Why did Norton switch front rotor sides?

hobot wrote
Yes balancing out L/R brake forces is the common lore but I don't believe its a factor - just lore.

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Well Norton certainly did, there's a reference to it in the NOC service notes c/w electric start 1979, text by none other than Tim Stevens and John Hudson.

Cash

Appreciate the feedback Mylar and the devoted attention to Cdo flying ease. The question is merely winter bored academic to me, as once I spiffed up my two Combat they did not drift or wobble till going rather slow towards an intersection or stop. In searching reports of compensating for drift, even with hands on, the vast majority report drift left and all were d/t to some fault that others did not have on same type bikes and no drift complaints, Harleys' to sports bikes.

Cash I have the Service Notes but skipped 850 issues as I'm a 750 only dude. Do they explain why the switch? On this note I bet if the rotor had significant less mass it would be less issue on which side its mounted. I'm stuck with RH rotors on my Combats and do get a slight slow delayed LH drift that easy to compensate for hands off, but its about same on my dual rotor rigid frame SV650. So I thought its more universal innate road crown tire inter face issue than brake spin pushing it.

hobot said:

Every cycle I've ridden in N America drifts more or less hands off up the road crown to the left. There is some difference between bias vs radial tires whether it seeks more to climb a crown or tends to run down off it. Related to principle of flat belt drives and crowned pulley rim. Meaningless mystery for snowed in day off. Most known they had to reverse thread the rotor side's bearing retainer ring or circlip it but why bother after Combat bombs almost sunk Norton by that time?

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They reduced cost by eliminating one mudguard brace. Probably more truth in this than any other reason.

illf8ed said:

They reduced cost by eliminating one mudguard brace. Probably more truth in this than any other reason.

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Any truth to the rumour that you can't actually fit the front mudguard brace with the caliper fitted on the left side ?

The cost saving may have been somewhat accidental ??

JimC said:

I was guessing the lugs were cast symmetrically and could be machined from the either side. I haven't looked, ,.

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Apart from the heavy rib for the caliper not quite being central, and the axle mounting arrangements not being reversible, there is also the minor matter that the lugs on the slider for the mudguard brace rods would then be on the inside, near the wheel.

And the studs for the mudguard U-shape fork brace would on the outside, tricky !!

Always worth a look to check things are feasible. Maybe thats where Umberslade Hall got its reputation ? !! (Not that Umberslade Hall had anything to do with Nortons...)

Since no one has an answer to this .. think about weight distribution on the new Mk 111 model . The starter motor attaches to the primary ,very heavy ,all left side weight ,starter reduction gearage n' more stuff. Move the front brake to left side to join up with new rear brake assembly weight to create a more balanced overall weight on the vehicle ? Just a thought.

They reduced cost by eliminating one mudguard brace. Probably more truth in this than any other reason.

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Knowing Norton priorities near the end you really had me going with your reasoning till I realized they could of just removed the front fender brace and left the caliper on the RH.

To nullify the 850 LH mass bias - moving brake to the LH makes even less snese.

My guess is a fork order got mixed since past makers likely would no longer take Norton credit, so to save their production they diddled a lower cost solution to use what they had. I think that's why Norton forks came limited to 4" travel, they had so many of shorter springs to use up.

Mystery remains.

OK i read the 'why caliper in front or back of forks.
i now offer up a new theory of why Norton bothered to switch sides. The 850 was so stable sluggish steering compared to the 750 they moved mass ahead of steering center to help it turn by less pilot effort. Opposite of below. Open to counter points of my 'reasoning'. Someone switch caliper mounts on 850 stem angle, fork offset to RH and get back.

The reason 1970's California riders started moving the calipers behind
the fork legs was to *reduce the mass ahead of the steering pivot*.

The forks supposedly won't waggle and hunt so much when disturbed by a
bump while you're leaned over, but it's an almost imperceptible
difference that only an engineering type would notice.

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I would have thought any savings by removing stays etc would have been lost in the modifications to the front wheel bearing locking system.

And, the reason why Norton retained the 4.5" fork travel was due to a couple of sliders snapping back in 1966 or 67. This story has been well covered on this site with some great photos showing how the extra travel brings the fork bushes too close together resulting in a loss of slider support. Basically the Roadholder sliders are too short to accomodate any extra travel.

Cash

And, the reason why Norton retained the 4.5" fork travel was due to a couple of sliders snapping back in 1966 or 67. This story has been well covered on this site with some great photos showing how the extra travel brings the fork bushes too close together resulting in a loss of slider support. Basically the Roadholder sliders are too short to accomodate any extra travel. Cash

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I would much like to be educated by your '67 fork fracture reference. I've hit stuff and deep hole at 50 mph in pasture and unpaved paths and threw bike and me up high with a teeth slamming shock through forks but didn't fracture or bend them. They just instantly compressed to over lap again on next loading. There are many using my extended fork via spring spacers and not bad reports I know of so far. I really doubt any have tested as harsh as me and even I wouldn't of tested that hard on purpose, ugh.

Again best sense I glean for the switch was to -unstablizie the fork so less effort to steer. It cost extra to switch must of been a good reason. But maybe not so mystery remains to me.