CVT Belt Tips
Heat is the #1 killer of belts!
On today’s high power CVT belt equipped UTV's, the drive belt is the weak link. The CVT’s enemy is heat. Heat build up can be caused by several different factors. Driving habits, lack of belt break-in time, vehicle modifications, and most importantly, improperly aligned or adjusted belt and clutch system. In extreme cases, a well maintained and cared for CVT system can help a belt last up to 10,000 miles. If your machine is burning-up belts frequently, it is likely that the belt is not the problem.
Driving habits affect the life of your CVT belt. One of the biggest issues regarding driving habits, is using high range for all driving conditions. When high range is used in extreme conditions, it causes belt slippage and in turn excessive heat. Extreme conditions can be described as, slow speed over an extended distance, incline at slow speeds, deep mud, towing or plowing. Your owner’s manual will give clear instruction as to when it is appropriate to use low/high range.
Lack of belt break-in time can also affect the longevity of your CVT drive belt. There seems to be a wide range of opinions about the amount of miles it takes for a belt to “break-in” (30-50 miles at approximately 70% power seems to be the average), but the common factor is the need to seat the belt. The belt needs to surface itself to the sheaves. Once again, if the belt has not “broken-in” to the sheaves, it will slip and cause heat build up. Follow belt manufacturer or owners manual guidelines. Use care and allow time for break-in before any extreme riding. More details for proper break-in can be found further down on this page.
Vehicle modifications are a double edged sword as far as performance is concerned. Simple bolt-on modifications let you tailor your UTV to your riding area or conditions, but it also creates a need for adjustments to the CVT system. Over-sized tires feature benefits such as increased ground clearance, better handling, and better traction. The downside would be a loss of power, throttle response, and increased belt slippage. Over-sized tires weigh more than stock tires, which can contribute to belt slippage, but lightweight aluminum rims can offset some of the weight. The largest problem with oversize tires is that it affects the overall gearing. The OEM’s have went to great lengths to tune the clutch for the optimum RPM where horsepower and torque peak. Ground speed also plays a role in this equation. When adding taller tires (thereby changing the gearing), it alters this “sweet spot”. There are clutch kits available that alter engagement and other aspects of clutch performance to compensate for larger tires.
Maintenance, meaning alignment and adjustment, is of paramount importance when it relates to belt longevity. Belt deflection is a measurement of how tight or loose the belt is. This measurement should be checked at installation, after break-in, and at regular intervals thereafter. The sheaves or parts of the “pulley” that the belt rides on should be clean and smooth. Alignment of the clutch sheaves is also something that should be checked. It is even possible that motor-mounts could be loose or worn causing alignment issues. Your owners or service manual will have instructions for maintenance and adjustment tolerances. Check out the SDi clutch alignment tool found under the "Polaris" and "Accessories" section of the website to help ensure the absolute best alignment of your RZR clutches.
Adjusting, aligning, and maintaining your CVT system can be an advanced procedure and should be performed by a qualified mechanic. Once again, if you are constantly destroying your belts, it is likely that the belt is not the problem.
Proper CVT Belt Installation & Break-In
People often ask us which belt will last the longest. The answer to that question is you can get great life from most of the top manufactures belts with proper installation, belt break-in and driving habits (assuming you have no other mechanical issues that need to be addressed). The installation and break-in component of that equation is arguably the most critical and often skimmed over by UTV owners, especially if you are doing a trail side repair and anxious to get ripping again. In this month’s article we will walk you through proper installation and belt break-in to help you maximize belt life.
The first step in proper installation is to always being prepared with the correct spare belt for your machine and all the necessary tools, regardless if the repair is happening in the comfort of your garage or in the middle of the Glamis sand dunes. Often overlooked in the trail tool bag is the secondary clutch spreader tool, a knife to cut away any tangled belt cord remnants, scotch brite pads, contact parts cleaner and some clean shop rags. It is also a good idea to wash your belts ahead of time with mild dish soap and warm water. This removes any oils left behind from the manufacturing process. If you are washing the belt at the time of install, be sure to let it dry completely before proceeding.
Follow the owner’s manual for your machine to remove the clutch cover and gain access to the clutches. Use the manufacturer provided or aftermarket secondary clutch spreader tool to spread the secondary clutch sheaves and remove the old belt. If you grenaded your belt you will need to take time to completely remove any tangled cord pieces from your primary and secondary clutch. Be sure to check behind the clutch sheaves to make sure there is no cord wrapped around the shafts back there. You may need to use a knife to help cut away any tangled cord, being careful not to damage the clutch sheaves. You will also want to take some time to ensure you have removed ALL broken pieces of the belt from your CVT inlets and outlets. I have seen guys rush through a belt change without realizing that their CVT exhaust duct was completely clogged up with belt shrapnel. This results in hot air having no way to escape the CVT clutch cover, cooking the newly installed belt very quickly.
The next step is to prepare the clutch sheaves. To get the best results of newly installed belts, the CVT sheaves must be cleaned of all old belt residue, glazing, and oils. The best way to do this is to lightly scuff the faces of the clutch sheaves with a Scotch Brite pad in a cross-hatch pattern. Follow this up by cleaning the surfaces thoroughly with contact parts cleaner. It is best to spray the contact cleaner onto a clean microfiber rag and then wipe the faces of the sheaves clean. Repeat until the clutch faces are completely cleaned and let dry. Cleaning the sheave surface until all contaminants 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.
At this point, you can proceed with installing the new belt. If your belt has been exposed to any kind of dust in storage it is a good idea to rinse it off with water and let it dry prior to installing. CVT belts are not directionally biased, however, it is recommended to install them with the label lettering facing toward you to keep the belt direction consistent if you ever remove and reinstall for any reason. Remove the clutch spreader tool once the new belt is in place and spin the secondary clockwise by hand to move the belt back into its idle position on the sheaves. Then reinstall the clutch cover, being careful to reconnect all the inlet/outlet ducts properly.
As much as you would love to go shred the dunes again immediately after fixing the belt, it is critical to follow the correct belt break-in procedure. For belt break-in, I have always had good success following the Gates Powersports recommended break-in guidelines.
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 3/4 throttle within the first 30 miles of installation.
› Stop engine and allow the 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.
Taking the time to properly install and break-in your new belt may be tough when you are anxious to get back to riding again. Take your time, enjoy a few frosty beverages during the process, and understand it is bound to happen sooner or later in a UTV. A little extra time spent on the front end pays off dividends in maximizing your belt life and performance.