Secondary Belt drive

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gripper

gripper

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Dec 3, 2010
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I know Comnoz has a belt drive on his disc braked rear wheel, but how difficult would it be to shrink a belt pulley onto a turned down rear drum on a 70 Fastback? I've briefly searched for any threads on here. Is there likely to be a clearance issue at the back of the primary chain case or along side the rear wheel? Just something to do to while away the long winter evenings before I scrap the old drum and gearbox sprocket.
 
I think the challenge, much like trying to get a replaceable sprocket is there's not a lot of meat back there.

I think madass or someone is coming out with a new hub. That might work better.
 
I thought only low-powered machines (like Harleys) could use a belt final drive due to the width necessary to handle the power. Recently I read an article about belt final drives that basically said if a modern sport bike had a belt drive, the belt would have to be 5-6" wide! :)
 
I thought only low-powered machines (like Harleys) could use a belt final drive due to the width necessary to handle the power.
Click to expand...

my god!

I thought our 1970s Commando qualify as low powered given they have only some 45 hp stock !

are not our motors less powerful than big twin displacement harleys weighing hundreds more pounds with belts working just fine for tens of thousands of happy owners reporting really no big issues?
 
Our Snorters can handle any darn belt system you could create.Lea is a machinist-tradesperson who tackled it, I believe it still uses a drum, but she would know more.She has machined alloy clutch components too for belt.
 
Modern belts have the capacity to handle a lot more power than most of us will ever use. My Buell 1125r is in the 140 hp, 80 ft tq category and advertised as having a 168 mph top speed. Belt problems are not common with these bikes.

Bob Oswald has done at least one Commando rear belt drive. Jim Comstock has not babied his ride. I say live the dream
 
I need to come up with something for the bike in my avatar picture. I have tried several times to find out more about QPD's kit, but I can never get a hold of him. And Jim is too busy to make kits to sell :D
 
Yes Lea fitted a QDT iirc but had issues she outlined to point she re-did most the primary to final drive pulles and fittings. LIkely a google with search terms and accessnorton will pull up the threads on belts Lea impressed us with. Jim Comstock also went through a couple re-do on his final belt drive so may stumble on his detailed in not setting us straight again here.
 
Lea had difficulties with the rear belt drive and had gone back to a chain when I talked to her at Barbers this year.

A rear sprocket can be made as a layover for the original sprocket, just leave the teeth intact.
The rear of the chaincase must be machine away behind the clutch drum for front pulley clearance. Jim
 
I worked with Ozzie of QPD to make a Belt Final Drive for my slimline featherbed project.
He is trying to retire, and isn't the worlds best communicator - it took over a year.

... putting it mildly, clearance has been a major issue, and I am not sure I would want to to it again.

I think the Commando would be the same as the Featherbed in that you would need a custom or heavily modified (read butchered) swinging arm.
 
I didn't have to do anything to the swingarm to install the belt. The only clearance issue was the backside of the primary chaincase. Jim
 
I'm going to adapt a Buell XB9R system. With the Kimtab wheels and custom swingarm I can make the pulley fit with an easy to make adapter spacer.
 
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