Home Forums Gear Hunting Trucks and Four-Wheel Drives At what percentage of miles, do I become a tower?

It’s not overdrive that will kill a transmission, it’s long hard pulls with an unlocked torque converter

I'm pulling mostly on flat landscapes. Once a year (4K miles or so) to high plateau (Wyoming or Montana).

When in mountainous country. Use the tow mode and decide when you want it to shift. grades. Lock out 5th and 6th and slow down and let it pull. Really steep pulls , lock out 4th at times. It all depends how much I am hauling and pulling. I run about 16,000 pounds in my hunting rig.Truck camper, trailer



And when it is unlocked , the 6th or 5th gear is essentially overdrive.There is no switch anymore where you select OD. If you let the computer constantly select the highest gear the truck will pull in, it will continuously shift.That will shorten the life of the transmission .Probably in flat land there is not a problem. Where I drive there is. Foothills and two 10,000 ft passes to get where I hunt. Even around home at 7600 feet I have serious hills

5th and 6th gear are always OD, whether or not the TQ converter is locked. 6 speed Allison transmission gear ratios are as follows:

1st. 3.094:1
2nd 1.809:1
3rd 1.406:1
4th 1.000:1
5th .711:1
6th .614:1

OD isn't some "system" outside of the normal transmission, it's just any gear that's higher than 1:1.

"Tow/Haul" mode doesn't "lock-out" OD. Tow/Haul adjusts shift points to typically hold more RPM both shifting up and down. Tow/Haul will generally result in a "stiffer" or "harder" shift as well by reducing the amount of slip allowed. Tow/Haul doesn't lock out any specific gear and really has nothing to do with OD, OD is simply a gear/gear-ratio.

How can one tell if the TC is locked?

" Tow/Haul doesn't lock out any specific gear " Wrong.My Owners Manual for my 19 Duramax /Allison specifically states that when in tow mode, with shift selector in L, not D, you will have access to the gear you select and all gears below that. So if you select 4th, then 5th and 6th are locked out. If you select 3rd, then 4th, 5th, and 6th are locked out and you only get 3rd, 2nd, and 1st. .It will not shift up into those 4th, 5th or 6th. I'd call that locked out.

Maybe it is in the transmission and not torque converter, as I am not a big gear head, but of you are pulling a pretty good load, have the transmission in Drive in hilly country or say from Kansas city to Denver where you are constantly climbing, you can sure fry the transmission before too long. Don' t know about present but previously Fords were notorious for that. You sure don't want to use Cruise Control either.( That is in the Manual too)

I drove almost 1500 miles this past hunting season with a heavy load. All hills/mountains were in tow mode,only flat Interstate was not. About 1/3 of that. I'm pretty sure I know how it works .

That’s not tow/haul, that’s manual mode. Tow/haul is the button recessed into the end of the shifter lever. Tap it and a trailer icon lights up on the dash. That’s tow/haul mode. You are describing manual mode, which is different.

If you say so

We have an '18 Toyota Highlander with the v6. There's nothing in the manual about what gear to use while towing. It does have what they call the PWR mode. Near as I can tell, it adds power to the engine but has nothing to do with the tranny. I asked the local dealer what gear was recommended while towing and he said to just use the PWR mode. It also has an alternate shift mode that limits how high of a gear you can be in. It also doesn't mention a torque converter. I'm still dubious. I can't find anything on the web about it.

In your Ford you can press the "+" on the +/- button on the gear lever and display 1-6 above your gear designator on the instrument cluster. This corresponds to gears 1-6 in the transmission. When NOT engaging Tow/Haul, You'll see a 200-300RPM drop between 35-45MPH holding stead speed without actually shifting from 4th to 5th. You'll feel it "unlock" about the same speed @ about 35-40 when decelerating when you feel the engine braking diminish and RPM will drop to idle almost like you stepped on the clutch or put it in N.

When all 6 gears are displayed on your cluster, the transmission will always try to get to the highest gear it can hold. You can press the "-" and 6 won't be illuminated, and is locked out/unavailable, you can press "-" again and lock out 5th, etc, etc, etc. This is different than running in Manual mode where you choose the gear and it'll hold that gear until you shift.

PWR mode should hold each gear longer (higher RPM shifts) and downshifts @ higher RPM as well. It keeps you in the upper end of the RPM range nearer peak HP/TQ. I suppose w/variable valve timing there could be algorithms written/engaged to skew towards power rather than MPG as well.

You are correct. Putting it into Tow/haul while in D with the "button" brings in a shifting stabilization mode such as Horse 1 explained. However the manual says if the transmission is shifting too much, drop it down into a lower gear. I don't know if using +/- switch on the shift lever does that while in D, the manual doesn't say, but I do know if you switch to manual, you can. You still have to use the Tow/Haul button. Seems to me, if it is shifting too much,you are going to overheat the transmission as I posted earlier, if you don't use the manual mode. Personally after driving 5/6 speed manuals and diesels going up hills an coming down with heavy loads, I would prefer selecting what gear I am in even though this Duramax has quite a bit more pulling power than my old 98 Dodge. It does work exactly how I described. I double checked the manual to be sure. I will leave it at that and leave others to decide what they will do.



I had an Acura Legend that was similar. It had a Sport Mode Don't know it it was transmission or engine ,but you selcted it with a button near the shift lever

If your engine speed tracks your road speed, your TC is locked.

Practically speaking, if while cruising you press the gas and engine speed increases without a corresponding increase in vehicle speed, TC is unlocked. TC locked feels and acts like a manual trans truck with the clutch pedal out.

GM 4l80E transmissions will drive you bonkers, trying to keep that one locked up under load or going downhill. Most newer autos can be duped into staying locked at most speeds by employing tow/haul and/or judicious use of the manual up/down shift button, with the idea being to keep the engine rpms up and avoiding lugging.