Difference among 750 crankshafts

I note that Norvil lists three different part #'s for 750 crankshafts. One is for Atlas, G15 etc, one is for Atlas plus 750, and 850 and one is for early Commando.
I spoke to Les on the phone inquiring about the difference among these cranks. He told me that the only difference is the balance factor and the orientation of the keyways.
Can anyone verify that this info is correct? I seem to remember that the drive side crankshaft cheek on the Atlas, G15 was different either in overall length or taper length from the Commando.
Also, does anyone know what difference there would be between early Commando and later Commando cranks?

Thanks,
Ed

060571 - Pre-200000 750.

063106 - 200000-on 750 (due to the introduction of the timing-side roller bearing).

http://www.nortonownersclub.org/support ... e-releases

Service Release No. 68
Nature of Release Revised main bearings
Models Affected All years and models of Commando
Distribution Worldwide

Explanation
We are introducing a new roller main bearing arrangement in production almost immediately. The fitting of this bearing arrangement reduces overall width between the main bearings and increases timing side main bearing journal diameter.

For service purposes we shall in future supply only the crankshaft of the latest size, Part No. 063106.

Click to expand...

064254 - 850 Mk 1 & 2.

065660 - 850 Mk3.

To memory (I'm sure others will chime in with any corrections), the Atlas, G15/N15, and P11 cranks are the same and differ from 750 Commando cranks in not only balance factor, but the drive side (primary) has a shorter length and different taper due to the three row primary sprocket on the Commando. The '73-'74 850 Commando crank would have a slightly different balance than the 750 due to increased bore (I suspect). The electric start 850 crank has a different drive side (primary) than the earlier 850 cranks and I believe is a little wider.

Thank you for the replies.

L.A.B.- Do I understand correctly from your reply that the pre-200000 Commando cranks are not suitable for the timing side roller bearing upgrade (superblend or otherwise)?

Ron-Your memory agrees with mine.

Can anyone else offer their knowledge?

Thanks,
Ed

APRRSV said:

L.A.B.- Do I understand correctly from your reply that the pre-200000 Commando cranks are not suitable for the timing side roller bearing upgrade (superblend or otherwise)?

Click to expand...

No, I don't think so.

Edit
http://www.nortonownersclub.org/support ... e-releases
Service Release No. N2/9 ('Superblend')
.
.
.

Note: The new bearings may also be fitted to advantage to 1971 and earlier Commando machines, provided care is taken fitting the inner spool to the right side crankshaft journal (was 1.1807in. - 1.1812in.) diameter, now 1.1812in. - 1.1815in. diameter. Also crankshaft fitted end float should be checked, and shimmed where necessary to provide 0.010in. min. 0.020in. max. end float using shim part number NMT2196A as necessary.

Click to expand...

Hi All,
I agree with Les.
The cranckshaft lenght, both side, is absolutly the same for all; i have used for all FAG roller superblend.
The only differences could be the factory balance and surely that Atlas/G15/N15/P11 have the cranckshaft drive side keys rotate.
Agree with Ron about 850 ES cranckshaft more widht (but same lenght).
Ciao
Piero

Atlas -At TDC... sprocket key is 3 oclock alternator key is about 1 oclock... flywheel 23316, RH side bearing 1.1807-1.1812
750 commando -At TDC... sprocket key is 3 oclock alternator key is about 7 oclock... flywheel 06-0732, RH side bearing 1.1807-1.1812
After 1971/200000+ 750 commando -At TDC... sprocket key is 3 oclock alternator key is about 7 oclock... flywheel 06-0732, RH side bearing 1.1812-1.1815
all are same taper and length and thread
service release no N2/9 says all early cranks can use late bearing (ie superblend)
However I am not 100% sure when the flywheel(casting 06-0732)(pn06-0731) changed from 23316, I'd have to rip down an engine or two to confirm :?:

I have no problem removing fag or ntn bearings from the cranks since I use a good bearing puller such as OTC 1122. It is very obvious from observed physical damage that hacks use all sorts of chisels hammers and other destructive and damaging devices to remove bearings. :shock:

Pre-200000 Commando cranks are OK for Superblend bearing upgrade. I have installed on my 1970 commando.

Thank you Piero, Dave and Baldy.

Ed

Interesting . . . .