RV.Net Open Roads Forum: Tow Vehicles: Tow/Haul off or on(ram)

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Tow Vehicles

Open Roads Forum  >  Tow Vehicles

 > Tow/Haul off or on(ram)

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 5  
Prev  |  Next
Sponsored By:
Grit dog

Black Diamond, WA

Senior Member

Joined: 05/06/2013

View Profile


Offline
Posted: 08/05/19 03:34pm Link  |  Quote  |  Print  |  Notify Moderator

"but does it do anything at highways speeds on flat roads?"
Depends on the load. If the truck will pull the load in 8th gear then even in tow/haul, it will hit 8th gear.


"Yes Sir, Oct 10 1888, Those poor school children froze to death in their tracks. They did not even find them until Spring. Especially hard hit were the ones who had to trek uphill to school both ways, with no shoes." -Bert A.

B.O. Plenty

Minnesota

Senior Member

Joined: 02/04/2010

View Profile



Good Sam RV Club Member


Posted: 08/05/19 03:52pm Link  |  Quote  |  Print  |  Notify Moderator

ShinerBock wrote:

The TC clutch does not release even in normal mode as you slow down until you get down to a certain speed. Tow/haul lowers this speed threshold. The main thing tow/haul does is change shift points. It holds gears longer when up-shifting to keep you higher rpms for more power. This is better for your transmission when towing. It also downshift earlier when decelerating to help slow down the vehicle quicker. This is not good for your transmission, but it is not that bad either.

Another thing that some transmissions do in tow haul mode is increase the line pressure threshold. This changes the shifts from nice smooth shifts to more firm shifts. This is good for your transmission because it decreases clutch wear and creates less heat due to decreasing the amount of time the clutch slips at each engagement/shift.
What he said....no magic, it's designed to make towing easier on your transmission. No reason not to use it.

B.O.


Former Ram/Cummins owner
2015 Silverado 3500 D/A DRW
Yup I'm a fanboy!
2016 Cedar Creek 36CKTS

stevemorris

ontario

Senior Member

Joined: 08/14/2011

View Profile



Good Sam RV Club Member

Offline
Posted: 08/07/19 02:26pm Link  |  Quote  |  Print  |  Notify Moderator

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


2017 Ram 1500 4door, 4x4, 5.7 l hemi, 8 speed
2008 KZ Spree 260

RoyJ

Vancouver, BC

Senior Member

Joined: 10/19/2006

View Profile


Offline
Posted: 08/07/19 03:26pm Link  |  Quote  |  Print  |  Notify Moderator

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.

Groover

Pulaski, TN

Senior Member

Joined: 10/17/2007

View Profile


Online
Posted: 08/07/19 03:50pm Link  |  Quote  |  Print  |  Notify Moderator

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.

Sam Spade

North Central Florida

Senior Member

Joined: 11/05/2015

View Profile


Offline
Posted: 08/07/19 06:35pm Link  |  Quote  |  Print  |  Notify Moderator

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 ??


'07 Damon Outlaw 3611
CanAm Spyder in the "trunk"

Lynnmor

Red Lion

Senior Member

Joined: 07/16/2011

View Profile



Good Sam RV Club Member


Posted: 08/08/19 06:38am Link  |  Quote  |  Print  |  Notify Moderator

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.





Grit dog

Black Diamond, WA

Senior Member

Joined: 05/06/2013

View Profile


Offline
Posted: 08/08/19 09:20am Link  |  Quote  |  Print  |  Notify Moderator

^ 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

Red Lion

Senior Member

Joined: 07/16/2011

View Profile



Good Sam RV Club Member


Posted: 08/08/19 10:26am Link  |  Quote  |  Print  |  Notify Moderator

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.

Walaby

Georgia

Senior Member

Joined: 11/10/2014

View Profile



Good Sam RV Club Member

Offline
Posted: 08/08/19 12:44pm Link  |  Quote  |  Print  |  Notify Moderator

I use Tow haul every time I tow.

Mike

* This post was edited 08/08/19 03:08pm by Walaby *


Im Mike Willoughby, and I approve this message.
2017 Ram 3500 CTD (aka FRAM)
2019 GrandDesign Reflection 367BHS


Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 5  
Prev  |  Next

Open Roads Forum  >  Tow Vehicles

 > Tow/Haul off or on(ram)
Search:   Advanced Search

Search only in Tow Vehicles


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:

© 2019 CWI, Inc. © 2019 Good Sam Enterprises, LLC. All Rights Reserved. | Terms of Use | PRIVACY POLICY | YOUR PRIVACY RIGHTS