

Norton crankshaft flange squaring

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