One reason is the tundra was already several hundred pounds heavier than the silverado, plus Toyota does not have the "hydroforming" process GM and Ford have, I believe they have a patent on this, so boxing the whole frame would be more expensive for toyota than to use the C channel. Plus they beefed it up to be just as strong as the GM frames.

The drawbacks. Look at a 2006 Tundra next to a 2007. The 2006 has much tighter panel gaps than the 2007. The 2007 actually has rather large body gaps. Toyota said this was on purpose to give the truck a more "rugged look." I'm calling BS on that. The reality is their frame is not stiff enough to HAVE tight panel gaps on the truck because of flexing. It's a strong frame, but it has a lot of flex to it.

New silverado. The gaps are REALLY tight on these new trucks, due mostly to the VASTLY improved and more rigid frame rails.

Look at a tundra and silverado side by side, the silverado actaully (for once) appears to have a better build quality than the Tundra.

That's my take.

 

Forgot to add: what it really comes down to is that it would be WAY too expensive to box the massive frames for the large trucks. A boxed frame is no stronger than a c frame, if both are designed correctly. What it truely boils down to is the amount of flex. The less flex you have, the tigher you can get body panel gaps. Some flex is necessary, if you look at the slow motion commercials showing the silverado going over bumps you see the bumper flex very little up and down, now check out nissans titan commerical when you get a chance. The bumper is literally moving almost an inch and is almost hitting the fenders.

Big trucks don't need tight panel gaps, and the LONG frames need to flex over steep and rough terrain. 1/2 ton pickups need tight gaps (reduced wind noise and increased aerodynamics) and a stiff frame to created a platform for higher towing capacities, payload capacities, and better suspensions.

Look at the tundra VS Gm PAYLOAD capacities model for model, GM has the tundra whipped.

 

I don't think that was Proud you were thinking of: http://web.camaross.com/forums/showt...me#post4484980

 

Many things, like boxed frames, are engineering overkill driven by a marketing mentallity of "bigger is always better", and people like to get boners over such things.

If someone truely needed a more rigid frame, bigger ring gear, or more torque on a regular basis out of their truck they'd buy a 3/4 or full ton truck.

 

Let's get this straight...

I SLAMMED them for trying to play off an ECONOMICAL decision for a "payload" issue. They claimed they chose not to box the frame because it would have "decreased payload" or some such BS. Like 10 more lbs of steel in the frame would have decreased the payload by 10 pounds or something. Call a fish a fish or a duck a duck - and I have no problem with it.

The thread took a turn into oblivion, and I bailed out. My time is too valuable to waste debating issues that are insignificant. That's why I am not going to get lured into this thread either except for this post.


Eric Bryant and PacerX are both VERY astute engineers... I bet they can tell us lots about mass moments of inertia, bending moments, the buckling equations, distribution of stresses over area, stress-risers, fatigue life calculations, and why boxing is "better". In fact, I think someone on this forum actually does frame design and analysis - I don't, at least not to pay my bills every day. I will tell you this much - there is a HUGE difference in the suspension design of commercial road tractors as compared to 1/2-ton p/u trucks, and there is even a significant design difference between a basic 1/2-ton and a 1-ton p/u. Start looking at suspension design and intended use, and you will see why road tractors have a 5/8" thick channel as opposed to .120-.179" thick frame on a 1/2 ton.

My bottom line - Toyota ADMITTED boxing is better - that's why they did most of their frame that way to begin with, but they did not do it 100%, and tried to claim it would affect their payload if they had.
I call BS on that as a reason.
I say they couldn't do it for patent infringement, costs, or complexity, and decided to dump the excuse on "payload".


PS - I knew it was me that you were after... that's why I posted what I did right behind your post.

 

... as they SHOULD.

 

No, I'm pretty sure it was him. If you dig further back you will see his comment was actually directed toward me. In an older thread than the one you linked to he was flat out saying we'd see Tundras with failed/bent frames because of the 'weak c-channel design'. I challenged him as to why if c-channels were so horrible, he had no problem with the fact that the GMT-800 platform used them all the way up until the GMT-900 came out for 2007 and all of a sudden now that GM finally moved up a step, he belittled a design for not being on par in that one regard.

 

EXACTLY Either design is already overkill and nothing more then marketing.

How many times have you had the frame of your C channel truck just snap in half over the last 50 years they have been making trucks?

 

I was under the impression that increasing modern day BOF strength was moreso about torsional and bending rigidity which keep the ride from being 'wiggly/sloppy' and allow the suspension to do its job within more accurate and predictable confines.

 

From what I understand, big rigs need to flex b/c of the very large loads they carry(80K Lbs.?). If the big rigs had boxed frames, they wouldn't flex, they would snap. Boxed frame on p/u is good b/c they do not need to flex due to lower load capacities & helps ride quality.

 

That's correct.

 

At one point GM was having a problem with trucks that had bent rails showing up at dealers. Turns out the guys hauling the trucks around were way overtightening the staps used to hold the trucks in place during transport, bending the frames. I think this was an issue with the first hyrdoformed rails. Weren't those first introduced on the GMT-800's?

Dan

 

The only time your going to notice any stiffness is if you go offroad and hit a ditch at such an angle to have opposite diagnol tires touching the the other too opposite ones off the gound.
Besides me how many people really do that.
On road I can't imagine anyone feeling a difference.
They want the behemouths to handle better maybe quit adding so damn much useless size to them.
Boxed frame will probably just add more weight.

 

I broke two jeep c-channel frames. never broke a boxed frame on any jeep ive had

 

I do performance cars... I don't visit extreme off-road sites.
Couldn't link to anything like this even if I knew how to Google.