Last post on Mar 29, 2007 at 5:33 AM
You are in the Toyota Tundra
What is this discussion about?
Toyota Tundra, Chevrolet Silverado 1500, Truck
#1955 of 2059 Re: Lag time... [kdhspyder]
Mar 28, 2007 (6:57 am)
In 2005, 60 percent of SUV occupants killed in crashes were in vehicles that rolled over. In comparison, 46 percent of deaths in pickups and 24 percent of deaths in cars were in rollovers.
Just out of curiosity, what portion of that 46% of pick-ups were RCs? ECs? Crewcabs? My guess is that most were crewcabs or ext cabs, very few RCs. High center of gravity is the culprit here, and SUVs have the highest, followed by Crewcabs, ext cabs, then RCs. This is the reasoning that GM uses for not using Stabilitrak on RCs. But they will, keep in mind, when they go to something like this standard, it affects nearly 1 million vehicles/year, not 100-125K. So it takes time to ramp up. Just a fact of life in the manufacturing world. Same reason the 6.2s and the 6 spds are only available on a limited basis, give them a year to ramp up and then judge them. If Toyota were making 1 million Tundras this year, I would be curious to know what limitations they would have as far as availablity and standard features.
#1956 of 2059 Re: Lag time... [erich1965]
Mar 28, 2007 (7:51 am)
FBF are NOT stronger than C-channel when it comes to bending strength (vertical load). C-channels are stronger in this regard pound for pound. Heavy duty trucks use c-channel frames because they are stronger and more efficient (strength to weight ratio) for carrying weight. FBF are better in torsion. Please don't claim "engineering principles" without references. Read what I posted before (#1123):
Common sense tells us that a FBF should be stiffer than a C-channel frame given that they both have the same depth or height, width, and thickness. But let’s examine the numbers to see if it is stiffer and by how much. For example, let’s compare a C6x10.5 C-channel to an HSS6x2x5/16 rectangular section (Both can be found in the AISC Manual of Steel Construction). I chose theses two because they are similar with regards to external dimensions and we don't know the exact dimensions of the frames in questions. A C6x10.5 section has a depth of 6.0 inches, a width of 2.03 inches, web thickness of 0.314 inch, flange thickness of 0.343 inch (the flange is actually at a slope but it’ll suffice for this discussion), and weighs 10.5 lbs/ft. An HSS6x2x5/16 has a depth of 6.0 inches, a width of 2.0 inches, a wall thickness of 0.291 or ~5/16 inch, and weighs 14.8 lbs/ft. These are published NOMINAL dimensions by the way.
The section property that measures how stiff a section is in bending is its Area Moment of Inertia (not to be confused with Mass Moment of Inertia for all you ME’s out there) normally represented by an “I”. The bigger the “I”, the more load it can carry before being overstressed. The Moment of Inertia for a C6x10.5 is 15.1 in^4. The Moment of Inertia for an HSS6x2x5/16 is 15.3 in^4. Therefore the rectangular section is stiffer than the C-channel, but by only 1%. But the rectangular section weighs almost 41% more than the C-channel. Hmm…let’s add 41% more steel to increase the bending stiffness by 1%. That’s because the “extra” material is added in the wrong location to be effective for bending resistance. The extra material needs to be added as far away from the centroid as possible. That's where Toyota reinforced the frame rail on under the cab, at the top and bottom flanges.
So what if we picked a C-channeled that weighed about the same as this HSS section, a C8x13.75 for example (weight = 13.75 lbs/ft). It has a moment of inertia of 36.1 in^4. That’s 235.9% increase in bending stiffness compared to the HSS6x2x5/16.
#1957 of 2059 Re: Lag time... [erich1965]
Mar 28, 2007 (8:01 am)
I don't think anybody has argued that a FBF is going to be stronger than an open c-channel, but what proponents of the FBF frame have failed to address is how this makes any difference in actual performance/capability/etc. of the truck. My best guess here is that Toyota doing the tripletec frame probably saved money either through labor or cost of materials or both.
The features you did mention that were advantageous for Toyota but would be coming for the Silverado just illustrate the point of Tundra being very good in those respects. They are available now and even though others will eventually bring those types of features, that in fact reinforces the advantages of this design. Same goes for things vice versa. But as much as any of these pros/cons for these trucks are illustrated here, the real problem is that most people don't actually go see both vehicles to really see for themselves these pros/cons.
I was at both a Chevy dealer and Toyota dealer 3 times each this year and at a GMC dealer once. For me all trucks are very capable and great. For my particular needs the Tundra is fantastic in the areas that are most important to me. Even things that aren't readily discussed like how the Navigation system on the Tundra is much, much better than what is on the Chevy. Still those are secondary things for some and not a deal breaker. But the important thing is that for those that actually want those types of things now, they'll choose that truck. For others that won't be the case.
Either way, this thread has gone on way too long...
#1958 of 2059 Re: Lag time... [titancrew]
Mar 28, 2007 (8:05 am)
Interesting post! I wouldn't mind trying to find out what actual numbers for each of the major trucks were in terms of their frame construction. So far none of those specs seem to be available form the public vehicle web sites...
#1959 of 2059 Re: Lag time... [titancrew]
Mar 28, 2007 (8:08 am)
Nice numbers Mr Engineering dude. But last time I checked, neither the Tundra nor the Gm uses standard AISC structural profiles for their frames. They are thinner gauge, formed steel shapes. So, NONE of your numbers mean a darn thing relative to this discussion. Pound for pound, the FBF IS stonger than a C channel based on the material thicknesses and profiles used on these trucks. Now, on cement truck, dump trucks, etc, they may actually use AISC structural shapes for their frames. Different situation completely. Nice try though.
BTW if a C or a reinforced C is superior to a box, then why didn't Toyota use it for the entire frame?
#1960 of 2059 Re: Lag time... [erich1965]
Mar 28, 2007 (8:22 am)
So do you in fact have those numbers since you seem to be an expert in this area?
#1961 of 2059 Re: Lag time... [belias]
Mar 28, 2007 (8:33 am)
I looked at the frame display at our local auto show (and at a Ford dealer too) that showed cross sections of each of Toyota's frame sections and I witnessed it for myself. Did I take measurements? No, didn't have to to see that the material thicknesses were similar. Common sense is a very valuable attribute to have. Toyota even reinforced the weaker C section in the area under the cab, why? if the C section is superior, it shouldn't need reinforcing now should it? And why is the area under the cab worthy of reinforcing and the area under the bed isn't? The FBF is equally strong front to back without any reinforcing. Why can't you toyota people admit that FBF is better without seeing performance numbers? Weight/strength ratio is a measurable number that does have merit.
Still waiting for the defense of the chincy stamped, bolted in crossmembers too. You all seem to avoid this part of this discussion. Why?
#1962 of 2059 Re: Lag time... [erich1965]
Mar 28, 2007 (8:37 am)
Because last time I checked, automotive engineers design vehicles, not automotive common sensalists... Don't worry jreagan, glad to have you back! Just out of curiosity though, why do you care about the frame so much? Did you have problems with your previous vehicles due to poor frames? Did you have a frame break, crack or rust up?
#1963 of 2059 Re: Lag time... [belias]
Mar 28, 2007 (8:44 am)
This is the dumbest thing i have heard yet. And who the heck is jreagan?
Nope, never had a problem with frames, just pointing out that the GM's is superior and you Toyota people just cannot accept ANYTHING being better then the Tundra's, no matter how obvious it is.
#1964 of 2059 Re: Lag time... [erich1965]
Mar 28, 2007 (8:44 am)
BTW, you selectively chose not to address my point about the construction of the frame regarding bolted in, stamped cross members. Please answer my question on my previous post as to how that is as good as tubular members welded through both sides of the boxed frame. Oh wait, that doesn't help the "performance" of the truck either, sorry, my bad.
Yes the FBF's might be stronger, I'll grant that, depending on design, steel thickness, steel grade of course.
Still with this presumably stronger frame what does a truck owner gain? OK it's stronger......and..?
No T900 2WD can tow as much as a Tundra 5.7L and most 4WD's are at best equal.
One F150 configuration with the FBF can slightly out-tow a Tundra but the rest of the line is way below the Toyota's capability.
No Dodge Hemi Ram can out-tow any Tundra and most payload on any Ram are far below the Tundra.
None of the others in the class are as quick whether unburdened or carrying or towing.
There is no single measurable benefit. The fact that the FBF is likely stronger is a feature....but where's the benefit.
Regarding the frame construction I can't comment since I am not privvy to any of the engineering data. Unless you are a mechanical engineer in the auto design area I guess we'll have to say that time will tell. Durability has never been a problem with the modern Toyota's. In fact it's reputation is quite the opposite. They get the benefit of the doubt. I'm also sure that the T900's will pass the test of time also.