Belt vs Chain final drive

[SpeedRacer93]

I did some searching and can't find any real answers,  what are peoples thoughts on belt vs chain final drive?  This is for a motorcycle powered streamliner. 

Chain drive packaging is a little easier/narrower but brings in chain/salt issues.

Belt drives can be a little more efficient compared to chain but if both are setup correctly I think they should be within 1-2% of each other.

[Stainless1]

I've been looking at belt vs chain.... the trick with each is proper tension... and space.  The belt requires a lot of space and tension and maintaining that tension.  In my lakester I have room, but as the swingarm moves, it changes length a little, making belt tension critical.  The chain tension is not as tight and tension is not as critical... the lakester uses a fairly simple tensioner.  You can see it in my build thread... somewhere...

[SpeedRacer93]

Stainless,

I was thinking you talked about belt drive in your build but saw you went with a chain.

I know from blower belt drives I have worked with you need to get the tenson right but those don't move up and down so easier to get the tenson right. (OK blower drives may move up and down but if they do move you have other problems besides belt tenson.)

Plus if you go by true ratings a 2 inch wide belt is not that high for torque so you may have to go with a 3 inch belt which can create space issues.

[Stainless1]

I figured I could make a 2 inch belt work, power wise... but I could not figure a way to get it to tension properly... so back to chain. 

Video of the chain, on the dyno
https://www.youtube.com/watch?v=iDWUlglFBlY
 

[SpeedRacer93]

I figured I could make a 2 inch belt work, power wise... but I could not figure a way to get it to tension properly... so back to chain. 

Video of the chain, on the dyno
https://www.youtube.com/watch?v=iDWUlglFBlY
 

I am wondering if a automotive accessory belt tensor would work on the slack side of the belt.   Maybe one from a semi truck.

Two other crazy ideas would be to mount the engine on the swing arm by extending the pivot infront of motor (I have seen some pictures on that setup on the forum for a rear engine roadster.)   Or mounting the motor on a seesaw setup, Motor on one side and axle on the other side of the pivot.  The shocks/springs could be in front of the motor.  You would need additional body clearance for the motor movement.


 

[Elmo Rodge]

You might keep the belt tight but at the expense of that heavy old motor hopping up and down. Sounds scary to me. 
Wayno

[SpeedRacer93]

You might keep the belt tight but at the expense of that heavy old motor hopping up and down. Sounds scary to me. 
Wayno

I said they were crazy ideas...LOL

[Stainless1]

I think the output pulley at the swingarm pivot or a jackshaft at the swingarm pivot is the only way you will get enough tension.  Looked up the required tension for a 2 inch x 8mm tooth drive belt.  Basically if you are using a 24 inch tire you need about 4000 tire rpm to go 285... if I did the math right.
Anyway attached is the calculations from Gates.

[JimL]

There is a lot of good info online for the belt conversions in primary drives (Norton for example).  When I built my clone of a 1949 Mustang Delivercycle I used their guidance.  I was running a 4000 rpm Honda engine connected to a "cut down/welded" Kawasaki KDX 175 crankshaft.  I used an overdrive ratio to make it work.  That provided me with about 5500-6000 rpm crank speed for the 6-speed trans in the Kawasaki bottom end (which ran a chain drive to a compact diff).

Anyway, the main lesson was that "if you can't turn the middle of the belt 90 degrees sideways with your fingers, it is too tight".  I ran that trike for several years with no problems from the belt drive.

I had always thought they had to have tension, but it turns out I was wrong.

[SpeedRacer93]

I think the output pulley at the swingarm pivot or a jackshaft at the swingarm pivot is the only way you will get enough tension.  Looked up the required tension for a 2 inch x 8mm tooth drive belt.  Basically if you are using a 24 inch tire you need about 4000 tire rpm to go 285... if I did the math right.
Anyway attached is the calculations from Gates.

The 119 to 131 lbs is the same tenson as a 4 or 5 rib accessor belt (140 lbs and 150 lbs).  A 12 rib on a Cummins 14 ltr is 300 lbs.

[SpeedRacer93]

So thinking about things, one of the advantages of the chain is ease of ratio and chain changes because of the chain master link.  With the belt most ratio changes would need to be done on the motor side.  I order to change the belt or the rear end pulley you would almost have to take the swing arm off to get the belt off and on.  The belt would most likely go between were the swing arm mounts to the frame.  With a lakester you may be able to get the belt outside the frame mount but on a streamliner it would hard due to the wheels inside the body unless you do the narrow tire setup like the old setup on Bockscar 3.0.

[superleggera]

A drive belt is a great option given the technology available and durability benefits.  I talked with Sam Wheeler about it twice and the integration into his rebuilt streamliner -- it was a great option given his power application requirements. Question is how to integrate it into your chassis setup?  For my motorcycle streamliner, I went with a chain for the singular reason that I have it configured to run different engine platforms as needed over time.  If I used the same engine setup on a regular basis over a period of years, I'd do the belt setup without any hesitation.

[Rex Schimmer]

A belt drive without an additional tensioner is about 98% efficient and chain drive is around 90-91% efficient, so it looks like the belt is a good choice until you come to the "constant" tension required for the proper operation of the belt. I have, as I will bet Stainless has also, many sketches and drawings of possible ways to have suspension and a belt drive and after all of the consideration and thinking we still are using a chain. Remember if you use a belt and mount the drive pulley to the engine/tranny output shaft (assuming you are running a motorcycle engine) you have to build some sort of outboard support bearing for the output shaft as the required belt tension will kill the output shaft bearing. If you do not run any suspension then a belt is pretty simple but with the present day salt conditions I think suspension is a requirement.

If you go with a chain use a good drag racing chain that is not O ringed, much less friction if you keep it properly lubed.

Rex

[AHG]

ALL of the World Record setting motorcycle streamliners I have viewed used chain for the final drive.