The Unapproachable Norton Commando

DaveC · Posted: Thu Jun 10, 2004 1:58 am Post subject: Tyre Alingment

Greetings Folks,

Have been happily running Dunlop's K70 on the front and K81 on the rear on Daisy. Seems the rear is a tad out of alingment and has been eaten up rather badly by the 5k miles on it.

Have a new rear on it's way from MAW. Any tips on how to align the rear tyre?

Checked the Workshop Manual and it holds no clues I could find.

bill · Posted: Thu Jun 10, 2004 3:17 am Post subject:

if you have a helper try an 8 foot floresent bulb on both sides. the distance should be the same from frount to rear an both sides.

bill

MichaelB · Joined: 14 Jan 2004 Posts: 446 Location: Yorba Linda, CA

Over the years I've tried bulbs, string, steel rod, conduits and more to align the front and rear to no avail.
I finally settled on this. I welcome feedback. With the Norton 'offsets', there might be something wrong with this thinking. But here goes.

I believe the tires should be in the middle of the frame, front and rear.
I remove the tank, seat, front and rear fenders. Pull a string from the triple tree stem along the backbone along the top of the rear tire. You will then be able to see the alignment of the wheel. Once you align the axle straight, you will be surprised were the wheel is sitting in the frame.
The wheel/tire on my Mark III was off 5/16" to the left!!!

Then I dropped a string with a plumb bob through the center triple tree stem to see were the front was in relation to center. It was off 3/16" to the right, the opposite side of the rear off set. That's 1/2" of total misalignment. No wonder the thing wobbled around and shook it's head.
My Mark III was bone stock right down to the air cleaner and mufflers when I got it. There is no reason to believe the wheels had been messed with. I believe it came that way from the factory.
Note, this is a Mark III with the rotor on the left so the offset was to the right. If I were to switch the wheel around with the rotor on the right, the offsets are both to left making the wheels more in alignment, but off center of the frame 1/4" + or -.

If you look at the rear wheel / fender alignment on most Commando's you will notice the wheel off set to the left. Why is this?? I have a hard time believing that 'NORTON', "The World's Greatest Roadholder", winner of numorous Isle of Man, world renown for there handling would purposely build a motorcycle with wheels off set of center.
I don't know what the factory off set specs are, but I chose to have the wheels corrected to the frame. I took them to Wheel Works, a very respected wheel builder here in SoCal. Gary, the owner, was able to correct the front the 3/16", but could only get 3/16" correction on the rear. Remember it was out 5/16". The hub is now so far off center, he said he would have to redrill the wheel to get the proper angle for the spokes. I chose not to. I had him mount up a fresh set of Avon Venoms and balance them.
I have to say the whole wheel and tire thing was the best thing I ever did to that motorcycle.
Gary has been in business over 25 years and commented that the Norton wheel has been one of the more troublesome ones.

I since acquired two more Commandos, both have the rear wheel out of alignment. Again I ask, WHY IS THIS?????

debby · Joined: 15 Apr 2004 Posts: 898 Location: Boulder, CO

Hmm. Need to check this on my bike. It has a low-speed headshake from 30-40mph and wiggles in raingrooves...

Debby

illf8ed · Joined: 30 Dec 2003 Posts: 474

Hi Debby,

The wiggle from rain grooves is the tire you're using. Original type such as Dunlop K81, the worst, or Avon Roadrunner are bad for this. The newer Avon Super Venom thread pattern has no problems.

Head shake could be stearing bearings if they have gotten dry. Out of aligned front and read wheels will cause "dog tracking" and unusual tire wear. 5,000 miles on a rear tire isn't that bad unless there is an unusual wear pattern.

debby · Joined: 15 Apr 2004 Posts: 898 Location: Boulder, CO

The bike does have K81s front and rear. They're 10 years old so I will need to get new tires soon. Had been wondering what to buy. Super Venoms it shall be!

Could you explain what you mean by dog tracking? I don't think I've heard that phrase before.

Debby

norbsa48503 · Joined: 07 Apr 2004 Posts: 1034 Location: Flint, Michigan

Dog tracking made famous by Nova's. jeep's and many other cars. When the rear is steped out from the front as a happy dog will sometimes do when starting a hunt. Mike at Walridge Cycle told me once that any bike no matter what parts are mixed together should have the front tire centered under the steering bearings if not the bike just won't work right. On Commando's it's common to find the sprocket side of the swing arm bent upward thus tipping the rear wheel and making any alignment imposible. When starting any front to back check put the bike on the center stand or tie it to opposing walls like you would a horse being shoed. Use a plumb bob on the front wheel and adjust the the bikes side to side attitude so that the front wheel is dead plumb. Shimming the center stand with card board works but tieing the bike between walls is best because you don't have the center stand in the way for the latter alignment of the wheels. Now don't move anything and go to the rear wheel and plumb bob that. If it is not the same you have to fix that before you align the rear to the front. Let gravity be your guide.norbsa

MichaelB · Joined: 14 Jan 2004 Posts: 446 Location: Yorba Linda, CA

Norbsa, If I am following you right, you are taking different alignment measurements. The front is the right to left centering of the tire in relation to the fork, the rear is the vertical alignment in relation the frame.
I have seen the poor vertical alignment on Commandos and had concluded it was Iso driven.
This is the first I have heard of the swing arm being a common problem. Makes sense. Do we know if this is problem that develops or is it poor manufacturing specs.

illf8ed · Joined: 30 Dec 2003 Posts: 474

Hi Debbie,

Norbsa is right on the money with the dog track definition.

Regarding the Avon Super Venom tire selection. I'm not at home and don't recall the exact model code I'm using. The rear is a 100/90x19 and the front a 90/90x19. I went with the small tire on the front due to recommendation from others. It's supposed to steer quicker. In fact it does and to my taste steers too quickly. Next time I'm putting the same 100/90x19 on front and back.

norbsa48503 · Joined: 07 Apr 2004 Posts: 1034 Location: Flint, Michigan

MichaelB, The upward bend on the drive side of the swing arm comes from the chain driven forces acting over time. The wheels on a Commando do not dog track from the factory. This is not a Norton thing this is all British bikes that have seen 20 years plus duty. The wheels need to be vertical before they are aligned. You also need to take into account the different tire and rim sizes and shimm out your straight edge to half the distance of the difference if there are different tires front to back and or different rims. You have to check this with straight edges and tape rules ahead of time. Don't assume anything check it out, be as fussy as you can because getting it wrong could cost you dearly. norbsa

DaveC · Posted: Sat Jun 12, 2004 5:20 am Post subject: Tyre Alignment

Worked on the rear a bit yesterday. I have no unusual wear pattern, it shows even wear right down the center of the tire.

I thought 5K for this rear was not so good. I ran Super Venoms before switching to the Dunlop K70/K81 combo with hopes of getting more miles on the tire and would have I think if the rear had not been so far off kilter.

I measured the distance between the edge of the tire and the inside of the swingarm and tried to get the tire centered there. Still am a bit to the right, but the tire tracks much better.

Have not noticed any handling problems up to 90mph, mainly becuase I have not taken Daisy above 90.

Have a new tire enroute. Will do my best to get this one tracking right! Thank you all for the info.

Dwardo · Guest

My Commando has exhibited low speed headshake ever since I rebuilt it completely. Last year I went to a lot of trouble to get the engine cradle straight in the frame by following the instructions in "The World's Straightest Commando" article (I'll try to supply the url to that if anyone hasn't read it). I too believe that the isos are the primary culprit in Commando wheel misalignment. To make a long story short, my wheels are pretty well aligned now and it didn't make a bit of difference in the head shake. Nothing I have done has cured this and I am learning to live with it. It only manifests itself when I have my hands off the bars anyway. I don't know if it did it before, because before I moved the brake caliper to the MK3 position, it would immediately dive to the left when I removed my hands; I think moving the caliper was worthwhile.

norbsa48503 · Joined: 07 Apr 2004 Posts: 1034 Location: Flint, Michigan

Here's a link to that long letter, http://www.vintagenet.com/phantom/wsc.html It's a good read. norbsa

The Unapproachable Norton Commando

At the end of 1967 the Norton Commando was announced.