Can you believe I limped it home on that!

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I'm running a 520 conversion and managed 14k miles before the front sprocket started to hook. That was a machined Commando part. I now have a Dommie item in there which is 1/4" as std, so no need to narrow and damage hardening but I think that's unlikely to be a problem, more the steel its made from.
 
I am really surprised that it would wear out in only 15,000 miles. I often put 20,000 miles on a chain. At that point the sprockets often still look ok. Sometimes I replace the sprockets and the chain. Sometimes I just install a cheap industrial chain and ride it for another year or two, then often the sprocket is mildly hooked. On my Triumphs and Nortons I use 530 chain with no O rings. I keep them oily, either with chain lube or gear oil. Once a year or more I boil the chain in a mixture of gear oil and paraffin wax. That mixture seals the chain and holds the oil in.

On some of my modern bikes with O ring chains you never even have to adjust the chain before the tire wears out. The sprockets also show little wear.

The only time I experience the chain jumping was on my Ducati Darmah. It had a 530 chain and a pretty small sprocket, probably only 15 teeth. That sprocket still had teeth on it, although they were badly hooked. After that I switched that bike to a more modern O ring chain and bigger sprockets and I never had any trouble again.
 
If you had oiled the chain-you wouldn’t have got home at all because with it lubed it would have kept slipping :!: :twisted: :roll:
 
Can you believe I limped it home on that!

Well I did some more investigating and dug out some old sprockets from the 68-74 vintage:
the two on the left:
A P11 69 and the one below is from my 74 Interstate. Both are used and have a little hook showing from wear.
here are the rockwell numbers:
69 19 tooth Rockwell C 62.7, 62.6
74 20 tooth Rockwell C 63.4,62.1,62.1 Note I did multiple hits. Now that is hard.

The sprockets on the right are from two different parts suppliers here in Canada and are current production.
both are my guess from the same manufacture which have "Made in England" stamped on the back side and are black oxide coated.
I have tested these and found that the material hardness has much to be desired. The material was below the Rockwell C scale and showed an average hardness of 86-87 in the Rockwell B scale...about equivalent to low carbon steel.
These did not come in Andover Norton packages and were shipped with the packs as you see. I would like to know if anyone else found any similar results. I would like to know what Andover Norton is manufacturing and what the specs are for their sprockets.
Cheers,
Thomas
CNN
 
Looks like someone is taking a shortcut, buying in mild steel sprocket blanks, machining the centre and then not heat treating but applying a chemical blacking agent before bagging.
 
kommando said:
Looks like someone is taking a shortcut, buying in mild steel sprocket blanks, machining the centre and then not heat treating but applying a chemical blacking agent before bagging.
Click to expand...

Agreed - they should be named and shamed.
 
Update report :cry:

Well my final comments on this investigation is as follows:
I purchased a 04.0010/21, which is a 520 size / Atlas sprocket from Andover Norton on April 2016, (right from the source) and found the same tell tail identification marks on the stamping from the manufacturer. After testing it seems that the three suppliers are purchasing these from the same source. Results were the same with a Rockwell B scale of 87-88. Soft steel. :x :( :x I mentioned the results to ZFD and to Mark at British Cycle Supply and told them my findings. Look for new old stock unless the suppliers wake up.
Happy trails.
Cheers,
Thomas
CNN
 
CanukNortonNut said:
Update report :cry:

Well my final comments on this investigation is as follows:
I purchased a 04.0010/21, which is a 520 size / Atlas sprocket from Andover Norton on April 2016, (right from the source) and found the same tell tail identification marks on the stamping from the manufacturer. After testing it seems that the three suppliers are purchasing these from the same source. Results were the same with a Rockwell B scale of 87-88. Soft steel. :x :( :x I mentioned the results to ZFD and to Mark at British Cycle Supply and told them my findings. Look for new old stock unless the suppliers wake up.
Happy trails.
Cheers,
Thomas
CNN
Click to expand...

Same sprocket observations. Posted here a year ago. : some-andover-norton-transmission-parts-quality-escapes-t22412-30.html

Be aware. It matters.
 
Old OEM 21t take off, about 62RC old OEM 19t take off about 68RC, new "made in england" 19t, about 18RC, not sure of when or source :( Just tested 2: 21t sprockets "made in england" I got from BCS last year, not AN ... soft as butter 12 on the RC scale... going back to vendor.
..similar results with the RGM 24t, 23t. 22t "made in england" got them many years ago

OK folks what do you think...MAJOR RIP OFF TIME with intent... or just normal incompetence :mrgreen:
:roll:

Will be interested to hear if the "factory" (AN) has changed the factory sprocket drawings to be 12RC like they changed the 06-1084 specs which is now a chilled iron cam.

Kind of eliminates any value in the statement "original factory drawings"

Thomas I salute you :mrgreen:
 
Thanks dynodave,
I salute you back. I am glad someone else in the forum who had hardness testing equipment stepped up to the plate and verified my findings.
We can only see if the purchasers do anything about it.
I bet it won't be soon. :shock: Probably why Comstock uses a belt drive final now. :wink:
Maybe some from the forum can crank these out with toolsteel grade on a CNC.
I will be happy to Test them. :mrgreen:
Cheers,
Thomas
CNN
 
Thomas sorry it took so long to reply, I meant to much earlier in the week, honestly.
I measured the hardness on just about everything that I handled for the MKIII, both used and replacement items.
I take 3 measurements, discard the first considered necessary to settle the anvil and braile, then average the two remaining, that is the number recorded in the pic.
You can see the dimples in each photo, reasonably close to the area of interest.
The pic's below are from late August 2012, the ANIL item was purchased 1 week earlier and may not be representative of current stock.
This below is what was on when purchased from second owner, not unreasonable to assume OEM considering the condition on the rest of the motorbike :
Can you believe I limped it home on that!


This below came with the motorbike in the spares, DOM unknown:
Can you believe I limped it home on that!


This below is the item purchased from Clubman early August 2012.
I think it is well finished and I had no hesitation using it.
Can you believe I limped it home on that!

Can you believe I limped it home on that!

Can you believe I limped it home on that!

Can you believe I limped it home on that!


All the Best.
 
xbacksideslider said:
http://www.wikihow.com/Harden-Steel

Maybe just harden them ourselves.
Click to expand...

Who is going to volunteer to determine the alloy of each different identifiable sprocket product since they would probably need a different treatment based on the steel's spec. I do heat treat some steels on items I make, but the process (temp) varies wildly based on the steel.

It looks like Norton factory had a handle on sprockets and possibly ANIL(BSA Regal). BSA Regal actually made stuff... though I don't know which specific stuff they did make.

I finally checked every one (18t-19t-20t-21t-22t-23t-24t) of my "Made in England" sprockets and they are all very low RC12-15.
All the old Norton motorcycle factory ones were in the high RC50 to mid RC60's.
 
I came home on my 71 with the rear brake drum/sprocket completely cracked in a circle about mid radius if the drum. I was amazed when I saw what had happened. I noted that the new drum/sprocket had reinforcing bulges in that area. Strange that I have never heard of any other failures in that area.
 
dynodave said:
Who is going to volunteer to determine the alloy of each
Click to expand...

Not I my good man. No lab facilities at the current salt mine other than a whip and a Wilson Rockwell tester and my colleagues with lab access are retired or on the wrong side of the turf.
A mount and OES would be nice but that would only tell you about the mount anyways, not the actual one going around with the output shaft.
I say if you can give her three dimples near the teeth, do so and make a useful determination from there.
One may also use the file hardness test in the home "man cave lab" for a simple surface hardness determination too. Some comfort possible with that approach I suppose.
If all else fails you may still limp home, it has been proven by Thomas. Quite an accomplishment.
All the Best.
 
"One may also use the file hardness test in the home "man cave lab" for a simple surface hardness determination too. Some comfort possible with that approach I suppose."

That's what I used. :idea:
 
If the steel is as soft as the Rockwell tester is showing, these may not do any better with quench hardening. I lean more towards the manufacturers not case-hardening after building the parts. Case hardening is great for something like sprockets (and chain), as it keeps the load-bearing properties of the softer (less crack-prone than hardened) metal, then adds a hard wear surface. It can be done "at home", but requires a furnace capable of maintianing a high temp for a long duration of time. One poster writes at http://www.practicalmachinist.com/vb/ge ... me-320973/

"I collected some charcoal from a long since dead half burnt hardwood tree, most likely an iron bark... The barium carbonate came from ebay... Sodium carbonate from hardware store in the pool chemical section and calcium carbonate was very finely crushed marble..

What size to crush the charcoal to was a guess.... Some other instructions say it must be very finely crushed. These instructions say larger chunks around 10mm... After following how the process works I went with the larger chunks... Reason being the materials all react to create a carbon monoxide gas which the carbon in the gas penetrates the steel when the steel is above a certain temperature (a bit over 800 degrees C) If the charcoal is fine it could hinder the CO from reaching the steel or that was my reasoning which could be untrue.
Anyway I crushed to charcoal to a size and sieved out the fines and the large bits...

Measured up the % amounts by weight...

425 grammes charcoal
50 grammes Barium Carbonate
15 grammes Calcium Carbonate
10 grammes Sodium Carbonate

mixed with the charcoal in a water slurry mixture, then heated the mixture until the water evaporated...
Made up a steel container to hold the test pieces out of 3" water pipe. the container was vented each end with a 3/16 hole but the lid was only held on with wire..... The test piece was a toolmakers clamp I made awhile ago out of mild steel.. dead soft.. Surface ground most of the surfaces. I cleaned the parts with acetone before putting them in the container to remove all traces of contaminants... Then did not handle them with bare fingers. Overkill probably..
Put some case hardening mix into the container and added the test pieces, with about 15mm gap between the sides of the container.... Filled to the top with case hardening mix and wired the lid on.
Dialed in the temperature to 925 degrees and waited.....and waited. Takes about an hour and a bit to get to 925 degrees.
5 hours later, with the outside of the kiln quite quite hot (this kiln loses a lot of heat not that I have even used a kiln before though)
Opened door and was greeted with a lot of heat, grabbed the canister and removed it... Cut the wires removed the lid and poured the contents into a steel tray.... Grabbed the parts and quickly quenched them...
They were quite clean... Put them on the surface grinder for a clean up.... They had warped and had to take up to 0.15mm off to clean the sides up fully...
Put them on the rockwell hardness tester... Came back at 60HRC... success!!!!
No idea of the depth of hardness.."

As you can see, this might be something that should have been done before we ever got the sprockets. Maybe we could all pool our newly purchased items, and send them to a shop that has that capability.

Nathan
 
You can get sprocket teeth flame hardened.

It may be an option as in my humble opinion, I know I have a lot of them, the vast
majority of steel on the market is crap.

Andy
 
AntrimMan
Thanks for posting. Even the RC 56 I could accept from your lower pictures.
Cheers,
Thomas
CNN
 
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