Tow/Haul

[Dean2]

You're not going to burn out your transmission by not using tow/haul. The entire thing is computer controlled. You're more likely to damage the engine by lugging it.

These aren't the transmissions of old where T/H locked out overdrive.

You are wrong about this. The 8 speeds are great transmissions but they shift a bunch more often. More shifting is NOT a benefit to the transmission. Tow Haul is designed to restrain that, as at least one of its functions.

 

[Riccochet]

You are wrong about this. The 8 speeds are great transmissions but they shift a bunch more often. More shifting is NOT a benefit to the transmission. Tow Haul is designed to restrain that, as at least one of its functions.

We can agree to disagree. Shifting is not going to hurt a transmission. T/H is more to keep engine RPM's up where the engine makes its power. It's going to shift the same just at higher RPM's. And when you brake it's going to down shift to raise those RPM's for engine braking. It's just a different shift strategy based on RPM's.

 

[Grams]

2021 1500 Hemi 4x4. I will be hauling a 6'x12' U-Haul trailer from Northern Colorado to Somerset, KY. Almost all of the trip is Interstate Highway.
My truck came with the class IV receiver hitch, Electronic Roll-Mitigation and Stability-Control, Trailer Sway Damping and Trailer Brake-Controller. Is the tow/haul feature something I should use on the highway?

ABSOLUTELY! YES! …if you value your transmission.

 

[Grams]

We can agree to disagree. Shifting is not going to hurt a transmission. T/H is more to keep engine RPM's up where the engine makes its power. It's going to shift the same just at higher RPM's. And when you brake it's going to down shift to raise those RPM's for engine braking. It's just a different shift strategy based on RPM's.

Wrong! Read the Owner’s Manual. It changes the shift-pattern, it suspends overdrive to prevent overheating the transmission, and does NOTHING directly for the engine (which meets it’s criteria by observing driver-input (accelerator-pedal-use) versus speed.

 

[Curmudgeon]

Wrong! Read the Owner’s Manual. It changes the shift-pattern, it suspends overdrive to prevent overheating the transmission, and does NOTHING directly for the engine (which meets it’s criteria by observing driver-input (accelerator-pedal-use) versus speed.

This could vary by 3rd/4th/5th Gen, or by transmission. I was wondering about this myself and tested it 2 days ago.

2014, 5.7L, 8-speed, 3.21 rear, no load no tow. Selected 8th gear from steering wheel while doing 75mph on the highway, trans stayed in 8th, but I thought maybe only because of the speed, so I waited for an good up-hill, slowed down to 55mph and provided enough pedal to maintain 55mph. "ECO" light went out but trans stayed in 8th.

even if I manually dropped down to 5th, when I bumped it up to 8th the trans followed by shifting to 8th.

I will say I can feel the change in shift points, it surely hold each gear longer and makes my stock exhaust sound nice when stopping for a left turn at the bottom of a 1/2 mile uphill grade near home. I get into it pretty good and it sounds awesome.

I also like getting the RPMs just that much higher (and watching the traffic behind me disappear like the snows of yesteryear.



.

 

[Dean2]

This could vary by 3rd/4th/5th Gen, or by transmission. I was wondering about this myself and tested it 2 days ago.

2014, 5.7L, 8-speed, 3.21 rear, no load no tow. Selected 8th gear from steering wheel while doing 75mph on the highway, trans stayed in 8th, but I thought maybe only because of the speed, so I waited for an good up-hill, slowed down to 55mph and provided enough pedal to maintain 55mph. "ECO" light went out but trans stayed in 8th.

even if I manually dropped down to 5th, when I bumped it up to 8th the trans followed by shifting to 8th.

I will say I can feel the change in shift points, it surely hold each gear longer and makes my stock exhaust sound nice when stopping for a left turn at the bottom of a 1/2 mile uphill grade near home. I get into it pretty good and it sounds awesome.

I also like getting the RPMs just that much higher (and watching the traffic behind me disappear like the snows of yesteryear.



.

If you use the gear limiter switch you will over ride at least part of the tow haul programming. Try that same route and leave the selector in D. I think you will see different shift behaviour. On my 2500, it does not shift into 8 as long as the selector is in D. If I use the limiter switch I can shift it to 8. I have my display set up so it displays the gear I am in, even in D.

 

[Curmudgeon]

@Dean2 I'll have to try that, I guess I'll have to try counting the shifts. I don't know any other way to know what gear it's in, mine doesn't display the gear unless I bypass at the steering wheel, which is why I chose that method.

Repeating for emphasis, the only load on the truck was me. No passengers, empty bed, no tow. I would assume my transmission might/would stay out of 8th if it was loaded down in some way. Seems reasonable.

At 75 mph my engine is right at 1500rpm, at 55mph maybe 1200? Probably not ideal when loaded down! Dropping to 7th usually only adds about 300rpm though.

 

[MD Sledhead]

With 3.92 gears the tow haul will go into 8th on it's own... however, 8th gear is 2000 RPM at 69-70 mph.
I towed 24,000 of the 100,000 miles my 2014 had on it when I traded. Always used tow haul unless I was pulling a small, empty trailer.
Towed my big trailer (24'x8.5'x6' enclosed) most of the time. Empty it was 2100 lbs. But even with a v-nose it sometimes felt like I was pulling a parachute.
@Dean2 - are those imperial gallons in your MPG calculation? They are much larger than a US Gallon.

 

[vetteyog]

On my 2012 1500, with a 6-speed when I engaged tow/haul mode transmission will not go into 6th gear. Other than that the only real benefit is it changes the shifting pattern. So it runs in the higher rpm range; and disables MDS. I say use it if you got it, won't hurt anything.

 

[Tulecreeper]

If you use the gear limiter switch you will over ride at least part of the tow haul programming. Try that same route and leave the selector in D. I think you will see different shift behaviour. On my 2500, it does not shift into 8 as long as the selector is in D. If I use the limiter switch I can shift it to 8. I have my display set up so it displays the gear I am in, even in D.

Mine will shift into 8th at about 65 MPH with or without using my limiter. That is without using T/H mode.

 

[Tulecreeper]

@Dean2 I'll have to try that, I guess I'll have to try counting the shifts. I don't know any other way to know what gear it's in, mine doesn't display the gear unless I bypass at the steering wheel, which is why I chose that method.

Repeating for emphasis, the only load on the truck was me. No passengers, empty bed, no tow. I would assume my transmission might/would stay out of 8th if it was loaded down in some way. Seems reasonable.

At 75 mph my engine is right at 1500rpm, at 55mph maybe 1200? Probably not ideal when loaded down! Dropping to 7th usually only adds about 300rpm though.

When I leave it in 'D', I also can't see what gear I'm in, but I can check anytime just by activating my limiter. It will show me what gear it is currently in, then I just hit '+' until I get back to 'D' again.

 

[Docwagon1776]

@Dean2 I'll have to try that, I guess I'll have to try counting the shifts.

Does the 8 speed use every gear every time? I know the 6 speed skips a gear, I think it's 2nd gear there are two options for. I haven't paid attention in my PW if it runs through each one or not.

 

[Riccochet]

Wrong! Read the Owner’s Manual. It changes the shift-pattern, it suspends overdrive to prevent overheating the transmission, and does NOTHING directly for the engine (which meets it’s criteria by observing driver-input (accelerator-pedal-use) versus speed.

There is no overdrive on the ZF8 in the traditional sense. T/H does not lock out any gears. I pull 9000 lbs in T/H and still go in to 8th gear on my current and last truck. It does change the shift strategy to hold gear longer under load. It'll still upshift to the highest gear it feels it can get away with. And will downshift a gear or two under braking.

That's all it does. Helps keep the engine in the power band under acceleration and helps keep RPM's up during braking.

 

[Tulecreeper]

Does the 8 speed use every gear every time? I know the 6 speed skips a gear, I think it's 2nd gear there are two options for. I haven't paid attention in my PW if it runs through each one or not.

Mine will use all 8 if I get it up to 65 MPH. Between 50 and 65, it will stay in 7th.

 

[Docwagon1776]

Mine will use all 8 if I get it up to 65 MPH. Between 50 and 65, it will stay in 7th.

I mean the shift pattern. Does it actually go 1-2-3-4-5-6-7-8 every time, or does it skip gears depending on load? The 6 speed never goes 1-2-3-4-5-6, it goes 1-2a-4-5-6 or 1-2b-4-5-6. If you just counted the shifts you'd think it was a 5 speed.

 

[Curmudgeon]

Does the 8 speed use every gear every time? I know the 6 speed skips a gear, I think it's 2nd gear there are two options for. I haven't paid attention in my PW if it runs through each one or not.

interesting thought and I don't know, haven't noticed. With 8 gears to choose from it sound plausible.
The way I have the steering wheel adjusted just a bit high for easier ingress/egress I have to lean forward to see the lowest part of the display. Not ideal for extended periods while driving.
The crazy people will get me.

 

[Docwagon1776]

interesting thought and I don't know, haven't noticed. With 8 gears to choose from it sound plausible.
The way I have the steering wheel adjusted just a bit high for easier ingress/egress I have to lean forward to see the lowest part of the display. Not ideal for extended periods while driving.
The crazy people will get me.

I know the Ford and GM 10 speeds don't hit every gear every time, up or down shifting. The 8 speed in these trucks is so smooth I, like you, just haven't noticed and never really thought to question it until reading this thread.

 

[rzr6-4]

I know the Ford and GM 10 speeds don't hit every gear every time, up or down shifting. The 8 speed in these trucks is so smooth I, like you, just haven't noticed and never really thought to question it until reading this thread.

I've never driven one, but from what I've read it seems like you can end up in 8th just going 40-50 mph around town. If that's the case, I would think it would skip gears. Otherwise you A) end up shifting after every 5-6 mph of acceleration, which would not feel smooth at all, or B) you would reach your cruising speed, lets say 45mph but you are still in 4th, so now you have to upshift 4 more times.

Far from an expert on this, but with no load I would think so.

 

[Tulecreeper]

I mean the shift pattern. Does it actually go 1-2-3-4-5-6-7-8 every time, or does it skip gears depending on load? The 6 speed never goes 1-2-3-4-5-6, it goes 1-2a-4-5-6 or 1-2b-4-5-6. If you just counted the shifts you'd think it was a 5 speed.

Yes, I've watched mine many times upshift and downshift and have never seen it miss a gear. During downshift I have noticed that it will stay in a higher gear than I think is necessary, though. Like I will be approaching a stop sign and even when I'm down to 5 MPH it will still be in 2nd or 3rd.

 

[Docwagon1776]

Yes, I've watched mine many times upshift and downshift and have never seen it miss a gear. During downshift I have noticed that it will stay in a higher gear than I think is necessary, though. Like I will be approaching a stop sign and even when I'm down to 5 MPH it will still be in 2nd or 3rd.

Maybe that contributes to how smooth it feels? One thing I didn't like about the F-150 Raptor is how often it seemed to be gear hunting and the lag for highway passing as it skipped down several gears. GM did a better job on the programming, IMO, or maybe it just responded better behind the 6.2 NA motor vs the 3.5L turbo'd.