Bye-Bye, Body on Frame?
New models won't make it with a truck chassis. But body-on-frame vehicles haven't seen their last hurrah.
Partially, it’s because Chevrolet already sells two full-size SUVs (Tahoe, Suburban), a full-size crossover (Traverse), and a smaller crossover (Equinox). Then there’s the Acadia, a GMC-only midsize SUV. But the real reason? Body-on-frame trucks, at least in the U.S., are a surefire way to kill a new model before it even has time to linger.
Just ask Kia, which introduced the body-on-frame Borrego for 2009 and gave it the sweep that same year. When my colleague Bill Griffith tested one for The Boston Globe, he wrote that the “V8 version’s ride was rough enough to be disconcerting, even after trying lower tire pressures.” Like a garbage truck.
The Nissan Pathfinder is switching to unibody construction for 2013, the once popular Ford Explorer has ditched both the V8 and truck frame, and the Lincoln Town Car -- the only body-on-frame sedan still on sale here -- is departing forever after this year.
Unibody construction makes for a more carlike experience. The body floor, pillars and roof are welded together as one unit, and the engine and suspension hang off on subframes. They are lighter and more rigid than a body-on-frame chassis, which uses two thick steel beams braced together under a separate, mounted body.
Some off-road purists say that body-on-frame vehicles, because they allow more torsion, tend to take a beating better, and they’re mostly right. That’s why every pickup truck, save for the Honda Ridgeline, and full-size van uses a body-on-frame design. Their tough, simple construction allows for superior towing, payload and overall durability in heavy-duty use. Plus, as Hemmings notes, body-on-frame vehicles are cheaper to repair after an accident -- hence the reluctance for taxi companies and police agencies to give up their Crown Vics. They’re also heavier, meaning a fuel-economy penalty is unavoidable.
But has the unibody truly decimated the body-on-frame chassis? By my count, 22 body-on-frame vehicles are on sale in the US, excluding pickups, vans and heavy-duty commercial trucks. Let’s take a quick look at why they still exist when compared with their typically better-handling, better-riding and more efficient unibody competition.
Jeep Wrangler – The original American rock-crawler won’t ever change its beefy body-on-frame design. It’s the last bastion between real trucks and wannabes.
Nissan Xterra – With the Pathfinder becoming “softer,” the Xterra is a less expensive, more hard-core ride for committed SUV buyers.
Nissan Armada – The owner of a dog-grooming business down the street from me uses an Armada to haul her 165-pound Great Dane. She needs this truck more than anyone.
Nissan Pathfinder – The 2013 Pathfinder will share its unibody platform with the brand-new Infiniti JX. The current Pathfinder is simply old.
Infiniti QX56 – Everything is enormous and overkill on this superluxe rig. For some reason, everything that fails to gain attention in the Lincoln Navigator -- huge V8 engine, houselike proportions, is working for Infiniti.
Toyota FJ – Another classic, albeit with three windshield wipers. See Jeep Wrangler.
Toyota 4Runner – See Nissan Xterra.
Land Rover LR4 – It’s heavy, about 5,500 pounds, and floats above the earth. But it’s also one of the most serious SUVs imaginable when the road gets rough. None of its buyers care that it gets 13 mpg in real-world driving.
Range Rover Sport – The bigger Range Rover rides on a unibody developed in tandem with BMW. The Sport rides on the LR4 chassis, yet there is nothing sporty about it; buyers, meanwhile, eat up the Sport like free-range chicken.
Lincoln Town Car – The very last rear-wheel-drive, full-size American sedan without a unibody chassis. Livery drivers are seriously worried that no other car will replace the Town Car's smooth-riding, long-lasting performance for the money.
Mercedes-Benz G-Class – The Cold War relic that keeps on giving. Built on the same chassis since 1979, this German troop transport defies any and all logic, especially when the sticker gets to $130,000.
Absolutely none of these vehicles returns decent fuel economy. Many, like the Infiniti and Rovers, are ultrapricey. Others, like the Wrangler and FJ, are in unbeatable niches. Most, if not all, make no sense to European citizens crushed under $8-per-gallon gasoline.
So while it’s tough, if perhaps even impossible, to launch a completely new body-on-frame truck, it’s apparently quite simple to keep the gas-guzzling brutes we have. What red-blooded, truck-loving Texan would disagree?
Clifford Atiyeh has spent his entire life driving and riding in cars he doesn't own. He was raised in Volvos and has grown to love fast, irresponsible vehicles of all kinds. He lives in Boston, is a member of the New England Motor Press Association, and has reported for The Boston Globe, Car and Driver, Popular Mechanics and The Times of London.
LS1 bird, yes i agree with the crumple zones and your post.
the old chrysler unibody did not leave much to be desired (i know many will not like this).
the horrible leaf spring mounts where just welded to the trunk and in a short time would break through the trunk floor.
if you had to change a tire and jacked the car, doors would never shut right again.
and they collected salt quickly and rotted out quickly the way they where designed.
i was a die hard body on frame person for a long time, these newer platforms do hold up pretty good now. (still prefer rear wheel drive).
I think it's more of the matter of 50 years of chassis improvements, safetly standards, and technology rather than simply unibody vs. full frame.
Comparing apples to apples, I think if you were to take say a '62 Chrysler (I think they were unibody by then), and perform the same test against a '12 Chrysler 300, the results would be pretty much the same, with the newer car faring much better.
Or take a late model Crown Vic (full frame), vs. a 50 year old full frame Ford, and once again, the newer car would win.
Or to make it interesting, just reverse the test, with the the modern full frame Crown Vic vs. the 60's Chrysler unibody. I'm betting the newer Ford would win, due to technological improvements.
The greater understanding of crumple zones and crash forces are what really protect the driver.
the laws of physics can not be denied is true that is why the frame transmits severe shock to the passengers. the dummy was wearing the old belt seat belts. and the steering column decapitated the dummy. the unibody like the 59 was also totaled but, using mercedes type technology where weaker metal at the front and stronger towards the passenger compartment absorbs and decreases the shock effect where as the the 59 increased it. the newer cars are built safer!
i agree with the person on towing capacity 100 percent, that is why i like manual transmissions over a automatic as well.
like i said earlier i would only want a frame on body pick up truck for its pro's. i would not only feel safer but, i would definitely be safer in a 2009 impala than a 1959 impala.
The statement that body on frame vehicles transfer the force of the collision to the passenger is not the slightest bit true. The laws of physics cannot be denied. The stronger vehicle always wins in an accident. The test you mentioned with the '59 Chevrolet was rigged in many ways. For example, the '59 car had the engine, transmission, radiator, and drive shaft removed. It also had the steering column disconnected from the mounting point under the dash board, among other things. The test Dummy was also not wearing a seatbelt, and the front seat was unbolted from the floor of the car. Hardly a representative test, but they are trying to sell you the new Impala, not the '59 model. How did you expect the test to turn out under those conditions?
yes the pathfinder flip flopped, i forgot sorry!
police cars have always had unibody cars for many years (not all where), all the chrysler or mopar products.
now they have dodge charger, chevrolet impala, and ford 500's.
i believe all are some sort of unibody not sure with impala (w-platform) and 2 are front wheel drive, not sure if they are all wheel drive!?
the frame on body is worse to the passengers than unibody. the unibody wins. have you ever seen the crash test between a 1960 chevrolet impala versus a 2010 impala??
the unibody wins, the dummies would have lived in the 2010 but the 1960 the driver was decapitated and the shock waves that transmitted to the passengers from the frame are horrible!
Body on frame construction is stronger and lasts much longer but is naturally heavier. Look at the long term taxis, police cars and construction pickups used for the past 40 years and you won't find any without a frame. Plus if you are in an accident the framed vehicle always wins. Placing numerous airbags in these newer unibodies does help protect the occupants but just look at the structural damage difference.
Newer isn't always better.
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