GVWR and Building Heavy

[TeCKis300]

Reading various builds and the 45 gallon aux tank thread got me thinking back again on this topic. I'm curious what kind of curb weight some of the built rigs are weighing in at. I'm sure waaaay over GVWR. This is rarely talked about on these boards as we're generally focus'd with building up and adding gear. Almost never are we trading gear for something lighter.

As much as we're not a Lotus, I strongly believe Chapman's philosophy of "adding lightness", or tempering weight, certainly still applies. Because just about everything works better when lighter.

Weight is an interesting slippery slope. Consider armor. It's used to protect the structure from rock damage, and has to be at least some minimum robustness to put up with hits without too much deformation. Consider a lighter built one that is designed for a ~7000lb rig. Now that we build out the rest of the rig, it's closer to 8000lbs. Will that same rear bumper take a hit on behalf of a 8000lb rig? So we may need a heavier build Slee one, increasing the weight of the buildout. Then we pile in gear for an expedition and we're now at 9000lbs. Will that bumper take that hit? Even if it does, will the frame we're trying to protect handle it?

Same thing with carrying spare parts. CV axles? They are probably indestructible on a lighter overland setup. Now a 9000lb+ build with drawers and the full complement of gear and spare parts? Yeah, it's prob no longer bombproof at this load level.

On a more concrete point, looking at GAWR (gross axle weight rating). On my LX570 (is the LC the same?) it's:
Front: 3595lbs
Rear 4300lbs
That's a pretty generous 7895 lb capacity for a rig that's GVWR 7275 lbs.

It's just something to consider, to balance builds with weight in mind.

 

[TonyP]

I'm sure waaaay over GVWR.

Nope.
7300, armored, loaded with camping gear, drawers full of tools, full tank, 35s, driver in the seat.

I suspect I'm even lighter now.

 

[bjowett]

FWIW, the stock rear axle on the Tundra is purportedly rated at 5500 lbs. This information came from an employee at the Hino plant which manufactures the assemblies. They did not mention if they were speaking if the 10.5" or the 9.5". Everything but the center section and axle shaft diameter is the same, though, as far as we are aware. The 200 axle is built heavier in how the tubes taper into the center section, when compared to the Tundra. The point here is to show even if you are at the limit, the Toyota axle is well overbuilt... no surprise as to why they last so long.

 

[gaijin]

FWIW, the stock rear axle on the Tundra is purportedly rated at 5500 lbs. This information came from an employee at the Hino plant which manufactures the assemblies. They did not mention if they were speaking if the 10.5" or the 9.5". Everything but the center section and axle shaft diameter is the same, though, as far as we are aware. The 200 axle is built heavier in how the tubes taper into the center section, when compared to the Tundra. The point here is to show even if you are at the limit, the Toyota axle is well overbuilt... no surprise as to why they last so long.

Good to know, but when discussing loading wouldn't it be prudent to think of the Rear GAWR as a system - tires, wheels, springs AND axle - rather than just the axle? I know you are well aware of this, I don't mean to imply you are not, just trying to avoid the impression that one suspension component, i.e. the rear axle, dictates the GAWR.

Run tires with an inadequate Load Limit and GAWR doesn't matter.

Run aftermarket wheels with inadequate Load Rating and GAWR doesn't matter.\

I guess I'm just sensitive to the plethora of posts soliciting opinions on wheels, for example, without ever addressing whether they meet the design requirements to sustain the GAWR.

/Rant Over

HTH

 

[Sandroad]

A couple other data threads.

GVWR, how much can a 200 safely carry?


Weigh In - 6800 lbs loaded (7000 w/ Wife and Her Gear)

 

[linuxgod]

As @Sandroad mentions, this is a good thread to read: GVWR, how much can a 200 safely carry?

Lovells makes a GVM upgrade for use in Australia, which officially upgrades the GVM (Aussie equivalent of GVWR) by 500kg to 3800kg (1800kg front/2000kg rear). Their kit includes only the following:

• 2 x Lovells Heavy Duty Front Coil Springs
• 2 x Lovells Heavy Duty Rear Coil Springs
• 4 x Lovells Gas Legend 36mm Twin tube, Long Travel Gas Shock Absorbers

Note there is no tire, wheel, front or rear UCA or LCA, sway bar, diff, or brake upgrades as part of the kit. Even the tire pressure stays at 33psi (230kpa) for stock. So from this I would infer that upgrading the *right* springs and shocks is sufficient to upgrade your carrying capacity to 8395# (7295 + 1100), and that the rest of the vehicle is capable of safely carrying the additional load.

Seems to me the question becomes what spring rate is required to achieve that additional load carrying capacity?

 

[TeCKis300]

Consideration for how much total weight is one thing. The perspective I'm coming from is also to stay as light as is reasonable. That might be odd to say when we start with a platform that is breathing on 6000lbs stock. But everything is stressed more when running heavy, even on a heavy duty platform. Dynamic performance can suffer, from acceleration, to climbing, to flotation on soft stuff.

Keeping tabs on weight can have considerable benefits to performance, both on road and rock crawling. Another thing to keep in mind is while higher rate springs might seem to be an upgrade, there may be compromises. Specifically if the truck build-out doesn't demand it, extra spring rate inhibits articulation. There's a right balance to spring rate between carrying capacity vs articulation.

 

[Taco2Cruiser]

Consideration for how much total weight is one thing. The perspective I'm coming from is also to stay as light as is reasonable. That might be odd to say when we start with a platform that is breathing on 6000lbs stock. But everything is stressed more when running heavy, even on a heavy duty platform. Dynamic performance can suffer, from acceleration, to climbing, to flotation on soft stuff.

Keeping tabs on weight can have considerable benefits to performance, both on road and rock crawling. Another thing to keep in mind is while higher rate springs might seem to be an upgrade, there may be compromises. Specifically if the truck build-out doesn't demand it, extra spring rate inhibits articulation. There's a right balance to spring rate between carrying capacity vs articulation.

I’ve currently got BP-51s cranked to 25mm of preload up front. But I have a winch bar and winch, so it makes sense.

In back I have 2723s, with nothing added. No bumper, no drawer system, no roof load.

The axles flex all the way to bump stops quite easily. So I wouldn’t worry about articulation, it’s too far out of our reach with available spring rates.

For example, my old mud drag truck, weighted 3,300 lbs (and that’s with a 454) but we had 1,000 pound springs in it. You don’t want flex while mudding. But that is the level you have to get to to limit articulation.

As far as armor strength, .120 DOM sliders, 3/16” skids plates, bottom of bumpers with 1/4” plate. Done.

I wheel pretty hard, heck I broke a big rock at last months Southern Appalachian Expedtion with my sliders, slamming the truck so hard that I stalled it. STALLED! A 5.7L in 1st gear, low range, with 4.88s at 4,000 rpm. Just image the torque, and I hit so hard I stalled it. And .120 DOM sliders didn’t bend, dent, or bow.

I agree with you that the heavier things get, the stronger things need to be to handle it. But even a 9,000 lbs 200 series doesn’t need anything more than a light FJ Cruiser.

I think what really matters is how you wheel it. My rock buggy weights 2,000 lbs, it has a couple skids on the bottom, and they are 1/2” steel. Weight isint the issues, it’s rock bouncing the thing.

I just can’t see a situation where some one with a 200, is driving so hard that they need 1/2” steel skid plates. There is a benefit to maybe .188 DOM sliders. Even @TonyP, and he beats his truck like it owes him money.

 

[TonyP]

I think it does owe me money at this point. I should have gotten into a less expensive hobby, like knitting or something.