Modern Tire Dealer

JUN 2019

Magazine for the professional tire industry

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M T D J u n e 2 0 1 9 34 P a s t , P r e s e n t , F u t u r e : M o u n t i n g / B a l a n c i n g MOUNTING MISTAKE: TOO MUCH OR TOO LITTLE LUBRICATION Scribner recommends a lubrication product that is a vegetable oil-based paste with a short shelf life applied by a brush. Lubricate the rim barrel, rim drop center balcony edge and bead toe edge area. Avoid rim bead seats and tire beads. "Do not use too much lubrication to prevent tire slippage. Index the inner tire sidewall to the rim edge when done balancing to be able to check for rim to tire slippage if vehicle returns. Too little lube and the tire doesn't seat properly, and eccentricity problems can cause ride disturbance issues." MOUNTING MISTAKE: FAILURE TO IDENTIFY, PRETEST AND REPROGRAM TPMS If the TPMS sensor is at the valve, it has the potential to be damaged. "Test and make notation that TPMS sensors are working before service. is will protect you from customer accusations that you damaged their TPMS," says Scribner. MOUNTING MISTAKE: FAILURE TO MINIMIZE WHEEL RFV ECCENTRICITY Scribner says to reduce RFV (radial force vec- toring) eccentricity and provide a smoother ride, use a tire rapid inflation technique as recommended best practice by many tire manufacturers. e three steps are 1) with the valve core removed, perform a rapid seal, seating and inflation, 2) deflate the tire, 3) re-inflate the tire and install the valve core and bring air pressure to placard inflation pressure. BALANCING MISTAKE: FAILURE TO VALIDATE THE WHEEL IS CENTERED Back-cone mount and use a flange plate from the front whenever possible to best center the wheel. Some very wide wheels and larger light truck wheels may require spacers and larger cones to be front cone mounted. When in doubt, use a centering repeatability check to validate the wheel is centered. "To validate the wheel is centered, the process is simple, mostly unknown and rarely done," says Scribner. Clamp the wheel and take a balance measurement. Note the location and the amount of weight required to balance the wheel. Unclamp the wheel and reposition the adaptors and the wheel to a different clock position, reclamp the wheel. Take a second balance measurement. e weight amount and location should repeat closely to within the smallest round-off incremental size of wheel weight used. BALANCING MISTAKE: HIDDEN RESIDUAL STATIC IMBALANCE Scribner says most wheel balancers use dated soware with fixed dynamic blinding of 0.29 ounces per plane often display- ing "0.00oz__0.00oz" when residual static imbalance can be as high as 0.58 ounces. He says the best solution is static minimization soware, which compensates automatically and eliminates residual static by shiing weights to reduce residual static imbalance lower than the round-off setting. e "okay" solution involves the use of a third static residual weight display, if available, allowing the operator to add a third weight or shi weights. e "poor" solution is to balance in a "fine mode" to lower than lowest round-off increment. BALANCING MISTAKE: FAILURE TO ADDRESS RFV ECCENTRICITY When using a wheel balancer with RFV eccentricity (non-uniformity) measurement capability, check RFV eccentricity, minimize if needed and mark the high-spot of the assembly. Unless the tires are new, before measurement the vehicle should be driven about 10 miles to remove any temporary flat spots. Sensitive vehicle should be less than approximately 0.025 inches R1H (radial 1st harmonic of runout), less sensitive vehicles up to approximately 0.040 inches. If limits are high, remove the assembly, loosen the beads, lubricate the tire, rotate 180 degrees, re-inflate and remeasure. BALANCING MISTAKE: RANDOM WHEEL-TO-VEHICLE HUB MOUNTING Once the assembly is off the balancer, placing the assembly back on the vehicle hub with the high point (R1H radial runout) is another opportunity for improving ride quality. e idea behind the hub pilot is the hub-to-hub bore fit is supposed to center the wheel. "e fact is it is oen much too loose and the clearances are enough to allow gravity to shi the weight of the wheel to rest only on the upper part of the hub creating a gap in the bottom. Even the smallest gaps result in an egg-shaped motion upon rotation that can cause huge errors in imbalance and run-out eccentricity stacking that causes tire force vibration." Scribner says the company's HubMatch wheel mounting helps reduce eccentricity by subtracting the high point of the assembly from the hub bore clearance of the wheel to the axle hub. TIPS FROM HENNESSY INDUSTRIES Vanderheyden specified six tire mounting and balancing errors that impact ride quality. MOUNTING MISTAKE: CLAMPING FROM INSIDE Many technicians clamp wheels from the inside, which can cause the jaws to leave marks on the inside of alloy and steel wheels. Today's wheels, whether alloy or steel, should only be clamped from the outside in. "is not only prevents the wheel from shiing or walking during demount, it can also stop the wheel from spinning on the clamps during mounting of the top bead. Using a rim clamp tire machine equipped with a protected jaw such as Grip-Max Plus Clamps alleviates this issue," says Vanderheyden. MOUNTING MISTAKE: METAL- TO-METAL CONTACT When changing a tire on a wheel with black paint or powder coating, having the mount demount head adjusted properly along with using a poly head instead of metal is a great way to eliminate metal-to-metal contact that can scratch or mar coated or painted wheels. is is a very common and costly mistake and is easily avoidable by using the correct technique and accessories. MOUNTING MISTAKE: INCORRECT USE OF BEAD LOOSENER When using a side-mounted bead loosener, in the interest of speed, many technicians will place the side shovel too far from the bead of the tire, which can cause tire damage. Hennessy Industries breaks down the causes of improper balancing in tire shops into the following percentages: • Improper centering ...................... 60% • Residual static unbalance........... 10% • Improper wheel weight usage ..... 7% • Drive train vibration........................ 6% • Balancer calibration ...................... 5% • Eccentricity problem...................... 5% • Improper lug nut torque................. 4% • Bent wheel rim................................ 2% • Other ................................................. 1% (Included in "Other" is force variation at .05%.) Tires won't balance? Here's why

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