Axle Fail leads to Brake drum bearing replacement Issue

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Stillreel

Stillreel

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Axle failed (see below) with scoring near end of dummy axle.
Axle Fail leads to Brake drum bearing replacement Issue


Cannot figure out how to get brake drum hub apart. No circlip. Appears to be peened into place.
Axle Fail leads to Brake drum bearing replacement Issue

and
Axle Fail leads to Brake drum bearing replacement Issue


Bearing feels rough in there. Do I need to replace the entire hub ($$$)

Wondering what year this drum is from. Fitted onto my 71 Commando.
Axle Fail leads to Brake drum bearing replacement Issue


Thought suggestions appreciated

BC

71 Commando (Not going to the Mods & Rockers this weekend)
 
The peened part is just the dust cover for the bearing, you can file down the folded over edges to get it out, we can probably drum up a spare axle to get you to the event this weekend.
 
I used a Proto J-shaped gapping tool and the smallest wire .035 barely fit in and I was just able of lever the washer off
 
dont worry about destroying the dust cover as you will fit a sealed bearing so there really is no need to fit the dust cover on reassembly 4203 2RS bearing
 
What causes it guys? Stress / flex? Over tightening? Raw untamed Commando horsepower :wink:
 
basically its a poor design. other 2 piece axle setups have the long axle pass thru the short stub axle eliminating this problem.
for a start the axle is only about 1/2" diameter at the bottom of the thread, its not gonna take a lot of abuse for it to cause problems.
They need to be carefully setup, thats why some guys never have a problem, Of course we all know what the proper fix is
 
Fast Eddie said:
What causes it guys? Stress / flex? Over tightening? Raw untamed Commando horsepower :wink:
Click to expand...

I snapped mine while tightening the axle after adjusting the chain. That was about 40 years ago. I chalked it up to a weak bolt (or a strong kid with a long wrench). Been careful of torque ever since.
 
I got the one piece axle and installed it with the threads on the right side of the bike. That way I can keep the axle partly installed to hold the drum/chain while I change the tire. No need for the stub axle.
 
Thanks all; I'll get the dust cover off and look inside. SO just heat up and pound the double row bearing out?

acadian said:
The peened part is just the dust cover for the bearing, you can file down the folded over edges to get it out, we can probably drum up a spare axle to get you to the event this weekend.
Click to expand...

I've been looking forward to this for awhile. Walridge has the part but it won't get here in time. PM if you have one I can fit. I'll do the bearing later.

madass140 said:
basically its a poor design. other 2 piece axle setups have the long axle pass thru the short stub axle eliminating this problem.
for a start the axle is only about 1/2" diameter at the bottom of the thread, its not gonna take a lot of abuse for it to cause problems.
They need to be carefully setup, thats why some guys never have a problem, Of course we all know what the proper fix is
Click to expand...

Madass; can you send image of 1 piece axle?
 
Don't forget that there is a circlip that retains the bearing.
Don't pound on the dummy axle until it is removed.
You will see it when you remove the washer.
 
I have one of Don's stainless 2-piece axle kits for a bolt-up hub, sitting on the shelf. I think all it needs is a different spacer (or modification of the one it has on it) and it will work on the cush hub.

Don?

I got it as partial payment from a client when he switched to one of my box section / big bearing swingarms.
 
acadian said:
The peened part is just the dust cover for the bearing, you can file down the folded over edges to get it out, we can probably drum up a spare axle to get you to the event this weekend.
Click to expand...

It is easy to make a punch tool to push back the peening a bit and get the metal shield off without destroying it. You could grind a matching radius on a big screwdriver (a Harbor Freight one) or the original Norton tire irons in the tool kit look about right without grinding. I just saw this trick in an old Briggs and Stratton Model A manual from the late '30s. There was even a drawing of the tool!

The one piece axle is the way to go (and I don't like most mods).

Russ
 
So how many owners even know the correct torque that should be applied when tightening thier rear wheel spindle and nut?? The answer is, I suspect, NOT MANY and I doubt more than 5% of owners even have let alone use a torque wrench to give the correct torque.
In my youth I cannot remember even seeing in my Norton workshop manuals a torque figure for the rear wheel fixings and we would simply find the longest spanner and stand on it as we did not have a torque wrench ......thus we very probably stretched the threads that could possibly of led to failure at some point in the future. Did not Norton change the thread form from cycle to UNF? If so that was a really 'clever' move which should of reduced the torque values to be used because the UNF thread form has a sharp stress raiser at the root of the thread whilst the cycle thread is radiused. Quote. Prevention of Failue in Metals.1941. ' Any thread is a stress raiser, smoothly radiused threads are better than sharp threads. But might is right and the Whitworth thread form is extinct'.
Engineer to Win page 145 gives some 'interesting' stress figures .....
Medium carbon steel. No thread 37,000 PSI....UNF thread 13,000 PSI ...Whitworth thread...21,000 PSI.
Alloy steel. No thread 73,000 PSI....UNF thread 19,000 PSI....Whitworth 22,000 PSI.
Oh how I remember those days when what was left of British industry ended up using BA, BSF, Cycle, UNF, UNC Whitworth etc thread forms and to confuse matters even further metric! What??!!Spend money changing all our many thousands of drawings to metric threads...DREAM ON.
Wonder how many second hand rear wheel spindles /dummy axles on E Bay have been over tightened in their life??
Personally the only Norton manual I can remember that gave the torque figures for the rear wheel fixings was the late Mk3 one.
Then of course do the grades of stainless steel used by those manufacturing stainless wheel spindles have similar mechanical properties to the wheel spindle material employed by Norton? Do such items come supplied with recommended torque values??
I bet the owner of that failed wheel spindle has not even bothered to have it examined by a metalurgist to determine the cause of the failure.
 
J. M. Leadbeater said:
I bet the owner of that failed wheel spindle has not even bothered to have it examined by a metalurgist to determine the cause of the failure.
Click to expand...
Yes, whenever I break a bolt or strip a screw, I run it right over to my local metallurgist to find out what the hell could have happened.
 
J. M. Leadbeater said:
I bet the owner of that failed wheel spindle has not even bothered to have it examined by a metalurgist to determine the cause of the failure.
Click to expand...
Sort of right. I worked in a metallurgical lab, the "Met Lab" for 12 year so did the failure analysis myself.

The torque setting were correct but after disassembly, I'm looking at the faulty bearing (dry/burned). It may well have been the original bearing and I should have replaced it when I put the machine together three years ago. Hindsight.

Re: Metallurgy: As mentioned, I worked in the mechanical test and metallurgical department at Alcan R&D lab (Kingston) for 12 years and easily recognized a combination shear/torsion failure (single point nucleus with apparent spiral/taper). I think I can rationalize it as this (if interested); the bearing started to bind on the axle, which was possibly already weakened by bending fatigue concentrated at the narrow diameter thread point. As others have pointed out, it is a poor design and the threads have consistently been the point of failure. With a sharp acceleration, the axle further bent into the spinning bearing, seizing into it and then twisting off. No need for microscopy for this analysis. The fracture is hallmark torsion/shear and all other components are sound.

I've decided on the one-piece from Don and will order it tonight.

Thanks for the input.
 
J. M. Leadbeater said:
So how many owners even know the correct torque that should be applied when tightening thier rear wheel spindle and nut?? The answer is, I suspect, NOT MANY and I doubt more than 5% of owners even have let alone use a torque wrench to give the correct torque.
In my youth I cannot remember even seeing in my Norton workshop manuals a torque figure for the rear wheel fixings and we would simply find the longest spanner and stand on it as we did not have a torque wrench ......thus we very probably stretched the threads that could possibly of led to failure at some point in the future. Did not Norton change the thread form from cycle to UNF? If so that was a really 'clever' move which should of reduced the torque values to be used because the UNF thread form has a sharp stress raiser at the root of the thread whilst the cycle thread is radiused. Quote. Prevention of Failue in Metals.1941. ' Any thread is a stress raiser, smoothly radiused threads are better than sharp threads. But might is right and the Whitworth thread form is extinct'.
Engineer to Win page 145 gives some 'interesting' stress figures .....
Medium carbon steel. No thread 37,000 PSI....UNF thread 13,000 PSI ...Whitworth thread...21,000 PSI.
Alloy steel. No thread 73,000 PSI....UNF thread 19,000 PSI....Whitworth 22,000 PSI.
Oh how I remember those days when what was left of British industry ended up using BA, BSF, Cycle, UNF, UNC Whitworth etc thread forms and to confuse matters even further metric! What??!!Spend money changing all our many thousands of drawings to metric threads...DREAM ON.
Wonder how many second hand rear wheel spindles /dummy axles on E Bay have been over tightened in their life??
Personally the only Norton manual I can remember that gave the torque figures for the rear wheel fixings was the late Mk3 one.
Then of course do the grades of stainless steel used by those manufacturing stainless wheel spindles have similar mechanical properties to the wheel spindle material employed by Norton? Do such items come supplied with recommended torque values??
I bet the owner of that failed wheel spindle has not even bothered to have it examined by a metalurgist to determine the cause of the failure.
Click to expand...

and after that lengthy diatribe I am still waiting (on bated breath) for the elusive torque spec you seem to have exclusive knowledge of...

pete.v said:
Yes, whenever I break a bolt or strip a screw, I run it right over to my local metallurgist to find out what the hell could have happened.
Click to expand...

I do the same thing when I break a twist tie...
 
Dang thing just up and CRYSTALLIZED!

See them teeny little crystals there? Yessir, it crystallized.
 
I have never experienced a broken rear axle. I weigh 170 lbs without riding gear/helmet. I use no torque wrench... only a 12" long ring spanner. I put my left foot on the rear brake pedal straddled over the bike while I torque(tighten) up the spindle. I keep an eye that the chain adjuster on the right hand side gap to stay close with the nut contact point. I apply maybe 50-60 # or when my brain say click. My eyes aren't bleeding from wrenching to torque and its with one arm. I don't try to kill it. So far the spindle has never come loose or broke.
Cheers,
Thomas
CNN
 
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