Danger Alert rear axle and adjusters. (2010)

On 6/27/2010 5:11 PM, Mike Sullivan wrote to BI list:
> Interesting failure today, stopped off to visit friends after Mallory Park, when
> I recommenced my journey and pulled away, bike suddenly felt like it was
> hinged/twisting under the seat, this was at 10-15 mph - bluntly was too
> scared to go any faster!
>
> When I stopped and looked down my nearside (chain side) chain tensioner had
> failed, it's fractured about 1/4 inch in on the inner sided (closest to wheel)
> and has 'peeled' outwards away from the bike with the bolt in situ
>
> I'm just gald that it didn't happen when I was 'making progress' on my way to
> Mallory else I'd be writing from a hospital bed! Interestingly I 'd noticed over
> the past couple of months that on occasional corners things didn't feel quite
> right, a bit 'squirmy' (have been checking lots of tyre pressures). I'm now
> suspecting that the fracture must have been extending and finally failed with
> the new power from my Amals (heh, heh, see other thread)
>
> Am in a complete bind, due to leave for the Spanish rally in a week or so, will
> have to farm this out due to work commitments.
>
> Has anybody else experienced this failure, it would seem quite unusual. Could
> it be metal fatigue or should I be looking for a cause? Should I be looking for
> any other problems in this area (e.g. swing arm, wheel bearings etc?). I will be
> getting both adjusters renewed!
>
> Cheers
>
> Mike
> Mk III Commando
>
> shit weekend:
> reversed into whilst reversing car
> my last amal needle clip broke (tho' managed to scrounge a spare)
> glass fell out of right wing mirror on the A607 this morning
> mobile phone screen slowly bleeding to death after being damaged at Mallory
> now this...
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Mike,
I've had similar event, when axle broke and let clamp force go on RH so axle adjuster on wrong side of axle motion to keep it from twisting tire over into fender edge and swingarm.

But I was going 90 mph standing full upright on tar patched seamed cement hwy
w/o a care in the world when my slow poke buddy passed me like 110 to flag me
over and point to the smoke screen 1/2 mile long. Caught just short of blow out.
But rump rod made so stable I never felt a hint of doom. It did act like yours
on starting off til over like 6-8 mph, with hose clamp holding axle
mostly in line with chain side. Was a bucking bronco then suddenly
just perfectly fine. Took a few starts to get my reflexes ready for
the whip wobble, very similar to a blow out just below full stop.

OH YEAH another thing to keep in mind when axle or adjuster
lets go, it can activate the rear brake intermittently on
costing slow w/o power, or drag and burn up riding on.

I highly recommend safety wire or something on retain axle up against
adjusters, same as safety spring on brake levers, very rare till its your one in a row events.
Be very suspect now of two piece axle integrity at its stress riser known hazard at stud axle joint.
Magnaflux or better just re-new as they do have fatigue life limit we've found.

hobot

Michael Taglieri wrote:

Maybe its the new fangled cushioned rear drum that shocked the
axle stress riser or just luck of the draw even with cushion in clutch.
Blow outs and broke axles tend to fling bike at least 1/2 lane out
of line which is enough to toss into wrong lane or off the edge.
hobot

>>>>>>>>>>>>.
In 2003 I rode on the BSAOCNC's fall ride. It ended up at a picnic ground (The Cheese Factory) in Marin County, CA.
Great fun. I got an award! http://www.strappe.com/pics/B50/plaque.jpg

A year later I talked to a friend (Commando rider) who had left the grounds that day, rode a mile or two and had his rear axle snap.
It threw him into a steel guardrail.
He was shaken, of course. Said if the crash had been at a slightly different angle he would have lost his leg, crushed against that guardrail.

Listen to Mike Tagilari, guys and think about solid axle conversion of factory item.

-Jim Stewart

>>>>>>>>>>>>>>>>>>>>>>>>>>>...
hobot repeats >>>
Something to retain the RH axle from moving backward
to cause a lean-twist of rear wheel from time-fate of impending axle
fracture is the main message in this subject.

hobot repeats, his rump rod'd Ms Peel felt Nothing AT All
going 90 mph tip toes on pegs and finger tips on throttle grip
leaving a cloud of smoke behind. Rump Rod = Safety Feature.

ok, you got me worried!

Does someone make a ready to install one piece axle for our Commando?

I'll be posting more old and new reports of Commando axle fractures
as I come across them until the message sinks in.
I remember over a dozen cases reported in last decade
I know of, not counting my own in '04.

No one yet offers a solid axle conversion but
Michael Tagilari in NYC did his with a 17mm axle and just had
to open up some spacers and inner races IIRC to make his work
pretty easy.

In mean time some way to retain RH axle from snatching
backwards will reduce most the toss down danger till begining
to feel things ain't quite right and check in a safe place for
surprise relief you actually planned ahead for the un-thinkable.
I used hose clamps in my emergency far away from home
but did have to ride using zip ties careful 6 miles to shopping
center for sturdier bodge. Hi speed ain't so bad, as the nearly
almost stopped and starting off buckeroo behavior.

hobot

I broke a Mk111 spindle unscrewing it when I first had mine. It sheered at the change in diameter, leaving the thread in the stub axle.

I don't know of course just how hard it had been tightened by previous keepers.

would be easy to make for mk3 at least- just a longer axle and drill out a spacer?

Geoff Haines g_haines57@HOTMAIL.COM, from the soon to close NOC list today.

Steve,
Here's another one for you.
I have snapped a rear axle on my race commando, just past the threaded section.
I was powering up a hill round a slight bend doing 80mph and all of a sudden the rear wheel went very wobbly.
Initially, I thought I must have neglected to bolt up the axle properly, but it had snapped.
Maybe from bump-starting? Almost made it back to the pits, too!
The hub was a bolt-up, not a cush drive.
I ended up replacing the axle with a one-piece unit.

Regards,
Geoff

Kind of scarry! Is this just a concern on the MK-III disc brake type hub or has this been happening with the drum brake hubs too?

Back when I was racing my PR in the late '70s and early '80s I broke two of the stock two piece axles, so I replaced them with a one-piece axle, and then broke it. After that, I switched to mag wheels, and went to a larger axle in the process. That's when I broke the swingarm right through the adjusting slot. To fit the larger axle, I had to mill the slot to the accomodate it, and I think that made it a bit thin. Fortunately, although I had a couple wild rides when things broke, I didn't crash. I finally concluded that the original axles and the first one-piecer had broken because I had introduced some bending stress when adjusting the rear wheel to align with the front. I realized that I was having to hold the wheel significantly crooked (in relation to the swingarm) while I tightened the axle nuts. With all the ways the isos and frame can get out of line, I wouldn't be too surprised if that was the cause of some of the other broken axles I've heard about. I solved the problem by making a new swing arm designed for the larger axle. I also straightened the frame and made sure the iso adjustments kept everything in the correct plane. The end result was having both wheels in the same plane with no bending force on the rear axle. On the other hand, I've never had a problem with my street Nortons, and I've had several over the years, all with the stock two piece axle.

Ken

Of course I also had a front fork slider break, right through the axle hole, diving into the horseshoe at Daytona, so maybe I just had a little black cloud following me around in those days. I did crash on that one. I had the fork leg welded back together by the mobile machine shop that used to show up at the AMA races back then, and went out to try again. It cracked through the weld, but I noticed it before I crashed again, and decided the race gods were sending me a message. I called it a day and broke out a cold brew instead.

Ken

My bike, (74 850 with a Drouin) has a Mk3 swing arm with the Norton sheet metal chain adjusters.
On three seperate ocasions I folded the chain side adjuster up when powering up in first / second gear.
It did not matter how tight I had the axle torqued up, it still pulled the axle free.
This winter I installed an Old Britts changable sprocket carrier and a 520 chain. While things were apart, I installed a solid axle made from a Honda 350/450 axle 17 MM as per Frank Forster/ Mike T's instructions.
Basically the axle needs to be cut down to fit and threaded for a 5/8-18 castellated nut. the axle is inserted from the drive side swing arm which needs to be enlarged as well as the speedo drive & bushing. A new bushinng needs to be made to match the bushing on the dummy axle. (Note The honda axle is very hard, you will need a machine shop or a good lathe to do the threading).
And I found the Honda chain adjusters to be exact same as the Norton ones except much , much stronger. I currently have one Honda chain adjuster on the drive side and have had no problems. I will need to machine about an 1/16" off the other swing arm in side face in order to fit the other chain adjuster. Next Winter

Bruce MacGregor said:

My bike, (74 850 with a Drouin) has a Mk3 swing arm with the Norton sheet metal chain adjusters.
On three seperate ocasions I folded the chain side adjuster up when powering up in first / second gear.
It did not matter how tight I had the axle torqued up, it still pulled the axle free.
This winter I installed an Old Britts changable sprocket carrier and a 520 chain. While things were apart, I installed a solid axle made from a Honda 350/450 axle 17 MM as per Frank Forster/ Mike T's instructions.
Basically the axle needs to be cut down to fit and threaded for a 5/8-18 castellated nut. the axle is inserted from the drive side swing arm which needs to be enlarged as well as the speedo drive & bushing. A new bushinng needs to be made to match the bushing on the dummy axle. (Note The honda axle is very hard, you will need a machine shop or a good lathe to do the threading).
And I found the Honda chain adjusters to be exact same as the Norton ones except much , much stronger. I currently have one Honda chain adjuster on the drive side and have had no problems. I will need to machine about an 1/16" off the other swing arm in side face in order to fit the other chain adjuster. Next Winter

Click to expand...

Picture?

The thing you forget is that it is, what it is, an ADJUSTER, assisting in adjusting chain tension and alignment. Not for stabilizing the axle from for and aft movement. There are many examples of the later on later model bikes. Rick

On my SV650 the adjusters have a ring around the axle so helps
restrain axle fixed, with or w/o clamp nut tightened.
This may be the easy cheap way to restrain RH Cdo axle so
if it breaks, it may not be noticed until slowing way down
or on first take offs, at rates pilot can compensate or not
get too injured if causes a crash, unless off course impaled
or run over.

hobot

Bruce MacGregor said:

My bike, (74 850 with a Drouin) has a Mk3 swing arm with the Norton sheet metal chain adjusters.
On three seperate ocasions I folded the chain side adjuster up when powering up in first / second gear.
It did not matter how tight I had the axle torqued up, it still pulled the axle free.
This winter I installed an Old Britts changable sprocket carrier and a 520 chain. While things were apart, I installed a solid axle made from a Honda 350/450 axle 17 MM as per Frank Forster/ Mike T's instructions.
Basically the axle needs to be cut down to fit and threaded for a 5/8-18 castellated nut. the axle is inserted from the drive side swing arm which needs to be enlarged as well as the speedo drive & bushing. A new bushinng needs to be made to match the bushing on the dummy axle. (Note The honda axle is very hard, you will need a machine shop or a good lathe to do the threading).
And I found the Honda chain adjusters to be exact same as the Norton ones except much , much stronger. I currently have one Honda chain adjuster on the drive side and have had no problems. I will need to machine about an 1/16" off the other swing arm in side face in order to fit the other chain adjuster. Next Winter

Click to expand...

Good info, but just wanted to add that the CB450K(x) axle is 20mm (CB750 is too), not 17mm like the 350...

Reviving/updating this thread as additional info has come up, i will be focusing on what Hobot initiated, any & all reports or info of 2 piece axles breaking.

The issue is more pressing for mk3 owners, as a fix hasn't been fully resolved or info is incomplete, It is also considered a weaker setup than prior,

whereas, pre mk3 owners have for years now, been able to & have upgraded to a 1 piece axle with a known history, made available from madass.

This came up 2010
norsa1 said:

The 850 Commando has eaten it's third rear wheel axle. Something is wrong but I am stumped. The rear wheel is an Atlas which does not have the rubber shock absorbers but I don't think thats the problem. The primary drive is still using the chain. The swingarm appears to be straight the axle assemby seems to be correct. IThe axle breaks right at the end of the thread where the axle bolts into the dummyh axle. Suggestions greatly appreciated.

- Hobot was doing this, when he had a 2nd axle failure, on a diff bike




hobot said:
Just updating, 2 days ago broke my 2nd dumbass axle on second Combat just making lazy unloaded circles in a parking lot. Its lurking you all beware and might pack a rescue kit.

Oct 21, 2010 comnoz said:
Torque them to spec. Don't use stainless axles and if you ride aggressively or carry a big load put a one piece axle in it. Jim

- note the last sentence
Oct 22, 2010 comnoz said:
Dave, I have used both diameter axles but I think it will be easier to find a 17 mm axle. 350 Honda or several Yamahas used the right length. It is nice to use a milling machine to widen the swingarm slot but I have done them carefully with a carbide burr on the bike. Clean off the paint and scribe lines before you start.
I have broken several of the stock axles in the past. I have never broken a solid axle. Do not modify an axle by shortening it or cutting threads. The roll and finish at the threads and head is important. Hard washers can help spread the load and make things more rigid. I have modified any Norton that I have planned on putting much time on. I have been known to use them hard and I don't like having to worry about that. Jim

Jan 30, 2012 hobot said:
Oh yeah, btw Colin Sharpe on BI list just posted his SS axle upgrade fractured. It's Radioactive fissioning back there, how lucky to ya feel...