1951 Chevrolet 3100 Truck on 2040-cars

Auto blog

Is the skill of rev matching being lost to computers?

If the ability to drive a vehicle equipped with a manual gearbox is becoming a lost art, then the skill of being able to match revs on downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. The usefulness of rev matching in street driving is limited most of the time – aside from sounding cool and impressing your friends. But out on a race track or the occasional fast, windy road, its benefits are abundantly clear. While in motion, the engine speed and wheel speed of a vehicle with a manual transmission are kept in sync when the clutch is engaged (i.e. when the clutch pedal is not being pressed down). However, when changing gear, that mechanical link is severed briefly, and the synchronization between the motor and wheels is broken. When upshifting during acceleration, this isn't much of an issue, as there's typically not a huge disparity between engine speed and wheel speed as a car accelerates. Rev-matching downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. But when slowing down and downshifting – as you might do when approaching a corner at a high rate of speed – that gap of time caused by the disengagement of the clutch from the engine causes the revs to drop. Without bringing up the revs somehow to help the engine speed match the wheel speed in the gear you're about to use, you'll typically get a sudden jolt when re-engaging the clutch as physics brings everything back into sync. That jolt can be a big problem when you're moving along swiftly, causing instability or even a loss of traction, particularly in rear-wheel-drive cars. So the point of rev matching is to blip the throttle simultaneously as you downshift gears in order to bring the engine speed to a closer match with the wheel speed before you re-engage the clutch in that lower gear, in turn providing a much smoother downshift. When braking is thrown in, you get heel-toe downshifting, which involves some dexterity to use all three pedals at the same time with just two feet – clutch in, slow the car while revving, clutch out. However, even if you're aware of heel-toe technique and the basic elements of how to perform a rev match, perfecting it to the point of making it useful can be difficult.

GM recalls 330,000 fullsize trucks for airbag replacement

General Motors has announced a recall of 330,198 fullsize pickups in the US in the aftermath of the announcement made on May 19 that doubled the number of vehicles being called in to replace Takata's defective airbag inflators. That announcement expanded the nationwide recall to an estimated 33.8 million vehicles in the US. Heavy Duty versions of the 2007 and 2008 Chevrolet Silverado and GMC Sierra are included in GM's move, for the purpose of replacing the passenger airbag inflators. The announcement made by the National Highway Traffic Safety Association cited long-term exposure to moisture as a possible cause of the inflator issues. GM says it isn't aware of any problems with the recalled pickups due to moisture, nor has it had any reports of crashes, injuries, or fatalities, and has not received any complaints. GM will notify owners, who can then take their trucks to the dealers to have them repaired free of charge. You'll find a statement from GM and the recall notice from NHTSA below. Related Video: General Motors Statement General Motors is recalling 330,198 2007 and 2008 model year full-size Chevrolet Silverado heavy duty and GMC Sierra heavy duty pickup trucks in the U.S. to replace the passenger air bag inflators manufactured by TK Holdings Inc. (Takata). This recall implements Takata's air bag inflator equipment recall announced on May 19, 2015 (NHTSA recall number 15E-041). GM is not aware of any humidity-related ruptures in Takata air bag inflators in any GM-badged vehicles in the field and knows of no crashes, injuries, fatalities or complaints regarding air bag performance in these vehicles. Including Canada and exports, the total number of vehicles being recalled is 374,715. Population breakdown: United States 330,198 Canada 39,630 Exports 4,887 Total 374,715NHTSA RECALL NOTICE: Report Receipt Date: MAY 28, 2015 NHTSA Campaign Number: 15V324000 Component(s): AIR BAGS Potential Number of Units Affected: 330,198 Manufacturer: General Motors LLCSUMMARY: General Motors LLC (GM) is recalling certain model year 2007-2008 Chevrolet Silverado 2500HD and 3500HD trucks manufactured November 28, 2006, to August 29, 2008, and 2007-2008 GMC Sierra 2500HD and 3500HD trucks manufactured November 27, 2006, to August 29, 2008.

GM natural gas-powered vans recalled due to possible leak

General Motors is recalling almost 3,200 of its compressed-natural-gas powered utility vans because of possible leaks. GM and the National Highway Traffic Safety Administration (NHTSA) released a notice last week saying that 3,196 Chevrolet Express and GMC Savana CNG vans are on recall, though no accidents have been reported due to the possible issue. The recall is specifically for vans for model years ranging from 2011 to 2014. The recall stems from a potential leak from the compressed natural gas high-pressure regulator, and such a leak could cause a fire or explosion. GM will replace the vehicles' high-pressure regulator in order to fix the problem, will do it free of charge and is instructing owners to contact Chevrolet or GMC customer service to arrange for the parts replacement. Utility vehicle makers like General Motors have pushed for fleet sales of CNG-powered vans and trucks for the past few years and have touted them for their cheaper refueling costs relative to standard gasoline, not to mention the fact that natural gas can be readily sourced from throughout North America (thanks, fracking). According to CNGPrices.com, compressed natural gas sells for about $2.22 a gallon, on average, while the AAA is pegging the average price of gas at $3.34 a gallon. NHTSA has posted information on the recall here. Featured Gallery News Source: NHTSA via Reuters Green Chevrolet GM GMC Natural Gas Vehicles CNG gmc savana