Sprocket Hardness?

robs ss

robs ss

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Has anyone tested the hardness, in the teeth area, of generally available sprockets & drums?
(this thread is to prevent further derailment of the "What did you do..." thread

I am seriously considering buying a spare drum and countershaft sprocket (22T).
One question that comes to mind, at least to me, is how well the teeth have been hardened. @Tornado reported that he had recently replaced sprockets due to his old ones becoming shark toothed. I've suffered that before too.

I'm aware of some commercially available hardening compounds (eg: Cherry Red) that could easily be used at home with flame heating, but.. is it necessary?

So.. has anyone tested (or know of someone who has tested) sprockets for hardness?
Cheers
 
robs ss said:
Has anyone tested the hardness, in the teeth area, of generally available sprockets & drums?
(this thread is to prevent further derailment of the "What did you do..." thread

I am seriously considering buying a spare drum and countershaft sprocket (22T).
One question that comes to mind, at least to me, is how well the teeth have been hardened. @Tornado reported that he had recently replaced sprockets due to his old ones becoming shark toothed. I've suffered that before too.

I'm aware of some commercially available hardening compounds (eg: Cherry Red) that could easily be used at home with flame heating, but.. is it necessary?

So.. has anyone tested (or know of someone who has tested) sprockets for hardness?
Cheers
Click to expand...

You’re just looking for excuses to use your new toy !!
 
FWIW...I milled my rear drum sprocket (new AN part) to accept 520 chain with standard China made tool steel end mill.
Sprocket Hardness?
 
I am serious here though.
Proper hardness would reduce wear of the sprocket and chain and extend time between adjustment requirements.
Maybe commercially available sprockets are properly hardened - I don't know.

The sceptic in me says that some businesses might machine a 3/8" sprocket down to 1/4" and not bother with re-hardening.
They wouldn't do that though... would they? :oops:
 
MikeG said:
FWIW...I milled my rear drum sprocket (new AN part) to accept 520 chain with standard China made tool steel end mill.View attachment 121290
Click to expand...
I doubt rear sprockets are as hard as front/countershaft sprockets! Don't forget, many applications use Dural rear sprockets.

Equally, I'm not sure hardening suits the friction characteristics of the drum. I suppose any hardening would focus on the teeth?

Of course, if you had machined the other side, you could have increased tyre clearance! Or were you maintaining the chain line?

I have a full set of 530 rear sprockets machined on the inside for tyre clearance! Even though 520 blanks would have been available off the shelf.
 
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Yes - I doubt it's commercially viable to find a castable steel that can achieve good hardness and the expense of doing the hardening.
The drum is very heavy for a sprocket

Still - if no-one has done it (we'll see?) it would be interesting to what could be achieved.
 
I bought a brake and hub assembly from Don Pender recently and machined it to suit 520 from 530 and it is hard. Probably flame or induction hardened like most front sprockets. But i don't think a rear sprocket has to be hard because of the large diameter. I think chain lubrication is important if you want things to last as long as possible. A lot of people don't lube their o ring chains for fear of getting a dirty wheel! And every thing probably wears out quickly as a result. But they probably don't do many miles!
 
MikeG said:
FWIW...I milled my rear drum sprocket (new AN part) to accept 520 chain with standard China made tool steel end mill.View attachment 121290
Click to expand...
Best I can tell, the originals were case hardened. Assuming the current AN drums are also case hardened, you milled it off and may have a short life.

The one Item I consistently buy from RGM is their Commando cush drive drum for 520 chains: https://www.rgmnorton.co.uk/buy/commando-cush-drive-rear-wheel-sprocket-5-8-x-1-4-uk-made_4239.htm AFAIK, they are case hardened. They do not wear fast and are less expensive than the standard one from AN. They are advertized as UK made.

I'm no metallurgist, but as I understand it, you would not want a hardened drum as it would be too brittle, but a case hardened one will save the sprocket teeth without making the drum brittle.
 
velo54 said:
I bought a brake and hub assembly from Don Pender recently and machined it to suit 520 from 530 and it is hard. Probably flame or induction hardened like most front sprockets. But i don't think a rear sprocket has to be hard because of the large diameter. I think chain lubrication is important if you want things to last as long as possible. A lot of people don't lube their o ring chains for fear of getting a dirty wheel! And every thing probably wears out quickly as a result. But they probably don't do many miles!
Click to expand...
Velo,
I run an x-ring 520 chain with an RGM rear drum and the only maintenance I do is to wipe it down periodically with WD40.This combination has been on for over 10,000 miles with excellent results. I do appreciate not having to clean the rear rim constantly running shouldered alloy wheels.
Just my two cents but I would do it again.
Mike
 
Hi Mike, I run an X ring 428 chain on my 500 velo and the only maintenance i do is lube the chain and constantly clean the rim! This combination has been on for 37,000 miles. Chain and sprockets still excellent. I don't appreciate constantly cleaning the rim, but that's ok. Chain always looks grubby. I do like the look of clean chain and wheels. Got rid of the mud catchers a long time ago. All the best, Graham.
 
I have been using Motul chain cleaner followed by (a few hours later to ensure the chain is dry!) Motul C4 lubricant. There is very little fling, especially after the first ride.
A while back I posted this wheel & tyre protector, which makes application less messy.
robs ss

Post in thread 'Tools You Have Made to Maintain your Norton'

The recent thread on chain types and maintenance got me thinking.
This is made from 1mm polycarbonate sheet (from local hardware shop) and slips up behind the chain and drum (the cut-out is for the drum)
Gives protection to the wheel, etc while washing and relubricating the chain on the bike. Just needs a few sheets of newspaper under it to keep the floor clean.
It rests forward against the centre stand. The 380mm dimension suits my bike on scissor-jack. Needs reducing if only on centre stand.
Cheers

Tools You Have Made to Maintain your NortonTools You Have Made to Maintain your Norton
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I seem to do this every 500 miles of so.
Cheers
 
The hardness and ductility of a steel depends on its chemical composition and the heat treatment. For something which is tough and not brittle 3% nickel and 1% chromium might be good. Some rear sprockets are aluminium.
 
Drum brakes are usually either cast iron or aluminium with a liner. For a race bike - spool hubs with sprockets and discs are usually better. My mate has a Triton 650 with a decent drum front brake. It is two BSA cast iron 8 inch drums mounted with a spacer between them. It is heavy, but excellent - that is very rare. Usually with a drum front brake, it is dangerous to brake in the middle of a corner.
 
....unless there is a train crossing in the middle of the corner - in which case it is dangerous not to brake!
But the hardness if the sprocket is irrelevant... No?
 
CanukNortonNut

Thread 'Can you believe I limped it home on that!'

Well it was a nice day outside; cool…barely 50 degrees Fahrenheit. Still it did not stop me so I was out with the 74 Commando Interstate and just hitting some of the twisty roads where I live, which are totally nothing compared to the Asheville NC Rally I went to this summer. We are pretty much considered flatlanders in Southern Ontario. I was just trying to roll the Odometer to the 50000-mile mark just to finish off the season. I was coming up to a T intersection with another M/C rider slowly creepin up behind me. Well just to show off I pull out and give it the boots and all of a...

850commando

Thread 'replacement countershaft sprocket quality'

the basketcase 73 needs a new countershaft sprocket. I ordered one for a well known supplier with the promise of "made in England".

the original sprocket which came of the bike tested at a rockwell c 64 hardness, the replacement was stamped "made in England" but can't even get on the rockwell C scale. it showed a surface hardness of 88 brinell. it looks like the original sprockets were through hardened, and the new stuff just has a surface hardening.

does anyone supply good sprockets with the quality of the original ones?... i'm sure there are may who will sell the surfaced hardened...

Sprockets! | Norton Owners Club

www.nortonownersclub.org www.nortonownersclub.org
 
74ok said:
CanukNortonNut

Thread 'Can you believe I limped it home on that!'

Well it was a nice day outside; cool…barely 50 degrees Fahrenheit. Still it did not stop me so I was out with the 74 Commando Interstate and just hitting some of the twisty roads where I live, which are totally nothing compared to the Asheville NC Rally I went to this summer. We are pretty much considered flatlanders in Southern Ontario. I was just trying to roll the Odometer to the 50000-mile mark just to finish off the season. I was coming up to a T intersection with another M/C rider slowly creepin up behind me. Well just to show off I pull out and give it the boots and all of a...

850commando

Thread 'replacement countershaft sprocket quality'

the basketcase 73 needs a new countershaft sprocket. I ordered one for a well known supplier with the promise of "made in England".

the original sprocket which came of the bike tested at a rockwell c 64 hardness, the replacement was stamped "made in England" but can't even get on the rockwell C scale. it showed a surface hardness of 88 brinell. it looks like the original sprockets were through hardened, and the new stuff just has a surface hardening.

does anyone supply good sprockets with the quality of the original ones?... i'm sure there are may who will sell the surfaced hardened...

Sprockets! | Norton Owners Club

www.nortonownersclub.org www.nortonownersclub.org
Click to expand...
Yes I remember starting that thread and going down that rabbit hole... quite a few years ago.
Go for the EMGO-Taiwan Norton sprocket (Dynodave's post #63) as it is closer to Original Spec. in Hardness. Nothing has changed for the" Made In England " type in all these years. They figure that not too many people ride there Nortons for any high mileage to worry about it.
Part number: 95-91221 for a 21 tooth final For the Emgo brand. I also Tested these at: 54.2, 51.1, 53.9, 56.6 Rockwell C...after I got 2 in the post. 2nd one was 52.9, 55.5, 54.8 RC.
Drums will be soft.
Cheers,
Tom
 
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