Pelican Parts Forums - 2015 Z06 Corvette

Interesting sometimes tragically misinformed article.

Let's start with the torque tube. The Rambler TT was a design that predates the Rambler by decades. Basically the design he describes is a tube that goes from the tail transmission to the live axle. The axle thus pivots about a point at the transmission (note, the Rambler used coil springs, not leaf springs as was common with rigid axles in the 1960s).

I'm not sure which car was first to use a torque tube such as GM introduced to the Corvette with the C5. It would appear that GM took the idea from the 928. As with the 928, the tube deals with torsional loads between the engine and gearbox as well as maintaining alignment between the two. It is not part of the structure of the chassis. Remember that the engine and gearbox are mounted with rubber isolators so no chassis loads can be fed through the torque tube.

The engine, like most of the recent Corvette motors is a marvel of power in a small package. I suspect the SC was selected over turbos because a turbo installation would have taken more space under the hood. The SC was able to fit in the V of the motor. Turbos would have been far more complex. The SC was also an evolution of the ZR1 setup. That said, I'm sad to see GM didn't best the old LS7 motor.

I'm very curious about the ability of the new auto box. Traditional autos can shift very quickly. Drag cars that still use multiple gear rations, ie not top fuel cars, use planetary style gearboxes because you can shift them VERY quickly. A traditional auto, like the dual shift systems has multiple clutches. Thus you stage one clutch to engage as the other is disengaging. Net result it a VERY fast shift. Of course there is a world of difference between the theoretical ability of such a system and what can be done reliably for 200,000 miles with acceptable NVH. Still, I wouldn't write off a traditional auto vs DSG.

The 60% number for stiffness is vs the old Z06/ZR1 chassis. I can believe it given the number of other changes to the chassis. I suspect that most of that 60% number has nothing to do with the roof panel. The big change is likely due to the new transmission tunnel. Starting with the C5, the Corvette's primary chassis structure connecting front to rear is the Lotus inspired central backbone (Dave McLellan says as much in his late 90s Corvette book). This central backbone consists of the transmission tunnels (3 sides of the box) and a removable bottom plate. In the C5 and C6 the bottom plate was placed below the torque tube but above the exhaust pipes. In the C7 the plate was placed below the exhaust pipes. Net result is the backbone box is larger. Just as a larger tube is stuffer than a smaller one, a larger box is also stiffer. Note that the C5 and C6 were both very stiff chassis but the updates simply make them that much better.

A note about the suspension. The Corvette suspension is not tied to the driveline any more than in any other car. The suspension arms are all attached to the chassis and associated subframes. Thus the torque tube has zero part of the car's suspension. Too bad the article didn't say anything about the active LSD. That is one of the big handling upgrades to the car. A big help vs the older car's torque sensing LSD.

There was a note about GM engineers being hampered. Well all engineers are hampered to some extent. That said I don't look at this chassis and see a set of engineers who were hampered by much other than the need to use a corporate engine family and perhaps an inability to source a DSG (demanded for market reasons) for a reasonable price. I guess we could also cite the front-rear layout as hampered but that setup is not without it's benefits.

Oh, the stylist in my opinion didn't do a good job. The new interior sheds the low rent look of the older car (the C6 materials and fitment were similar to the same age Boxster/Cayman but the styling really made the stuff look lower rent than it was).