1. Determine your Comet Series Type. Visit How to Identify Comet Torque Converters if you need help.

2. Measure the "Outer Diameter" (O.D.) of the driven pulley on the jackshaft, write that measurement down.

3. Measure the "Center Distance" (C.D.); which will be the exact distance between the center of the engine crankshaft and the center of the jackshaft... the measurement must be precise. Write that measurement down.

4. Use the two measurements; the driven pulley outer diameter and center distance measurement to determine the correct belt part number from the relevant chart below. Should your machine's center distance fall between the center distance (C.D.) settings listed here, select from the two belts the one with the larger outside circumference (O.C.) for best wear and to avoid machine "creep" during idling.

CAT99 and TC88 Systems that use 5/8" top width belts are now obsolete and are no longer available. However, some 5/8" top width replacement belts are still available. Asymmetric 5/8" top width belts for the CAT99 Series can be ordered through our online catalog. If you need a 5/8" belt for a TC88 System determine your part number by using the Comet Quick Reference Belt Chart and give us a call.

3/4" Top Width - 20 1/2° Asymmetric (18° + 2 1/2°) - 0.40" Thick - Kevlar Type

Select belt for the nearest approximate shaft setting. Check belt tension. The belt should be at it's highest point in the driven pulley flanges. Remove the outer half of the the driver clutch. Squeeze the belt down and pull it forward as shown. Position the engine so that 1/8" to 3/16" of clearance is provided around the clutch bushing/hub.

5/8" Top Width - 20 1/2° Asymmetric (18° + 2 1/2°) - 0.40" Thick - Kevlar Type

3/4" Top Width - 30° Symmetric (15° + 15°) - 0.40" Thick - Kevlar Type

7/8" Top Width - 30° Symmetric (15° + 15°) - 0.45" Thick - Kevlar Type

If you don't have the proper belt part number, two measurements are required. First, measure the outer diameter of the driven pulley. The 40 Series Driven Pulleys have a 7-1/2" outer diameter. The 44 Series Driven Pulleys have an 8-1/2" outer diameter. Second, measure the distance between the center of the engine crankshaft and the center of the jackshaft. If you look at the belt chart below you'll see that the measurement must be precise. This is the only way to be sure you are selecting the exact belt required for your machine. Use the two measurements to select the proper belt from the chart.

Comet belts are not elastic and should not be viewed as a rubber band. With the sophistication of drive belts and drive systems found in today's machines, the drive belt can do much damage to the entire system if the proper belt is not used or if the drive system is not properly aligned and adjusted. In earlier years, the drive system was considered a part of the machine that merely blew alot of belts. Many belts then were of the variety that if the drive system was not properly aligned and adjusted the belt would stretch and in most cases disintegrate before doing much damage to the clutch or driven unit. Today, however, emphasize belt and drive systems have attained such sophistication that if the drive system is not properly aligned or adjusted, or if the wrong belt is used, the belt may tear up the drive system before stretching or breaking. For that reason alone, and to eliminate the expense, trouble and possible safety hazard of blown belts or damaged clutches, the drive system on your vehicle should be given extra care to be sure it's operating properly. Basic guidelines are that the belt be checked periodically for uneven wear. If any irregularities appear in the system or on the belt, have the system adjusted immediately.

Check to make sure all of the black plastic cam buttons in the driven pulley are in place. Do not run the system if any of the buttons are missing. Missing buttons will allow the driven pulley to open too far allowing the belt to fall down into an area of the pulley where rivets are present. These rivets will destroy the belt. The buttons also keep the movable sheave from spinning, they reduce friction between the cam and the movable sheave and they prevent metal to metal contact thus acting as shock absorbers. The buttons play a very important role in the performance of a torque converter system. If you do have to replace buttons, glue the buttons into place with contact cement or a similar product.

If your system is "eating belts" do not install a new belt until the problem has been corrected. A destroyed belt is the symptom of another problem.

Erratic engagement is most often caused by the driver clutch that is mounted on the engine crankshaft. The flyweights in the clutch are sticking or the movable sheave is binding on the hub. Knowing how they work may help you determine why yours doesn't. As engine rpm increases, the flyweights push against the outer drum and force the movable sheave (pulley face) toward the engine causing the belt to travel at a greater circumference around the driver clutch. This action in turn causes the belt to force open the driven pulley, allowing the belt to travel at a lesser circumference around the driven pulley.

As engine rpm decreases, the spring in the driven pulley closes the pulley forcing the belt to a greater circumference. This action overcomes the force of the flyweights against the movable sheave and causes the driver clutch pulley to open, allowing the belt to travel a lesser circumference around the driver clutch.

When the engine is at idle, the driver clutch pulley should not engage the sides of the belt. The belt should be loose in the pulley and resting on the bronze bushing around the hub. The bronze bushing serves to protect the belt from rubbing against the spinning hub at idle and also to support a portion of the movable sheave as the sheave moves toward the engine during engagement.

The movable sheave must be able to slide freely on the splined hub without binding. Disassemble the driver clutch and clean away any dirt or lubricant residue using an automotive parts cleaning solvent. Do not use a petroleum based lubricant inside the driver clutch or between the hub and movable sheave. Use a dry, molybdenum based lubricant. The extreme heat and pressure inside the driver clutch chars most petroleum based lubricants. Petroleum based lube also collects dirt which causes increased wear. Graphite lube is better than petroleum lube, but it also eventually leaves a residue that builds up on the parts, causing them to bind and require more frequent cleaning. Experience has taught us that Max Torque Lube (or equivalent) works best.

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