Tow/Haul off or on(ram)

[stevemorris]

I w the discussion about the ford tow/haul system, how about the Ram
in our case, 2017 1500 with the hemi and 8 speed

we use T/H all the time when towing and definetly see a difference in acceleration and braking, shifting at higher engine speeds and earlier downshifts

we also use the manual shift buttons on very twisty steep hills for engine braking and going up those steep hills

but does it do anything at highways speeds on flat roads?

[IdaD]

Dave H M wrote:
This thread was interesting from the standpoint of how much bad information and lack of knowledge was expressed. :S

Perhaps interesting but certainly far from unique on this site.

[Dave_H_M]

This thread was interesting from the standpoint of how much bad information and lack of knowledge was expressed. :S

[hotpepperkid]

Lynnmor wrote:

RoyJ wrote:


I'd like to know what transmission does that.

In most, OD off means exactly that - overdrive gears are not used, only up to and including direct drive.

Again, *most* transmissions would lock up sooner in direct drive, with OD off. I've never come across one where in OD off it stays in direct but with the converter unlocked.

You might want to check what transmissions have direct drive, mine doesn't.

Must be a very old one. Even my old Ford 2000 has a locking torque converter. It locks up even when OD is off

[hotpepperkid]

Lynnmor wrote:

RoyJ wrote:


I'd like to know what transmission does that.

In most, OD off means exactly that - overdrive gears are not used, only up to and including direct drive.

Again, *most* transmissions would lock up sooner in direct drive, with OD off. I've never come across one where in OD off it stays in direct but with the converter unlocked.

You might want to check what transmissions have direct drive, mine doesn't.

Must be a very old one. Even my old Ford 2000 has a locking torque converter. It locks up even when OD is off

[hotpepperkid]

Groover wrote:

kellem wrote:
I use tow mode and OD off every time I tow.
Less shifting = cooler transmission.

Another trick for a cooler transmission is to take it out of drive if you are going to be stopped very long. I have seen that in a couple of my owner's manuals. One even warns that the transmission will overheat if left in drive too long while stopped.

That takes a long time

[larry_barnhart]

I use tow mode when we tow. neighbor has a 2008 ram 5500 and a new just bought a 2019 5500. He can't tell any difference on the 08 towing or not and solo driving on the trip home same story but not towing. I don't understand why not.

chevman

[ShinerBock]

The direct drive ratio is the gear the input shaft and output shaft transfers the same amount of torque. Both are spinning at the same rpm in a 1:1 ratio. You have under drive gear ratios, a direct drive ratio, and over drive ratios. The direct drive does not have to be directly connected to the output shaft in order for it to be called the direct drive gear ratio.

[Walaby]

I use Tow haul every time I tow.

Mike

[Lynnmor]

Grit dog wrote:
^ But it does have a gear ratio or 2 that are close to 1:1, so what’s your point?
Many newer auto transmissions don’t have an exact 1:1 ratio gear any longer. And many do.
What is worth noting, is there is nothing magical that happens at 1:1, it’s just another step in the gear ratios from under-driven to over-driven.

And “OD off” is a thing of the past that was used on 4 and 5 speed transmissions to limit upper gear ratios. No different than manually shifting it via the gear shift or range buttons to limit the upper gear that the trans will shift into.
I’ve not seen it on any vehicles I’ve driven in recent years that have 6 or 8 speed transmissions.

The point is that older transmissions had a direct drive straight thru the transmission and didn't have the friction of running it thru a gear set.

[Grit_dog]

^ But it does have a gear ratio or 2 that are close to 1:1, so what’s your point?
Many newer auto transmissions don’t have an exact 1:1 ratio gear any longer. And many do.
What is worth noting, is there is nothing magical that happens at 1:1, it’s just another step in the gear ratios from under-driven to over-driven.

And “OD off” is a thing of the past that was used on 4 and 5 speed transmissions to limit upper gear ratios. No different than manually shifting it via the gear shift or range buttons to limit the upper gear that the trans will shift into.
I’ve not seen it on any vehicles I’ve driven in recent years that have 6 or 8 speed transmissions.

[Lynnmor]

RoyJ wrote:


I'd like to know what transmission does that.

In most, OD off means exactly that - overdrive gears are not used, only up to and including direct drive.

Again, *most* transmissions would lock up sooner in direct drive, with OD off. I've never come across one where in OD off it stays in direct but with the converter unlocked.

You might want to check what transmissions have direct drive, mine doesn't.

[Sam_Spade]

RoyJ wrote:

I'd like to know what transmission does that.

Maybe I'm a few years (decades ?) behind on transmission design.

I though that the LAST thing that happened on up-shifting was locking the torque converter.....AFTER the highest gear was engaged.

Then anything that took it out of the highest gear (overdrive) ALSO unlocked the converter.

I assume you are saying it doesn't quite work that way anymore ??

[Groover]

kellem wrote:
I use tow mode and OD off every time I tow.
Less shifting = cooler transmission.

Another trick for a cooler transmission is to take it out of drive if you are going to be stopped very long. I have seen that in a couple of my owner's manuals. One even warns that the transmission will overheat if left in drive too long while stopped.

[RoyJ]

Sam Spade wrote:

kellem wrote:
I use tow mode and OD off every time I tow.
Less shifting = cooler transmission.

Maybe not.

OD OFF keeps it out of direct final drive.

The torque converter is in constant use and likely will tend to make it run a bit HOTTER.

The act of shifting up and down does not itself generate any more or less heat.

I'd like to know what transmission does that.

In most, OD off means exactly that - overdrive gears are not used, only up to and including direct drive.

Again, *most* transmissions would lock up sooner in direct drive, with OD off. I've never come across one where in OD off it stays in direct but with the converter unlocked.

[stevemorris]

did a non scientific test today!
t/h on and off, at highway speed(110 kmh) flat road
rpms's the same(so same gear) and mileage according to the dash reading was identical. transmission temp the same