GM should have gone to unibody construction. Much much much stiffer and more rigid than a boxed frame can ever be. If they are really trying to innovate that's what they should have done.
FYI...Fully boxed frame is not a new innovation. It's been around since forever. Same for unibody. Each type of construction has pros and cons.
Up to this point, unibody construction has offered stiffness and rigidity for
onroad applications...theoretically I guess someone could design a unibody vehicle that is strong enough to stand up to the stresses and abuses of off-road and work use, but with the exception of Land Rover's Integrated-Body-on-Frame for the LR4 (which comes with a huge weight penalty and really isn't a true unibody), I have yet to see anyone successfully develop and implement such a design.
The whole reason for having a body-on-frame construction is to mitigate or prevent the vehicle's body from twisting or fracturing during off-road or work use. Yes, all body-on-frames, by their nature, will encounter some amount of twist. But the principle, as I understand it, is to build a frame to be as rigid
as possible so as to allow the suspension, not the frame, to conform and work with whatever terrain is being encountered. That's why Toyota still builds the 4runner (and Prado) and Land Cruiser (200 series and 70 series) and Hilux on fully boxed frames - to keep the frame as rigid as possible in order to reduce twist and stress.
The Toyota, and Tundra, to my knowledge are the only BOF vehicles that Toyota makes with C Channel frames, which are less rigid and do twist quite a bit more than the traditional box frame. I'm sure someone could throw out some advantages associated that kind of design, but for the purposes of off-roading and utilitarian use, a boxed frame does make more sense....hence why Toyota uses that design for the rest of its BOF offerings.
The new Hilux still have drum brakes too btw. The Tacoma actually stopped 2 feet shorter than the Colorado. So rear drums performed just as good in this application.
http://www.caranddriver.com/compari...ng-performance-data-and-complete-specs-page-4
The Tacoma, at its heaviest, comes in at around 4400lbs:
http://www.toyota.com/content/ebrochure/2016/tacoma_ebrochure.pdf
The Colorado, with the diesel, will come in at around 4700lbs:
http://media.chevrolet.com/media/us/en/chevrolet/vehicles/colorado/2016.tab1.html
Factoring that and different weight distributions and the different payload ratings, I don't think we can consider these braking test results as a definitive comparison of drum brakes versus disk brakes...in principle, disk brakes do provide much better stopping capabilities, which is why most modern vehicles, including most Toyotas, use them over drum brakes.
The unibody comment was in regards to people wanting a stiffer chassis. It is a fact that unibody construction is much much STIFFER than a ladder frame (c-channel or boxed section). Stiffness is not the same as strength. Most people don't seem to understand that. Is the C-channel as stiff as a boxed frame? No. Is it weaker. No. But if you want a stiffer chassis, get a unibody.
Yes frame twist will happen. It's all about mitigating or minimizing frame twist, not eliminating it. When it comes to boxed frames versus C channels, one design is better at that than the other.
Yes. Ladder frame construction is better for "truck" duty than a unibody. Why? Because it can flex and bend without breaking. But if you go by the comments regarding Toyota's construction method, they don't want that. They want stiffness. You want stiffness, get a unibody. Nothing wrong with a unibody if you're cruising mostly on pavement. It's superior to a ladder frame truck in terms of on road ride and handling and packaging.
Refer to my discussion above.
