by Hib Halverson
November 26, 2014
imagery by GM Communications.
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It’s freakin’ amazing that General Motors is going to come to market with a car like the ATS-V. We expect Corvettes to do 0-60 in three-nine, do the quarter in the 12s and top out at 185+. But–an American small coupe or sedan which can do that? A Cadillac which can match a 2015 BMW M3 from 0-60 and has a higher top speed? Now that’s freakin’ amazing!
The ATS-V won’t go on sale until late in 2015, so at this writing, at the end of November 2014, no one but a few GM development engineers have driven one, but just prior to the L.A. Auto Show, Cadillac released a lot of technical details about the car. The V-Net Staff reviewed all that data, directed some follow-up questions to media contacts at Cadillac and GM Powertrain, then compiled this technical briefing. Let’s start with the car’s chassis.
The ATS, built on GM’s “Alpha” platform, has pretty good structure already, but, when Cadillac puts the fabled “-V” on the decklid then tells us the car will, “…have impressive track capability” you know the engineers who do V-Series ride-and-handing had to make some changes. An ATS-V’s underbody structure has reinforcements, such as an aluminum shear panel at the front of the chassis, a strut tower brace, engine compartment braces and strengthening of certain parts of the rear underbody, which make the car 25% stiffer. Improvements in chassis parts were required, too. The smallest -V gets a 50% increase in front roll stiffness via higher rate springs and stabilizer bar. Front suspension compliance is reduced by replacement of traditional suspension bushings with “zero-compliance, cross-axis ball joints” and more rigid suspension links. The ATS-V uses a ZF variable-ratio, electric power steering gear which is calibrated for increased effort to give the driver improved steering feel.
In the rear, the ATS’ five-link suspension has be upgraded for V-duty with higher rate springs and stabilizer bar. It’s, also, been revised for decreased roll center migration and improved anti-squat geometry. Some components, such as bushings and suspension cradle mounts were stiffened. A stronger driveshaft and and axle shafts with increased “asymmetry” (driver-side shaft is stiffer than the passenger-side unit) damps power hop during maximum acceleration. Lastly, but certainly not least, all ATS-V drive axles are equipped with an electronically-controlled, hydraulically-operated, limited-slip differential, or “eLSD”. A computer-controlled, hydraulic clutch allows the differential to have any mechanical connection between the two rear tires, from no connection (“all slip”, or an “open diff”) to fully-locked (no slip), that the eLSD control module deems necessary for maximum handling performance. We could write an entire article about the vehicle dynamics advantages of the eLSD but, for now, suffice to say it’s an amazing advancement in chassis technology which will help make an ATS-V easier and more fun to drive though the twisties of your favorite back road and will make the car bad fast on a road course.Next Page >>