Great white

iTrader: (1)

I'm not exactly sure what you are trying to say with overweighting, but they specify two weight classes J2807: under and over 8500 GVWR.

As long as the vehicle can hit the performance requirements for it's category, they can keep piling on the trailer weight.

Whatever hits the limit first (chassis or engine) is the limiting number.

Be it 5,000 lbs trailer or 25,000 lb trailer.

A 2.7 probably can get the same load moving as a 3.5 with the same gearing. But it may not be able to achieve the same acceleration rate on the flat or on a grade or on the grade start. So it gets "down weighted" until it can. That may very well be 2400 lbs of trailer. I don't know exactly becasue I didn't do the testing. You have to trust the OEM's there. But believe me: if they could have given the 2.7 the same rating as the 3.5 you damn well know they would of! It's all about sales baby!



Arguing gearing and terrain doesn't really hold water when talking about the published numbers. Terrain can be anything anywhere and the J2807 is an attempt to quantify the trucks performance across makers to a standard so consumers can have ha;f a chance of shopping for the vehicle they need/want. Gearing is accounted for in any of the OEM towing charts (IE: different weights for different gearing and configuration) they produce after applying J2807 testing to the particular combination.

I don't see a flaw in the J2807. It's not governing legislation, it's testing parameters.

I think you're trying to apply commercial vehicle thinking to consumer level trucks and it just doesn't convert over like that. There's a lot more at play (legally) with commercial vehicles and towing "overweight"....

11screw50

The problem is that they still play their games.

145" wb 4x4 5.0 Screw.
3.31 - 9,000lb
3.55 - 9.100lb
3.73 - 10,600lb

the 3.31 and 3.55 have the same frame, springs, axles/housing, brakes, etc. If 9,000lb is the SAE J2807 number for the 3.31's, there is no way 9,100 is the number for the 3.55's. I only included the 3.73's to illustrate that clearly the brakes, frame, springs, etc are not the limiting factor because the only difference between the 3.31/3.55 and the 3.73's is the axle (8.8HD vs 9.75)

So its still marketing. I think the 3.31 and 3.55 are rated so closely to push those who do not plan on towing heavy toward the 3.31's (so they don't feel like they are giving up much of anything).

I am sure there are plenty of other examples, I just don't have time to look for them (this one I remember since it's what I have).

Not saying SAE J2807 is necessarily flawed but it would be better if it somehow required them to not publish derated numbers. My guess is the 3.55's should be closer to 9600-9800 if the other two numbers are correct (while admitting that there is a small possibility that the axle is the weak link that limits the 3.55's to 9,100, I highly doubt that is the case).

Great white

iTrader: (1)

J2807 doesn't "uprate" or downrate" anything.

It is just testing parameters. It's not flawed, it just is what it is.

The OEM's do the actual testing of their vehciles and "agree" to follow J2807 specifications to make one OEM's numbers comparable to the others.

J2807 is a voluntary thing for them, it's not legislation. But if everyone else is doing it and you're not, you're open to negative marketing from the other OEMS.

Just as an FYI, here's Ford's actual testing rig:



It's basically a rolling dyno rig that can induce drag to simulate weight or grade and if you believe it, accurate frontal area. That way they can certify their ratings for grade with never actually having to climb one.

Now, the OEM's are a different story than anything the SAE produces as test parameters. They can adhere to the testing parameters or not. They can lie about results or not. The test rig can be calibrated right or not.

If there's error in the numbers, that's where it lies.

I'll say it again here so it's not buried in test like above:

If the OEM's could rate a 3.55 truck more than a 3.31 truck, you darned well know they would do it!

They'd sell more 3.55 to "tow-ers" and it would make no difference to those not towing.

I'd also say there is more at play in the ratings than most will ever understand. My 2016 Supercrew 4x4 157" is rated at 10,600 with the 3.55's. BUT: with max tow and 3.55's it's 11600. so there's more going on than what you see on the face of the specs. That's the part we don't know....

So, unless you want to say ford's rating are BS, that's what you have to take as truth.

If it's a lie, it's Ford lying. Not SAE or J2807....


PS. Just so everyone knows, I'm not arguing. Just discussing.

Gene K

In commercial truck gearing is definitely influenced by the terrain being operating in. If you operate in Florida you don't order the same gearing for the same loads as those that operate in the Northwest.

I don't see why that would be any different in pickup. Axle gearing (assuming adequate startability) doesn't really effect ultimate speed on a hill it just effects how many downshifts are required. People that operate in flatter terrain can use taller gears without excessive shifting.

In our personal use despite Ford's rating the difference in the 3.5EB and 2.7EB is 1 gear size and 1000 lb.

Despite Ford's ratings the base TiVCT 3.5 won't even come close to keeping up with 900 lb less.

But we are getting away from my premise. Rate of acceleration is not a legitimate way to rate towing. Wonder what the acceleration rate is for a 550 Cat with 4.33 and 44" tires with a 320,000 lb Permitted Load. I seriously doubt it meets J2807.

Great white

iTrader: (1)

You're comparing what you would order to what the OEM's tested. Commercial trucks are ordered for a task, consumer trucks are "do it all's".

J2807 was created to give the consumer half a chance to have comparable numbers between Ford, GM, Toyota, Chrysler, etc.

Commercial reasoning doesn't straight across transfer over to consumer reasoning.

acadianbob

it should be about just the weight capability, but, consumers expect a certain level of performance. Therefore, I believe that smaller motors are rated for less because they would get complaints about acceleration, hill climbing, etc. otherwise.

Gene K

J2807 Asside my point remains.

Chassis, Axles and Brakes based on what you want to tow.
Power based on how fast you want to go.

I would much rather pull a 10,000 lb trailer with a F250 I-6 4.9L (300) than a Lightning.

Gene K

My understanding of J2807 is while a manufacturer using the protocol has to pass with the amount of weight they rate at they are under no obligation to test at higher weight.

This may protect consumers from themselves by preventing them from buying to little truck. The manufacturer may have an interest in selling more truck if he can make more money.

When a 3.23 geared base 4.3 Chevy is rated at the same weight as a 2.7EB 3.55 and we know trucks with the same chassis, springs and brakes are rated at more I have to wonder why. At least when both are supposed to be J2807.

I think the base truck numbers are accurate and I think the top numbers are accurate. In the middle I think some sandbagging is going on.

The 5.0 3.31/3.55/3.73 being a good example.
The 2.7EB gets no jump from the EBPP (3.73 9.75) so I don't think that is the issue.

Great white

iTrader: (1)

Gene K

I'm going to leave it alone now.

Like I said I was a little upset at Ford for refusing to give us a tow rating.

2.7EB 3.15 apparently has no tow rating.

NOT "Towing Not Recommended" just no existing rating that anyone can find.

We are going with 5000 lb unless someone can come up with something better (since that's what a base no tow package truck has).