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GM recalls select Tahoes, Yukons, Escalades for rear driveshaft issue

GM is recalling a number of its full-size SUVs due to an issue with the rear driveshaft assembly that could ultimately result in driveshaft failure. The actual number of total vehicles involved in the recall is small at just 1,789, but it’s spread out across the entire 2021 model year full-size GM vehicle lineup. That means a small number of every model is being recalled, including the Chevrolet Tahoe, Suburban, GMC Yukon, Yukon XL and the Cadillac Escalade and Escalade ESV. GM traced the issue back to certain driveshaft assemblies with ball bearings that were not properly heat treated. If theyÂ’re not properly heat treated, GM says that the balls may deform over time, causing noise and vibration. Continue to drive in this condition, and GM says the affected joint in the driveshaft assembly could seize, causing loss of drive power. However, the problem wonÂ’t present itself all at once, as GM says there will be a gradual increase of noises and vibrations before total failure. For those few owners with affected vehicles, GM says that it will replace the left and right rear driveshaft assemblies with properly-built units. Per usual with recalls, this will be done at your local dealership at no cost to the owner. If you have one of the recalled SUVs, expect to be notified mid-March. Related video:

GM patent reveals new two-stage turbocharger

Modern turbochargers may be some of the best ever made, but performance is something that engineers are always trying to improve. According to GM Inside News, General Motors (GM) is hoping to alleviate some of the negative aspects of a two-stage turbocharger setup with a newly-patented design. The patent, that was filed on May 19, 2016, reveals a clever bypass system that allows the engine, a four-cylinder unit, to optimize both the low-pressure and high-pressure inlets for its respective functions. According to the filing, a conventional two-stage turbocharger setup is engineered to allow both turbines to operate simultaneously at low and mid engine speeds. At high engine speeds, only the low-pressure turbine works. The setup can't isolate either the low or high pressure side, which can impair low-end performance. GM's new two-stage turbocharger setup looks to eliminate this by linking the high-pressure turbo to the exhaust manifold through the high-pressure inlet duct. The low-pressure turbo is attached to the high-pressure turbo by a low-pressure inlet duct, which is linked to a connecting channel. A single actuator that is housed in the exhaust manifold creates a bypass that can opens the high-pressure inlet or close the connecting channel. Depending on what the engine load and speed is, the ECU guides the actuator—a single rotating spindle with discs corresponding to flanges on the high and low pressure sides—to isolate one of the two turbos. Isolating the turbos allow the respective inlets to be engineered for the best possible fluid dynamic performance. The setup should increase performance and decrease lag. There's no word on what car this setup will make an appearance on, but it will most likely be used in premium vehicles before trickling down to the rest of GM's vehicles. Related Video: News Source: GM Inside News, AutoGuide via GM Authority Cadillac Chevrolet GM Technology Sedan turbo patent engine turbocharging

Next-gen Chevy Silverado and GMC Sierra may use carbon fiber

It's been generally accepted that the next generation of full-size GM trucks will use some sort of strong, lightweight material for the beds while retaining steel for the cab. While aluminum seems like the most obvious choice, according to Automotive News, the Chevy Silverado and GMC Sierra will incorporate both aluminum and carbon fiber in their beds. The publication cites sources from within GM, though it seems the introduction of this comparatively exotic material mix is still a few years off. While carbon fiber is both stronger and lighter than steel and aluminum, it takes significantly more time and money to produce, essentially relegating the material to small-volume cars. The main benefit for trucks is the resulting reduction in weight to improve fuel economy without sacrificing the tough, rugged capabilities truck buyers expect. The Ford F-150 made the switch to aluminum for the 2015 model year and it's proved highly successful. It seemed like it was only a matter of time before the competition followed suit. Automotive News says that the next-gen trucks will launch with aluminum beds and that it will take a couple of years before we'll see any carbon fiber incorporated into the design. Even then, only look for the composite material on higher-trim models, with a trickle down to lower-spec trucks possible further in the future. In 2011, GM announced it was working with Japan-based Teijin Limited on a carbon fiber reinforced thermoplastic. There's a good chance that material's introduction will be on trucks. Related Video: News Source: Automotive News Plants/Manufacturing Rumormill Chevrolet GM GMC Truck