Pull to the left cured !

Greetings,
Awhile back there was a thread regarding a Nortons pull/veer to the left and someone(?) came up with a suggestion found in some(?) Norton tech article somewhere(?) stating that the cure is swapping fork legs side to side. Well, I tried it and it worked, I can't explain it, but, it worked.
A little history, purchased bike in 2000, it has always had a slight pull to the left (actually bars wanted to turn right, which made bike go left). I had tried straight edges, strings, levels, laser levels, plumb lines from the ceiling, tie-rod headsteady(tilts engine cradle), and purposely mis-aligning rear wheel just to check, ALL did not help.
Swapped forks last week cured the problem, unfortunately had to leave off front fender stay, but, I can live with that.
Maybe it was the weight of the calipher hanging on the right (its no light weight)? Maybe its the added air drag now on the left? Maybe its the reversed offset of the front rim (although, the tire was and still is centered between the forks), I don't know, but, at last I can sit centered on the bike and it goes down the road straight !

GB

Nice that it does a straight line now...but my question would be ... why? No reason, based on the mere fact of putting the caliper on the other side. I'd be more inclined to think something was not correct, that got corrected when you took everything apart and switched the parts around. Maybe you had it misaligned and corrected it when you put it back together. Strange stuff here. I'd have gone with a bad iso, rubbers pushed to one end of the tube inside there. Mine will pull a bit to the side, can't ride too long without a hand on the bars...but I know, or at least think... that is because the rear wheel is not centered in the frame when you view it from the back, a matter of redoing the whole wheel and such, not worth it just to ride without hands. Bet some of the others will have some input here, as to me, there is no logical reason why that should have made such a difference...or am I wrong?

Come on guys! Either back me up, or tell me I don't know what I'm talking about. One way or the other...we will all learn something... :wink:

hewhoistoolazytologin said:

Bet some of the others will have some input here, as to me, there is no logical reason why that should have made such a difference...or am I wrong?

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Fitting the brake on the left-hand side to cure a tendency to pull to the left isn't really a new idea though, (this actually being mentioned in the NOC Service Notes published in 1979). I think the factory was aware of this phenomenon, and it could have been the reason for the changeover to a L/H front disc in the first place on 850 Mk III models (and apparently some late Mk IIs as well -according to various publications?)
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The NOC Service Notes also includes a warning about reversing the R/H brake wheel (hub) as the bearing lock-ring can then be unscrewed by the opposite rotation of the wheel.

The tyre would also need to be changed on the rim so that the correct front tyre rotation direction was used if it applies to the particular tyre type.

I've never seen a pre-Mark 111 with the left hand brake but I did obtain a hub from a late 850 (presumably Mk11) Interpol which had been dismantled for spares and it had the circlip bearing retainer. It did, however lack the machined groove on the opposite side to the disc so once assembled it was visually indistinguishable from the earlier type.

I can't offer a photo in evidence as I machined a groove for my Mk111

It seems certain that a number of "Mk111" components found their way into Mk11 production but I don't suppose we'll ever know exactly what !

Live and learn...but I will have to check mine, I think mine drifts to the right rather than to the left. Only when "no hands" though. How about some counter weight? Or has anyone tried putting an air scoop on the other side to pull the drift straight? Just a thought.

hewhoistoolazytologin said:

Live and learn...but I will have to check mine, I think mine drifts to the right rather than to the left. Only when "no hands" though. How about some counter weight? Or has anyone tried putting an air scoop on the other side to pull the drift straight? Just a thought.

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If Tim Stevens who wrote the NOC Service Notes couldn't explain the reason then it's probably not too obvious. Road camber and tyre wear will also have an effect. I think that an impartial test would have to be done with new tyres on an airfield.

This is splitting hairs but the drum braked models did have an airscoop on the right and I've never heard of them pulling.

I'd be inclined to suspect that it is more to do with inertia around the steering head but putting the caliper in front of the leg is a bit contrary to what we all thought was best practice at the time.

Norvil legs had the caliper at the front on the right. Did that alter anything ? I've never had the pulling left problem. Most bad handling Commandos can't make up their mind which way they want to go

feedback

Hi,
Well, I quess we will have to put this under interesting phenomenon. Thanks L.A.B. for the headsup on the bearing lockring, I'll check on it, although, I can't possibly see how it would ever come unscrewed short of having the wheel bearing seize.
Regarding the tires, I am currently running Dunlop TT100 Roadmasters while, having a non-directional tread design they are marked for front and rear rotation. I have been told that in some instances this has to do with the way the internal carcass is wound. I'm not going to worry about it too much, seeing that the identical rear tire receives torque in both directions due to drive train and braking forces.

GB

Re: feedback

geo46er said:

Dunlop TT100 Roadmasters while, having a non-directional tread design they are marked for front and rear rotation GB

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Different than K81s? Not familiar with Roadmasters... but if you switched my front wheel around, the arrow for front wheel rotation would be pointing towards the back... Must be reason. After going to all the trouble of changing around the fork parts, etc, would seem to me worth the time to set the tire correct...before...you find suddenly out why the manufacturer went to the expense of paying some person the wages to put the arrow on the sidewall... :wink:

Even if the tire has no rotation arrows, I seem to recall being told in a tire shop, that a tire takes on a "set" after running in one direction, and shouldn't be just switched to run the other way....or is this an old wives tale?

Re: feedback

geo46er said:

I have been told that in some instances this has to do with the way the internal carcass is wound.

Click to expand...

Yes, and is the reason for the direction arrows, as most tyres are designed to withstand turning forces in one direction more than the other, the maximum force being transmitted through the front tyre during braking and on the rear when accelerating, so should be fitted the correct way if arrows are shown.

(A tyre fitted with the direction arrow showing the wrong way would get an immediate failure ticket at a UK MOT (yearly road-worthiness inspection test) at least.

Re: feedback

hewhoistoolazytologin said:

Different than K81s? Not familiar with Roadmasters...

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The K81 has always been the 'Dunlop Roadmaster TT100' to give it its full title (should say it on the tyre in big letters?).

Picking up on the lock ring thing, the NOC notes make reference to a replacement lock ring for use when reversing the wheel- no. 066612 but it no longer seems to be listed.

Perhaps punching the edge of the ring or drilling and tapping for a lock screw might be a good idea ?

Don't forget, it's a Norton. If it can come undone, it will

Yup...left pull... :wink:
Yup...Roadmaster.

Pull not bad enough to be distracting, so all is in green. Maybe someday I will worry about it, but not now, still handles wonderfully, so no need to mess with it...best to all of you!