Monday, 01 July 2019 17:19

ASA Webinar Wednesday Addresses Belt Slip

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On June 19, the Automotive Service Association (ASA) hosted the newest installment in its Webinar Wednesday series.

Bobby Bassett, North America National Training Manager for Gates Corporation, presented “Belt Slip: the Gift that Keeps on Giving,” focusing on the reasons that components for the accessory belt drive system (ABDS) have high rates of warranties and return to the shop repeatedly. ASA Vice President Tony Molla served as host, welcoming attendees and introducing Bassett.


Basset said his goal was to enhance attendees’ understanding of the complete ABDS and how one component can impact another. Bassett stressed, “We can’t do it like we used to. Technology is changing every day. We are going to discuss industry information that’s creating failures all over the world.”


Using the example of repeatedly filling a tire with air, Bassett pointed out, “You have to stop using the Band-Aid approach and find the root cause. If you are replacing the same component for a second time for the same reason, fully inspect the system for proper diagnosis before reinstalling yet another component.”


According to Bassett, based on a sampling of alleged warranties returned to the factory, 40 percent of radiator failures are due to the condition of the coolant and 40 percent of returned batteries merely needed to be charged. Ninety percent of timing belts fail just after a belt is installed and 99.8 percent of returned serpentine belts were forced to failure.


“A lot of components are forced to fail and there are lots of excuses for the failures,” Bassett said. “Collision repairers own the liability for the repair, so it falls on us if we accept the customer’s advice based on those excuses.”


After exploring the advantages and disadvantages of serpentine belts, Bassett discussed how modern belts are made with ethylene propylene diene monomer (EPDM) rubber and need to be replaced at approximately 90,000 miles. He explained, “EPDM wears differently so cracks are minimal, if any. Just five percent of belt wear will allow the belt to slip under load. Rib wear is the predominant wear indicator and visually difficult to determine unless using a belt wear tool.

The belt must always point to the root cause of the failure. When a customer comes in, you need to gauge belt wear.


Addressing the problem of belt whip where the belt whips as it rotates over the back of the system, Bassett explained that this creates torsional vibration and the solution is to create an aramid cord belt. He provided detailed information on the wear-and-tear parts of the serpentine belt drive components, emphasizing, “The belt has one job—to transfer the power from the crank, but the ABDS is not just a belt; it’s a system that includes the belt, the tensioner, system pulleys and related accessories, and the repairer needs to verify that everything in the system is operating correctly.”


Belts can only tolerate a misalignment variance of one degree, and excess variances often lead to belt noise. Bassett explored belt noises related to tension and alignment, reiterating “The belt is doing its job which is to grip the pulley and create friction, but it is being forced to slip.”


After sharing some trouble-shooting tips for Micro-V belt noise problems, Bassett covered some common perceived belt failures and he described the tensioner’s two job functions: maintaining the correct belt tension throughout the tensioner’s duty cycle and dampening the impulses from the engine as each cylinder fires. Bassett then identified the four failure modes of a tensioner.


Like a tire that requires four things to ensure proper performance (proper tread, alignment, balance and air pressure), the belt’s proper performance relies on proper rib depth, alignment, dampening and belt tension. Bassett added, “Belts and tensioners were designed as a system. Correct alignment and tension are critical to the system. For best results, replace both together.”


Next, Bassett covered modes of belt failure and understanding those failures. He wrapped up his webinar by describing the Gates Solution to the problem. “Without proper tension, even the best new belt can’t efficiently transfer power. Kits get to the root of the problem. A worn or noisy belt is only part of the issue. Tensioners wear at the same rate as the belt and should be replaced together.

A worn tensioner can make a new belt wear up to two times faster. Loose parts take more time to source or may be forgotten during the repair. Performing a complete system repair doesn’t add much time, but it adds a lot of value and protects against returns. Be part of the solution.”


For 24/7 belt training, Bassett recommended visiting navigates.gates.com or gatesaftermarkettrainingcenter.com. He concluded by taking questions from attendees.


ASA’s next Webinar Wednesday is scheduled for July 17 with Gene Jensen, Automotive Lubricants Trainer for Chevron/Havoline, discussing “Automotive Lubricant Fundamentals and Trends to Optimize Your Oil Program.” On July 24, ASA will offer a bonus webinar featuring Elite Worldwide President Bob Cooper as he presents “Four Easy, Cost-Free Ways to Bring in More Customers.” For more information on ASA or to register for their webinars, visit asashop.org.

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