3D Motorsport Clutch on Briggs Powered Schwinn

msrfan

Well-Known Member
Sep 17, 2010
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Southern California
Except for the clutch, this is a pretty traditional build for me. Standard Chicago Schwinn cantilever frame cruiser with a Briggs flathead engine. This bike is being built by my grandson, Greg, and me for his friend James's dad, Tim. He's given us some design parameters, like full fenders and rear rack, and is leaving the drive train to us. So we're going to experiment with the manual clutch.



First, I turned the sprocket down on a lathe and screwed it back onto the clutch basket, as it supports the bearing. Then I machined a solid 3 1/2'' pulley until it fit where the sprocket used to be. I fastened it to the basket with six countersunk screws from the inside. I may need to machine a pocket on the outside of the pulley for another support bearing.






Next I made a 5'' aluminum pulley with a 3/4'' center and broached a standard 3/16'' keyway to fit the jackshaft.






So we're starting with a 2 1/2'' engine pulley going to the 5'' jackshaft pulley for the primary drive. Using a standard Whizzer 15'' pulley on the rear wheel powered by the clutch pulley will give us the desired overall drive ratio, same as most Whizzers.
The engine will slide in it's mount to tension the primary and the rear wheel will do the final drive. That's the idea anyway so we can make a solid mount for the jackshaft/clutch assembly. The keyed shaft will be supported by bearings with the clutch sandwiched between them and the other pulley will be outboard.
That's as far as we got so far. I sold Tim a moped fuel tank and Greg will supply the motor. We've acquired the rear pulley and some heavy spokes also.
Next I'll lace the new spokes into the S-2 rims that came on the bike and install the pulley.
 
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3dmotorsportLLC

New Member
May 13, 2016
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San Diego
That is looking great so far. You won't have any bearing related issues as a result of belt tension- just tighten up the tension until it stops slipping.

If it's something that you're concerned with, you could always go with a 15T sprocket, which has the bearing directly in line with the sprocket teeth. Or as you suggested, press in a second bearing right next to the first.

If you want to go the latter route, let me know and I'll send you an extra bearing.
 

msrfan

Well-Known Member
Sep 17, 2010
1,799
95
48
Southern California
That is looking great so far. You won't have any bearing related issues as a result of belt tension- just tighten up the tension until it stops slipping.

If it's something that you're concerned with, you could always go with a 15T sprocket, which has the bearing directly in line with the sprocket teeth. Or as you suggested, press in a second bearing right next to the first.

If you want to go the latter route, let me know and I'll send you an extra bearing.
Thanks. I'll let you know if there's any distortion with tension. Don't want the friction plates binding in the basket.
 

curtisfox

Well-Known Member
Dec 29, 2008
5,155
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minesota
HO! Here we go, got to watch this. Thinking on buying one of these clutches myself. As always love your work and builds................Curt
 

curtisfox

Well-Known Member
Dec 29, 2008
5,155
1,578
113
minesota
Working on my own version ( antique style old Rudge motor cycle ). If that falters then I will by. Mean time will watch msrfan's build, and maybe loner,LOL................l.Curt
 

MkowaOweno

New Member
Nov 1, 2016
2
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Russia
Got the Briggs outboard mounted on the boat couldnt run it on maiden voyage because we were on an electric only lake. Im going to get the steering wheel assembly throttle and shift cable made and connected next and then Ill see how it works on the river.
 

msrfan

Well-Known Member
Sep 17, 2010
1,799
95
48
Southern California
Wondering, reason for clutch mounted on Js...what is advantage? What happened to pics?
Hey scratch, finally getting back to your question. The clutch mounted on the jackshaft allows for a narrower engine.

Meanwhile this build has stalled while the owner gathers more resources. The good news is I decided to use the belt clutch on a different bike and have a build thread with lots of photos.


http://motorbicycling.com/showthread.php?t=62250