why not a v-belt?

prime mover

prime mover

Member
#1
#1
From the engine to the jackshaft? I think I'm gonna try it and if it sucks it wont be hard to change it to a chain, a lot of people talk about slippage and power loss but why are they used in so many other applications? pumps, winches, washers, and not to mention cars, how many hundreds of horsepower have I revved a small block turning a alternator pulley the same size? the ones that hold more power like the water pump are a little larger with more surface area.
any facts out there?
 
125ccCrazy

125ccCrazy

Well-Known Member
#2
#2
prime mover said:
From the engine to the jackshaft? I think I'm gonna try it and if it sucks it wont be hard to change it to a chain, a lot of people talk about slippage and power loss but why are they used in so many other applications? pumps, winches, washers, and not to mention cars, how many hundreds of horsepower have I revved a small block turning a alternator pulley the same size? the ones that hold more power like the water pump are a little larger with more surface area.
any facts out there?
Click to expand...


don't forget that your turning barely any weight with little drag on an alternator compared to trying to move 150-200lbs or more with bike and rider... Most of the belt applications like you mentioned have little drag to bog them down and cause slipping...
Once you got rolling you will probably be okay, it will be the initial take off and then any uphill pulls that will give you trouble..

try it, if it doesnt work go with a chain or a torqueconverter set up..
 
F

Family Dad

Member
#3
#3
i have that setup on my columbia and it works good for me. im 200 lbs and it doesnt slip at all. you might have to try different size pulleys to get the ratio you want.
 
Oldsalt

Oldsalt

Well-Known Member
#5
#5
Get a catalog on belts and sheaves [pulleys] from your local bearing supply house and take a look at the "A" and "B" belt data. It gives RPM at HP at various sheave diameters. It will quickly become evident that belts are a very viable alternative to chain. That is, if the components are properly chosen. Soon as I get a chance I'm going to do it.
 
shoe

shoe

#6
#6
"don't forget that your turning barely any weight with little drag on an alternator compared to trying to move 150-200lbs or more with bike and rider " If you ever do any car repair you will know that this is wrong ,, testing an alternator will slow down an engine ,, its more drag than you think ,, I can remember when taking the alt belt off at the drag strip was a hop up mod ,,
 
Vette

Vette

Member
#9
#9
Since the belt is used on the primary side of a jackshaft system, the load on the belt is reduced by the amount of gear reduction from the jackshaft to the rear wheel sprocket.
This would be about the same belt load as with a torque converter system, of course trying to run a v belt setup without a jackshaft would not work at all.
I am going to change a bike over to belt since I already have a belt clutch and the bike seems exceptionally noisy with two chains running on this bike.
 
prime mover

prime mover

Member
#10
#10
part of the reason I'm doing this is all I need is a jackshaft, I have lots of pulleys and bearings, the sears bike already has the mounts for the jackshaft, and I'm gonna run the clutch on the shaft to the wheel and maybe a band brake on the outside of the clutch, oh yeah I'll have to buy a band too.
 
J

jimh

#11
#11
The Sears bikes with jackshafts had a 3"band brake on the jackshaft, also a scrub for backup. You should be able to run a belt from the engine to jackshaft without a problem. backyard builders scratch built mini has a belt drive all the way and he says it works fine. I have an engine with a strange crank that is 5/8 and keyed at the end. I plan to do the same thing you are. Belt to jackshaft, and clutch on jackshaft to drive the rear wheel.
 
E

Engine Dad

New Member
#12
#12
The modified bike I just picked up has a belt drive from the clutch to the jackshaft. It looks like the previous owner did it with pieces he had laying around I need to clean up the whole assembly, but I can tell you that a belt will definitely transfer power with no problem.

 
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