Hay Jake, or anyone else, where can I find a belt drive like this?
I have a dual carb non provision 503, need redrive.

That gyro was cool, I wonder what happened to it.

It's flying in Michigan.
If I had to do it over again I would build a multi V-Belt system.
OOooooorrrr, yu can make an adapter and use this A-Box I got for you, Zero Hour by the way.
2.58:1

Kinda, sorta, like such?

I have a drive I think.... When I get home I'll look OK?

Coolness!

Yeah, but I would line the pullys up better

Whats the benefit of such a set up?
Just curious.

When you have a nonprovisional engine you can not put a gear box on it.
Some old 503's have no way to bolt up a gear box.
583 and 670 at least have the blank bosses to machine and tap to install a box.

Or you could run a Kawasaki, polaris, arctic cat, yamaha, etc, etc,

Early "Drifters" had such a belt drive. You had to make sure that you kept the belts tight though - regular adjustments.

Ok cool. Learn sumthin new every day.

Sooo.....why lots of little belts vs on big fatty?

It spreads the load Hen.... and you can loose a belt and still have 4 left in place (as long as the lost one doesn't go under the remaining ones. The one I had on a 532 machine was good at everything except full power at slow speed, the pulleys would get hot.... but cruising it was awesome. You can buy matched sets of belts too, which is good...

I don't know why the one in the pic has the motor at a different angle to the prop shaft? Maybe it is an optical illusion or camera angle thing?

It is a nice cheap redrive tho and can be made to fit any motor.... each belt can carry about 15-20Hp and you can make the pulleys to have as many belts as you need (or few)

What Muz said plus a big cog belt is like a sloppy gear drive and causes vibration and sheaves wear.
A wide micro-v is better but harder to get pullys the right size unless you make them.

They are good on a low power motor like a 447 - 503 and they are very forgiving of a little misalignment (or not so good construction) .... the things you have to watch out for is any sort of oil, grease or water even getting on the belts .... even from greasy hands.... but if you overgrease the shaft bearings and any gets on the v belts or pulleys, they just slip wildly which can be a letdown at an inconvenient moment Wear in the pulleys can occur too if belts are let to run too hot too long

When the pulleys are cold, the belts can be a bit loose, once the pulleys warm up, this can overtighten the belts. Once the pulleys have warmed up and grown to their correct size, the belts will slip less. If you take off with the motor warmed but the pulleys not up to temp, they can slip... if you tighten the belts so they don't slip when cold, they will wreck bearings when hot. The best thing is to have a tensioner on the slack side under power, which keeps tension on the belts as pulleys change size and actually gives the belts a little more purchase on the pulleys... but this adds weight and extra bearings and things. Don't plan on doing a 'go around' if you get caught in a rain storm you might not be able to get full power to the prop.

You notice alot of these issues when doing thrust tests.... on my 532 the belts were fine at 1/2 throttle... even 3/4 throttle, but as it reaches full power, the belts would start screeching and squarking and the friction will soon get the pulleys real hot. I would say it would be an excellent drive for a 503.... they don't need any dampening, they are kind on crank shafts and props..... and you could knock one up in an afternoon

Scotty here is the pic of the re-drive.
2 1/4" wide cog.
The large pulley is about 7 1/4 and the small one is about 2 3/4 ??? or something.
May have to machine the insert for the little one for the shaft of the Rotax
Free of charge.

CooL! That would be a good start!

That would be a 2.62:1 ratio if that was the cog measurement and not the total O.D.

Yeah.... treat it like a sprocket setup... count the teeth Bro.... count the teeth

FICKYALL!


Scotty the small one has 21 teeth and the big one has 63 soooo now the smart ones will figure out the ratio because I ain't doing the math!