Author Topic: Monty chain conversion  (Read 456 times)

Offline SeeDoubleYou

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Monty chain conversion
« on: July 11, 2018, 18:04 »
Sorry I know its been done on here, but I cant work out whether the things Ive read relate to a triple or to a 500 so here goes:

Can someone let me know what 520 or similar chain I can run on a 500 race bike? Is there an equivalent front sprocket from something Japanese I could use perhaps? Ill be drilling and machining the rear sprockets from aluminium blanks so thats not an issue

Thanks


Offline KERMIT1200

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Re: Monty chain conversion
« Reply #1 on: July 11, 2018, 19:18 »
Hi,
 Buy a 530 gearbox sprocket and turn it down to fit.
I'm not aware of a 520 gearbox sprocket  off  another that you can use.

Andy

Offline Tippie

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Re: Monty chain conversion
« Reply #2 on: July 11, 2018, 20:49 »
Talk to Jason the Chain Man who has taken over the mantle from Andy re good racing chain.
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Offline LaverdaIan

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Re: Monty chain conversion
« Reply #3 on: July 12, 2018, 00:20 »
What Andy said.. I'm running 520 on Monty, but that what was required to do it.

 8)

Online Dellortoman

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Re: Monty chain conversion
« Reply #4 on: July 12, 2018, 01:46 »
Buy a 530 gearbox sprocket and turn it down to fit.

They're made from hard steel so I'd guess they're not that easy to turn down (not actually tried it myself).

It may need to be ground rather than turned with a cutting tool.
Location: Tasmania, Approx 4253S 14723E

Online sfcpiet

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Re: Monty chain conversion
« Reply #5 on: July 12, 2018, 06:53 »
They're made from hard steel so I'd guess they're not that easy to turn down (not actually tried it myself).

It may need to be ground rather than turned with a cutting tool.

It can be done, with the correct tools and a little patience.

Grinding actually requires a lot more patience...

piet
180s feel quick, 120s are...      If it ain't broke, fix it till it is.

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Offline GregT

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Re: Monty chain conversion
« Reply #6 on: July 12, 2018, 08:19 »
It can be done, with the correct tools and a little patience.

Grinding actually requires a lot more patience...

piet

It's easier if the sprocket is softened first.....Just heat to cherry red and allow to cool slowly.
To reharden post machining, heat to cherry again and quench in oil.

Online Dellortoman

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Re: Monty chain conversion
« Reply #7 on: July 13, 2018, 01:39 »
Quenching is a bit of a mysterious art. Some people use water, others choose oil.

Oil quenching gives a slower cooling rate than water. It is less likely to induce internal stresses (and possibly cracking in some alloys) but you lose a bit of hardness.

Cracking is not usually a problem in most carbon steel alloys, so I normally quench steel in water. Mainly because it's easier to get a bucket full and is less messy than oil. If you're worried about brittleness, you can temper it after quenching. Just crank your oven up to its highest temperature and chuck the sprocket in for a couple of hours. That'll be enough to relieve internal stresses and reduce brittleness.

Another quench method is to set your hose nozzle to a fine spray and then spray the sprocket until the surface just loses its red glow, then let it continue to cool slowly in air. The quenched surface will be hard, and the slow cooled core will be more ductile for toughness. The heat from the core as it cools will also self-temper the quenched surface metal. It takes a bit of finesse to get it just right, so probably not a reliable method for a novice metal worker.

When I was an engineering student, the metallurgy lecturer said that heat treatment of steel was developed in medieval times when they were making a lot of iron alloyed edged weapons. But it was as much alchemy as it was science. Apparently they got good results with swords that were quenched in urine. They wouldn't have known at the time that urine contains nitrogen which would have diffused into the surface metal, giving a kind of case-hardening effect. There were all sorts of hocus-pocus quenching recipes in the middle ages, like swords should be quenched in the urine of a red-headed boy, or the urine of a pregnant cow.

Anyway, if you want to give it a try, heat your sprocket up to cherry red and then piss on it.  :D
Location: Tasmania, Approx 4253S 14723E

Offline Robin Webster

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Re: Monty chain conversion
« Reply #8 on: July 13, 2018, 07:48 »
I had a bunch of fronts and rears made to suit my 500 in 520, wasnt a problem. Try the usual suspects.

Robin.  :D
Wishing I was Racing.