My first experience with "The Weave"

Have you checked the rear swingarm bushes for wear ?
If you can grab the swingarm, and waggle it side-to-side, then it can steer the bike for you.

If dry, those bushes wear quite rapidly.
And if the chain is too tight, it gets worse.

I replaced some quite worn bushes on a low mileage 850 when acquired.
Rear wheel could move, quite a long way...

swooshdave said:

I would not run 4.10 on the front of early bikes.

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And the reasons are?

I have ridden with some pretty out of balance tires that were uncomfortable but didn't make my bike weave. Not to say it is impossible.

My checklist for the sudden onset of a weave is- starting with the most common.

1. tire wear or low pressure
2. broken or loose headsteady
3. loose engine to cradle bolts. They don't have to be falling out- just loose enough that they can slip.
4. broken rear axle [hard to miss that one]
5. loose or broken spokes

Then of coarse there are a lot of things that can wear and cause weave such as iso's and swingarm bushings but I wouldn't call that a sudden onset. Jim

My two Combat came with 110/410 front tires and all I've ever put on them - till this year, following forum advice - which I now feel a mistake for me - as its definitely added to my braking distance and care not to lock up and I don't notice any benefit of 100 for faster lighter steering. You're call but I'm done with that experiment - once new 100 wears out, never again for me.

Oh yeah, I can't tell ya how much unknown slow leaks on front and or rear has helped me in racer like skills of recovery in Weaving Wobbles Hinging. I highly recommend some low air practice so a slow leak never ever surprises you, as it feel identical to wind gusts, at first, till the control actions reverse their effects about time tube rips apart, you'll be ready for it.

comnoz said:

I have ridden with some pretty out of balance tires that were uncomfortable but didn't make my bike weave. Not to say it is impossible.

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Perhaps I could have added that badly out of balance wheels contribute nothing to good braking or steering, not necessarily anything to do with a weave...

If the wheel is out of balance enough that at some speed it resonates with the suspension and frame compliance then it can help onset weave from other sourses but by itself should just annoy the rider and heat and wear tires more.

One early wierd out of the blue no sense to it hinging would hit going straight and easy or leaned hard on it -pre Peel with new tires but not gone through any restoring, Weeks of depression after some months of just fine. One day had primary open for clutch grime and checked triple chain slack a few time then stood up, then sense of familiarly hit, then checked again to observe that chain flop was same freq and was tugging on the clutch/main shaft wobble which was tugging on the swing arm which was tugging on the cradle which was tugging the front iso gap side to side, which was oscillating the forks. i've a very low opinion of the sleeve bushes lubing in lower gears in AMC gearboxes ever since.

The early Commandos came with 3.25 x 19 front tires, and the front fenders were sized for these narrower tires. If I recall, your '68 fastback didn't have a front fender because a PO put a bigger tire on.

I think you'll find the handling a little better if you had the right size tire on. In fact, I think you should have the same tire I've got on the Ranger, an Avon 3.25 x 19 Speedmaster.

I'll take it down to Laser Wolf next week and you can have a good look at it.

cruiseing over the rise on the Auckland M'way , a bloke in T shirt shorts and I think thongs , on a Z1r ( the bikini fairing one ) glanced over his shoulder
so moir Norton , & snapped the throttle on . I hit the picks and veared left , all fingers crossed .
the kwickersaki did a big L-R sine curve weave , on the second it spat the back clear & Him Up .

luckilly they all fell down upright , as there was a bit of traffic about .

Moral of this story ; LOOK where youre Going . :lol: 8) (not backwards when hitting the gas )

willy mac said:

swooshdave said:

I would not run 4.10 on the front of early bikes.

Click to expand...

And the reasons are?

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I don't think the frame geometry was designed for them.

Did a bunch more reading, now the things i'm gonna change are rear shocks, then get a Dave Taylor head steady. I know i need a skinnier tire on the front and thats in the works but i don't believe that could cause the issue i'm having. Whats really weird to me is the bike rides AMAZING below 60, corners awesome, feels razor sharp and still balanced....then you get up past 60 and it's like a different bike.

I've always kept the 3.00-19 on the front of my bike and never experienced any weaves. But I don't ride like the devil's heatwave either.

Dave
69S

The better the tires re: tread depth ,the worse. Just before replacement seems more forgiving.

Any one who thinks it take riding like the devil just has not ridden over mildly on rough enough road &/or wind conditions with or w/o worn factory or non issue size tires, flat or fully inflated. Duh go back and read the initial post again, not even going fast enough in top to hardly enter isolation zone rpm. If not please refrain from coming across as such a innocent novice or imply those that experience are behaving immatural in any way measured. Of course it much easier to induce the harsher one goes but some times its totally unavoidable d/t the combo of conditions even holding back below legal and easy speeds, its an innate action that can onset anyone on regular non tri linked Commando. Get back to us when this sinks in. Everything one can do to a Cdo to stifle oscillating weave turning into tank slapping wobble only moves its onset to higher speeds for more sudden and dramatic onset. I tell people who have not yet experienced it to try lowering tire pressure a good bit one end or both to learn how to behave when weave hits w/o it being a fault of their own. Wish I'd gotten to learn my first low tire weave control on my terms.

I only know of a one in a row 1/3 robust 2/3s half flexy linked Cdo that is immune to wild speed or high wind or rough surface or blow outs to THE Hinge.

one of the road testers found a out of true back wheel was iresponable , or VcV .
sittingon a flat for years would getthe tread out of round . Theirsbounced / weaved over70 with the naff rim .

Spinning the wheel with athing against the tread'd show if its true .

Havent posted results yet because i've been trying for the last month to get this piece of junk fiberglass tank to not leak gas without ruining the original patina on the exterior of the tank. That's a whole 'nother story. Anyway weave is gone and the results are interesting.

1) i was running mid 30's PSI in the tires like i'd used on every motorcycle i'd ever owned. I know people have posted about PSI being so important and i decided to try it because A: it was free and B: Wes Scott told me 26/28 is what he would run. So i did that, and i would say 70% of the weave instantly disappeared. Mind Blowing that air pressure could cause that condition.

2) finally took the 4.10 off the front and put on the correct 3.25. This got rid of the rest of the problem! WTFBBQROFLCOPTER


Now the bike rides awesome, like it should. So much fun, so flickable, had it up to 85 no problems. WINNING :^)

I hope this thread helps someone in the future. Thanks to everyone for their input.

Who'd of thot. To Continue the tire air course > try rear 1/3+ low for a short bit then top it and lower front 1/3+ for a bit then let rear down too - then never EVER forget the subtle sensations blending with wind and road texture or the groin grabbing tank slapping major ones.

In my misspent youth, on my old drum brake '71 750 I'd run 17 psi in the 4.10 K81 on the rear and 19 psi in the 3.60 K81 on the front. That was for aggressive riding in Griffith Park where the average speeds were low and the pavement was bumpy/ripply and the low pressures made for quick warm up and much better traction - never a weave - but rarely got above 80 mph there. In that era though, LA's freeways generally had "rain grooves," and with normal pressures in those same tires that Commando would occasionally go into a weave. Go figure.

My current Commando, a '73 750, did go through a period when it would weave and I found that moving my butt back tamed it; since then I went to some slightly narrower Avons and the weave is gone, although it is still alive in my head.

Hehe rubbedrawrump, that's about how low I go on Combats to cross mud thats deeper that the tire size. I've not liked what my bikes felt like when a rear got a slow leak to get a few lb lower than front. One thing I notice if rear lower than front is the hands off weave onsets more. When I get balance about right the bike seems easiest to steer. On street tires I like 28 rear 26 ft and on more aggressive dual purpose tires I like a couple lbs lower for best all around feel. If road play intened then I air street tires 30-32 rear and 28-30 front. Tire age conditions alter the fine tune, generally lower lb as they wear. Loaded to the gills improves load swaying with a bit more air. One neat thing I noticed is the harder the tires aired the sooner and deeper the isolation occurs. Some day try like 50 lb in tires for a while, it may change your sense of judgement on what your feelling getting through.

I remember that weave when I first got my MK3 new in '75. Scared the hell out of me but then thought, ( at age 26) "what the f was that" and tried it again. Ya and at about 80 or so it did it again! Over many many years of owning and servicing and rebuilding this bike and with a lot of differant tire combo's and pressures I can say that she doesn't do this any more. (and I can honestly say out of all the posts here and on other forums I frequent, {Triumph Rat} {Triumph TR8 cars} this is the first time I've refered to any of my machines as "she") I think close iso adjustment, tire press, and oh yes getting rid of those 10" highrise bars that I had to have in 1975 all contributed to the fix. By the way hobit I think you are a really smart guy but I don't know what the hell you're talking about half the time.

I'm rather sure this is why the factory changed the steering angle on the later, 850 frames and yokes, to stabilize the handling. Norman White said many racers preferred the earlier frames because they turned faster, but the downside was that they were scarier at speed. When building my bike, one of the old timers said I should look for a 850 frame and yokes for "better handling".