Go Back   iRV2 Forums > iRV2.com COMMUNITY FORUMS > Vintage RV's
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Thread Tools Search this Thread Display Modes
Old 10-13-2015, 12:29 PM   #1
Senior Member
Vintage RV Owners Club
Join Date: Sep 2015
Location: East Moline, IL
Posts: 169
Why would I need to turn off OD?

We just bought a 91 Class C, 460 Ford on an E350 chassis. Over the speedometer (see pic top) is a hand made label that states "Turn OD Off". There is a button (see pic left) that will turn it off and I was told by the previous owner that he always turned the OD off because of this label. But he didn't know why, it just said to so he did. Now I have left it on while highway driving and OD seems to work just fine. So my question is, can anyone explain WHY this label exists and WHY would I want to turn off the OD?
Attached Thumbnails
Click image for larger version

Name:	OD Pics.jpg
Views:	38
Size:	202.4 KB
ID:	109534  

26' 1991 Class C Ford Tioga Arrow
DW, 2 Shih Tzu furkids and me
Youtube Channel: "https://www.youtube.com/channel/UCCJ...vVa8upNDtZ2dZg
CaptainGeezer is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 10-13-2015, 12:42 PM   #2
Join Date: Nov 2014
Posts: 70
Just a quick guess, but I will suppose that the first owner was towing something heavy enough to cause the transmission to shift in and out of overdrive continuously.

EV2 is online now   Reply With Quote
Old 10-13-2015, 02:12 PM   #3
Senior Member
hayward3411's Avatar
Join Date: Feb 2015
Location: Huntingtown, MD
Posts: 201
X2 Overdrive off when towing.
Earl & Sharon, 2008 Fleetwood Expedition, ISB 6.7
hayward3411 is offline   Reply With Quote
Old 10-13-2015, 03:15 PM   #4
Senior Member
Commercial Member
Join Date: Aug 2012
Posts: 577
Best would be to investigate what the owner's manual says for that chassis. Many modern engine/transmission controls allow OD when towing and manage the shifting better than old wife's tales.

Sent from my iPad using iRV2 - RV Forum
TravellingRVDoctor, LLC
shiggs68 is offline   Reply With Quote
Old 10-13-2015, 03:16 PM   #5
Senior Member
38Chevy454's Avatar
Join Date: Aug 2013
Location: Tijeras (Albuquerque), NM
Posts: 649
Agree, turning OD off keeps the trans in 3rd gear (1.00 ratio) to keep the trans from hunting between 3rd and 4th when towing or pulling slight hills. It also keeps the trans from getting too hot when towing. It won't really hurt having OD off when not towing and on flat ground, just makes the engine run at higher rpm and less mpg.

So run with OD on when you can, it is designed to be used under lighter loads and flat ground. If you find it hunting between, such as on a slight uphill, turn the OD off will keep it form switching between gears.
2005 Kenworth Showhauler truck conversion.
. 44 ft, Cummins ISX15 450 hp, 10 speed, twin screw
I used to have a handle on life, but it broke
38Chevy454 is offline   Reply With Quote
Old 10-13-2015, 03:44 PM   #6
Senior Member
Join Date: Sep 2012
Posts: 4,023
I would respectfully disagree with turning it off when towing. It sounds more like somebody who was not willing to pay attention to his shifting. Possibly because they were clueless about torque and horsepower curves. The easy out was to leave the OD off. The better answer is to leave it on unless one needs the forced down shift usually proactively shifting when going into a hill and/or coming down one. If one is towing and needs to shut off the OD on flat ground they are probably towing too much.
nothermark is offline   Reply With Quote
Old 10-13-2015, 08:15 PM   #7
Senior Member
Wdebarmore's Avatar
Monaco Owners Club
Join Date: Mar 2014
Posts: 185
I turn my off on long down hills for more engine braking.
1988 34' Executive Industries - Executive Prestige
5.9 Cummins, Allison AT542
Wdebarmore is online now   Reply With Quote
Old 10-13-2015, 08:36 PM   #8
Senior Member
Join Date: Jun 2010
Location: Anacortes, WA (Stick & Brick)
Posts: 2,508
Modern automatic transmissions are a lot smarter than their drivers are. The chassis manufacturers have a lot of master's degree engineers (and a few Ph.D's) working on these systems.

Just leave the selector in "drive" and don't try to second-guess the thing, All you'll do otherwise is burn more gas than you need to and cause excessive wear on the engine by causing it to rev more than it needs to.

Frank Damp -Anacortes, WA,(DW- Eileen)
ex-pat Brits (1968) and now ex-RVers, as of 08 Dec 14.
frankdamp is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Mid Coach Turn Signals Gasman 2 Entegra Owner's Forum 111 06-26-2016 07:31 PM
Is there a way to turn off 6A DC charging from generator? CountryFit RV Systems & Appliances 20 10-02-2015 11:17 AM
Brake and turn signal not working at the trailer plug Divide Wee Ford Motorhome Chassis Forum 22 09-16-2015 02:37 PM
Turn Signals Light Up When Brake Pedal Is Pushed MarkinOR Monaco Owner's Forum 5 05-06-2014 04:05 PM
Useage of turn signals wagonmaster2 iRV2.com General Discussion 42 10-25-2013 11:31 AM

» Virginia Campgrounds

Reviews provided by

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 09:49 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.