Body on frame vs unibody

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Body on frame vs unibody. Been reading that unibody is better in a accident. Better fuel mileage. Yet it seems that a full size pickup full frame and a unibody SUV (assuming full size) in a front end collision the pickup seems to come out on top. Some factors could come into play like larger engine / 4wd in the pickup. What's your opinion and what do you prefer? Seems most SUV's are going unibody.
 
If I were towing things or off-roading, I'd prefer body on frame. Otherwise unibody all day, better handling.
 
Originally Posted by oilpsi2high
body on frame seems to last longer, especially in the rust-belt areas.
I've never heard of unibody cars with such catastrophic corrosion that they needed to be recalled like frames on pickups.
 
Originally Posted by littleant
Body on frame vs unibody. Been reading that unibody is better in a accident. Better fuel mileage. Yet it seems that a full size pickup full frame and a unibody SUV (assuming full size) in a front end collision the pickup seems to come out on top. Some factors could come into play like larger engine / 4wd in the pickup. What's your opinion and what do you prefer? Seems most SUV's are going unibody.

Off roading and towing: Body on frame.
Everything else that comes to your mind: unibody.
 
Originally Posted by maxdustington
Originally Posted by oilpsi2high
body on frame seems to last longer, especially in the rust-belt areas.
I've never heard of unibody cars with such catastrophic corrosion that they needed to be recalled like frames on pickups.


Ford Windstar had recalls for the rear subframes literally falling apart due to corrosion.
 
Originally Posted by bdcardinal
Originally Posted by maxdustington
Originally Posted by oilpsi2high
body on frame seems to last longer, especially in the rust-belt areas.
I've never heard of unibody cars with such catastrophic corrosion that they needed to be recalled like frames on pickups.


Ford Windstar had recalls for the rear subframes literally falling apart due to corrosion.

Windstar? I would guess that was least of the problems.
 
Unibody. I don't think it is as fuel and cost efficient to put duplicate metals for cosmetic (body) and structural (frame) vs one that does both. Repair will sure cost more though if you are in a collision.
 
The laws of physics tend to win out in collisions-in the old days (mid '80s-early '90s) the company I worked for used S-10s-they would fold up like an accordion in a crash (body on frame). An S-10 vs. the fully loaded unibody Transit 250 I drive now would be ugly for the S-10! IMHO, it really depends an the application, for a small FWD economy car unibody is cheaper to build, but if you're hauling heavy or towing full frame is a must.
 
Well, with Transit 250's weighing in at 4900-5100 pounds versus an old s-10 at just over 3000 pounds it seems that it would be an easy win for the Transit for sure!

My Wife was recently rear ended by a full size Volvo SUV while stopped at a traffic light. The Volvo pushed her RAM forward almost a car length with brakes locked! The results were Volvo totaled and RAM with almost 7000.00 damage.


I am very glad she was not in an S-10!
 
Originally Posted by littleant
Body on frame vs unibody. Been reading that unibody is better in a accident. Better fuel mileage. Yet it seems that a full size pickup full frame and a unibody SUV (assuming full size) in a front end collision the pickup seems to come out on top. Some factors could come into play like larger engine / 4wd in the pickup. What's your opinion and what do you prefer? Seems most SUV's are going unibody.



Simple. Unibody the vehicle protects you because it absorbs the energy of the impact, with body-on-frame YOU take all of the impact. Basically your organs get sloshed around in your body cavity, less so with unibody.

Vehicles designed for towing need body-on-frame so there's a trade-off.

Now IMO in terms of injuries I'm going to opine the likely outcome.

UB + BOF = Bad for UB, Okay for BOF
UB + UB = Good for all
BOF + BOF = Bad for all
UB + stationary object = Bad for UB
BOF + stationary object = DEATH for BOF.
 
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Lots of variables available here.
Gauge of metal used
Overhang of "decorative metal".
Overall weight (mentioned above).
Design. I'd love to see a side-by-side of my 1972 Corolla against a 2019.
 
Keep in mind that most "SUVs" these days are just cars/minivans with a more truck looking exterior to cater to soccer dads who don't want to have their testosterone levels challenged.

A little strategic addition of high strength steel and whatnot, and then the change in sheet metal is all it takes.

There's a reason why trucks and busses are still BOF.

Doesn't make unibody bad. But the discriminatory of "SUVs" is just a little funny to me. It's because they're catering to sales, status, and an optic, not an actual use profile.

In terms of outcomes, don't underestimate unibody. Yes, a big, heavy, strong steel frame makes for a good battering ram. I was first on scene at a severe accident (55moh head on around a curve) once, and was #urprised how well a little chevy Aveo or some similar little thing did in protecting the family of four inside...

BOF often has a height (hitting softer parts) and a mass benefit. I think that skews the outcomes to some extent.
 
Production trucks and busses are kept BOF because their platforms are multipurpose and need to be kept versatile/adaptable. NOT because of strength.

Hard to convert a unibody truck to a tow, tank, utility, box, flat, etc. Trucks and busses would be EXPONENTIALLY more expensive if they were produced unibody style and each had to be developed and produced individually.
 
Originally Posted by maxdustington
Originally Posted by oilpsi2high
body on frame seems to last longer, especially in the rust-belt areas.
I've never heard of unibody cars with such catastrophic corrosion that they needed to be recalled like frames on pickups.


Mazda 6, Ford Windstar, Dodge Caliber...

Look at how many cars are running around with rotted out rockers. On a truck, that's cosmetic. On a unibody, that's part of the integrity of the car. Most of these end up so rotted out that they can no longer be lifted off the ground. Never seen a truck do this aside from Toyota but that was a manufacturing defect and not part of the design.
 
Originally Posted by emmett442
Production trucks and busses are kept BOF because their platforms are multipurpose and need to be kept versatile/adaptable. NOT because of strength.

Hard to convert a unibody truck to a tow, tank, utility, box, flat, etc. Trucks and busses would be EXPONENTIALLY more expensive if they were produced unibody style and each had to be developed and produced individually.


Agree on versatility. That said, body on frames are strong, especially in torsional strength when compared to unibody vehicles. The frame takes most of the stress, when the body of a vehicle is forced into different orientations, often at the same time (fr off road use, towing, etc). A unibody will require a lot of engineering to deal with the stresses, which is why you dont see them offering the highest towing ratings (though there are some capable unibody off road vehicles from Jeep), though that management of stresses across the whole body is why they can do quite well on impact impact, granted with more extensive damage and in some cases long-term compromised integrity.
 
Seems to me that "anything" can be engineered. You can make stupid flimsy frames--IIRC there was a Hot Rod article about some early 60's Pontiacs where they drilled lightening holes in the frame (and acid etched the fenders, aluminum hood and probably a few other tricks)--and as a result the frame needed bracing to go down the production line. I know my parents Astrovan had a front subframe but was unibody otherwise--and rated to tow 5k. Ridgeline is unibody and rated for 5k and some large payload.

Jalopnik quotes up to 7k on unibody--I didn't read the link too closely but I saw that mentioned.
https://jalopnik.com/mid-size-trucks-dont-need-frames-1785674405
 
Originally Posted by supton
Seems to me that "anything" can be engineered. You can make stupid flimsy frames--IIRC there was a Hot Rod article about some early 60's Pontiacs where they drilled lightening holes in the frame (and acid etched the fenders, aluminum hood and probably a few other tricks)--and as a result the frame needed bracing to go down the production line. I know my parents Astrovan had a front subframe but was unibody otherwise--and rated to tow 5k. Ridgeline is unibody and rated for 5k and some large payload.

Jalopnik quotes up to 7k on unibody--I didn't read the link too closely but I saw that mentioned.
https://jalopnik.com/mid-size-trucks-dont-need-frames-1785674405


The new Durango SRT can tow 8,700!
 
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