one piece axle for mk3 commando

A couple of years ago I hit a deep pothole that bottomed the rear suspension and destroyed my rear rim. Surpringly perhaps, the axle held.

Glen

L.A.B. said:

It is a known problem and not just the 850 Mk3.

Another MK III broken axle (2018)

Pulled into my shop just as rear tire went flat. Thought what good fortune to have it happen right there. Repaired tube and, just snugging up rear axle, it snapped! Nothing new, classic fatigue crack - fine grain crack 2/3rds through until the final third broke. I remembered Hobot was counting...

www.accessnorton.com

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Ok, I read the linked thread from 2018 and I have to side with Andover on this one. Take 60,000 bikes, half a century of use, abuse, modifications, neglect, non-original replacements and it comes as no suprise that somewhere, sometime, someone breaks something.
Commandos were ubiquitous in the 70s; the police racked up 100k+ miles then sold the bikes on (to folk like me) yet there were no rumours about wheel spindles breaking. And through all these 45 years of ownership, no one has ever come up to me and said "you want to replace those rear axles you know".

All of which is to say, there is no compelling reason to replace the rear axle because you fear the failure of the original item. A straight-thru, one-piece spindle can be a good mod when combined with other changes to the way the wheel hub, sprocket, carrier and spacers are fixed and one might argue that Norton should have done this when the rear wheel was redesigned for the Mk3. They didn't but you still can. However, to come back to the OP, finding a bit of 17mm bar and drilling out a perfectly useable stub axle to make a spacer is not the answer.

stanthomas said:

Ok, I read the linked thread from 2018 and I have to side with Andover on this one. Take 60,000 bikes, half a century of use, abuse, modifications, neglect, non-original replacements and it comes as no suprise that somewhere, sometime, someone breaks something.
Commandos were ubiquitous in the 70s; the police racked up 100k+ miles then sold the bikes on (to folk like me) yet there were no rumours about wheel spindles breaking. And through all these 45 years of ownership, no one has ever come up to me and said "you want to replace those rear axles you know".

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A couple of points. Number of Mk3 models built is far less then 60 000 samples. more like 5000 samples. The pre-Mk3 models had a stronger two-piece rear spindle/stub axle design than the design NV made for the Mk3. I doubt the police Mk3 models racked up 100k miles before being sold off.
As for your last statement, the spindle/axle fatigue problem is confirmed by ZFD, so maybe you didn't pay attention at the time?
Why ZFD thinks the problem has ceased to exist is beyond my comprehension. The introduction of a radius alone is hardly the answer. Maybe the answer is simply that bikes do not gather high mileages anymore?

-Knut

In the other post L.A.B posted a photo of a spindle (maybe his)?



And in the same thread Joe (ZFD) stated "The Mk3 rear axle breakages were legion in the old days of original Mk3 axles. The drawing was later updated and all new axles now have a radius where the originals had a sharp 90° corner where the thread starts."

So is this one of the failure prone articles?

stanthomas said:

Ok, I read the linked thread from 2018 and I have to side with Andover on this one. Take 60,000 bikes, half a century of use, abuse, modifications, neglect, non-original replacements and it comes as no suprise that somewhere, sometime, someone breaks something.
Commandos were ubiquitous in the 70s; the police racked up 100k+ miles then sold the bikes on (to folk like me) yet there were no rumours about wheel spindles breaking. And through all these 45 years of ownership, no one has ever come up to me and said "you want to replace those rear axles you know".

All of which is to say, there is no compelling reason to replace the rear axle because you fear the failure of the original item. A straight-thru, one-piece spindle can be a good mod when combined with other changes to the way the wheel hub, sprocket, carrier and spacers are fixed and one might argue that Norton should have done this when the rear wheel was redesigned for the Mk3. They didn't but you still can. However, to come back to the OP, finding a bit of 17mm bar and drilling out a perfectly useable stub axle to make a spacer is not the answer.

Click to expand...

I have known about the commando rear spindle breaking from around 1980 admittedly I have only seen two broken spindles that were both on different mates commandos
These were both pre MK3 commandos one was a 750 one an 850
I don't think spindles were easy to buy at that time? My mate made a new one at work ,he worked in the royal small arms at that time
He still owns the bike

batrider said:

Dunno about Mk3 but on earlier bikes you can turn the one piece axle around and pull it only partially out, so you still get the quick change feature. The chainguard holds the brake drum in place. Not difficult.

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That is what I do, nut on the speedo side.

robs ss said:

I understand the designed-in weakness of the two piece rear axle - and maybe I'll change mine.
There is, however, a benefit (especially with cush-hubs) with the two-piece for road bikes. That is the rear wheel can be removed, to repair or replace a tyre, without disassembling the LH side - which can be a PIA to reassemble and squeeze back into place - especially pre-MkIII.
Are any one-piece owners willing to comment on the comparative ease/difficulty the one-piece axle presents in this scenario?
Cheers

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It’s not a problem at all. I flipped the one-piece axle around so that the nut is on the other side. When pulling the wheel just don’t pull the axle all the way out and it’ll hold the brake hub, etc.

cliffa said:

In the other post L.A.B posted a photo of a spindle (maybe his)?

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Yes.

Reversing a one piece axle to put the nut on the right with push type adjusters is common. (afaik)
I did that on my TL1000 so with a knee against the tyre/tire when the nut is tightened it rolls toward the adjuster and not away, possibly leaving a small gap.



Is there a one piece axle even available for a Mk3 to date. (If the pre Mk2 will not work)

Dommie Nator said:

What will the revised torque figure be please?

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It won't be. See the thread linked by L.A.B. [post 7] and gortnipper [post 16] In that thread, go to page 2, post 25, although it would be best to read the entire thread.

74ok said:

Is that revised manual the one on facebook?

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No, my edit is not "online". FYI, it's only for the 75 -77 Mk III models. If you own a Mk III and would like a copy, send me a private message [aka conversation] . I'll need your email address to send it to you. Just click on the "Start Conversation" icon below/left of this post.

mean gene said:

Anybody have a print or sketch of the one piece rear axel?

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- prior to 75

Time Warp said:

Reversing a one piece axle to put the nut on the right with push type adjusters is common. (afaik)
I did that on my TL1000 so with a knee against the tyre/tire when the nut is tightened it rolls toward the adjuster and not away, possibly leaving a small gap.

View attachment 84025

Is there a one piece axle even available for a Mk3 to date. (If the pre Mk2 will not work)

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- If the info in this 2018 post is current, no.
madass140 said:
Sorry I dont do an axle for MK3's

- Then this thread may be the only doable or known, at least to some extent, option for mk3 owners.

- If the first post here is correct (prior axles are 9/16)
bobnorsaki said:
the mk3 two piece axle is 17mm. If you cut the stud off the stud shaft and open it up to 17mm you can insert a one piece axle. I have used the axle from a 1983 kawasaki gpz 750. one must redeuce the length of the shaft and put threads on it for it to fit the swingarm.

- then there are a ton of pickings out there, not to mention wheels, including for pre 75s converted to 17mm axles.


- as far as cutting threads goes
daveh said:
I remember Jim Comstock advising not to cut the threads on a wheel axle but I think he mentioned that he managed to find some of the right length.

I have seen spindles on race bikes cut to length at the hexagon end, threaded and a nut screwed on, and then welded in place. The weld is then cleaned up on a lathe. The material is too tough to cut with a die. Threads would be cut on a lathe. Would an engineer care to comment on this approach?


- pre 75 but relevant
Bruce MacGregor said:
I turned a thread on the RH end of the new axle to take 5/8" fine thread nyloc nut. Big mistake,as the new nut shook loose on the freeway, allowing the axle to move out of the RH swing arm slot, there by locking up the rear wheel@75 MPH, I Immediately replaced with a cross drilled hole & castellated nut retained by a cotter key. No other problems ..
Cheers Frank

I'll add,
The Honda axle is very hard, you will not be able to thread it with a die.
If you bike has the flimsey chain adjustors (850) try to fit the heavy duty Honda ones.
Keep the length of the new axle a little long so that you have enough extra length to drill & pin to hold the nut on.


- I'm assuming the 75 speedo drive is a diff part# & good to go
coz prior to that
Bruce MacGregor said:

the axle hole in the speedo drive box must be opened up.


- dunno the details on ~ 'as done on mklll by Frank Forster'
norbsa48503 said:
Her's a copy of that old info:
From: Michael Taglieri <miket--nyc@j...>
Date: Sat Mar 12, 2005 10:46 pm
Subject: Machining Speedo Drive for Commando Solid-Rear-Axle Conversion

Therefore (inspired by Frank Forster, who did the same thing on a MKIII

Well, after due consideration, I bought 2 axles from Don - one for the 650ss and one for the 74 Interstate.
Not fitted yet but I have to say they look GOOD!
They will obviously, to me at least, never fail in a way that is/was a risk with the two-piece.
Cheers

robs ss said:

Well, after due consideration, I bought 2 axles from Don - one for the 650ss and one for the 74 Interstate.

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Yes, Don's axles for earlier models are nice, but how is your posting a contribution to this thread which is about the Mk3?
It's been made clear by Don himself, he doesn't do rear axles for the Mk3.

-Knut

mdt-son said:

Yes, Don's axles for earlier models are nice, but how is your posting a contribution to this thread which is about the Mk3?
It's been made clear by Don himself, he doesn't do rear axles for the Mk3.

-Knut

Click to expand...

Yes.. ahem... a bit of overzealous typing before really thinking about thread topic. Sorry!

cliffa said:

In the other post L.A.B posted a photo of a spindle (maybe his)?

View attachment 83992

And in the same thread Joe (ZFD) stated "The Mk3 rear axle breakages were legion in the old days of original Mk3 axles. The drawing was later updated and all new axles now have a radius where the originals had a sharp 90° corner where the thread starts."

So is this one of the failure prone articles?

Click to expand...

afaik, it's the only picture ever posted, I can't tell by the wording prior to that

update to prior post

FF post Jan 30, 2012 mk3 1 piece axle

Donlon39 said:
"It's been several years since I converted my MK III to solid rear axle (BEFORE the original broke), and I merely made up spacers (two, I think) and filed the swingarm forks wider to accept the Honda 17MM axle. As I recall, the wheel bearings required no mods or replacements.
I DID find out the hard way that a new Nyloc nut was inadequate, as I got to enjoy a locked rear wheel slide into the freeway median after the axle moved out to the left side and the wheel tipped. It's now secured by a cotter pin.
I've found that by sliding the axle out to the left side, the sprocket can be left in place while removing the wheel."

Frank Forster

mdt-son said:

A couple of points. Number of Mk3 models built is far less then 60 000 samples. more like 5000 samples. The pre-Mk3 models had a stronger two-piece rear spindle/stub axle design than the design NV made for the Mk3. I doubt the police Mk3 models racked up 100k miles before being sold off.
As for your last statement, the spindle/axle fatigue problem is confirmed by ZFD, so maybe you didn't pay attention at the time?
Why ZFD thinks the problem has ceased to exist is beyond my comprehension. The introduction of a radius alone is hardly the answer. Maybe the answer is simply that bikes do not gather high mileages anymore?

-Knut

Click to expand...

How is the pre 75 spindle stronger? I'm thinking the pre 75 axle @ 9/16 is smaller

As far as ZFD goes, i assume that his comments about selling 'legions' in the past down to 1 in the last few years doesn't mean much?

He did say the above, after some updates, but didn't follow up on that part, to confirm it.

74ok said:

How is the pre 75 spindle stronger? I'm thinking the pre 75 axle @ 9/16 is smaller

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The pre-Mk3 axle is 9/16" and so is the thread.

The Mk3 axle thread is 1/2" (UNF).
Edit: The Mk3 dummy axle external thread is 9/16" UNF.