Body on frame

[SummitRunner]

I'm coming from three years in a 2004 Jeep Grand Cherokee WJ Overland. It was an amazing vehicle (except for poor reliability). I now have a 2004 4Runner 4WD Limited V8. The vehicles are in the same class and have similar size and weight, so I'm comparing them directly.

I took the WJ all over back roads in the desert and mountains. Sometimes the trails got very rough and steep. I really appreciated the solid front and rear axles in the WJ going over obstacles. But never once did I think "boy I sure wish this was body on frame".

Maybe it's a towing thing? I can see where body on frame is stronger while towing. But doing moderate wheeling I don't see any advantage. There are plenty of WJ rock crawlers whose suspensions are holding up fine. What exactly breaks on a unibody when doing casual wheeling?

I understand hard core wheeling is a different thing. That's not my hobby. I use 4WD in order to reach remote locations, such as Saline Valley via south pass near Death Valley. It is a very long, steep, rough trail. I'm not going on the Rubicon trail any time soon.

For my style of driving (75% highway, 25% back roads/trails) I much prefer the design of the WJ: solid axles front and rear, unibody. The unibody improves ride on pavement by reducing harshness. It reduces weight and improves fuel economy. The solid axles are great for going over obstacles.

Here is what I wish Toyota would do:

Rav4 - unibody, double-wishbone
4Runner - unibody, solid front/rear axles
Land Cruiser - body on frame, solid front/rear axles

 

[Inv4drZm]

A strong unibody design is pretty similiar to a BOF design, just all 'glued' together.

I appreciate the simplicity and modularity of the BOF design. With the bushing mounts the body/ride is isolated well and I'd imagine its better than a unibody w/ SFA on the street.

I really don't think a solid axle has a huge advantage offroading until you go over 35" tires. Lots of center clearance with IFS. You really don't gain more travel, numbers wise, with a solid front axle but it keeps the tires planted to the ground giving more traction while rock-crawling.

I really like the IFS design on the 4Runner. It's easy to build a desert wheeler and you can still swap to a SFA if you wheel more in the rocks. I'd imagine it's harder to convert a SFA to IFS than IFS to SFA.

 

[SPMNN]

But why don’t you want the 4Runner to be a BOF truck? I don’t understand that. I get that it’s not a selling feature for you, but there are a ton of other options out there for you, including the Jeep Grand Cherokee. And Toyota already makes the Highlander, what would a uni-body 4Runner accomplish?

From a business sense, the 4Runner shot up in sales when most other manufacturers stopped making midsized BOF suvs. I don’t see any real reason to change. If anything, they should be pressing their advantage in this space before Ford starts stealing into their market share with the Bronco.



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[gfxcruncher]

I doubt you’re going to find a whole lot of support for your wish list here...

IMO the BOF design perfectly fits in their lineup, there’s a reason you see the Taco, Tundra and 4Runner in the same adds crashing through fences and going off road (and not a Highlander). The day they abandon BOF with this platform will be the day you no longer see it in those ads and marketing materials.
The only experience I have with SA is when I was on a trip with a guy driving a Rubicon, Wrangler, YJ or whatever... He kept coming over the comms asking the group to slow up cause he was having problems with the speed at which we were taking fire roads and moderate rocky terrain. I’ll take my IFS.
Having worked in an auto body shop replacing integral panels on unibody vehicles, there’s no way I would do what I do in my truck if it was a unibody design. For example, the inner fender skirt, which is basically the shock tower, is nothing more than formed 12g steel held together by spot welds covered over with seam sealer. No way, and I’m by no means an extreme off-roader, or “overlander” as the they like to call it these days.
Since almost all other manufacturers of mid size suvs has abandoned BOF, why not just look at them?

*edit below
In no way trying to sound like an ahole or anything...

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[Rightside Up]

No thank you.

 

[Oldmanb777]

The issue is, on a unibody, the body flexes as the truck needs to flex over obstacles. On a BOF the frame flexes, and the body pretty much doesn't. So ultimately when you flex a unibody enough, the doors don't close, alignment suffers as things get bent. The frames don't take a set like a unibody must do to be stiff enough.
Don't get me wrong. We loved the GC's we have had. (5) Dead nuts reliable, and very durable. We have one with over 500k on the odometer. Live axles are certainly better for rough off road work. But for most that isn't what they do with their cars, and independent is better on the road. Tracks better, wears tires better, rides maybe better, but has lots of moving parts to worry about.
It just doesn't flex enough to keep the tires on the ground, like a live axle. Articulation is vague at best with independent suspension. But good enough for most applications, and probably a good trade off. Personally I would take a live axle any day over independent suspension. I prefer the rugged trade off to the "mall" crowd needs.