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GM opens official investigation into C8 Corvette transmission leaks

In March 2020, a month after Chevrolet began customer deliveries of the 2020 C8 Corvette, a GM dealer technician created a Reddit thread about a leaking gearbox in a Corvette with 32 miles. That car hadn't even been sold yet. Since then, as a search of "C8 Corvette transmission leak" shows, it's been tales of woe for some owners. Something in the Tremec TR-9080 transaxle in the back of the mid-engined Corvette doesn't work as it should, the fault able to cause codes that the transmission needs service, or that the driver needs to shift to park. In some cases, the battery would die because of follow-on issues after the initial transmission code, that code preventing the car from powering down. As Autoevolution reports, GM filed paperwork with the National Highway Traffic Safety Administration in August to look into what's going on. Between forum threads and GM's investigation document, there are several issues mentioned. The most common appears to be the dual-clutch transmission leaking fluid due to gasket failures like the one suffered by one owner at 858 miles, and another for an owner currently enduring a second leaking transmission. The Midengined Corvette Forum reported that Chevy engineers redesigned the TR-9080 pan, fitting Corvettes with the new unit at some point in the 2021 model year. The original pan was stamped steel unit affixed to the engine with two studs and 13 bolts, plus "reinforcement plates." The updated pan is said to be a cast aluminum unit affixed with two studs and 17 bolts, omits the reinforcement plates, and gets a new machined new groove around its edge to seat the gasket seal. The GM paperwork now at the NHTSA mentions a P1789 code, and says one reason for it could be "debris on the park position sensor magnet causing an incorrect position reading to the TCM." This might be caused by another issue mentioned in forums, which is clogged transmission filters. GM gives instructions for returning transmission filters to the company, and a poster on one forum said the Corvette tech at the dealer where he bought his Corvette told him the automaker "requires every used transmission filter to be returned to GM."  Whatever's going on, the problems haven't stopped, and they go beyond the P1789 code. Over the weekend, a 2022 Corvette owner posted on Corvette Forums that he got a check engine light on his car after just 850 miles.

GM will recall 3.5 million pickups and SUVs to fix brake issue

WASHINGTON — General Motors Co is recalling 3.46 million U.S. pickup trucks and SUVs to address a vacuum pump issue that could make braking more difficult and increase the risk of a crash. The recall, which covers 2014-2018 model year vehicles, including some Cadillac Escalade, Chevrolet Silverado, Chevrolet Tahoe, GMC Sierra, Chevrolet Suburban and GMC Yukon vehicles, was triggered because the amount of vacuum created by the vacuum pump may decrease over time, GM told the National Highway Traffic Safety Administration (NHTSA) in documents posted Wednesday. NHTSA opened a preliminary investigation into the issue in November 2018, and said it had reports of 9 crashes and two injuries related to the issue. It provided GM in July with additional field reports that prompted the automaker to open an investigation. The company did not immediately say on Wednesday how many injuries or crashes are linked to the issue but said it could impact braking in "rare circumstances." GM said dealers will reprogram the Electronic Brake Control Module with a new calibration that will improve how the system utilizes the hydraulic brake boost assist function when vacuum assist is depleted. GM said the vacuum assist pump, which is lubricated with engine oil that flows into the pump through a filter screen, can in some cases lose effectiveness over time, as debris such as oil sludge can accumulate on the filter screen. GM told NHTSA that prior model years used a different brake assist system design, and vehicles manufactured after 2018 were not equipped with the affected pump design. Recalls Chevrolet GM GMC

2016 Chevy Volt powertrain technical details

The last time General Motors launched a Chevy Volt, it was operating without really knowing how people would use the plug-in hybrid. Sure, it had experience with the EV1, but the Volt was a new kind of car, and you can see in the archives just how much time GM spent explaining this fresh, new powertrain to potential customers. Then, once the vehicle was released, the company collected voluntary data from a large number of owners to learn about their driving and charging habits. The company also asked them what they wanted most in the new version. There's got to be an algorithm buried somewhere in GM headquarters that was used to take all of the numbers GM collected and spat out the headline figures for the 2016 Volt: 50 miles of EV range and 41 miles per gallon. Another important number – price – is something GM isn't talking about yet (expect it in April or May), but the company is sharing some powertrain details about the upcoming car. At a preview lunch in Detroit last week for the SAE 2015 Hybrid & Electric Vehicles Technologies Symposium that's happening now in California, GM engineers Peter Savagian (who is presenting a paper on the new inverter used in the updated Volt) and Tim Grewe (talking about the entire second-generation powertrain) sat down with AutoblogGreen to tell us about the Volt's all-new propulsion system: The overall gist is that the new Voltec 5ET50 drive unit is lighter, smaller and more powerful thanks to a redesigned two-motor traction drive. As previously reported, the new engine is a 1.5-liter DOHC four-cylinder that offers 101-horsepower (at 5,600 RPM). Grewe said it's "great for range extension." The electric motor side of the powertrain offers 149 motoring horsepower from a two-motor, continuously variable transaxle. Initially, the new engine will be made in Mexico. GM will move production to Flint, MI during the first year it makes the 2016 Volt. The battery is slightly bigger in the new Volt – 18.4 kWh compared to 16.5 in the current-gen – and will have less range variation in the cold. GM is also using more of the overall capacity in the pack in the 2016 Volt than in previous versions, but is not saying how much more. GM is not ready to publish acceleration times just yet, but the 2016 Volt has improved numbers, especially when going from 30-60 miles per hour. Most everything on the new powertrain has become more efficient compared to the first-gen Volt.