Fully Boxed Frame
 

Maybe I'm in the dark here, but can someone tell me why Toyota will no longer put a fully boxed frame on a truck, yet they'll put a fully boxed frame on their SUV's? Am I loosing it or does this counteract conventional wisdom?

probibly just cost...
In any case I was disapointed when I saw that the new frames are just open C channels..

Because Dana is building their frames. American designs, American built.

The 4Runner and Land Cruiser frames are fully boxed. Built and designed by Toyota in Japan.

Yet the Sequoia has a C-channel frame built by Dana, just like the Tundra and Tacoma.

The new Taco is C-channel? What garbage........

James

It is probably just as strong as anything else. If it wasn't it wouldn't have been built like that...

Well the new Tacoma has a fully boxed frame under the engine up until about the middle of the front seats roughly. Then I believe it's reinforced C-channel until somewhere past the arches and then C-channel towards the bumper. It's a decent frame fro it's intended uses but I hardly doubt it would hold a candle to the frame on 86-95 Toyota Trucks. I believe the new Tundra's frames are similar to the Tacoma's in configuration only thicker metal and wider cross members (obviously). There are benefits and pitfalls to either, but I can't for the life of me figure out why they go with deviate on a successful frame design found on their trucks other than trying to make the vehicle lighter. But a new 05+ Tacoma weighs about as much as my truck. The 95.5 to 04 Tacoma's weigh about 400 pounds lighter than my truck and the 05+ Tacoma's.

I know there are a couple of different things that u can buy to reinforce the frame but can you fab the frame to fully boxed, or will this create future problems with rock sliders and other items.

The Hilux here has a fully boxed frame. but then it's designed to carry twice the payload of the Tacoma..

didn't know that the Tundra uses a C-channel frame

Fully boxed frames transfer more road and terrain imperfections to the cab, so Toyota went with the C-channel in the passenger area to create a, you guessed it, nicer ride. Aw...thank you Toyota for being so considerate.
Alright, so I nit pick and whine about the frame too, but I have actually had mine put to the test, when an old lady plowed into our '05 D/C at 30 mph. $12,500 in cosmetic and front suspension damage, but no frame damage. I was surprised. 30 mph doesn't sound like much, but it sure feels like it when you get t-boned.

It's hardly about performance and reliability with any manufacturer these days. They are built to please Soccer Moms and Dads... bout it.

I'd just rip off the body and box the frame. Lawl.

Just a bit of info. Open C channel is used to allow flex. Too rigid a frame in some cases is bad. Over notice simi trucks use open c channel for there frames. Reason being with all the torque those engines put out if the frame was completly rigid it would begine to crack. Flex keeps the frame from cracking. I am sure toyota knows what they are doing. The new tundra has more torque than toyota has probably ever seen which may account for the open frame sections to allow for flex. Just an idea.

You mean those engineering experts at Toyota might actually know what they're doing?



:hillbill:

:bigok:

holy old thread batman

if the reason is engine torque, how come toyota suv's with the same engine have boxed frames? that includes the LC200 and LC70 with the newer V8 TDI..

Thats what I've thought as soon as I saw the ford commercials trying to show flex vs the tundras. Flexing is a good thing. I wouldnt want my frame to crack down the road. At least if it flexes, I can pull/push it back into place.

EXACTLY.

The real reason is cost and ride quality, and USA Toyotas do no see the same type of stress an overseas Toyota would see, so there is no need for a fully boxed frame. (in their eyes at least)

Has anyone ever had their C-channel frame deform? If it saves weight (and thus fuel), increase ride comfort, and reduces cost, then I suppose its a good thing, assuming they were way overbuilt in the first place.

I am curious whether anyone has actually had a frame problem.

this sums it up older yotas are overbuilt for reliability newer yotas are built to MEET the industry standards not exceed.

Judging a frame just by being boxed versus c-channel is very simplistic. That's like saying a vehicle will be better off road just because it has a solid front axle. If you want to judge something by looking at 5% of the picture... you should get used to being wrong a lot :)

Just a quick list of all the attributes that would affect frame stiffness:
Boxed vs. lipped C vs. C
Height and width
Material
Thickness
Cross members
Suspension and body mounting points

Yes, Dana makes the frame... but I highly doubt Dana designed the frame. I'm sure the frame is Toyota design. And what's the hit on American stuff... last I checked my Dodge was fully boxed, hydroformed from tip to tail. F150's as well. I think the new 1/2 ton Chevy's are as well.

But look at the Dodge chassis cabs... they switch over to C channel for those trucks, despite them having much higher GVWR than the fully boxed pickups. Does that mean C channel is better than boxed? Of course not... it is just one piece of the puzzle.

Some of the priorities they have to look at when designing the frame are
Cost
Weight
Stiffness
Fatigue strength
Package
Resonant frequency
Energy absorbsion in several crash scenarios

Stiff frames help with a good ride, not hinder it. This allows them to run a softer suspension and limts the forces that make it to the body (doors that rattle in their openings are BAD!). But you have to be careful about resonant frequencies in the frame. A stiff frame can have a higher natural frequency, meaning it can transer vibrations from engine/exhaust/driveshafts/etc. that would not excite a fexier frame with a lower resonance point.

You also have to be careful modifying stiff frames. If you weaken one section of it, that small area can see very high stresses since all the twist in the frame ends up occuring in that one region. Dodge has specific guidelines to follow when mounting hitches or aftermarket bodies to their pickups.

I also think open frames are better for corrosion resistance. I have a theory that the boxed frames trapping dirt and road salt is one of the reasons you see 10 year old Toyotas that are about to break in two in the rust belt. I've never seen an open frame have a problem like that.

Right on.

But just for clarification. Not disagreeing with cargun in anyway just don't want to do two posts.

Rigidity is good for handling, which is why most all frames are fully boxed around the front suspension. But as stated before too stiff a frame is not a good thing. Fatigue is what kills frames. Higher strength material which is stiffer does not mean it has a better fatigue life. A happy medium must be found. Too much stiffness leads to cracks which will really lower the integridy of your frame. Cracks propogate much quicker through stiff materials. Trust me I know what I am talking about.