Tow mode/overdrive - Page 2

**loufish** · 10-05-2006, 09:22 PM

Quote:

"To maintain engine braking efficiency and
electrical charging performance, do not use
overdrive."

Finally found the same statement in my 04' manual.
Kind of funny when people seem to fight this whole "don't tow in 5th/OD"

I tow a P/U tent trailer and do tow in OD...sometimes, but I know when my truck needs it or not.

JetDriver · 10-07-2006, 05:12 PM

Ahhh Found the quote your referencing on page 9-37.

The traditional reason for not towing in Overdrive is that it leads to the transmission constantly shifting in an out of OD which leads to transmission overheating. I can say from personal experience that even if the transmission isn't shifting at all being in OD can still lead to an overheat condition.

Earlier this year I was returning from a trip to New Orleans hauling a double axle enclosed U-Haul trailer that I'd used to deliver relief supplies down there. I was towing the trailer back empty with my 2WD S-10 V6 and I thought that given the fact that I was on flat ground with an empty trailer I'd be okay towing in OD. The engine temp was higher than normal but not excessively so and everything seemed fine otherwise until we started smelling something akin to the nastiest truck stop mens room you can imagine. The smell wasn't constant but after a while I went back to towing in 3rd (4 speed auto in the S-10). When I stopped for gas I discovered the back of the truck had a fine mist of oil covering it and the trans fluid was well and truly burnt.

The truck drove fine and after getting the trans totally flushed it showed no adverse effects but that was one of the issues that drove me to purchase my new 2006 Titan.

That being said one of the things I really like about the Titan with the Tow package is the trans temp gauge. Does anyone here have any experience towing heavy loads in overdrive with their Titan? Have you noted a difference in trans temp between 4th and 5th?

Thanks

TitanBlue · 10-07-2006, 09:18 PM

Always heardit is safer, because of less shifting (why 1:1 vs a bit beyond is so magical is still a little fuzzy) whether a 4 speed or 5 speed or 6 speed. Other reasons listed here had not occured to me, especially the electrical performance. Heavier loadwith trailer, and many don't realize full output does not occur at slower engine speeds.

Never OD still holds true.

**loufish** · 10-08-2006, 02:00 PM

Quote:

(why 1:1 vs a bit beyond is so magical is still a little fuzzy) whether a 4 speed or 5 speed or 6 speed.

Here it goes...you need a basic understanding on how an auto trans works, autos use planetary gears in which 1 of 3 gears within each planetary has to be held stationary to allow the other 2 sets to form a ratio. Now say in first gear if we have a ratio of 3.0:1, then for every lb/ft of torque applied to the planetary gear set, the stationary gear needs about 1/3 of a lb/ft to hold it stationary, so putting 300 lb/ft thru our 1st gears means the trans has to be able to hold 100 lbs to keep the stationary gear stationary.
Now as we shift gears, 2nd may have a ratio of say 2.0:1 so as in our last example, if we are running 300 lbs thru it, it now takes 150 lbs to keep the stationary gear in place.
When we get to 4th, which is 1.0:1 it takes 300 lbs to hold the 300 lbs we are putting thru the trans.
I hope by now you figured out the in 5th(OD) it will take OVER 300 lbs to handle 300 lbs because the OD has a ratio of say .74:1...

What does all this mean?
When you are towing in OD, what ever amount of torque you are running thru the trans, the trans has to hold even more then that to keep 5th from slipping. For most trans this is too much for too long, and over time can cause small amounts of slippage, and that can start to add up, and you have premature trans failure...
Also because of the amout of torque, the torque converter will un-lock before downshifting to 4th, and much of a trans heat can come from the converter slippage.

We should do a Tow sticky on this...

The above ratios are for the easy math.

pushingvws · 10-10-2006, 09:13 PM

i cant tell when my tow mode is engaged

Hector Bravo · 10-11-2006, 03:09 AM

The tow mode button lights up. It turns off every time you turn the truck off.

Hector

ablexus · 10-22-2006, 07:37 PM

Quote:

Originally Posted by Hector Bravo

The tow mode button lights up. It turns off every time you turn the truck off.

Hector

Don't worry about that guy, he's a box of tools. Check out his other gems:

http://www.titantalk.com/forums/sear...earchid=990175

Andrew

BroncoAZ · 10-24-2006, 05:10 PM

Does speed have anything do do with this towing equation? When I haul a 2500 pound empty trailer on flat ground (Tucson to Phoenix) I usually run at about 78 mph in OD. The transmission doesn't appear to be gear hunting, and the trans temp guage doesn't move. Sometimes it will go out of lock on the freeway overpasses, so I manually pull it into 4th for those. When the trailer is loaded (approaching 9000 pounds) I run at 75 mph in 4th gear.

Mitch

**loufish** · 10-24-2006, 10:07 PM

Quote:

Does speed have anything do do with this towing equation?

It does when talking about the torque converter locking up, but it has more to do with how much throttle you are pouring on...More throttle means more torque the trans has to deal with.

BroncoAZ · 10-24-2006, 10:20 PM

With the empty trailer at just under 3000 pounds I set the cruise and it doesn't seem much different than when I'm not towing (except for the overpass bridges where I manually put it to 4th). I use the cruise with the trans in 4th when the trailer is loaded. I pay far more attention to the sway of the trailer (my equalizer hitch shipped Monday) and try to anticipate passing and such further in advance.

In addition to the trans temp gauge I think every car should have a vacuum guage so the driver can evaluate the load on the engine moe accurately. Maybe I'll add one either where the non existant 4x4 switch goes, or in a pillar mount (if available yet). I have one in both of my other cars.

Mitch

ablexus · 10-25-2006, 12:06 AM

Quote:

Originally Posted by BroncoAZ

In addition to the trans temp gauge I think every car should have a vacuum guage so the driver can evaluate the load on the engine moe accurately.
Mitch

A phenomenal idea, I agree 100%. I ran an autometer boost / vac gauge for months before I was boosted... I thought it looked rice for a while, but it was great for telling me how much load my engine was under, calculating, among other things, the best MPG.

Andrew

Hector Bravo · 10-25-2006, 06:06 AM

To add to the discussion I'm pretty sure they say you should not use cruise when towing. (I don’t remember where in the manual I saw that.)

Hector

BroncoAZ · 10-25-2006, 07:49 AM

I knew someone would disagree with my use of cruise. I am very inconsistant with the speed when I'm not using cruise at highway speed. I will fluctuate from 5 under to 5 over. I can't see where cruise would hurt the truck at all. They are probably concerned that I should be paying better attention to speeds and following distances while towing. I'm generally a bit paranoid about towing a 9000 pounds 8.5' wide trailer on the highway at 75 mph with a 1/2 ton truck, so I am paying attention. My main concern is lane drift and sway.

Mitch

ablexus · 10-25-2006, 01:08 PM

Quote:

Originally Posted by BroncoAZ

I can't see where cruise would hurt the truck at all. They are probably concerned that I should be paying better attention to speeds and following distances while towing.

Mitch

Bingo. Running at cruise doesn't hurt your truck, the manual suggests it for attentiveness reasons.

Andrew

Hector Bravo · 10-25-2006, 06:11 PM

I am no self-professed expert so I was not disagreeing with or condemning your use of cruise control when towing. I was just pointing out what I think the manual stated.

On level ground I often used my cruise when I towed with my 1998 Suburban. I thought it made those long stretches of road much more pleasant.

Hector