Roller Balancing

[evilone]

I would think the heavier weights would want to spin out farther with less rotational force than the lighter weights.

True, but the lighter weights would want to move SOONER. who wants to test this? Not me

Do heavier weights equal a higher top end speed, and lighter weights mean fast early exceleration?

That's what i've heard and believe from personal experience.

[Wheelman-111]

Greetings:

There's a lot about this in the Tech Docs or somewhere.

Rollers don't add speed or acceleration, exactly. The forces they generate spinning around in your variator just act to balance the Contra spring pushing against the driven pulley. CVT = Constant Velocity Transmission, get it?

Subtracting variator weight - by choosing lighter rollers - moves the "balance point" up the rev scale. Adding weight moves it down. If you go too light, the engine spins up and beyond its torque and power peak, making the bike seem like it's in first gear. This of course is slow and will fry your bore if you abuse it. If you go too heavy, the belt will climb to the top of the drive face too soon, before the engine ever reaches its torque/power peak. This is slow too, like shifting into 5th while climbing a hill. You can't get off the ground unless a steep downhill intervenes.

I experimented a lot with this. Stock was 10 grams, which suits the stock engine's low-RPM grunt very well. Moving to 9 grams with a bore kit allows the engine to spin up a little more. When I added too-tall gears from Malossi (7.83:1) I needed to compensate with lighter weights just to get off the ground. Still lighter with a piipe that emphasizes high-RPM power over low-end grunt.

Early on, I bought a set of those "mixing rollers" off eBay. The set I bought had only 3 of each gram weight. I kept moving down until I found the combination that kept Flash II's engine singing in its "sweet zone" of 8250-8500 RPM. Remember each swap requires considerable disassembly. Nobody said tuning was for wimps.

Ideally, the variator will "top out" just as the groundspeed matches the rolling resistance and aero drag with the engine smack-dab in the middle of its power peak, howling in all its magnificent mechanical mayhem heading for the rarefied ether of ... well, something over 40 at least.

Anyway, with my setup, a set of six 5.6gram rollers seems about right. Your setup likely will not be the same. If you start changing rollers, don't muck with anything else - like the Contra spring - or you have to start all over.

[Arnadanoob]

So I must have slept through that physics lecture, because intuitively I would think the heavier weights would want to spin out farther with less rotational force than the lighter weights.

That being said, what does having mixed weights gain you? Do heavier weights equal a higher top end speed, and lighter weights mean fast early exceleration?

Here's a way to test your theory. Get a very light styrofoam ball and attach a string to it. Now imagine doing the same with a bowling ball. Now you try to spin both balls in a circular motion with only the string being the anchor to your hand. It's much easier to get the light styrofoam ball to spin circles due to it's lower inertial mass. The one with the bowling ball has exponential amount of inertial mass than the styrofoam ball so it'll require more force to get it moving. However because of the bowling ball's higher inertial mass, it also is less susceptible towards slowing down, which means when the variator's rotational speed drops, the first rollers to step away from the ramp plate will be the lighter rollers leaving only the heavier rollers to remain closer to the ramp plate.

Now translate this into what goes on in the variator, the rollers are at rest when it's closest towards the center. When the variator starts to spin slowly, the lighter rollers move out first because of their lower inertial mass (meaning they respond to even the slightest amount of force) compared to the heavier rollers. At some point the lighter rollers will beat the heavier rollers to the ramp plate and will start to push against it, however because the lighter rollers have much lower mass, it won't be able to move the variator all that much until the heavier rollers coincide with them on the ramp plate to add to the total mass of the rollers.

In reverse, the lighter rollers (due to their lower mass) can store less energy than a heavier roller. What this means is when the variator slows down, the lighter rollers give up pushing on the ramp plate first. The heavier rollers will be able to store more energy meaning once it gets moving, it's more hesitant to slow down... like rolling a bowling ball down the street, it takes more effort to get going but once it's moving, you get the idea. The heavier rollers will remain furthest away from the center of the variator when it spins down.

I'm sure you can try this if you have a roulette wheel with a glass marble and a ball bearing.

[Fishman43]

I experimented a lot with this. Stock was 10 grams, which suits the stock engine's low-RPM grunt very well.

Was this stock weight for and Aero? Will changing to a Ruckus variator change the best weights (just ordered a used one from a member here)?

I'm sure you can try this if you have a roulette wheel with a glass marble and a ball bearing.

d*** my gambling addiction.

[Wheelman-111]

Greetings:

10gs were stock in my '87, and (I've read) in virtually all the variated scooters up to 2001. Someone will let us know otherwise.

I'm inclined to think the same weights will work in one variator as well as another. It was the case with the 4 (yes, FOUR!) different variators that occupied Flash I and II's output shafts.

Noob's theory is interesting, but I disagree. Heaviest rollers push against the spring first and last, bearing most of the force all the time. The lighter rollers assist but the tension is highest where the heavier rollers wedge between the vario ramps and the plate. For sure they wear out faster.

[Arnadanoob]

One day when I'm bored out of my mind, I might consider making a modified roulette wheel with channels (so that the weighted balls can only move from the center of the wheel to the outer perimeter in a straight line like a variator).

The reason why I don't believe my theory is flawed is based upon mathematics. If you don't like the nerdy stuff, don't read on.

When a variator spins, the force that's applied to the lighter roller is no different from the force applied to the heavier roller because the variator is spinning at 1 speed for both. With that being said, the force being applied to the rollers are equal.

We know that Force = Mass x Acceleration

We agreed that the Force variable (F) is the same for both. So let's use a Force value of 10, thus F=10.
We know the mass of the object since it's measured in grams. Let's say that the lighter roller is 1, the heavier roller is 10 to keep things simple.

Now the question is the rate of acceleration.

For the lighter roller, F = M x a or 10 = 1 x a. The acceleration value for the lighter roller is 10.

For the heavier roller, F = M x a or 10 = 10 x a. The acceleration value for the heavier roller is 1.

As you can see the lighter roller will be the one to move first and at a faster rate than the heavier roller.


What Wheelman states is correct on the roller wear, the heavier rollers will wear down faster than the lighter rollers. This can also be proven using math.

Using the same formula for Mass x Acceleration = Force ...

Once the rollers are pressing against the ramp plate, its forward motion is limited by how much the variator is resisting movement. This will limit the acceleration variable for both the lighter and heavier rollers.

For this example the acceleration value is the same because both roller's range of movement is limited by a combination of the ramp plate and variator resistance. Lets use a value of 1 for a (acceleration). The mass of each roller is 1g and 10g (for light and heavy rollers). Now it's a matter of figuring out the amount of force being applied by each roller.

Lighter roller will show that F = (1g x 1), thus the Force value will be 1

Heavier roller will show that F = (10g x 1), thus the Force value will be 10

The heavier roller will be applying 10 times the amount of force of the lighter roller in this example.

[carp]

Hello, All I can say is by the time I finished that one, the last marble in my almost empty head was doing about 10,000 rpm and almost exited said head through my open gaping mouth. Once I recovered, I tried that experiment, first the Styrofoam ball flinging around got the cat all excited(she made one * of a mess trying to get said sty. ball). After I cleaned up said mess I tried the bowling ball(had to use piece of chain ,string just broke) got it going about 5rpm when it got a little heavy. it slipped, said bowling ball went... bowling? Cat got scared, tore up couch(right next to lamp and table that got... bowled). Please give instructions or at least warnings and disclaimers when suggesting said experiments. Thanks, Carp p.s. It wasn't that bad ,cat didn't tare up the couch.

[z50r-ghost]

-all i can say is "a million Hawaiians can't be wrong."

The best brands of rollers out there are: factory Honda rollers, Daytona, and Polini or Malossi.

These rollers all last a really long time, and are very smooth!

jc

[evilone]

Where the heck do you get daytona rollers? Did a search with no results.

[808BMW]

Try calling VT, I bet they have it.

FYI for those of you that don't know, Daytona also makes many other tranny parts such as ramps and center springs (probably more stuff too) and it is all top notch stuff.

[Arnadanoob]

Daytona rollers aren't cheap as they go for about 15 dollars for a pack of 3. If/when you decide to use them, make sure you're done "dialing in" your variator.

I personally have a set of semi-crappy rollers to use to find the right setting, then finalize the job with Daytona rollers.