Hate to say it, but not any more. The 2011-up GM HD's now have the strongest frames in the industry by a wide margin. Those twist videos are not a joke, boxed rails and tubular crossmembers welded on both sides of the rails makes a very strong structure. 60,000 psi steel doesn't hurt either. I do think Ford will equal them with the next gen. Super Duty though.


I liked to old DT's too. No way was Navistar/International ever going to sell those to another OEM, those engines were the 'family jewels'!

 

The f150's are stiffer, there is a difference between fame strength and stiffness.
Stiffer frame is ideal for most vehicles,
Frame flex is ideal for towing.
What GM has done in those frame flex videos is proven they want to build toys instead of work trucks.

They have proved they're truck is the best at something, but that something isn't what a towing vehicle should have as a design trait.

 

I was making a comparison between the Super Duty and the 2011-up GM HD's. I do not know the F-150 frame compares to the GM 1500's.


Frame flex is ideal for towing? How?


Consider the GM HD's do not need a weight equalizing hitch with heavier trailers where Super Duty's do.


GM didn't do that frame twist comparison with the Ram HD's because the Ram performed similarly to the GM HD trucks.

 

gm's frames are so stiff that when they get hit by a VW they crumble like a soda cracker.
they may be strong for twist, but they are so strong they break on impact.
a friend runs a junkyard. he gets gm's in that are totaled from broken frames, where fords would drive away with a little sheet metal replaced.

 

The stiffer the frame, the stronger it has to be.
A more flexible frame can absorb stress and flexing, without damaging the integrity.
A super stiff frame has to be stronger to keep itself from getting damaged.

The flex acts as an impact spring, allowing it to soak up impacts from bumps in the road, weight on it, etc.

Imagine how much bigger your ball joints would have to be, if the axles bolted to the frame without springs. Thats where GM's frame is at, it's stronger, but it's stronger to protect it's self, not to give you a better frame.

Similar to how cummins crankshafts are so beefy; did you know most of that strength is to protect the longer crank against vibration torsional damage, and it actually is not just made way bigger to be the strongest engine ever invented? Because the crank is longer than a v8 crank, the harmonic vibrations are more extreme, thus needs more strength to deal with that. So it's stronger, but not to give you a stronger crank, but rather keep itself together.

 

Did you know that harmonic crankshaft vibrations are much worse in a V-8 with a 90 degree crankshaft then they are in an in-line 6? In fact, an in-line 6 is about the best balanced engine around because of the 120 degree firing interval. Only 2 cylinders will hit TDC or BDC at any one time (that's where a lot of the harmonics come from). A long in-line 6 crank is under more torsional stress than a shorter V-8 crank.

 

Wow, that's really good to know. I am going to sell my Freightliner next week.


Those GM trucks will have a lot of company in the wrecking yards shortly.

 

An inline 3 is also perfectly balanced, and I don't have the right words for this, but they are balanced rotation-wise. lol. The inline 3 though has terrible end to end vibrations, so couple 2 inline 3's together, and they end to end vibrations even eachother out, and you have a perfectly balanced inline 6.
Thats right the torsional stress is a lot higher with an inline 6 than a v8.

 

them semi trucks frames flex like the dickins when they move around in them super low gears.

 

sure do!!
the W900 kenworth with the 600 hp kitty cat will lift the driver side tire off the ground if i go full on in low gear with the 18 speed trans when the trailer has a 75 ton excavator on it.
the T-800 tri-axle with the 500 hp Cat and 8LL trans, and the mack granite with the 460 and 8LL will skim the driver front when fully loaded at 80,000 lbs.

 

I've almost seen this many many times. Not losing ground contact, but close.

Also the f450 + frames are even more flexible, the more weight, the more flex you want.

 

They do, but that is not an ideal situation, and will eventually lead to damage. That's why most all your heavy haul 600 h.p. tractors have double or even triple frame rails, and a lot of highway tractors have single aluminum rails. Guess what, that frame on a Mack Granite is a lot stiffer than that under a Freightliner Coronado. Sure, pull some large excavator and even the Granite's chassis will wrap up, but do the same with a Freightshaker and you will bend it into a pretzel permanently.


Remember that the current Super Duty chassis was designed in 1999, and we are comparing it to the current GM HD chassis which came out in 2011. I have known engineers at both Ford and GM over the years, and neither group would purposely design a frame that would "crumble like a soda cracker".

 

The GM frame isn't designed to crumble like a soda cracker, it is designed to be strong and rigid.
The problem with a rigid frame, compared to flexible, is that although they might keep the truck more rigid and straight than a flexible frame, but after a certain point of force, the rigid frame will be stressed enough that it is damaged.

It's no secret that flexible frames are better in tow vehicles, which is I'm sure why the super duty series uses them. The f150's with their rigid frames, are not such a serious work truck, and that was probably why they got engineered the way they did.


GM has always seemed to sell you what you need, rather than what you think you need. The frames are no exception. They know that probably 90% of their heavy duty customers don't pull nothing. They also probably wanted to improve the empty unloaded riding characteristics, as the newer fords were really closing in on them in that aspect. Ride quality is one of GM's main features, without that, why would you buy one?

 

Actually, the ride in a 2011-up GM HD is worse than the 2010 and earlier truck with the more flexible chassis. Tire balance has also become more critical has the newer chassis transmits a lot more NVH to the cab. Many of the newer GM HD's have hydraulic cab mounts to counteract the stiffer frame.

 

Don't semi's use air bag cab mounts?
I'm sure I've seen em a few times.

Maybe I'm not in enough chevy's to notice, I thought the new ones rode pretty good.
Maybe just my opinion but I thought they were a+ for ride quality.
The new ford superdutys are also a+ now, I find.