How much can we go above GVWR??

[slooowr6]

Hi All,
I'm in the process of getting my 06 taco 4wd crew with long bed ready for a fourwheel eagle. Went to a landfill and weight the truck with me, my wife and a full tank of gas. The truck weights in at 4480lbs. The GVWR on the truck is 5450lbs. This mean the "legal" weight I'm left with is 970lbs. The eagle weights 690lbs without fridge, battery, water, propane and furnance. So to be realistic after the camper is loaded it would be close to ~970lbs. This leaves me with no more "legal" load capacity. :Wow1: So no weight capacity for slider, bumper, winch and all other good stuff.
I read the post of "How much does you Taco weight". Scott's Taco is at 5900lbs, I looked up on Edmunds the stock GVWR is 5100lbs this means Scott's truck is 800lbs above GVWR and looks like the truck is doing just fine, base on all the trip post he had. :smiley_drive:
I understand we can use airbag, helper spring, stronger damper, better brakes and etc to make the truck drives safe. But how much can we go above GVWR before the frame and other machenical parts (ex, axle, wheel bearing) starts to fail?
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[BajaTaco]

Excellent question. I don't think any of us really know the answer as to when the components will fail. And no doubt there are a lot of variables that will play into the answer, whatever it may be. I can say that I think the 97-04 Tacoma chassis/components are quite robust and there have been a lot of examples that are in excess of GVWR to use as a reference. Failure points that I am aware of are:

1. Rear frame area where frame elevation changes to rise up to wheel well area. (Reinforcement kits are available). I have not reinforced mine, and have not bent it so far (9 years)
2. Front frame horns where the bumper mounts to the ends of the frame. (should be reinforced for pulling/recovery operations).
3. Stock suspension springs/shocks are not up to the task of a heavy GVW.

I am not as familiar with the 05-07 Tacomas.

 

[Colorado Ron]

Man thats a tough call. Honestly I think we would all love to know that answer. I have often ran my fords over the GVWR. Never really had a problem that I could honestly pinpoint as being overloaded. Just keep an eye on things. If the springs looked worked, install airbags, etc.

 

[DaveInDenver]

This was easier when the pickup here was based on the Hilux. That truck with certain solid front axle or 2WD configurations is a 1-ton rated chassis and so even though the 4WD was a 1/2-ton truck here, it was really a stout truck. So the '95 and earlier pickups had a real ~1,000 lbs of additional capacity when you upgraded suspension. The rear axle, brakes and stuff were all sufficiently strong to handle a few hundred extra pounds, with the weak link being the IFS and even that I'd say is probably safely a heavy 1/2 ton system with 25mm or 26mm torsion bars.

But the Taco was never based on the Hilux frame. The '96-'04 Taco is it's own platform and is probably really a 1/2-ton chassis. The current Taco is I think based on the Prado/120 frame, right? That /might/ mean it's something higher. But the question is really what's legal and safe, right? If the Tacoma now shares the 120 platform, then I would feel safe in assuming that the /true/ GVWR is more or less a soft limit. All Toyota trucks (at least the Hilux, Taco, 4Runner, can't speak to the Tundra and Sequoia) seem to be built on the high side of their ratings and things like the clutches and brakes in Toyotas are reasonably sized, for example. I would feel safe with a 1st gen Taco at going over GVWR with some reinforcement of the rear part of the frame, for example. I don't think anyone really knows the real GVWR of any Taco beyond what the door frame says. There is a lot of empirical evidence to suggest that other than a few weak spots, the truck is plenty substantial. But honestly, even at rated load those weak spots are still a problem. I'd guess that the current Tacoma is probably equally strong, but the thing is that between the lack of miles on owned trucks and that it's really quite different from the 1st gen, the data just isn't there yet. It's tough being a guinea pig, but all you 2nd gen Taco owners who are building rigs are just that. I do think the springs are going to be weak, but that's almost always the case. But simply putting in an extra leaf might keep them from sagging, but the spring hangers or shock mounts could fatigue over time with higher-than-rated payload. That's only gonna be know after a few years of washboard roads. I think it comes down to what you think is safe, because if you're in an accident and it's determined it was due to malfunction because of overload beyond Toyota's recommendation, you'll be the one responsible ultimately.

 

[slooowr6]

I think it comes down to what you think is safe, because if you're in an accident and it's determined it was due to malfunction because of overload beyond Toyota's recommendation, you'll be the one responsible ultimately.

This is one of my concerns, I want to make an informed decision. The GVWR on the door does not tell the whole story, if you look at the 06 Tundra with the same config as mine the payload is only ~200lbs more.
From what I gather is the front end design on 05/06 Taco is same as 4 runner which is the same as Prado.
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[DaveInDenver]

This is one of my concerns, I want to make an informed decision. The GVWR on the door does not tell the whole story, if you look at the 06 Tundra with the same config as mine the payload is only ~200lbs more.
From what I gather is the front end design on 05/06 Taco is same as 4 runner which is the same as Prado.

Oh yeah, I hear ya. The only sure thing is the number on the door frame, beyond that it's all based on speculation and evidence. Toyota is a conservative company and the truck is more or less designed to be operated at GVWR for it's life. Think about all those Hilux pickups used as pseudo-military trucks that spend their whole life overloaded in 4WD being bashed over roads that we'd have to go out of our way to find. Driving on improved roads at couple of hundred pounds over is probably not a problem. But also the trucks we get are no longer nearly as closely related to those 3rd world trucks, so maybe they are less rugged. Hard to say.

 

[Robthebrit]

EDIT: I edited this because I was writing it at work and had to leave quickly, what was here originally was correct but was more in the form of my notes.

Owning a big heavy commercial truck you get to know all the weird laws regarding vehicle weight. Here is what I do know about the laws..

The DOT sets the guidelines and most states roughly follow it, all states reciprocate another states rules so if you are legal in your own state you are legal everywhere.

For California, light duty pickup trucks are rated based on unladed/empty weight, any weight fees payable are based on this weight. If you are registered as a pickup and the vehicle is used for none commerical purposes, you are allowed up to the rated gross vehicle weight of the truck even it that is over 10,000 (10,000 pounds is when weight certificates kick in). If a heavy duty pickup is used for commerical purposes you are allowed to be any weight upto 10,000 pounds but if you have a gross over 10,000 and you weigh more than 10,000 you need a weight certificate (most folks do not bother and nobody ever gets in trouble).

However, a bigger problem is your insurance which is probably void if you are over the manufacturers stated max weight, my policy clearly states this and I assume this clause would apply regardless of what mods you have made to account for the extra weight. If you cause an accident and they can link it to the truck being overweight, you'll have the book thrown at you. In this scenario they will also get you on another technicality, if you are driving with void insurance it is the same as driving with no insurance, in some states you can lose your license for this offense.

For those that care: A weight certificate, when required, states the gross weight of the truck and registration fees are paid based on this gross weight. You can artificially state a low gross weight if you have a big commercial truck and don't carry anything heavy or if you simply want to pay less in weight fees. Once you have a weight certificate you are busted big time if you go over what it says. The weight certificate in no way limits what you can drive, your none-commercial license is good to 26,000 pounds, the certificate it simply a method of obtaining money for heavy vehicles which put more wear on the roads.

I do not carry a weight certificate in the mog so I am limited to 10,000 pounds and I do not stop at weigh stations, I could claim its a private pickup and therefore exempt from weight certification and operate up to the rated gross of the vehicle, doing this involves the DMV and I hate the DMV. In addition they could argue the sides are removable and therefore its a flat bed which does need a certificate. The reason I don't have a certificate is because I don't see the point in spending extra money for the registration when all I carry is camping gear (in California the first few tons cost about $200 per year, remember its gross weight so you are paying it even when empty). Weight certificates are quite complex as it states max gross weight and max weight per axle, none of the limits can be exceeded when you are weighed. There are some sweeping exceptions for things like RVs, campers, big class A/B motor homes and historic vehicles.

In order to obatin the limits for a particular truck it should be in the service/technical manuals. These manuals are usually pretty good on the real limits, trucks are not always used on the road and when off road there are no laws to break, in this scenario knowing the real max weight is really important. Does anybody have the tech manuals for their truck? My mog's book states things like max axle weight, max gross weight (it has limits for on and off road but they happen to be the same). It does list different tow limits for driving on and off road tow weight, it also states the limiting factors.

As an aside: For my torque converter 416 the max straight tug weight is only limited by traction. If you weigh it down you can shunt around 1,000,000 pounds, nearly 450 tonnes!! Obviously the ground has to be flat as you are certainly not going to pull that weight up hill.

Rob

 

[slooowr6]

Rob,
Thanks for the great info, it's very interesting to read. But I doubt any pickup can get close to 10k lbs.
The Taco manual does not have much info on payload and tow other than tow is 6500lbs with tow package, payload is ~1300lbs. I can't even find recommend tire pressure when you load the truck with 1300lbs. The ONLY info on tire pressure is 29psi and it does not say what load that is good for. The stock tire has enough capability to take the load I just need to find out the correct pressure for it. It's a 245/75/16 with 109 load index at 51 psi. I guess most Taco owner do not load they truck like we plan to do.
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[OutbacKamper]

Rob,
.... I doubt any pickup can get close to 10k lbs.....

I thought most 1 ton pickups are rated at 9900lb GVW or higher?

Cheers
Mark

 

[Robthebrit]

I'll look at my dodge, I'll be right back...

EDIT: My dodge 2500 is 6000 rear axle and 5200 front axle and 9000lb total. 9900 pounds for the one ton version sounds about right.

I think you need to go to the 450/550/etc to get above 10,000lb and then you have a hard time arguing its a pickup, same problem I have.

 

[slooowr6]

I thought most 1 ton pickups are rated at 9900lb GVW or higher?

Cheers
Mark

Whoops, by pickup I meant the little ones, taco, frontier and etc. Not the big guys, F250, Ram2500 and etc.
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[VikingVince]

slooowr6,

Another way to look at the GVWR issue...if it helps your decision-making and peace of mind...is from the standpoint of manufacturers. Their main concerns are profit, quality (hopefully!), and expenses. Re expenses, they want to control the potential back-breaking costs of liability, warranty replacements, class-action judgments, and cost of litigation. SO, if an axle manufacturer has done extensive lab and field tests on an axle and they know it frequently cracks or breaks at say 6500 pounds, are they going to stamp it with a 6500 pound weight limit? No way! (IMO) My best WAG (wild-ass guess) is that they'll stamp it around 5500 or less to build in that margin of safety, to cushion themselves against the potential cost of liability. Soooo, my "guesstimate" is that our axles can handle 500-1000 pounds over GVWR (or more?) but if you're getting into the part of that range, you should do what's been suggested above - reinforce your frame, upgrade your suspension, maybe get airbags too - because we know there are sagging and frame issues at heavier weights over GVWR.

Rob - enjoyed your long post...there's lot of info there that would take someone hours of dealing with the bureaucracy to learn. One thing you said really caught my eye..."if you cause an accident and they can link it to your truck being overweight, you'll probably get the book thrown at you." REALLY? That's a very interesting concern...do we have an actual legal responsibility to keep our light pickups under GVWR? Are we adding to our liability if we don't? Quite frankly, I've never thought of that.

 

[erin]

I would be more concerned with the frame then the axles. If the newer model is like the old, the rear axle is the same or equivalent of the Tundra. At least non-TRD that is.

 

[Robthebrit]

slooowr6,

One thing you said really caught my eye..."if you cause an accident and they can link it to your truck being overweight, you'll probably get the book thrown at you." REALLY? That's a very interesting concern...do we have an actual legal responsibility to keep our light pickups under GVWR? Are we adding to our liability if we don't? Quite frankly, I've never thought of that.

As far as I can find in the DOT and CA vehicle code you are directly breaking any laws if you are over gross and under 10,000. There are laws for commercial vehicles stating they cannot be over gross and if you are over gross you must of exceeded the weight certificate and thats another problem. The insurance companies can impose other limits as they wish by limiting or refusing insurance, when you get insurance you have to play by the rules in the policy and those rules can be anything they want, the gross vehicle weight is an explicit clause in my policy.

If I was at fault in an accident, over gross, and prove the weight was related to or caused the accident then they would refute the claim, the other folks insurance company would then sue me directly and I would be on the hook for the entire cost. Sure you could sue your insurance company for not covering you but that would be a hard case and a whole new layer of BS to deal with.

In CA you have to file a report with the DMV after an accident if there is more $750 in damage or somebody is injured or killed. The DMV will check that your insurance is valid (it does not state what valid means) and this is how they could get you on the technicality. How it all works inside the DMV and whether they would actually put 2 and 2 together is an unknown to me, it certainly could happen but a lot would depend on timing, comminication between the DMV and insurance company and the contents of the police report.

How it would all work out in reality is probably best left unknown.

Rob

 

[slooowr6]

SO, if an axle manufacturer has done extensive lab and field tests on an axle and they know it frequently cracks or breaks at say 6500 pounds, are they going to stamp it with a 6500 pound weight limit? No way! (IMO) My best WAG (wild-*** guess) is that they'll stamp it around 5500 or less to build in that margin of safety, to cushion themselves against the potential cost of liability. Soooo, my "guesstimate" is that our axles can handle 500-1000 pounds over GVWR (or more?)

This is the part gets interesting, before the computer age all the calculations (Finite Element Analysis) to decide structure strength on a mechanical device are all done by hand. There is only so many calculation human can do so in order to make sure the structure can take the designed load engineer add a safty factor after all the calculation is done. For example, after calculation the steel plate needs to be 10mm, but to make sure we cover the part that the calculation might miss it's common at the time to give a safty factor of 2. Now instead of 10mm plate we use a 20mm plate.
Today with all the super computer and Finite Element Analysis software, engineer can do the calculation to a much higher accuracy. It's still common to give safty factor but instead 2 they use 1.2 or someting lower than before. In the above case now they will use a 12mm plate instead the 20mm plate.
I guess this is why we constantly hearing "they don't make stuff the way the used to". Before super computer a lot of stuff are way over built. On the flip side of this is now they can build stuff lighter, smaller without reducing the spec. But for us tend to strech the limit, the room to play will be less and less.

You can see I'm an engineer I think too much :sombrero: I should just load it up and keep an eye on everything. I bet they will do what you said, public spec 5500lbs, internal spec 6500lbs just to make sure their stuff does not break at 5800lbs.
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