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  • Interview: Darren Bohne, 2017 Chevrolet Colorado ZR2 Program Engineering Manager

Interview: Darren Bohne, 2017 Chevrolet Colorado ZR2 Program Engineering Manager

Engineering Awesome

Gary Witzenburg
Jan 31, 2017
Photographers: Courtesy of Chevrolet
Growing up just south of Buffalo, New York, Darren Bohne raced radio control cars as a kid and was helping his dad restore his grandfather’s ’46 Ford at age 14. “I tore into it and got all the operating systems up and functional, and that was the car I took to my Junior Prom.”
By 16, he was racing real cars at the local oval track. But about when it was time for college, another driver turned him into the wall and wrecked his car. So he put his racing career on hiatus and earned his mechanical engineering degree from General Motors Institute (now Kettering University). As a five-year co-op student, he worked for Cummins between class sessions, then sent a resume to GM, got an interview, and was accepted into a rotational College Graduate in Training program. Bohne's first assignment was helping development of the first ’00 Hummer H2 at GM's Milford Proving Ground. “I had been at the company about eight weeks when I got to go run the Rubicon Trail three times,” he enthuses. His second was on the quality engineering team at Fort Wayne Assembly. “Seeing all the day-to-day activities of building more than 50 trucks per hour on the assembly line gives you a whole different appreciation.” His third was product planning for the H2 SUT, another great learning experience.
Photo 2/5   |   Bohne Zr2
We recently chatted with him about his current job as program engineering manager for the just-introduced ’17 Chevrolet Colorado ZR2.
Truck Trend: What is your leadership philosophy?
Darren Bohne: When I set out on a project, I've made a practice of sitting down with a very clear vision and asking the team, “What is the magazine article you want to read?” We need to make sure up front that our vision of the product aligns with the visions of communications and marketing so we have no ifs, ands, or buts on what it will do. And any time I got into a debate about content, I said, “Let's go back to the vision. Does what we're talking about support the vision of the program?” That makes it easy to keep everyone focused.
TT: What was the vision for the ZR2?
DB: We started with, “What are the things we have to do with this truck?” It couldn't be a one-trick-wonder desert racer or a rockcrawler. We didn't want to make those compromises on a truck that we knew people would be driving every day. It did have to be a great rockcrawler, which drove the locking front differential, and a great desert runner, which drove the suspension travel. But on-road performance drove the damper technology. Instead of putting big external bypass shocks on it, we went after new technology to make it a truck that you can drive every day completely comfortably and still blast across the desert on Saturday.
Photo 3/5   |   Bohne Colorado Zr2 Off Road
TT: Not intended to be a Raptor competitor?
DB: No. The Raptor to me is a segment of its own, basically a trophy truck from the showroom. As we were kicking off this program, we said, “Let's build an off-road truck. What does 'off-road' mean to you?” And we got different answers from everyone we asked. My boss, who is from West Virginia, said, “We go climbing through old coal mining roads and mud holes.” West Coast guys said, “We go blasting through the desert to the sand dunes.” For hardcore rockcrawlers, it's Moab and the Rubicon. Here in Michigan, it's forest roads. The ZR2 has midsize benefit, and we wanted it to be a well-balanced truck that could do everything without major compromises. It's a great trail truck for running forest roads, but there is also a desert runner aspect to it, making sure we had the wheel travel and adequate power for that.
TT: So the ZR2 creates its own niche in that smaller size.
DB: Yes, it is a segment of one. There are inherent benefits to its size and available diesel engine. It can do so many things so well that I don't think anyone else has come close to being able to do everything that it can do.
Photo 4/5   |   Bohne Chevrolet Colorado Zr2
TT: What were the toughest challenges in getting it done?
DB: Probably the biggest challenge was the suspension. Everything from the control arm mounts outboard is all new—control arms, knuckles, steering gear, and rear axle. Everything takes the suspension outboard, and it was a significant engineering task to step up with a clean sheet of paper from the frame points out. We picked up a lot more wheel travel with longer control arms, but they also drive more load, so you have to make sure everything is reinforced to take it. So putting in the frame reinforcements and working through all the analytical and physical testing, we had to make sure that it was all well integrated. But the vision was there and the team was phenomenal, leaving no stone unturned on how to do things.
TT: Did moving the suspension outboard require new fenders?
DB: No, the sheetmetal is actually all common—you don't realize how much flare there is to a Colorado body until you start looking at it—but we added fender extensions to accommodate the wheels and tires. And that was another creative engineering solution. We wanted good retention, but thinking about the customer who is out running between rocks and scuffs one and wants to replace it, we went to a pushpin solution to be sure they were customer-replaceable.
Photo 5/5   |   Bohne Colorado Zr2
TT: What about the engines?
DB: One of the benefits of midsize is the mass advantage, so the torque and power of the Gen II high feature 3.6L V-6 is plenty sufficient. The power-to-weight ratio is very solid. We made some oiling system changes to make sure we had great off-road capability, but there were no changes from a power standpoint. We also have the great benefit of the available diesel, which no one else has. When we went to the Rubicon and Moab, that turbodiesel with its low-end torque made a nice rockcrawling package.
TT: Is the four-wheel-drive specific to ZR2?
DB: The transfer case is the same as the standard Colorado, but we had to increase the lengths of our front halfshafts and rear axletubes because of the added track width. The big key is the electronic locking differentials, a really big deal in that rockcrawling space. If you have just one wheel on something solid you're going to go through it. And then within all of what we integrated into the off-road mode—throttle progression, traction control calibration, ABS slip models—you can do things specifically for customer needs. One thing is that other manufacturers typically allow locking the differential only in low-range for rockcrawling. But we have a desert-racing prerunner crowd running mostly in two-wheel drive that want the benefits of a locked axle at high speeds. So in off-road mode, we allow unlimited speeds with the rear axle locked. With the benefit of multiple modes, we can set the truck up for exactly what each person wants to do.

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