Black Beauty

[katastroff]

2k contra spring AKA "the belt eater"

Have you tried a 1,5k ?

[90GTVert]

As humanshield said, use a genuine Bando belt if you aren't already. Careful with cheap ones as it appears some from China may be clones. Second choice would be Gates, but I still prefer Bando.

A 1000RPM contra paired with lighter weights may get you similar performance without the addition stress on the belt and it'll be easier to service.

[boostnjuice]

I agree with everything you are saying about the function of this pos setup, however I need to figure out how to fix it. If that means better parts than so be it!

So, if you were to build the best available, what would you use? What parts/brands?

[boostnjuice]

Also, I'm currently running all stock springs, and 4g rollers.

One thing I really don't like is that the non-variator drive face surface is very course, whereas all others are smooth. This may well be as this is the only half that drives the Belt and it might be for traction.

And I know that the bearings in the rear pulley are bad and this is adding heat to the equation. But just at a stand still.

[90GTVert]

I'd guess the DrPulley CVT stuff is among the best. Quite pricey though.

I went through a bunch of belts years ago. It started with buying some cheap Chinese belts. Breaking them sometimes just a few miles from home. Even tried Gates. It broke quick too. Went back to Bando and my problems disappeared. I was experiencing this on both a 139QMB and a 1E40QMB and both stopped destroying belts when I switched back to Bando. I went through painting parts of the belts and the CVT so I could see any form of contact and all kinds of stuff before I finally switched back. About pulled my hair out. I know I sound like a Bando advert, but that experience convinced me to stick with them. Not saying they'll work miracles for you, but I'd try one.

If a pulley is really rough it may be a problem. Pulleys shouldn't need much of a finish to allow grip.

[FrankenMech]

I am currently running a Gates belt after my OEM Bando belt failed on the driven side with only a few K on it. I don't have any experience with the Gates yet. I have had a lot of experience with Gates industrial products. I know nothing about Bando.

The outer steel pulley finish is probably OK. Just remember to clean and prep the pulleys as described in the Gates literature (posted here somewhere) to remove the residue from the old belt.

I don't think there are any 'Good' parts. The CVT design is the problem when transmitting continuous power. Driving only one side of the belt does not help either. It reduces the power transmission capability of the belt. The rubber band CVT just won't stand up to continuous power transmission. Belts slip when they transmit power and produce heat. Belts also heat up when they are flexed especially in a small radius. Thinner belts reduce that source of power loss and heat. Heat means power loss. Heat also destroys belts.

I am not positive because I only have a 50cc scoot but it looks like the larger displacement engines have a long spline on the crankshaft that may help drive both sides of the variator. I suspect that drive may have to go through the plastic slide bushings on the aluminum variator. That would seem to me to be adding another failure point. I have no experience with the larger displacement CVT setups though. Driving both sides of the belt would help spread out the heat load on the belt.

As an example the automotive serpentine belt was designed for transmitting more power with less heat and power loss. It acts like several thin V-belts. People don't install new serpentine belts correctly either. They just slap a new one on without resurfacing and cleaning the pulleys which leads to early failure in many cases.

[boostnjuice]

Well I ordered a Bando Kevlar yesterday from parts for scooters. I hope it's the real thing not a knock off. I'm a half hour from their warehouse so I will have it today. My stock belt was Chinese, the second was a "gates" but was printed different than most I've seen. The third was a Gates but with normal printing and lasted the longest.

I would open up my case but with it being my DD I can't have issues with rain.

[FrankenMech]

FROM GATES:
Tech Tip TT004-13
www.gates.com/~/media/Files/Gates/Automotive/Resources/Product%20and%20Application%20Bulletins/Gates%20TT00413.pdf

To ensure optimal operation of newly installed belts, the CVT sheaves must be cleaned of all old belt residue, glazing, and oils. Cleaning can be accomplished by carefully scuffing belt contaminates off the sheave/belt contact area with a mild abrasive such as 220-400grit sandpaper, Scotch Brite Pad, or Steel Wool. Follow up by cleaning the surfaces thoroughly with soapy water and or brake cleaner until all impurities have been removed. Cleaning the sheave surface until all contaminates have been removed is vital to future belt and CVT operation. If any particles remain, belt slip and a noticeable drop in vehicle performance can occur. If a belt is to be removed and reinstalled during future maintenance, it is highly recommended that the belt is reinstalled in the same direction as before to match belt wear profile to contact with the corresponding sheave profile.

New Belt Break In Process:
New CVT drive belts require a break-in period of at minimum 30 miles to maximize belt life and performance. The goal of the
break-in period is to properly wear in the belt to match the sheaves before applying maximum engine torque. By conservatively running through the entire shift range, proper belt contact over the entire sheave/belt contact path is optimized to eliminate belt slippage and drastically increase the belt’s lifespan.
Follow these guidelines to accomplish proper Belt-Break in:
› Vary vehicle speed and engine RPM to shift belt through normal operational range.
› Do not exceed ¾ throttle within the first 30 miles of installation.
› Stop engine and allow belt to cool down every 15 minutes of use.
During break-in period, the following activities SHOULD BE AVOIDED:
› Aggressive Acceleration or ‘Jerky’ throttle movements at
low speeds.
› Holding engine/vehicle speed constant for extended
time periods.
› Pulling Heavy Loads.
› Long run times without complete CVT/belt cool down.
By following the break-in process carefully, the belt surface will wear in to match the individual CVT sheaves to maximize grip performance and dramatically reduce heat, glazing, and future wear.

Although G-Force belts are not directionally biased, it is recommended to install them with the label lettering facing toward the user to keep belt reinstallation consistent.


ALSO POSTED HERE:
49ccscoot.proboards.com/thread/11602/cvt-belt-replacement-pulley-cleaning