'Rear Ends' in Your Tow Vehicle

[JohnandDonna]

When we decided to order our 2020 30' International I did my research on tow vehicles and decided to order exactly what we wanted. We decided on a 2020 Ram 2500 Megacab with the 6.4 Hemi. When I was considering the gear ratio my wife brought up a good point. We were not buying this for millage, it was for capacity. Therefore I ordered the truck with the 4.10 limited slip rear end. I have now towed grades and flats and am very happy with my choice. Plenty of power! Only downside is when fueling. On the interstates, especially the ones with tolls, they direct RV's to same area as the big semi's. However most times the pumps there are only diesel. Also you run into situations where you go to the auto side for gas, it is not configured for my 52' foot land train (Truck just over 20' and AS about 31'). Just something to be aware of.

[PecanMan5]

With the new 6and 10 speed transmissions nowdays, I have dropped that from my equation. I simply lock out the top gear while cruising to remain in a good torque range and not lugging with a load.

[starpicker]

Howdy,
I purposefully got a 2020 F250 Diesel Platinum with the 1050 of torque and y’all know the rest. I specifically asked for a 3.31 rear end. My logic went along the lines of some others here.

My 2019 Airstream 33’ FB was approx 8200lbs and I had no need to pull 30,000 lbs. with a 10 speed trans and that torque. So I pulled from STL to Estes Park, CO and got 20mpg and 22mpg on the way back. Dealer gave me, (I know, they never give you anything), a 200,000 power train warranty so I did not need to worry about that. At 70mph I’m taching about 1250-1300 rpm. Kept it in drive mode for the overdrive and no sweat at all. Your experience may differ but without the Airstream the mileage is better. Which is 90% of the time for me. I never goose it or try to do burnouts, but with no towing, it will scat getting on the interstate. I’ll just never have a need to pull super heavy stuff. Consider higher if you do.

[Sdale]

Originally Posted by Ray Eklund

No one seems to consider their Tow Vehicle's... Rear End gear ratio. You choose a color, an interior and options inside the cab you like and make the purchase. Rarely does anyone ask about the Rear End. Often the heavier trucks like a 3/4 ton or heavier have HIGHER REAR ENDS for a reason. They haul or tow larger weights.

Mechanics call them Differentials. Layman call them Rear Ends. Street mechanics understand both terms.

My F350 Diesel has a 3.55 Differential. It works very well towing a 27 foot Airstream. If you are towing a 30 to 34 foot Airstream... a 3.73 differential would probably be better for your needs.

The ‘caveat’ is that the HIGHER the Ratio number, the easier it is for the Tow Vehicle to pull a heavier Trailer... but your Gas Mileage will suffer. Lower Rear End... higher gas mileage when not towing. Higher Rear End... lower gas mileage when not towing.

Fords have an identification plate for their... Rear Ends. So would other pickup trucks. the 4x4 have matched Front and Rear Differentials. I did not check, but when in 4x4 if they are mismatched, trouble when engaged.

The Lower the Rear End... the better your gas mileage without a trailer in tow. The Higher the Rear End... the worse gas mileage. This is the trade off when towing and if you spend more time Not Towing.

I remember in the 1960’s that the Hot Rodders wanted the larger Differential Casing for a 4:11. This gave the ‘hot rod’ a great boost offf the line... but topped out the engine RMP into Red Line quicker at higher speeds. A 3:08 Rear End was a bit sluggish at the start, but when the RPM began to increase... so could its Top Speed.

I wanted a Higher Rear End in my Hot Rod... a 4:11. I could get a 3:73. Why? Because the Casing was larger in the 4:11 and would not fit into the casing of a 3:73. Learned that at 20 years old. My rear end had to stay as it was.

Take some time and check your specifications on YOUR Tow Vehicle. If you notice it is a bit of a struggle to get moving from a stop light... it could be YOUR REAR END.

Google: Ford Differential Options as an example.

Those bragging about GREAT gas mileage probably have a LOW Rear End Ratio. Those with a lower gas mileage having a HIGH Rear End Ratio.

A drive shaft turns 3.55 times to turn a wheel. A 4:11 Rear End turns the drive shaft 4.11 times to turn a wheel. This is how I see it. Your engine will have a Higher RPM with the 4:11 but be moving slower than the 3:08 at the same RPM. We called it "Top End". Red Lining... your engine's maximum expected RPM before things become 'iffy'. Two bolt mains. Four bolt mains. My Diesel may have Four Bolt Mains... I would not be surprised. I need to check that out.

What is your Rear End... experience? My 3:55 pulls our 27 foot International easily and the additional cost of fuel is just the price I pay to tow in comfort.

Please correct me with any errors. My 'Hot Rod' days ended when I had married and a family in the last century. Sometimes... you have to consider that a Rear End does have better uses... and that is for towing.

I like mine, how about yours?

Fun post ....I was very careful to choose the 3:42 rear end ratio for my Silverado 6.2L 1500 HD towing package.....however as a new RV'er I already thinking about trading for the 2500HD diesel with 2x the torque and heavier everything.

From my hot rodding days however we referred to the 4:11 gears as the low ratio and the 3:73 as the high ratio even though the numbers invite the reverse. :-) Your towing and fuel economy comments were right on the money.

[tjdonahoe]

Owned 2 rams with 6,7...3.73. Was excellent....my new one has 3.54...very good...in the mountains I put it down 1 into 5..down hill same drop 1..the Chrysler 6 speed is double overdrive..

[Silver.Sanctuary]

Originally Posted by Ray Eklund

No one seems to consider their Tow Vehicle's... Rear End gear ratio. You choose a color, an interior and options inside the cab you like and make the purchase. Rarely does anyone ask about the Rear End. Often the heavier trucks like a 3/4 ton or heavier have HIGHER REAR ENDS for a reason. They haul or tow larger weights.

Mechanics call them Differentials. Layman call them Rear Ends. Street mechanics understand both terms.

My F350 Diesel has a 3.55 Differential. It works very well towing a 27 foot Airstream. If you are towing a 30 to 34 foot Airstream... a 3.73 differential would probably be better for your needs.

The ‘caveat’ is that the HIGHER the Ratio number, the easier it is for the Tow Vehicle to pull a heavier Trailer... but your Gas Mileage will suffer. Lower Rear End... higher gas mileage when not towing. Higher Rear End... lower gas mileage when not towing.

Fords have an identification plate for their... Rear Ends. So would other pickup trucks. the 4x4 have matched Front and Rear Differentials. I did not check, but when in 4x4 if they are mismatched, trouble when engaged.

The Lower the Rear End... the better your gas mileage without a trailer in tow. The Higher the Rear End... the worse gas mileage. This is the trade off when towing and if you spend more time Not Towing.

I remember in the 1960’s that the Hot Rodders wanted the larger Differential Casing for a 4:11. This gave the ‘hot rod’ a great boost offf the line... but topped out the engine RMP into Red Line quicker at higher speeds. A 3:08 Rear End was a bit sluggish at the start, but when the RPM began to increase... so could its Top Speed.

I wanted a Higher Rear End in my Hot Rod... a 4:11. I could get a 3:73. Why? Because the Casing was larger in the 4:11 and would not fit into the casing of a 3:73. Learned that at 20 years old. My rear end had to stay as it was.

Take some time and check your specifications on YOUR Tow Vehicle. If you notice it is a bit of a struggle to get moving from a stop light... it could be YOUR REAR END.

Google: Ford Differential Options as an example.

Those bragging about GREAT gas mileage probably have a LOW Rear End Ratio. Those with a lower gas mileage having a HIGH Rear End Ratio.

A drive shaft turns 3.55 times to turn a wheel. A 4:11 Rear End turns the drive shaft 4.11 times to turn a wheel. This is how I see it. Your engine will have a Higher RPM with the 4:11 but be moving slower than the 3:08 at the same RPM. We called it "Top End". Red Lining... your engine's maximum expected RPM before things become 'iffy'. Two bolt mains. Four bolt mains. My Diesel may have Four Bolt Mains... I would not be surprised. I need to check that out.

What is your Rear End... experience? My 3:55 pulls our 27 foot International easily and the additional cost of fuel is just the price I pay to tow in comfort.

Please correct me with any errors. My 'Hot Rod' days ended when I had married and a family in the last century. Sometimes... you have to consider that a Rear End does have better uses... and that is for towing.

I like mine, how about yours?

When I was looking for a tow vehicle, I read everything on this forum I could find. Usually I found I love "put in brand" because I have one, and rarely if ever did anyone talk about "rear ends" which surprised me.

You are right of course. I finally bought the Toyota Tundra, which has a 4.33 rear end and takes a beating from enthusiasts as "unimaginative" and "old" but it does a great job pulling my Airstream, and it doesn't get very good gas mileage, so I use it almost exclusively for pulling the trailer. My wife and I have different cars for around town and long trips without the trailer.

I hope your post stirs up some thought, but I made my decision and dont' regret it at all, even though other trucks would have been fine too.

[Spaggs]

I have 2000 Ford Excursion 2wd 6.8 liter V10 with a 4:56 LS. I plan to tow a 28’ FC with weight maxed out. Read a bunch and found a lot of guys who had switched to the 4:30 wished they went higher. A lot of other towing mods have been made to make this vehicle a stable platform.
Don’t fear the gear!

[tjdonahoe]

Originally Posted by Silver.Sanctuary

When I was looking for a tow vehicle, I read everything on this forum I could find. Usually I found I love "put in brand" because I have one, and rarely if ever did anyone talk about "rear ends" which surprised me.

You are right of course. I finally bought the Toyota Tundra, which has a 4.33 rear end and takes a beating from enthusiasts as "unimaginative" and "old" but it does a great job pulling my Airstream, and it doesn't get very good gas mileage, so I use it almost exclusively for pulling the trailer. My wife and I have different cars for around town and long trips without the trailer.

I hope your post stirs up some thought, but I made my decision and dont' regret it at all, even though other trucks would have been fine too.

....high ratio is 3:54.....low ratio is 4:11..been trucking for 54 years..

[dbj216]

Shoot! I thought this tread was about how many passengers your tow vehicle can carry. I can carry 5 rear ends in my truck, not including the dog's.

David