Roll greater than 30º on trails doesn't set off the airbags :-)

We hit some seriously tough trails in a MI National Forest Saturday. The last trail saw one 4Runner pull a tire off the bead and a Jeep catch fire (!!). The Taco performed flawlessly. 4LO with rear locker and Mud / Sand mode engaged pulled me up a steep set of offset two-foot steps with no difficulties at all - seemed like it was just a bouncy trail, not something that was making other rigs need winches. At one point there was section about 100 meters long that set the roll gauge to max out at 30º and the truck didn't pull a Colorado on me - the airbags stayed right where they belonged. If anyone ever doubts the beast-mode capabilities of this truck out of the factory (OK, so 32" KO2's added) then they should come up to Cadillac MI and hit the Caberfae lookout trail backwards.

 

The airbags on the chevys are a fluke... Haha... Poor Chevy. Our trucks can lean quite far, the most I have had mine is probably around 40*, I was worried about tipping but I trusted my spotter. I wish I was smart enough to calculate the center of gravity of my truck and the actual static rollover angle.

 

If you hang it from a chain, the cg passes vertically through the connection point to the ground. LoL!

You got to do it from at least two opposing angles to trianglule it.


In reality, the cg is probably between the cab floor and seat bottom heights.

 

impressive. i came to say that after i got the truck i went up 33* on stock tires & stock everything. no drama, not even a slip.

 

Until you lift lol.

OP it takes more than angle to blow the Tacoma airbags. Tip angle is just one criteria at one set of parameters. Speed, inertia, pitch and yaw angle all play a part in deciding if you REALLY need an airbag or if you are just out messing around on a trail.
Just remember, engineers are solving problems you didn't know you had long before you need the solution.

 

I didn't pay enough attention in my physics classes to accurately calculate the exact spot of the cg. But I would agree that the rough cg is somewhere between floor board and seat bottom. Most of the mass is frame and drivetrain so that makes sense. With a small lift the rollover angle is still probably slightly past 45*.

 

Cheby forgot about a few of those parameters.

 

Good reading on Colorado airbag issues:

https://www.gm-trucks.com/forums/to...ent-while-soft-roading-details-images/?page=2

 

Here is the basic physics and for those who don't know how to use the math, it has tables showing generic Tacomas:

 

Check my attached file on rollovers above.

 

I can see if I can borrow some floor scales from work and determine the cg height with a jack and digital level, if people actually care about the cg height...
But I doubt anybody cares that much...

 

If only the airbags deployed in the YouTube video comparing the Pro to the ZR2. That would’ve been hilarious.

 

It gives you a good estimate in the tables I listed above. Surprisingly, there is not much difference.

 

Thanks for the document. I have one issue with this though, it doesn't define a static rollover very accurately. This document assumes that there is a moving force on a vehicle or some sort of momentum which is a dynamic rollover. I think that for our case in 4wheeling, the momentum can be removed from the equation since a smart wheeler would be moving very slow while the vehicle is leaned over. Unless the vehicle slides off the obstacle (creating a dynamic rollover scenario) then the only rollover we would be concerned about is a static rollover (where it's simply the tipping point of an object with no momentum applied). I think the document is great for the dynamic situation more than the static situation.

Now if we can have a generic document specific for our tacomas that had the center of gravity for a completely stock Tacoma (most commonly DCSB) then have some field that can be changed based on each vehicle modification (lift, tires, roof rack, etc.) then we can have a fairly accurate way to determine exactly what our static rollover angle would be.

 

Except there is no such thing as static rollover lol. You can't just park it on a hill and it rolls over. You have to be doing something, like moving, sliding, cutting the wheels, etc. While you think that slow movement does not mean much, it absolutely does especially if you are near the tipping point where just a few lb weight shift is enough to roll it.
One huge factor is tire type and pressure. E tires have a stiffer sidewall than P so it would not "bend" as easy and that means it would take more force to roll it. Same thing with tire pressure. Type of surface (loose dirt, rock, mud) is going to be another factor as well. Another factor is your suspension. Soft or hard, how much travel, etc.
Basically, dynamic rollover is complicated and no calculator or spreadsheet or formula is going to show you definitively when you are going to roll. Experience with the vehicle is the best solution.
I have rolled a few vehicles in my time (a 22' box truck was one) and I can tell you these things will tip much further than you think before rolling.

 

Purely tipping angle statically is simple given cg height= (h)and tire track. (I would assume use center of tire track =t)

Drawing on napkin, it should be
Tan^-1(t/(2h))

Correct me if I am wrong... doing it in my head. Of course this doesnt account for tire or suspension deflection under load.

 

Yeah I disengage SRS with the push of a button before I do any offroading.

 

If you are that close to rolling your rig shouldn’t it be a dedicated trailer queen instead of a daily driver? IMO if I am wheeling hard enough to worry about rolling or other catastrophic damage then I need to seriously re-evaluate my rig. Trail damage happens. I have folded in a fender and straightened it by sledgehammer method. Ripped a soft top and laughed about it. Both times with a Jeep that was trailered to and from the trails and could sit for weeks if needed to fix the damage. I have wheeled with guys with $25,000 in Currie custom axles who were afraid to get a pinstripe in their paint. I don’t get it. Either wheel super conservatively or come prepared and be ready for stuff to get f’d up.

If you are to the point where you need to calculate your roll over angle you are going to be in tears when shit happens and your calculations were right but a slide and grab destroyed your rig. Years ago I watched a guy at a motorcycle track day with 59 payments left make a 45deg angle in the middle of his frame. One payment made and a complete write off before he owned it a week.

 

Where's the fun in that? I have had rigs that I didn't mind rolling over but I like to drive to and from the trail in comfort. I don't need to take my truck to the exact rollover angle but I would like to know roughly where it is and stay about 5 degrees shy of it. What can I say, I like to be able to push my truck to its limits. I'm not afraid of a little rock rash or pinstriping, this is an offroad truck but I would rather not flop it over either.

You are correct, mostly. I am wrong however in the definition of a static rollover. It applies to helicopters specifically when landing on a slope and leveling the controls, the helicopter can roll over without any force applied. I was trying to assume a static rollover was more of a universal term. So in this case a dynamic rollover would be the appropriate term. I was saying that vehicle movement wouldn't be a factor because when I am leaned over I am going extremely slow to minimize any force of momentum which I would almost say it's not a factor in the equation.