When Norton flipped the Mk2 disc to the left side (317xxx)...

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Jdub

Jdub

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Did they also change the hub in any way to prevent unscrewing or similar? I understand the Mk3 had a redesigned hub identified by a shallow groove, and have read concerns about unscrewing the threaded cap if you flip a Mk2 from right to leftside, front of slider.

Hope this makes sense. I just acquired a Mk2 built after the shift and am pondering my options. Pictures to come.

John
 
Jdub said:
I just acquired a Mk2 built after the shift and am pondering my options.
Click to expand...

Can you be absolutely sure it came from the factory that way and wasn't done by a previous owner?
 
No, I cannot be sure, but am reading this change occurred in the later 317xxx series in the appendix of The Norton Commando Bible by Peter Henshaw. Frankly I prefer the shorter brake line, and more elegant tuck-in of the "behind the right slider" look. I am not a stickler on accuracy but did want to ask the experts here. Thank you all for your responses!
 
L.A.B. said:
Can you be absolutely sure it came from the factory that way and wasn't done by a previous owner?
Click to expand...

I agree. My Mk 11 850 is 319XXX built July August 1974 and it is definitely original right hand side. In 30 plus years of Commando ownership and reading I have never once heard of an original Mk 11 with a left hand disc.
 
Jdub said:
No, I cannot be sure, but am reading this change occurred in the later 317xxx series in the appendix of The Norton Commando Bible by Peter Henshaw. Frankly I prefer the shorter brake line, and more elegant tuck-in of the "behind the right slider" look. I am not a stickler on accuracy but did want to ask the experts here. Thank you all for your responses!
Click to expand...

Mmmmm. Mr Henshaw does seem to have a good CV for bike knowledge but this change date would be a new one for me. And definitely not correct for my bike and every other Mk 11 I have ever seen.
 
Jdub said:
No, I cannot be sure, but am reading this change occurred in the later 317xxx series in the appendix of The Norton Commando Bible by Peter Henshaw.
Click to expand...

There have been a few reports that late Mk2/2As had the disc on the left, which Peter Henshaw has apparently copied from a previous Norton publication (as well as a few other errors!), however, I'm not sure how accurate that original information is, and some other 'facts' in his bible are certainly inaccurate or at least questionable.

Moving the brake would require more than just a change of hub as the front mudguard stay cannot be fitted with the caliper on the left, also the brake hose, rigid pipe and bracket would need to be changed for 'Mk3' items or it would look odd.
The spoke pattern is also different between RH and LH disc wheels so a reversed RH disc wheel isn't too difficult to spot although it's not unusual for the complete front end to have been replaced with a later assembly due to accident damage etc.

Eddie Lawson's straight from the crate '317998' Mk2 with RH disc.
https://www.bonhams.com/auctions/20469/lot/345/

When Norton flipped the Mk2 disc to the left side (317xxx)...
 
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Re; “Eddie Lawson's straight from the crate '317998' Mk2 with RH disc.”

A small comment, Disc on R.H. side has probably got r.h. threaded bolts holding it on these are liable to come loose if no locking paste on threads is used, this could be the reason why they changed to the L.H. side?
 
All disc brake models from 1972 on had right hand thread nuts (not bolts) and studs on the hub to secure the disc. While threadlocker is not a bad idea, there are spring lock washers under the nuts. I have never seen or heard of these loosening.

There was a concern of using a pre-75 hub on the left side brake due to the bearing lock ring being right hand thread, but personally I cannot see how this could occur as the axle spindle and fork legs would prevent this from loosening.
 
Bernhard said:
A small comment, Disc on R.H. side has probably got r.h. threaded bolts holding it on these are liable to come loose if no locking paste on threads is used, this could be the reason why they changed to the L.H. side?
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For bearing lock rings yes, otherwise that seems to make no sense.
 
Well Eddie's bike is only a few cups of coffee on the assembly line from my 317982 Roadster project. Small world! Thanks for everyone's input on this topic.
 
that's to funny. if that's the case than why don't the right hand wheels fall off of every car on the road.

Bernhard said:
Re; “Eddie Lawson's straight from the crate '317998' Mk2 with RH disc.”

A small comment, Disc on R.H. side has probably got r.h. threaded bolts holding it on these are liable to come loose if no locking paste on threads is used, this could be the reason why they changed to the L.H. side?
Click to expand...
 
My mk 11A ex interpol had the disc on the left when I got it, it had extra holes in the holes to I assume accommodate the pipework. I've changed it to the right.
 
They would be really hard to see! :)

I've been told that the reason Norton shifted the disc to the left side was to eliminate the bikes tendency to drift to the left with hands off the bars. Why anyone would ride without hands on the bars is a different question. But a friend who changed his norton front disc from right to left said that it DID eliminate the left drift. As far as I know, he didn't do anything other than just move the existing parts from right to left and add a longer brake line.
 
Yes I’ve heard that as well Mike, and whilst I can’t disputed it with any evidence, the logic of it does not make any sense to me.

Does anyone really know if it’s true...and if so, why ?
 
MexicoMike said:
I've been told that the reason Norton shifted the disc to the left side was to eliminate the bikes tendency to drift to the left with hands off the bars.
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According to the NOC Commando Service Notes this was more than a "hands off" problem.
 
I swapped the left side brake on my mk.3 over to the right side and it developed the drift to the left,so I swapped it right back and the drift went away.
However my other mk.3 is perfectly fine with the brake swapped over to the right side.
No difference in the bikes , so who knows why ?
sam
 
bill said:
that's to funny. if that's the case than why don't the right hand wheels fall off of every car on the road.
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Further research appears to show older vehicles could have handed wheel nuts, but with left-hand thread used on the left-hand side.
Whether a disc would be affected I somehow doubt as I'm not aware of any reports of disc nuts slackening in service whichever side it is on then it would have been on the correct (RH) side from the beginning.

https://www.eng-tips.com/viewthread.cfm?qid=279674

https://www.cokertire.com/o-e-chrysler-lugs-left-hand.html
 
yea i remember the good ol days.chrysler was one of the users of left hand lug nuts on the left side and even had an L on the stud. also some large trucks. and guess what? the wheels on the left did not have a habit of falling off either.

L.A.B. said:
Further research appears to show older vehicles could have handed wheel nuts, but with left-hand thread used on the left-hand side.
Whether a disc would be affected I somehow doubt as I'm not aware of any reports of disc nuts slackening in service whichever side it is on then it would have been on the correct (RH) side from the beginning.
https://www.eng-tips.com/viewthread.cfm?qid=279674

https://www.cokertire.com/o-e-chrysler-lugs-left-hand.html
Click to expand...
 
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