Help me to understand the differences. Why can three trucks that are identical other than engines and transmissions (understanding that a diesel truck will have a higher GVWR and a lower payload because the engine weighs more than a gas engine), have towing specs that are so dramatically different. For instance, Truck A has a Gas engine and 3.73 gears. Truck B has the same gas engine and 4.10 gears and Truck C has a diesel engine and 3.55 gears. Why does Truck B have such a higher GCWR than Truck A, while Truck C has a much higher GCWR than both Truck A and Truck B but has a 3.55 gear ratio? Is it all about torque and HP? Why do manufacturers set such different GCWR allowances? Is it about wear and tear and over working engines and transmissions on trucks with gas engines that provide less torque and HP so things can break easier? Or is the Diesel truck not identical in other ways like a diesel engine will have an exhaust brake or brakes that are more stout as a standard feature so more weight can be stopped safely? I know the easy answer is "Don't worry about it. Just tow with a Diesel Dually" but I would really like to learn and understand. Thanks in advance!

Power, torque, suspension and brakes. Gear ratios are important in the difference between A and B. Truck C has so much more torque it doesn't use the same gears.

"Is it all about torque and HP?" Yes, and gearing.

All other things being equal, a engine with a 4:10 gear will be turning more rpm for the equivalent mph as a 3:73 gear. More rpm = more Hp and hence easier work to pull the load. A diesel develops higher Hp at lower rpms. A turbo charged engine (i.e.: ecoboost) develops higher Hp at lower rpms.

X2...and add for any given condition (speed, load, terrain, etc, etc) it takes X amount of HP How that HP is developed and delivered is what fj12 saidMassive internal components of a big block and diesel will have laws of physics not allow high rev'ing, but it develops higher torque in lower RPMs and is where gearing comes inJust keep the HP formula in mind : HP = torque x RPM / 5252fj12ryder wrote:"Is it all about torque and HP?" Yes, and gearing.

It's mostly about horsepower and torque.Truck A 3.73 (gas same engine)Truck B 4.10 (gas same engine)Truck C 3.55 (diesel)Here's hopefully an easy analogy. Ignoring the transmission picture the rear end ratios above as the same as riding a 10 speed bicycle. In a 10 speed you shift down to first gear and you pedal really fast yet go slow. You use 1st gear to start off and to go up a really steep hill. If you are in second gear you can start off a little slower but once moving you can go a little faster. You said the gas trucks are the same. So if you pretend the trucks above are bicycles:Bicycle A (3.73 gas engine) is always in 2nd gear and has a rider with skinny legs.Bicycle B (4.10 same gas engine) is always in first gear and has the same rider with the same skinny legs.Bicycle C (3.55 and a diesel engine) is always in third gear but has a professional (think Tour de France) rider on it.Ignoring bicycle C (diesel) for a minute:Rider B stuck in first gear(4.10), can pull more weight than rider A because it's easier to pedal and power the rear wheel. Of course once up to speed rider B has to pedal faster and use more energy to maintain the same speed as rider A who is stuck in 2nd gear (3.73). Now picture Tour de France rider C (3.55). Rider C is always in third gear. You would think that rider C would pull the least amount of wight because it's harder to get started from a stop. But rider C (diesel truck) has more torque (powerful legs) than rider A or B. So while rider C is stuck in third gear, his strong legs easily overcome the starting resistance despite being stuck in third gear and he can pull more weight than A or B. So:Rider C (Tour de France, diesel engine) even at 3.55 (third gear) can pull the most weight.Rider B in 1st gear (4.10 skinny legs, gas engine) can pull the second higher weight but has to pedal faster burning more energy (fuel).Rider A in 2nd gear (3.73 , skinny legs) can pull the least weight, but pedals a bit slower than B so uses less energy (fuel) to maintain the same speed.

Gas, Diesel, Gears and Towing | Good Sam Community

Grit_dog
Navigator
May 13, 2020
^Best post ever!
RobWNY
Explorer
May 13, 2020
LOL You made me laugh. That's how this RV thing works. One rainy Saturday afternoon, you're channel surfing and stumble upon a show about camping. Nice little tent, campfire, marshmallows roasting on a stick and the wheels in your head start turning. You know you're too old to be happy with a tent and a sleeping bag and you already have a SUV. You ease into a conversation and bring up the idea to your wife. Nice and nonchalantly. You: "Hey honey, any idea what you feel like for dinner?" Wife: "I was thinking maybe you could grill chicken and I would make some rice and a vegetable of some kind". You: "that sounds great! Lets go buy an RV!". You start by buying just a little single axle camper that the SUV can tow. Then you decide you want something bigger at some point but first you have to buy a truck. You buy a half ton thinking I can tow that 24' travel trailer I saw at the RV show, no problem. So you buy it. THEN you make friends with the guy next to you at the campground and he has a Fifth Wheel. He tells you he has been traveling across the country for a few years and just loves it! Before long, the wheels in your head are thinking...Man, we could travel across the country too if we had one of those. You can't get it out of your head. THEN...you drive by the auto dealer and sitting out front is this beautiful HD truck. Surely that will tow a fifth wheel, no problem. So you trade in your half ton truck for the HD truck and then buy a fifth wheel. A year later, you're at the RV show and you and your wife see the fifth wheel of your dreams. Just beautiful. It has all the bells and whistles, 5 slides, washer/dryer, king bed. The Salesman says...pfffft, you can tow this thing with a bicycle. No problem! You buy it and then realize you can't. Now what?............1 ton Diesel Dually sits in your driveway. Your wife looks at the truck and fifth wheel and then looks at your bank account and says..."We're never having grilled chicken and rice EVER and I mean EVER again! :)
rhagfo
Explorer III
May 13, 2020
RobWNY wrote:
nickthehunter wrote:
ppine wrote:
Rationalizing just enough truck and gas engines is a losing battle.
It's not hard to rationalize at all, once you figure out how much it costs.

Very true. People who are fortunate enough to be in a financial situation to buy anything they want, whenever they want, don't have any concept of what the word "Budget" means. Quick story.....We spent this past winter in Florida at a fairly nice resort. Lots of people there with more money than they knew what to do with. When my wife and I were invited to go with a group of these people on a week long cruise, they just looked at us with this odd look on their face when we said we couldn't afford to go. Like it didn't compute that there are people in the world that have to keep an eye on their money. But, I guess if they have never had to think about money, or it's been a long time since they've had to, they wouldn't really understand. My wife and I had a good chuckle over that.

Don't panic yet,that 6.4 is capable, you are only talking about 12,500#. If you are less than happy with its performance, change to the 4.10's and see how that works.

Know the budget thing towed the Copper Canyon for about 7 years with a 2001 Ram 2500 CTD with 3.55's. over GVWR, over GCWR. I had a small chip and it did ok. The 3.55's and 5 speed manual it wasn't the quickest off the line, but did fine in the hills. Now I am at about half of max 5er weight, next couple years we will look at a newer larger 5er.
RobWNY
Explorer
May 13, 2020
nickthehunter wrote:
ppine wrote:
Rationalizing just enough truck and gas engines is a losing battle.
It's not hard to rationalize at all, once you figure out how much it costs.

Very true. People who are fortunate enough to be in a financial situation to buy anything they want, whenever they want, don't have any concept of what the word "Budget" means. Quick story.....We spent this past winter in Florida at a fairly nice resort. Lots of people there with more money than they knew what to do with. When my wife and I were invited to go with a group of these people on a week long cruise, they just looked at us with this odd look on their face when we said we couldn't afford to go. Like it didn't compute that there are people in the world that have to keep an eye on their money. But, I guess if they have never had to think about money, or it's been a long time since they've had to, they wouldn't really understand. My wife and I had a good chuckle over that.
RobWNY
Explorer
May 13, 2020
I haven't really noticed a big jump between 1st and 2nd gear but the transmission doesn't shift like you think it should. It's quick to downshift but not the other way around. For instance, when beginning to climb a hill, the transmission will downshift to the appropriate gear but it stays in that gear longer than I would like after leveling out or after cresting the hill and heading down the other side. It's not that big of a deal. It just takes a few seconds longer than it needs to. This happens whether I'm in Tow/Haul mode or not. The computer controls everything. Even with Tow/Haul mode off and I try to "Manual" shift. If the computer doesn't like what you're trying to do, it won't do it. So if you're in 3rd gear and want to be in 4th gear, the computer won't let you change gears until the computers preprogrammed parameters are met.
nickthehunter
Nomad III
May 13, 2020
ppine wrote:
Rationalizing just enough truck and gas engines is a losing battle.
It's not hard to rationalize at all, once you figure out how much it costs.
rhagfo
Explorer III
May 13, 2020
The biggest issue I have heard of with the 6.4 Hemi and 68RFE trans is there is a rather large gear jump between 1st and 2nd.
philh
Explorer II
May 13, 2020
It's real simple.

Closer you are tow and payload weight limits, the more challenging it can be. the older the tow vehicle, the even more challenging it can be.
Grit_dog
Navigator
May 12, 2020
RobWNY wrote:
rhagfo, I may end up doing that in the future if I have towing experiences that I'm really not happy with. I won't pick up the new fifth wheel until next week and I'll have to tow it 4 hours to get home. Of course, it won't have any gear in it but it should give me a pretty good idea of things towing my empty fifth wheel that I'm trading in to the dealer and the new one back home. Obviously there will be further differences once I load up the new one but I should at least have a good feeling of what needs to be done if anything.

It's a balance between cost, your "wants" and how fast you want to get there.
Grit_dog
Navigator
May 12, 2020
ppine wrote:
Rationalizing just enough truck and gas engines is a losing battle.

Only in your world, bud. The millions of 3/4ton gas trucks doing work every day of the week would say different.

Don't confuse "rationalizing" with wants or actual needs.

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