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Asymmetric 3/4" belts are flat on one side, angled on the other. Flat side to engine.
White Arrows and the words "THIS SIDE TO ENGINE" are printed on the top of the belt.
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| Using The 6" Driven | Using The 7" Driven |
| High Speed .90 | High Speed 1.12 |
| Low Speed 2.68 | Low Speed 3.13 |
| Overall Speed Ratio 2.98 | Overall Speed Ratio 2.79 |
How does a torque converter work? The drive clutch is activated by centrifugal force from the engine crankshaft. The moveable sheave of the clutch is forced in as the RPM of the engine is increased. This contacts the drive belt. The drive belt will then be forced to a larger diameter within the clutch sheaves, thus pulling it to a smaller diameter within the driven unit sheaves. The moveable sheave of the driven unit is forced out, allowing the belt to seek it's smaller, high speed ratio diameter. As this happens, the speed from the engine transferred to the final drive is increased.
The asymmetric torque converter components use a 3/4" top width belt. The belt mass is desirable in applications requiring extra rugged driving ability, such as dune buggies, go karts, mini bikes, ATV's, grounds maintenance equipment, materials handling devices and industrial equipment. It's mounted with both stationary sheaves inboard requiring only minimum displacement.(All the working parts are on one side.)
The asymmetric type torque converter system has sheave faces that have different angles. The belt is flat on one side and angled on the other. In this case, the movable sheave face is 18° while the stationary sheave face is 2 1/2° for a collective angle of 20 1/2°. By having both the driver clutch and driven pulley fixed sheave faces on the same side (inboard) the system can be mounted on a fixed plate, in the same plane. See the 30 Series TAV2 Complete Kits. This offers some very significant advantages to mounting requirements in many cases. Noting the displacement diagrams you will see that the torque sensing cam assembly is mounted outboard adding further to the convenience of many installations with displacement problems. The asymmetric concept, having the 18° angle on one side requires less sheave face travel to lift the belt to larger, comparable pitch diameters of the symmetrical system. This makes it possible to force the belt to a diameter within the drive clutch (at high RPM) that exceeds the usual 1:1 ratio of standard systems. The 30 Series parts on this page are interchangeable with the 30 Series TAV2 Complete Kits which use an Asymmetric Driver Pulley and a 6" diameter Driven Pulley. Both the 6" and 7" diameter Asymmetric Driven Pulleys will be available again soon.
The spring and flyweight assembly in the driver clutch actuates the movable sheave and responds to engine RPM and should be replaced if the pins or springs are even slightly loose. If they are not VERY tight the loose pins and springs will prevent the pulley from disengaging. If your machine tries to take off by itself you may need to replace this part. Other problems that could be causing the system to be engaged all the time: dirty components with a lack of lubrication, worn out splined hub, the drum not correctly installed or a weak spring in the driven pulley.
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Adjusting the spring tension on the driven pulley changes the rpm range at which the unit shifts into high gear. The three numbered holes on the cam are used to change the spring tension. Hole #1 provides the least tension and allows the unit to shift gears at a lower rpm. This is good for flat ground. Hole #3 provides the most tension and allows the unit to shift gears at a higher rpm. This is good for hilly terrain. Hole #2 is the factory setting providing medium tension good for the most common riding conditions.
You must pre-load the spring when installing it into the driven pulley. After placing the end of the spring in the desired hole and aligning the flat spots in the center of the cam with the flats on the post, just before pushing the cam all the way on to the post, turn the movable sheave clockwise -- tightening the spring -- bringing the buttons past the points of the cam and into the next valley. While holding tension on the spring, push the cam all the way on to the post and secure it with the snap ring. When you release the movable sheave the spring should rotate it counter-clockwise until the plastic buttons press against the cam. The insert buttons must not "float" between the cams.
The "20" stamped on the cam indicates that it is a 20 degree cam, not that it is a Series 20 torque converter. The 20 degree cam is used on both the 20 and 30 Series torque converters. One way to tell the two apart is to look at the angle of the pulleys. On the 20 Series, both pulley sheaves have the same angle. On the 30 series, the sheave toward the motor is nearly flat while the opposite sheave is angled.
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Maintenance will include proper cleaning and lubrication of the driver and driven. Inspect the torque converter on a regular basis for dirt, frayed belts and any other potential problem obvious from a visual inspection. Always service units before each season. Maximum service interval recommended is each 50 hours of operation.
Drive and driven pulleys should be parallel. Friction faces must be smooth and free of dirt, corrosion, oil or grease. Belt must be dry, straight, and free of cracks, breaks and uneven wear. Operating the vehicle in a dusty environment will require more frequent servicing.
Use Dry Film Lubricant in all models of Torque Converters
Indicators of a torque converter system requiring cleaning and lubrication are erratic or jerky engagement upon acceleration and a tendency to apparently "lock" into a particular speed (a second cause of jerky engagement is an excessively loose drive chain). If either one of these conditions exist service the unit immediately. Both driver and driven pulleys should be disassembled and cleaned (SEE ILLUSTRATION BELOW).
C -- CLEAN
L -- LUBRICATE
Visit the Trouble Shooting Page for more information on malfunctioning Torque Converters. Belts eventually wear over time but a damaged or torn up drive belt always indicates that a problem exists with the system. Only replace your drive belt after the problem has been corrected. Components must be clean, lubricated and perfectly aligned to function properly.
If you own an older Manco 5 or 6 horsepower go kart powered by an Asymmetric Torque Converter click here to view the assembly sequence of your drive system. This is the old style Manco Factory set up that used a thick plastic cover that snaps down over two arms that stick out. The torque converter cover style and cover hardware may vary on later models, but the mounting plate, jackshaft, bearings and components are all the same. If your Manco brand kart is equipped with a 12 tooth jackshaft sprocket, you have #35 chain. If your Manco brand kart has 9 tooth jackshaft sprocket, you have #420 chain.
| Neutral | Low Range |
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| The asymmetric belt has no engagement during the idling of the engine. The system is Neutral--with no belt friction and no drag. | As the engine throttle is opened the Driver pulley flanges begin closing together via centrifugal force. The Drive Belt engages, driving the Driven unit pulley at it's largest diameter. This is the most powerful ratio of the system. |
| Intermediate Range | High Range-Overdrive |
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| As the engine R.P.M. increases, the Driver pulley flanges continue to close together. This action, in turn, is squeezing the belt out to a larger Driver unit diameter. This action is dependent on acceleration and lack of torque load on the Driven element, allowing its pulley flanges to open thus creating a smaller driven unit diameter. If the torque load is increased this ratio is reversed instantly and smoothly to its requirement. The ratios between low and high are infinite to meet all demands within its realm of capabilities. | At it's highest speed (overdrive) and lowest load demand, the Driven unit pulley flanges are wide open providing the smallest possible belt contact diameter. The Drive unit pulley flanges, at this point, are closed to provide the largest possible belt contact diameter. The unique asymmetric arrangement of the belt and pulley angles allow the belt to exceed diameters possible with the standard "V" pulleys, thus overdrive. |
Factory Authorized Distributor