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Old 02-26-2024, 08:58 PM   #1
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Question Towing In overdrive ON/OFF

Expedition 5.4 8900lb capacity with Overdrive option. Pulling FR MAC 205S of 2000lbs. Is it better to always pull in overdrive even on flat ground if doing 65mph or is is ok pulling a lighter load with overdrive off? With overdrive on at 65mph it runs 2400rpm vs 1800rpm with overdrive off? I hate taxing engine, but understand pulling with overdrive off can damage the transmission due to constant shifting. I see no posts on this topic and many would benefit from a good understanding of the strains on engine vs transmission.
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Old 02-26-2024, 09:15 PM   #2
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Backwards?

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Originally Posted by RobMArizona View Post
Expedition 5.4 8900lb capacity with Overdrive option. Pulling FR MAC 205S of 2000lbs. Is it better to always pull in overdrive even on flat ground if doing 65mph or is is ok pulling a lighter load with overdrive off? With overdrive on at 65mph it runs 2400rpm vs 1800rpm with overdrive off? I hate taxing engine, but understand pulling with overdrive off can damage the transmission due to constant shifting. I see no posts on this topic and many would benefit from a good understanding of the strains on engine vs transmission.
First of all, it sounds like your description of Overdrive states is BACKWARDS.

On the overdrive vehicles I've driven (including the 1959 Studebaker Lark with three-speed manual trans and overdrive), the overdrive gear was higher than 3rd. That means the engine speed was LOWER when overdrive was engaged than when it was not.

With a heavier load, you would likely NOT want to engage overdrive (which you are calling Off). Repeated shifting would not damage the engine or transmission. Lugging the engine (like shifting to third or fourth gear and accelerating) where it lurches IS BAD FOR THE ENGINE main bearings. If you see/feel that happening, disengage the overdrive (which you call On).

Also, many overdrives freewheel-coast. When you let off the accelerator, instead of the engine dragging the speed down, the vehicle coasts, as if you've shifted to Neutral or held the clutch down. You DO NOT want to let that happen on a long downhill. You will have to ride your brakes all the way down the hill which will cause them to heat up, which will cause them to lose friction and you will be in a deadly runaway condition. Never engage the overdrive in this situation.
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Old 02-26-2024, 09:55 PM   #3
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When I'm on a good open road I will run with the cruise engaged and O/D on. I'm usually running the speed limit and sometimes a little more. If I get into hilly country I turn O/D off to keep the transmission from jacking the shifts. My Ram 1500 with the 8spd transmission pulls best in 6th gear O/D off. On steep downgrades I choose a gear to match the speed I want to run this takes the O/D out of the system and enables engine braking.
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Old 02-26-2024, 11:38 PM   #4
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You are correct - I turn O/D off by pressing a button not turn it On. My Expedition(2003) only allows selecting 1,2 and Drive. I turn OD Off when towing. No idea how many high gears I have in DRIVE. Arizona mountains have 6-7% grades and I turn OD OFF to take advantage of engine braking on downhills. Uphill I have OD OFF and often slow to 50-55 and rev up to 2800 by top of hills. I am not sure if that is correct to do.
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Old 02-27-2024, 08:11 AM   #5
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We don’t know the year of the OP’s Expedition, nor what transmission it has. I run a 2019 Ford E-450 chassis with 6-speed, which may or may not be the same transmission the OP has. Total weight of the rig on this trip is around 16,000 pounds. I just leave it in drive and let it do it’s thing. It will be in 6th gear the vast majority of time. If it shifts down, it’s because it needs to shift down. Works great; no need to overthink it.

On a previous rig, with Ford 4EOD transmission, I also left it in D (overdrive allowed). The only time I’d punch OD-off is in anticipation of a hill, since the tranny was a little slow to react to the increased load.
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Old 02-27-2024, 08:25 AM   #6
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Just to clarify, overdrive does not mean (in most cases) what it did many years ago unless you are driving a big semi. Its just another gear in the transmission. Years ago it was a separate gear set outside of the transmission.

It generally means today that the gear ratio goes from being over 1-1 to being under 1-1 ratio. Im not a good teacher so I'm not going to try to explain what that means. I know what it means but am not good at explaining unless I was sitting across the table.

The best way to find out if your transmission is designed to handle the load in top gear (see how I prefer not to call it overdrive) is to read the owners manual. For decades many manuals have recommended against using the top gear for towing because it does not have the strength to handle the load, and/or it would lug the engine too much.
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Old 02-27-2024, 08:47 AM   #7
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Simple. Overdrive towing is harder on the transmission. Owners manual will say that. Overdrive doesn't maintain as much fluid pressure due to lower rpm for instance. There are other reasons.

The transmissions in the Expeditions that had the 5.4 are good but far from the best ever. I have burned up one of them ( supercharged Lightning with some added power....). I then built that one to be bullet proof.

Based on what I learned from that and others that have had failures, towing in overdrive just isn't worth the chance of overheating/stressing the transmission. The higher rpm the engine sees is NOTHING to it, actually easier on it in some ways too. Such as increased cooling due to water pump and fan turning faster. The difference in mpg will be very small.
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Old 02-27-2024, 08:48 AM   #8
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Quote:
Originally Posted by jjscsix View Post

The best way to find out if your transmission is designed to handle the load in top gear (see how I prefer not to call it overdrive) is to read the owners manual. For decades many manuals have recommended against using the top gear for towing because it does not have the strength to handle the load, and/or it would lug the engine too much.
I've always heard that, too, but i guess things are different nowadays.
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Old 02-27-2024, 10:04 AM   #9
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What I observed on my RAM with the 8 speed transmission is that the tow/haul mode when engaged changes the shift points higher relative to RPM but does not eliminate the availability of the highest gear. It simply wants a greater RPM to get there.

The Tow/haul mode also enables engine braking

If I’m on secondary roads I use it. If on highway/freeway/interstate I do not.
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Old 02-27-2024, 10:04 AM   #10
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Quote:
Originally Posted by realshelby View Post
......Based on what I learned from that and others that have had failures, towing in overdrive just isn't worth the chance of overheating/stressing the transmission. The higher rpm the engine sees is NOTHING to it, actually easier on it in some ways too. Such as increased cooling due to water pump and fan turning faster. The difference in mpg will be very small.
Adding to realshelby's comment, my tow vehicles are Fords with Ecoboost engines. I've read that locking out the higher gears and allowing the engine to run at higher rpms is easier on the engine. That doing so minimizes the boost required from the turbos to maintain a given speed. This tactic supposedly provides better mpgs, which seemed to be true on my last major camping trip. I'm not a trained mechanic so don't take this as gospel.
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Old 02-27-2024, 11:31 AM   #11
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Our 2011 Chev Silverado Crew cab 1500 LTZ has the factory tow option. When the TOW mode is engaged, the 6th gear is not used. This does raise the engine RPM, thus increasing oil pressure in the tranny and torque converter. This is much more reliable and safer for towing.

Bottom line, what does the owner's manual say about towing? That's the correct answer for your vehicle.

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Old 02-27-2024, 11:35 AM   #12
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For pulling 2000 pounds it hardly matters. Of course it is okay to pull with OD off. It just puts your engine in a higher RPM range.
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Old 02-27-2024, 03:12 PM   #13
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My take:
For reference, I tow roughly 5600 pounds with approximately 500 to 600 pounds in the TV bed, and humans weighing about 400 combined. I have a 2006 RAM 1500 with what's laughingly called a 4 speed with OD. In reality, it's a 3 speed with an electronic OD with several settings. I tow in the Rockies.

My philosophy is to not torture the transmission with lots of up and downshifts. Find the transmission's "happy place" and have it work there.

We do have flat land in CO...in high mountain valleys and down on the plains (half of CO is the Great Plains...like Kansas). On level ground, even with my load, the truck will settle in nicely with OD and cruise control on. But I can also select "tow-haul" so that the OD drops more quickly when I encounter a slight incline. If the transmission is dropping out of OD very much at all, I go for Tow-Haul mode. And if the transmission is still "hunting" a lot, I shut off the OD entirely...which puts the transmission in 3rd gear.

The fact is that, when towing in the mountains, I spend most of my time in second gear (good for about 65 MPH, but I'm holding more like 50 to 55 MPH on these two-lanes). When climbing mountain passes....11,500 feet with a normally aspirated Hemi gasser...I'm often in 1st gear. First is good for about 45 MPH at redline, so I set the cruise at 35 MPH to climb or descend, and that keeps the engine below 80% of redline. That engine speed is well within the engine's comfort zone. I can go all day at 80% of redline.

But returning to my point and a claim. Yes, your transmission is designed to downshift on its own when under load. But think about a FULL THROTTLE downshift and the stresses it puts on the transmission. My inclination is to do as little of that full-throttle downshifting as possible. Instead, I lift of the gas, make the downshift manually, then have at it. And I do NOT upshift again on long uphills if I'm well under redline.

Why? In the mountains, if you're climbing, you can floor it exiting a curve, get the downshift, and accelerate towards the next turn. What's next? You must typically lift off for the next turn, and the transmission will upshift into the highest gear available, only to be tortured through another full-throttle downshift as you exit the curve and hit the straight-away. That's hard on the transmission, and it's hard on the passengers.

Instead, find the sweet spot for the terrain you are in and choose that gear and stick with it. The transmission will be much happier. If it's flat, top gear can be great. But in rolling hills, your transmission and your passengers will be happier with OD off...and in some cases maybe even in a lower main gear. The typical climb to and descent from a high mountain pass in CO might be 40 miles total. And much of that 40 miles, in my case, will be in 1st gear at 35 MPH. That's usually the speed limit anyway, and with 12,000 pounds...between TV and rig, I have no business going any faster....especially on the way down.

Listen to your truck. It will tell you the gear to choose for the situation you're in. If it's constantly shifting, it's not happy. Go lower.
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Old 02-27-2024, 03:51 PM   #14
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When I'm on a good open road I will run with the cruise engaged and O/D on. I'm usually running the speed limit and sometimes a little more. If I get into hilly country I turn O/D off to keep the transmission from jacking the shifts. My Ram 1500 with the 8spd transmission pulls best in 6th gear O/D off. On steep downgrades I choose a gear to match the speed I want to run this takes the O/D out of the system and enables engine braking.
I have a RAM 1500 and curious on how you do this, I'm probably missing something or not aware I have this ability. Thanks in advance.
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Old 02-27-2024, 04:43 PM   #15
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My current Ram 1500 with the 5.7L Hemi (as well as previous 2011 Ram) has a Tow/Haul button that changes shift points for the transmission. It does pretty well while you're going through town and getting on the expressway. I have usually turned the Tow/Haul off once on the expressway for a long distance, and everything seems fine and the engine RPM drops a bit. I re-engage it when exiting the expressway. I can't recall if the current truck with the 8 speed transmission has an OD off button. I guess I'll have to look. IIRC the manual just says to use the Tow/Haul button when towing.
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Old 02-27-2024, 05:03 PM   #16
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I have the 10 speed transmission in a F150. I tow my 5th wheel (8500lbs loaded with water) mainly in 7th and occasionally in 6th. 8,9 and 10 are over drive. I recall that at 100 km/hr I’m at 2400 RPM which is a nice comfortable rev for me. In 6th I’m at 2700. I don’t go over 100 km/hr. With my 2011 F150 which had the 6 speed, I towed in 5th and sometimes 4th. I just think it feels better to not be in overdrive and maybe easier on the transmission with less shifting. This is all on mostly flat towing, in the hills it changes of course. And I am in tow / haul mode for the extra engine braking. On a side note, I also drive in tow/haul on steep hills when not towing for the downshifting/engine brakes and in the winter in the city on the slippery roads.
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Old 02-27-2024, 05:43 PM   #17
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Just monitor the transmission temperature. Most manuals will recommend not to exceed 200 degrees. Likewise for transmission fluid.

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Old 02-27-2024, 06:36 PM   #18
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I have a RAM 1500 and curious on how you do this, I'm probably missing something or not aware I have this ability. Thanks in advance.
I'm probably getting my two trucks mixed up. My 1996 Ram 1500 has the o/d button on the dash and my 2016 Ram 1500 has the rotary shifter. With the 2016 I am in tow haul mode and I then use the +/- selector to select the lowest gear I want.
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Old 02-27-2024, 07:29 PM   #19
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I have a tow mode with a 6spd auto. It essentially locks out 6th. I leave it in tow mode unless I get a long down slope. In those cases I will disengage tow mode to drop the rpms a little. It is a case by case basis
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Old 02-28-2024, 09:24 AM   #20
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Good policy

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Uphill I have OD OFF and often slow to 50-55 and rev up to 2800 by top of hills. I am not sure if that is correct to do.
This is a good policy. It will prevent you from overheating the engine or transmission.
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