Weave at speed on '68 mk 1

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Or wait until early November, then you can set fire to it on Bonfire Night :mrgreen:

We still don't have enough information. Did you have the weave before you rebuilt the bike? How old are the tyres and how worn are they? Just because they look OK doesn't mean they are. If you change the rear to an Avon Roadrider, you then have matched tyres and even if that's not the problem, you then have a spare when the other wears out. Are all the spokes nice and tight? Do you have an old type steering damper, which can make the steering feel odd? What is the fully extended length of the Maxton rear shocks centre-to-centre and is this the same as the standard Commando's? I think it's 12.9 inches but someone on the forum will know the figure. You say the weave gets worse when you lean forward, so try reducing the static sag on the front and increase the sag on the rear.
 
hi, matchless, my recent wobble was due to my headsteady. I have a vernier-style, and recently found it to have loosened up. After tightening, wobble was gone. I know your setup is different, but it just illustrates that movement at the head can get transmitted to the rear end. That seems to be what your forward/backward experiment points to: when you unload the rear end, it's free to shake more, and when you load the rear end, the shaking decreases. You alluded to tightening the isos, but have you tried really locking down the head too for a brief ride? Not sure how that would be done with the rod headsteady...
 
Swoosh maybe he should pull the tank and inspect for early frame crackage but don't know where this would occur,steering head upper ?
 
" A good Boy Scout , is allways prepared . "

" Drove past the pier this evening . It looked tempting. "

Exactly WHERE is this PIER , anyway. If you dont mind . :D :P

Mk 1 750 ? ? ? the ancient headlamp Ear Type ?

Weave at speed on '68 mk 1


or the wee tinny ear type ?

Weave at speed on '68 mk 1


The Early are apparently about the same Trail as the 850 ANYWAY . My ISOs liked 2 1/2 thou to 4 1/2 thou . at 5 ' the hinge ' ( a bit of slack )
was discernable on changes in trajectory .

ok , 68 Mk 1 infers first type . The Dreaded ' tram lineing ' or following road irregularities when the suspensions tight on ' peaky ' ( Triangular ) tyres
isnt entirely abnormal . Transformed by fitting ( the original type ) roadrunners , which are of a dissimilar cross section . V much more relaxed .

Try swaping wheels ( TYRES ) with your localNorton Neighbour to see if theyre incompatable ( those fitted ) . Original Front is 3.00 - 19 .
Haveing fitted a larger front , you WILL have raised the Front , and INCREASED the rake & trail ( Castor ) . which is what you want . :?

NOW , where was that pier again ? :P :| :mrgreen:
 
I have a semi compliant tri-linked Commando that takes all the guessing out of what and where Every Influence is coming from and doing - so able to apply those road life changing insights for normal un-linked Commando, so I repeat for what its worth or before you commit Cdo murder-Sacrifice > The end that causing trouble will cause less trouble when unloaded and more trouble loaded>

Some thing is too loose and or something is too tight or something is out of shape compared to its mate from ground up.
 
He should go tearing round a paddock / clay pan or Dirt Road , to get the feel of the thing a where its wotsits not sitting wright . :mrgreen:

Cant be too serious ALL the TIME . Get it out and go for it somewhere demanding at slower speeds .Or let a 20 year old lunatic loose on it
to suss the irregularity .
 
Matt,
Its really quite obvious where the pier is.....It's in the sea! The trail of the early bikes is approx. 4.2" & the very late 750s & all 850s is approx. 4.5". My 850 mk2a does feel totally different to the problem bike; much more stable & slower steering. Rather like the Queen Mary compared to a Riva speed boat.
As I mentioned in my first post the frame is neither bent nor cracked & I have tried various tyres all to no avail. This weekend I will fit an 850 headsteady & an old pair of Koni shocks. If this fails I may invest in a solid lead garden gnome to put on the back seat .
 
Matchless said:
If this fails I may invest in a solid lead garden gnome to put on the back seat.
Click to expand...

Certainly tongue-in-cheek statement above but it would be treating the symptom, not the cause and certainly counter to where a well sorted out bike should balance to.
 
Is the weave PIO (pilot induced oscillation) ? If you take one hand off the bars at weave speed, does it get any better? (big kahunas required) is your riding jacket flapping from left to right and tugging on the bars? How much do you weigh?
I've got a 70 fastback (same yolks as you) and it weaves above 80 but not two up. I've done most of the good mods including a rod end head steady. I have just spent some considerable time and effort to sort my wheel alignment out and after re-assembling my rebuild, discovered the wheels were still 12mm out of line. Ever seen a grown man cry? The problem is the headstock is not straight so the wheels are out of line in the vertical plane. There is no apparent damage to the frame and I've been struggling to line my wheels up for 37 years. I'm well pissed off as I've just had it powder coated. I reckon it came out of the factory like that.
The problem is, the rest of the Commando frame is so flimsy I don't think it is feasable to straighten the headstock without cutting it off and welding it back on.
The lead gnome and maybe a steering damper will cure the symptoms, In which case, who cares what the cause is?
 
gripper said:
I don't think it is feasable to straighten the headstock without cutting it off and welding it back on.
Click to expand...

I had my race Commando straightened after a few good get offs. They said the head stock was out of line by 12mm and they jigged and straightened the frame. It was just recently checked at Framecrafter.net and is spot on. The straightenening work was done by Computrac years ago so there is hope; maybe in another 37 years. :cry:

gripper said:
The lead gnome and maybe a steering damper will cure the symptoms, In which case, who cares what the cause is?
Click to expand...

Steering damper - good idea :D , lead gnome - bad idea :( ..................unless you like steering a bike that feels like the Queen Mary's anchor.
 
The three main thing to me are the ISO's, the tire pressure and the wheel alignment. Although triple tree bearings are a key components, they seem to magnify the symptoms rather than being a cause if worn or sloppy.

You said the tires were running true. Are they also aligned? A setup up with a straight edge across and both wheels/tires is needed for this. Bringing it aligned, checking the chain as you adjust, is very important.

The DT headsteady works for many people, but not me. As easy as it is to mount and remove this and the stock unit, it maybe be wise to try the stock unit just for shits and grins. I am not going to bash DT type units at this moment. It's just that I simply do not agree with its concept and it exhibited negative attributes for me.

Tires and pressure, ISO's, alignment and maybe swing arm bushings. It's fairly straight forward. The only other thing might be bad rear shocks, but that's a stretch.
 
Matchless says he has Maxton front and rear suspension, that's about as good as you can get your hands on in UK and is not a cheap option. His engineering background would indicate he's covered all the bases including swinging arm and headstock. There is nowhere else to go unless he only weighs 10 stone soaking wet!
 
My bike's weave gets WORSE when I transfer more of my 230 lbs. toward the rear, like feet on the rear pegs for changing position on long rides. The WORST one was cruising 80 mph, feet on the rear pegs, saw a BIG assed bridge expansion joint (it's a Northern frost heave thing) and lifted my arse off the seat a bit to save my spine from the jolt, and so began a VIOLENT weave gaining ground toward a tank slapper. :shock:
 
Furva , id get down and play Tarzan with the swing arm , to see if its rocking on the plates . And the rear wheel , to see if its rocking on the axle .
Both feet and hands , And maybe a 4 x 2 or two . ( or Two x Four in the good ole U S of A . a soft pine one ).

And see if theres the nice high pitch tinkle from the srewdiver on the rear spoke ( like a wind chime ) . Not a dull old tonk .

Now , Whers this PIER . again . :?
 
:wink: Just a shot in the dark, but it may be the Avon rear. I went through the same as you describe, years ago. After checking, replacing and rebuilding the things you mentioned, I gave up. Eventually, the rear tire needed replacing. To my surprise, no more wobble after I replaced the Avon with another Avon.
 
JimC said:
:wink: Just a shot in the dark, but it may be the Avon rear. I went through the same as you describe, years ago. After checking, replacing and rebuilding the things you mentioned, I gave up. Eventually, the rear tire needed replacing. To my surprise, no more wobble after I replaced the Avon with another Avon.
Click to expand...

Yes, eliminating the wobble boarderlines on a dark art.
I know that when mine went away, I wasn't quite sure what i did. I feel strong that it wasn't any one thing.
More and more, the tires show up as the most common remedy. Avons are good.
 
I would not hesitate to re-check that wheels are tracking true in line, both via static laser line [surveyor type] & dynamic [video &/or track analysis -ride bike over medium that leaves track marking path] , single track vehicles will surely weave -when/if wheels are attempting to take divergent paths.
 
You gentlemen certainly are on the ball. Yesterday I replaced the rear 100/90 19"Avon Superdoopa Venom with a new Roadrider !00/90 & guess what? The weave has gone. I sat on the M55 at between 90 & 100mph for several miles with,out being in fear of my life. The bike still feels less secure (that on rails feeling) than I would like , so the shocks are going back to Maxton for mods. & a change of springs. Hopefully this might give it a more glued to the road feeling.
Thanks for all the replies. I will report back at a later date.
Cheers,
Martyn.
 
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