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 only, but the testing equipment can see right through the short cut in fabrication. when the the surface hardening is worn off the sprockets will fail quickly also failing the chain.

does anyone know the grade of steel used in the fabrication of the original sprockets?

you might get a nos from Russells Falcon Road London

You are revisiting a problem well discussed about 2 years ago.
do a search...forums have amnesia you know!!!
The "made in england" are known to have an issue. I was told made by velocete? I don't know?
British cycle supply took back one of these new soft ones and sent me an EMGO sprocket....
The EMGO was very hard...IIRC 56RC (I have a tester), However the machining quality is a little less good and had to be offered to the sleeve gear and rotated a spline several time then it finally slipped on.

bummer the pix are gone

can-you-believe-limped-home-that-t23484.html

dynodave said:

You are revisiting a problem well discussed about 2 years ago.
do a search...forums have amnesia you know!!!
The "made in england" are known to have an issue. I was told made by velocete? I don't know?
British cycle supply took back one of these new soft ones and sent me an EMGO sprocket....
The EMGO was very hard...IIRC 65RC (I have a tester), However the machining quality is a little less good and had to be offered to the sleeve gear and rotated a spline several time then it finally slipped on.

Click to expand...

Yes i remember that discussion but could not track it down. how valid is your 2 yr old assessment of the Emgo sprocket. are the current emgo sprockets still up to the Rockwell 65c? and who stocks them?

You could case harden it yourself using a case hardening compound.

Kasenit replacement available on eBay for about £10 /100Gm (UK)

850commando said:

dynodave said:

snip
British cycle supply took back one of these new soft ones and sent me an EMGO sprocket....
snip

Click to expand...

Yes i remember that discussion but could not track it down. how valid is your 2 yr old assessment of the Emgo sprocket. are the current emgo sprockets still up to the Rockwell 65c? and who stocks them?

Click to expand...

British cycle supply took back one of these new soft ones and sent me an EMGO sprocket....
British cycle supply took back one of these new soft ones and sent me an EMGO sprocket....
British cycle supply took back one of these new soft ones and sent me an EMGO sprocket....

My RC # was incorrectly recalled but the EMGO was very hard

gripper said:

You could case harden it yourself using a case hardening compound.

Click to expand...

Or you could heat treat it yourself...

https://www.youtube.com/watch?v=ulfCxDsVTWo

https://www.youtube.com/watch?v=hw4Rl0uG7ok

Let us know how it goes!

850commando said:

...i'm sure there are may who will sell the surfaced hardened only, but the testing equipment can see right through the short cut in fabrication. when the the surface hardening is worn off the sprockets will fail quickly also failing the chain.

Click to expand...

As found from one of the main chain manufacturers (I think it was Diamond) ..."The hardening process of small diameter, small pitch sprockets (that's us) is usually a one-step procedure: heat treatment (electrical induction).This method is used to provide a high hardness at the wear areas, plus provide the ability of the tooth to absorb shock loads. This is accomplished by hardening only the wear area of each tooth while maintaining a ductile tooth core which is tough and resilient." If you're to the point where the case-hardening is gone, you've reached the useful life of the drive system, chain and all.

Nathan