Tundra frame compared to the Land Cruiser 200 and Ford F-150?

[Moyshe Kapoyer]

Hello,

since the frame of the 2007+ Tundra is at least similiar to that of the LC 200, ist it the same size frame rails? Or did it got stronger with years due to regulations/weight increase? Also how does it measure up to the Ford F-150?

What i know: The LC 200 has a solide 185x90x3.2mm profile, while the Ford git 225x70x2.5, so bigger but thinner.

Kind regards

Marcus

The 2015+ F150 has 3 frame thicknesses and is fully boxed from bumper to bumper.

 

[rruff]

2nd gen Tundra has a very flexy frame. Honestly I'm not totally convinced a rigid frame is stronger. Medium duty and up trucks tend to have flexy open c channel frames. RAM 4500 and F450 are c channel. A rigid frame is going to be better for anything mounted to the truck bed. That was a big reason we switched from a Tundra to a F250 to carry our camper.

F450 and 550 are open-C also. A lot of frames were open-C in the past and anything bigger than a 1 ton still is AFAIK.

The torsionally flexible frame is actually under less stress in cross-up situations because it can twist and keep the wheels on the ground. It is not inherently weak at all.

SUVs have boxed frame rails so it can make a rigid unit with the cab. This has been true of LC (I think), Sequoia and 4runners. Trucks have a separation between the cab and bed that allows more twist. I'm sure a driver for going to fully boxed frames is that the cab of pickups has gotten longer and beds shorter.

This is what the 2nd gen Tundra frame looks like. The transition from "reinforced closed-C" to the wimpy open-C happens where the front of the rear leaf mounts to the frame. On my truck this is well behind the cab (8 ft bed) but on most it's close to the rear of the cab.

This is a photo I took right after mounting the camper, to see how well the pivoting mechanism was working. It's just about on two wheels here. The front right tire is on a rock, while the left is in the ditch.

 

[Oshkosh-P]

Well even really bif Trucks like the MAN KAT are based on a fuly boxed frame

https://www.wohnmobil-selbstausbau.com/project/wohnmobil/media/fzupload7/1475_1_11794_fancybox.jpg

This design is a boxed fram front to rear with a L-Pice one top, so you get both the benefits of total stiffness and easily mountet stuff on top.

And this frame is used up until 45tons.

 

[plainjaneFJC]

Dodge hat boxed frames in theier 2/3500's since around 2004 i think, Chevy since 2011 and Ford since 2017.

I think a rigid frame is better on the road and equally good offroad if the suspension helps out. From the perspective of longevity a stiff frame will of course live longer compared to a frame that has to flex all the time.

However a stiff frame has to be heavier and generally larger in my opinion, or have much stronger steele, otherwise there is the risk of cracking.

All Land Cruiser since the late 80's where boxed and those have been mistreatet for decades now and still work. Same for the G-wagon, or the much heavier and bigger MAN KAT. The Humvee is fully boxed too.

So boxed frames can work very well offroad, but not if they are just used as a gimmick for better ride quality or even worse, the manufactorer wants to save weight with a boxed frame by usinf much much thinner sheets.

Are you sure the Dodge was fully boxed? Maybe it was boxed but didn’t have many crossmembers- I had a 2006 3500 with the Cummins and the motor torque would twist that truck pretty good.

 

[Oshkosh-P]

Yes AFAIK the 3rd gen Ram 2/3500 was already fully boxed. However it was and is always the smallest out of all 3 frame, aside from the chassis cab, which is open c in the rear end and similiar or bigger in size compared to the Chassi cabs of Ford and Chevy.

 

[rruff]

This design is a boxed fram front to rear with a L-Pice one top, so you get both the benefits of total stiffness and easily mountet stuff on top.

That appears to be true. I don't see any twist on these:


PnM's OKA also has a stiff frame, though it's smaller.

Not all MANs are stiff though:


I suspect weight and cost are factors. The stiff frame requires more and stronger steel in order to survive, and also increases the need for better suspension articulation offroad. Usually designers opt for letting the frame twist.

 

[Oshkosh-P]

Yes of course it was only the most expensive military line of MAN that used the boxed frame from the 70's till the 2010's, after that they optet for the cheaper HX series with a civilian open C.

The boxed section was 206x100x8mm, the L on top 150x70x8, however this was made out of one single piece, bent in this special form and only welded together on the top at one point, so way stronger than any boxed frame made out of 2 x c profiel welded into each other.

The oka is a classic boxed frame, but only 125x75x6mm, so thick but very small, not a fan of this idea.

 

[bkg]

Rigidity and strength are two different characteristics. There's no reason a rigid frame will necessarily last longer. You have to know the stress-strain of the material and design the geometry (tolerable flex) to be compatible. Leaf springs can last just as long as the frame, aircraft wings don't necessarily fail before the fuselage. It depends on how well the designer did and how the vehicle is used. We tend to fatigue our leaf springs sooner but we also flex them more and deeper than the majority of owners. Plenty of trucks are crushed with the springs they came with from the factory when they're not used quite as harshly.

It's part of the reason I assume Toyota had to leave the front section boxed. They use a high strength steel in the front which is more brittle, thus cannot tolerate as much deflection. The 1st gen Tacoma frame was too flexible. The problem I had was the camper shell would hit the cab roof. I never developed a permanent deformation but some people would. The 2nd gen flex is just slightly lower (still significant IMO) but also less failure-prone with a notable exception. The first 2 or so years, 2005, 2006, early 2007, the motor mount could fracture and collapse into the frame and required a production change to add gussets. This is a typical indication of weld heat issues and material brittleness in higher strength steels and was in the boxed section, not the open section.

My xtracab has dents on the cab from the top of the box. Very common.

People like to defend Toyota for their wet noodle frames. Many of those same people defend Toyota for not abandoning rear drums for almost a decade after other mfg’s did so.

Hard for many people to separate emotion from engineering. Is what it is.

 

[DaveInDenver]

My xtracab has dents on the cab from the top of the box. Very common.

People like to defend Toyota for their wet noodle frames. Many of those same people defend Toyota for not abandoning rear drums for almost a decade after other mfg’s did so.

Hard for many people to separate emotion from engineering. Is what it is.

I'd prefer a more rigid frame for my reasons but I can't complain with how long my trucks last. Two Toyotas spanning 24 years and counting. So Toyota has their reasons, too. Frame-wise the corrosion is what irritates me.

And I like drum brakes fine.

And my vinyl records through tube amps. I also still read paper books from the library. And turn fasteners with hand tools. Ride a steel hardtail singlespeed, hike in old Norwegian welt leather boots and telemark turn my skis.

So there. I do things the hard way intentionally.

 

[DaveInDenver]

I thought the reason the 4Runner and 200 series are fully boxed while the Tacoma and Tundra were not had to do with the 5 link suspension vs leafs. Sweers specifically stated that was why the 3rd gen frame went fully boxed.

Additionally, the 4runner and LC had a continuous body that is not going to want to cope with as much flex as a truck with a totally separated bed.

My understanding is that the c-channel frame helps dampen the jitters and wiggles that you get from a leaf sprung rear axle. This is something that was really apparent on my 2014 F150 but was mostly cured with a set of Bilstein shocks.

That's nonsense because prior to 1995 all Toyota truck in the U.S. were boxed frame and the HIlux and Land Cruiser ute always have been. And for their size and weight the Hilux and Cruiser have higher payloads, too. It's only the Tacoma and Tundra there were outliers. As has been noted having two major body assemblies on a flexible frame presents problems, too, like the box hitting the cab and denting it. Flex is less obvious on a pickup than doors that won't open on a wagon body, though.

 

[bkg]

That's nonsense because prior to 1995 all Toyota truck in the U.S. were boxed frame and the HIlux and Land Cruiser ute always have been. And for their size and weight the Hilux and Cruiser have higher payloads, too. It's only the Tacoma and Tundra there were outliers. As has been noted having two major body assemblies on a flexible frame presents problems, too, like the box hitting the cab and denting it. Flex is less obvious on a pickup than doors that won't open on a wagon body, though.

Want to see how flexy a 2nd gen tundra frame really is - do a brake stand and watch the cab/bed separate.

 

[DaveInDenver]

Want to see how flexy a 2nd gen tundra frame really is - do a brake stand and watch the cab/bed separate.

Another thing I noticed was the noise all the bed bouncing around of a 2005+ Tacoma makes driving down the road. I put thin Delrin slip washers between the box and mounts to quiet it down.

 

[rruff]

Want to see how flexy a 2nd gen tundra frame really is - do a brake stand and watch the cab/bed separate.

Mine is the DC long bed, so it should be the worst offender. I haven't tried that ^ trick, but right after I bought it and headed south on the 25 in Denver, it bucked like a frickin' bronco. If I had to drive that road very often (or one like it), no way in hell would I own this truck.

It's weird, because a C channel is better optimized for vertical stiffness that a boxed frame. The wimpy part of the frame is the rear 6'. And the beefy hitch surely stiffens the last 2'. The C is only 5.5" tall and 3.2" wide back there... and .16" thick. I don't know how that compares to other frames.

The rest of the frame that is closed C on mine is 7"x3.2" and it looks like the same thickness, with an additional C channel riveted in the top and bottom of that, so .32" thick top and bottom. That's well optimized for vertical stiffness... I'll take a WAG and say it's 3-4x stiffer than the rear part.

Nearly everything is riveted or bolted which led me to think it was a special high strength steel... but the front bed mounts and the shock mounts are welded in place for some reason. At any rate, these frames aren't lacking in strength based on the abuse that they are able to survive, but some added stiffness would be nice.

It wouldn't be that hard to do. Bolt or rivet or weld pieces of channel to the outside of the frame, then form lengths of flat steel to match up with them on the top and bottom. Since I took the bed off, I have plenty of room....

 

[bkg]

Mine is the DC long bed, so it should be the worst offender. I haven't tried that ^ trick, but right after I bought it and headed south on the 25 in Denver, it bucked like a frickin' bronco. If I had to drive that road very often (or one like it), no way in hell would I own this truck.

It's weird, because a C channel is better optimized for vertical stiffness that a boxed frame. The wimpy part of the frame is the rear 6'. And the beefy hitch surely stiffens the last 2'. The C is only 5.5" tall and 3.2" wide back there... and .16" thick. I don't know how that compares to other frames.

The rest of the frame that is closed C on mine is 7"x3.2" and it looks like the same thickness, with an additional C channel riveted in the top and bottom of that, so .32" thick top and bottom. That's well optimized for vertical stiffness... I'll take a WAG and say it's 3-4x stiffer than the rear part.

Nearly everything is riveted or bolted which led me to think it was a special high strength steel... but the front bed mounts and the shock mounts are welded in place for some reason. At any rate, these frames aren't lacking in strength based on the abuse that they are able to survive, but some added stiffness would be nice.

It wouldn't be that hard to do. Bolt or rivet or weld pieces of channel to the outside of the frame, then form lengths of flat steel to match up with them on the top and bottom. Since I took the bed off, I have plenty of room....

Do it... film it... cry over it.
The difference in quality of ride on my last CrewMax between factory and with AllPro sliders was very noticeable.

 

[rruff]

Do it... film it... cry over it.
The difference in quality of ride on my last CrewMax between factory and with AllPro sliders was very noticeable.

I got enough to cry over lately, building that damn camper...

But damn, it seems like it wouldn't be too hard... famous last words!