What determines tow capacity?

[tinner12002]

I read all of the inputs on tow capacities and I've looked at several truck ratings, F-450 and F-550 and the dodge 4500 and 5500.
When both dodge 5500 and ford f-550 are compaired, there seems to be an awful lot of towing and GCWR difference between the two, the dodge being 18K+ and the ford being 24K+ on towing. Both being chassis cabs, crew cabs, 4.88 gearing and 4x4 w/autos. Why is there so much diff between the two. Both of them are pretty close as to the diminsions of cab and frame, HP and torque not too far off from each other. I'm looking at a 5th wheel that would have a gvwr of 21K. I really wanted the reliability of the cummins diesel but from what I'm reading the dodge won't handle the tow weight of the trailer. Is there something I'm overlooking or am I figuring something all wrong?

 

[edjunior]

This is where you are getting into the differences in the actual frame, axles, brakes, etc.  Once you get past the HP, torque, and gearing, what's left is the actual physical build of each truck.  So Ford it appears builds a heavier frame, has heavier duty axles, and likely many other little things that contribute to the increased tow rating. 

 

[1275gtsport]

or....the two companies may be using different measurements??? who rates the trucks? is the an outside body like the American Standard Association that states what is measured? just asking.

 

[Marc L]

There are currently no standards, however SAE is coming up with a standard known as J-2807. More info on the following Truck Trend arcticle:
http://www.trucktrend.com/features/consumer/163_0910_truck_towing_capacity/capability_testing_new_sae_standards.html

Short version is that in order to claim a towing capacity of X, the truck will need to pass a series of test while towing said capacity.

 

[kymedic]

You can get the cummins diesel in the for F550's.

 

[Gary RV_Wizard]

The SAE (Society of Automotive Engineers) sets engineering standards for vehicles, but there currently is no SAE standard for tow ratings. A towing capacity standard has been written (J2807) and agreed upon but does not go into effect until the 2013 model year. For a summary see http://news.pickuptrucks.com/2009/12/new-sae-towing-standards-explained.html

A lot of factors go into a tow rating, and some engineering judgment is applied. Transmissions are one big item, as are universal joints, differentials, cooling, and of course engine power and braking. 

Ford has been beefing up their tow capabilities for several years now, and Dodge has simply not kept up. GM is closer behind Ford, but recent financial troubles caused them to cut back on developments in the 4500-5500 medium truck class. Right now, I think Ford is your only real choice for a 21,000 lb rig, unless you are willing to go with a Freightliner cab such as an FL50. There are companies that make some excellent RV haulers using the sport chassis version of the FL50. Spartan also makes a sport hauler based on their M2 chassis. With the Freightline ror Spartan, you get commercial grade engines and transmissions, much stronger.  Used ones are usually available too.

http://www.sporthauler.com/
http://www.sportchassis.com/
http://www.haulers.biz/

 

[PancakeBill]

PLUS, when going with the FL series you get the macho look.  Nothing like  a Freightliner pulling for impressing. 

This is just the frosting, the rest means you can tow and brake safely.

 

[tinner12002]

I actually have also been looking at the F-650, more so because it is available with the cummins, bigger brakes and allison auto. I'd reather have a little too much truck than to have one that labors all the time and just barely gets the job done. I didn't realize that the cummins was available in the 550 without it being an after market conversion, I'll have to check that out. The fords just scare me a little because they have just started building their own diesels which haven't been proven in the field yet, and I've heard too much bad about the 6.0. I emailed a dodge dealer about the diff between the dodge and ford and if dodge has any plans to increase their ratings, I'm courious to see what he has to say if he responds.

 

[glfredrick]

In my mind, a Ford truck cab and frame, with the Cummins diesel, and a good transmission like the Allison behind it, would be the ultimate tow package.

I've ran all the diesels from all the manufacturers, and the Cummins is the way to go.  I own an older 5.9 12V model that will put a hurtin' on a lot of other stuff out there and I've just scratched the surface as far as what I can do power production wise.

I like your idea of going big or staying on the porch...  8)  Just realize that the larger truck doesn't always have more power -- just larger suspension and tires.  You might want to surf a forum site for diesels like Diesel Bombers (http://www.dieselbombers.com/index.php?referrerid=20443) to see what other guys are thinking and saying, plus available power mods that work in the real world.

 

[ramcneal]

The fords just scare me a little because they have just started building their own diesels which haven't been proven in the field yet, and I've heard too much bad about the 6.0. I emailed a dodge dealer about the diff between the dodge and ford and if dodge has any plans to increase their ratings, I'm courious to see what he has to say if he responds.

One thing to know is that Ford didn't build the 6.0, nor did it build the 7.3 or 6.4, engine. Those were built by NaviStar I believe. Granted Ford put it's name on the truck so it had to take some responsibility, but in that case I feel the heat really should have been placed at the engine manufacturers doorstep.

I also understand your uneasiness regarding a new engine. I'd be willing to bet good money that Ford understands the need to deliver a rock solid engine else all the goodwill in the world isn't going to help them regain lost sales.

 

[Gary RV_Wizard]

Re the Ford/Navistar diesels, they share the glory and blame for the 7.3L, 6.0L, and 6.4L. It's a Navistar base engine, but Ford engineered a lot of the stuff that goes around it, e.g. fuel delivery, cooling, etc. The Navistar  MaxxForce 7 diesel is not the identical engine to what Ford was using. Plenty of blame to go around, which is why they are suing each other over who is at fault for the many problems with the 6.0 & 6.4.

Re new engines: Ford had every intention of delivering a rock-solid engine with the V10 too, but after a few months in the field, they were popping spark plugs and otherwise acting up.  No matter how well they test, they cannot anticipate everything that occurs in real life use.

 

[longhaul]

Looking at Dodge Body Builders Guide shows the 4500/5500 with a 26000 GCWR. Both have the same trailer tow rating. The main difference in a 4500 vs 5500 Dodge truck is the RAWR or payload ratings. The 4500 has a 12000 lb RAWR vs a 13500 lb RAWR for the 5500 truck. That equates to around 8000+ lb load for the 4500 and 10000 lb load for a 5500 truck. 

Most of these trucks are over 8k unladin weight (or simular weights) and some states require a GVW declaration for non commercial  registration purposes if the truck is over that weight.  Something to check with your vehicle registration office about.

 

 

[Stewie Griffin]

You can get the cummins diesel in the for F550's.

Please post a link that backs this up. The F550 does not come with a cummins, 6.7 powerstroke, no cummins. The F650 and up do offer various sizes in the cummins.
To the OP, the 6.7 cummins is a great engine but out of the box its nowhere near as refined or powerfull as the Ford 6.7. The cummins was having a lot of problems with clogged DPF's, may want to read up on that. Still a great engine but I'm not a fan of the truck that's around the engine, a cummins in a Ford with an Allison would be awesome but it would b my second choice, I really like the Ford 6.7 and the new 6 speed torqueshift trans. I believe Ford got it right, sometimes you have to do it yourself.

 

[Cycleman10]

Who is having trouble with their Ford 6.0? ....Actually I have one in a 2006 F-350 DRW and it has had no issues and just turned over 50K.  The issues with all engines is in the first release, which makes sense. 

 

[Gary RV_Wizard]

I can't find anything that substantiates the availability of a Cummins engine on a F550. In fact, everything indicates it is NOT available - only the 6.7L Ford diesel or a Ford gas engine.

But apparently the F650 and 750 come with a Cummins ISB 6.7L

 

[tinner12002]

Yeah, I hadn't found anything either that showed being able to get a cummins in the 550. I know ford tried to work a deal with cummins but nothing ever panned out. I've read how powerful the new ford diesel is but it' still a NEW engine with bugs still to be worked out, so thats why I'm being a little leary about it. Maybe when it's been out there for a couple years then a person could come back and say thats one heck of a motor.
I seen the GVWR of 26K on the dodge but thats not enough when I'm pulling a GVWR trailer of 21K. I think the fords advertise a 30K GCWR, the 650 being more I'm sure.