Finding the Right Balance
Q:My problem is with a '96 Chevy S-10 2WD six-cylinder pickup. There's a vibration in what appears to be the rear of the truck. It becomes noticeable between 60 and 75 mph. First, I had the tires balanced on the vehicle (I was told this is the best way to balance tires). The vibration was still there so I replaced the driveshaft center-support bearing and had the driveshaft balanced while it was out. After all that, the vibration was still there. So here I am $200 into a problem that seemed to be as simple as an out-of-balance tire.
A:There's a great tool out there that may be a necessity in accurately diagnosing your problem: The little lady is known as EVA (Electronic Vibration Analyzer). It's a mandatory tool in a GM service department (J-38792-A) and is manufactured by SPX Kent-Moore Corporation (they should have the part, if your local dealer doesn't). The EVA is an electronic device that can pinpoint the cause of an automotive vibration with the use of vibration sensors placed in the appropriate locations. You can then take it one step further with EVA's ability to balance a driveline when required. Your truck's vibration may stem from a number of different areas. For example, someone may have previously replaced a pinion seal on the rear axle and caused the problem. If the pinion yolk wasn't marked to the pinion shaft before removal and reinstalled in its original position, the assembly may have been thrown out of balance causing a driveline vibration. Improper driveline angles due to chassis damage or improper ride height could also produce a similar condition. Other possibilities include an out-of-balance brake drum, a bent axle, and tires or wheels out of specs even though balancing correctly. Finding a dealer with the proper tool and a technician who knows how to use it should be your next step.
Half-Ton GM Tranny Gauge
Q:I own a 2000 Silverado 1500. It's a great truck, except for one missing item: a transmission-temperature gauge as on the 2500 and 3500 models. From what I've been told, it's an easy change. I can purchase a new, standard instrument panel from GM for a 2500 or 3500 Silverado with the tranny-temp gauge. I'm told the replacement is easy. Then I can have the dealer flash the computer so the truck recognizes the new gauge. Will my truck retain its current mileage? Is the new transmission-temperature gauge a glorified dummy light like the engine-temperature gauge? I don't want to go through all this work and expense if all it's going to tell me is that it's cold, medium, or hot.
A:Mileage memory is stored within the instrument-panel assembly, so whenever you purchase or exchange a "cluster," it has to go through an authorized supplier to recalibrate and maintain the accurate odometer reading. I contacted an authorized General Motor's electronics service provider regarding the swap of the Silverado instrument cluster. The 1500 should have all the appropriate wiring, sensors, and computer programming to support a 2500 or 3500 series instrument cluster equipped with the transmission-temperature gauge. The folks I spoke with have done the job before without having to perform any recalibration of the powertrain-control module. However, the safe way to go before ordering any parts is to ask a Chevy service department to plug in the Tech II scan tool to confirm the presence of transmission-temperature data. The factory gauge is only going to offer minimum accuracy, which is all you need on the highway. As opposed to cold, medium, and hot, most read 100*, 200*, and 300* F. For more precise readings, go with a high-quality aftermarket mechanical or electronic gauge setup from a manufacturer such as Auto Meter Products Inc. (www.autometer.com; 815/895-8141). It can supply you with a quality product at a good price, but you'll lose the factory finish you wanted to maintain.