Look Ma- no chain

comnoz · Jan 25, 2011

Had to show off what I whittled out this evening. Jim

Hobot · Jan 25, 2011

Now that's bragging rights as cogs usually take lots of expensive jigs to get the teeth spaces just right. Now you'll have to break the chain oiling habit like me.

comnoz · Jan 25, 2011

hobot said:
Now that's bragging rights as cogs usually take lots of expensive jigs to get the teeth spaces just right. Now you'll have to break the chain oiling habit like me.

Forgetting to oil the chain will come really easy. Darn near have it down now. That's why I have to buy a new sprocket every year. Jim

pbmw · Jan 25, 2011

Did you machine it?
Pics of setups....

Hortons Norton · Jan 25, 2011

Is there anything you haven't thought of yet?????? Nice work Jim, My S-1 Buell has a final drive belt. Sometimes I wonder how it can take all that abuse, LOL. But belts can outlast chains by a long shot, And the buell was 91 h.p. stock.

comnoz · Jan 25, 2011

pbmw said:
Did you machine it?
Pics of setups....

Actually the center is a stock sprocket with the teeth removed with a tool post grinder. Then I pressed a steel ring over it and sweated it in place with brass and trued it up in the lathe . Then I cut the tooth contour with a staight 1/8 inch bit in a CNC mill. Jim

askdoctorday · Jan 25, 2011

That is damned impressive. What's the plan for the rear sprocket?

Hobot · Jan 25, 2011

Yeah, the lazy sprocket waster has not finished his cam belt drive just them whining gear drive and no effective compression release for skinny Icabod's like me.

There's final belt drive kits already for Triumphs and Commandos. Wider than a chain which might limit some tire sizes. Main weakness is if the edges get frayed, think grit, then can un ravel to end up jammed around the drive pulley. Definitely don't want to try Alaska trip w/o a few extras on hand.

comnoz · Jan 25, 2011

I have an adapter on my MK3 rear hub that accepts a common 5 bolt sprocket. I ordered up a piece of 1 inch thick aluminum disk 11 inches in diameter. I should be able to CNC it from that and then I will have it anodized. Jim

The new carbon fiber polychain belt is actually narrower than the 530 o-ring chain I have been running and much stronger. The price is scary though.

Jeandr · Jan 25, 2011

comnoz said:
Had to show off what I whittled out this evening. Jim

Déjà vu :wink:

Jean

Can't wait to see the whole thing completed. Did you use a commercial lenght belt?

comnoz · Jan 25, 2011

Yes, it's an off the shelf belt. I designed it using Gate's drive designer program. Jim

Jeandr · Jan 25, 2011

comnoz said:
Yes, it's an off the shelf belt. I designed it using Gate's drive designer program. Jim

Will you have to modify the swing arm or you played with the number of teeth on the front and back so that it matches the current position of the back wheel? What is the width of the belt you are using? (mine is a 20mm) Are you doing this for fun or are you planning to come out with a kit in the future?

Jean

comnoz · Jan 25, 2011

It is a 20 mm belt. I sized it to fit without modifying the swingarm. It came out at 30 to 63 teeth to be very close to my present ratio. It should come out about centered in the adjustment range and allow for + or -1 on the front sprocket. If their formula works like it is supposed to.
I don't foresee making this available as a kit in the near future. I have too many irons in the fire now.
Did you make up your own drive? Jim

Jeandr · Jan 25, 2011

I used a 32 tooth front pulley and a 70 tooth rear pulley and then chose the belt so that it was long enough which was too long for the stock swing arm, at any rate the rear pulley was too big and id not clear the left side of the swing arm, this led me to make a new swing arm and rather than have wasted space in front of the wheel, I put the oil tank there...

Jean

comnoz · Jan 26, 2011

Jeandr said:
I used a 32 tooth front pulley and a 70 tooth rear pulley and then chose the belt so that it was long enough which was too long for the stock swing arm, at any rate the rear pulley was too big and id not clear the left side of the swing arm, this led me to make a new swing arm and rather than have wasted space in front of the wheel, I put the oil tank there...

Jean

Yes I have admired your ingenuity in the past.
I looked into doing a belt 15 years ago but after talking to Gates I found I would need either very large sprockets, or a 30 mm belt unless I went on a major diet. I think with a 30-60 ratio on the rear they were saying I would exceed the tensile member strength of a 20 mm GT belt with 550 lbs bike and rider.
Since I geared up the primary and specified the carbon belt they said I would be safe with a passenger and luggage with the narrower belt. Jim

bwolfie · Jan 26, 2011

I like the belt idea, i might try it in the future. What's cool is Gates is making conversions for many things, including human powered 2 wheelers.

http://www.carbondrivesystems.com/insta ... hp?lang=us

Jeandr · Jan 26, 2011

comnoz said:
or a 30 mm belt unless I went on a major diet. I think with a 30-60 ratio on the rear they were saying I would exceed the tensile member strength of a 20 mm GT belt with 550 lbs bike and rider.
Since I geared up the primary and specified the carbon belt they said I would be safe with a passenger and luggage with the narrower belt. Jim

Some of HDs big twins run with 20mm belts so I figured that size would be OK for a smaller and less powerefull old Norton. My belt is kevlar, not CF.

Jean

Hobot · Jan 26, 2011

One neat feature of belts is they never need adjusting so can fix the pulley
centers distance. or put a belt tensioner on it, especially is swing arm motion
changes the slack/strain very much in use. hobot

comnoz · Mar 21, 2011

Well after trying to shape a sprocket from aluminum with the CNC I decided it was going to take days plus a pile of small shapers so I ordered up a custom profile cutter [ouch] and got the rear sprocket and carrier cut out this weekend. Still need to do some relief cuts to lighten it and make it trick.

bwolfie · Mar 21, 2011

comnoz said:
Well after trying to shape a sprocket from aluminum with the CNC I decided it was going to take days plus a pile of small shapers so I ordered up a custom profile cutter [ouch] and got the rear sprocket and carrier cut out this weekend. Still need to do some relief cuts to lighten it and make it trick.

Looking good. Can't wait to see the finished result. What's with the Lathe 101 no-no in the background?

Look Ma- no chain

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