Overdrive Off vs. Tow/Haul - Diesel Forum

mack109 · 05-03-2005, 07:45 AM

I have a 2004 Isata motorhome on an E450 chassis and a 2005 F250 SD XLT both with the 6.0L TD and Torqueshift 6 spd. The 2004 has the OD on/off feature on the shift stalk and the 2005 has tow/haul feature.

1. are these the same feature?
2. what exactly happens when your turn off OD or select tow/haul?
3. should all towing be done in the OD off or tow haul position?

I would appreciate any info. The owners manual for each vehicle gives little to go on. Having just experienced a transmission failure on the motorhome while towing in the OD off position (with only 10000 miles on the clock) I am wondering if I am doing something wrong. [img]/ubbthreads/images/graemlins/shrug.gif[/img]

CaptSkup · 05-03-2005, 07:51 AM

Are you sure your motorhome is equipped with the 5-speed Torqueshift transmission? What you are describing sounds more like the 4-speed auto usually found behind the 7.3 and gas engines. Never have seen a Torqueshift with a O/D button on the stalk, only tow/haul.

Casey_1 · 05-03-2005, 07:56 AM

[ QUOTE ]
Never have seen a Torqueshift with a O/D button on the stalk, only tow/haul.

[/ QUOTE ]
TorqShift transmissions in the 6.0L diesel vans have OD off, not tow/haul. I have no idea why, but that's the way it is.

OD off prevents the transmission from shifting to the highest gear, which is overdrive.

Tow/Haul changes the shift schedule so that it shifts to a higher gear at a higher RPM than in the normal mode. This helps move the heavier load. Also, the Tow/Haul will automatically downshift to help with engine braking. Tow/Haul will allow the transmission to shift to all gears including overdrive.

CaptSkup · 05-03-2005, 08:02 AM

Learn something new everyday. Wonder why the transmission is different in the vans/motorhomes, does Ford think people do not tow with vans/MHs? That just ain't right.

rock_doctor · 05-03-2005, 08:45 AM

Did not know this, personally I hate the shift points on the 5sp trans being able to lock out fifth and force it into fourth would be excellent. I wonder why they did not do this in all the trucks.

mark

HBO1 · 05-03-2005, 09:06 AM

[ QUOTE ]
I wonder why they did not do this in all the trucks.

mark

[/ QUOTE ]

Maybe because you are one of the very few that share that opinion? [img]/ubbthreads/images/graemlins/shrug.gif[/img]

motorjock · 05-03-2005, 01:48 PM

My OD off still lets it shift into 5th, just at a different rpm. That was my only complaint about pulling a trailer with it. Or just getting used to it.

mack109 · 05-03-2005, 03:44 PM

I appreciate all the opinions.

I don't think that the E450 will get into overdrive with the OD in the "off" position. My rpm's are always higher than they would be if that were the case. I much prefer the tow/haul feature on the F250 SD that allows top gear with altered shift points and engine braking on deceleration. This should give better fuel economy while towing, although it is brand new and I haven't towed with it yet. I have heard that, in the E450 with the OD off, it is essentially "direct drive" with fewer gears turning, less ATF shear and hence cooler transmission temps. Any opinions on that?

Mack

Casey_1 · 05-03-2005, 04:04 PM

[ QUOTE ]
I have heard that, in the E450 with the OD off, it is essentially "direct drive" with fewer gears turning, less ATF shear and hence cooler transmission temps. Any opinions on that?

[/ QUOTE ]
That's true, but the difference in temperatures is so small that it doesn't matter.

mack109 · 05-03-2005, 04:30 PM

I have a friend that overheated a tranny towing and now tows without switching off the OD with no problems. Most of my towing will still need to be done with the motorhome, which is why I bought a diesel moho in the first place. "To tow in OD or not in OD, that is the question"? [img]/ubbthreads/images/graemlins/confused.gif[/img]

OT · 05-03-2005, 08:11 PM

Are you sure the 6L in that E chassis/same as SD 6L? Same hp/tq. Has o/d button, could it have something to do with higher geared rear end in M.home VS SD? I dont know, just curious.

These a/ts are pretty smart. [img]/ubbthreads/images/graemlins/biggrin.gif[/img] You need to experiment. Trying towing w/o-d on. That tranny will know when to downshift. If it starts hunting (shifting down/up alot) you might want to turn o/d off as lots of heat is being generated. JMO!

Good luck...OT [img]/ubbthreads/images/graemlins/smile.gif[/img]

**andrewbalser** · 05-03-2005, 11:18 PM

It is a fact that the 6.0 in the E-series chassis are not the same as in the superduty, or in the class 7 F series. They are of a slightly lower horsepower, and I believe torque also. The more confined space of the E series constitutes smaller cooling systems i.e. radiator, and even a possibility of the absence of an EGR aftercooler??( not sure about this one ) But yeah, the specs are lower on the E series. The lessened cooling system capacity means, power must be force limited, to keep within engineering limits of the cooling systems cooling capability.

FamilyRide · 05-04-2005, 11:12 AM

I hoped one of the "van guys" would se this because I thought the 6.0 in the van's weren't matched up to a Torqueshift at first? [img]/ubbthreads/images/graemlins/shrug.gif[/img] I could be confusing it with something else, but I'm not sure you'd have a OD Off/On on a torqueshift as that could indicate very different controls.

Nat Lancaster · 05-04-2005, 11:36 AM

The van radiator is slightly smaller, but there is no intercooler on the van. that means lower boost(similar to the 94-97 F series with no intercooler)hence lower horsepower.
Don't know what trans behind the 6.0 other than I thought that the 6.0 bolt pattern wouldn't mate to the 4r100.

nat

Casey_1 · 05-04-2005, 12:24 PM

The 6.0L in any vehicle has only been mated to the TorqShift. Never to any other automatic. The 6.0L in any vehicle has always had an intercooler, too. The 7.3L vans didn't have an intercooler, but all of the 6.0L vans do.