Trailering with automatic overdrive transmission

   / Trailering with automatic overdrive transmission #1  

geneP

Platinum Member
Joined
Jun 28, 2000
Messages
815
Location
Central Mississippi, USA
Tractor
Case-International 385, Kubota L5450 w/LA1150A loader
The search function didn't reveal an answer to my particular question. I've always heard to use "Drive" when trailering with an automatic overdrive transmission. One reason given is that the transmission drops out of overdrive lockup frequently and increases heat from the torque converter slippage. Is it reasonably safe use overdrive if it doesn't require the lockup to drop out? My particular transmission is a 4 speed OD in an '02 Tundra with the V8. With careful management I can lock overdrive out on hills requiring lower gearing and use overdrive on flats, downhill, slight grades, etc. Is there potential damage for other reasons? Am I being foolish to even attempt it? Thanks for your advice.
 
   / Trailering with automatic overdrive transmission #2  
My understanding is there is nothing wrong with towing in OD as long as you are paying attention to what the trans is doing, if its shifting all the time, run it in direct. Where I believe people run into problems is blindly leaving it in OD and cooking the trans.

I towed a 8000 lb campler with a newer GM 6-speed auto (2 OD gears) If you put it in "M" and tow/haul, and selected "6" it would still stay in "4" (direct) most of the time, it would shift to 5th (OD) if going downhill, but if you put your foot in it, back to 4th. Truck was clearly happiest locked in "4" You could watch the trans temp gauge climb on harder pulls/uphill.

I tow with a 6-speed manual diesel now, camper or cattle trailer, or depending on the load and terrain it's only happy in OD (6th) flat going and downhill, or at 60-70 MPH highway speeds.
5th gear (direct) used lots 55 MPH or less.

Auto trans can't "see" what's going on, so it keeps shifting based on set points. If you were driving a manual and shifting between 5th & 6th every 2 seconds you'd pick the lower gear and leave it there. Apply same logic to auto and no issues?
 
   / Trailering with automatic overdrive transmission #3  
The reason used to be when the first started getting over drives and lock up torque converters, the rest of the transmission wasn't up to the task of towing locked up in OD. The clutches and bands would start to slip. The torque convertor takes a lot of the abuse out of the clutches and bands when its not locked up. They since have started making the rest of the transmission better so it takes a little more abuse even when locked up. Its still a good idea when towing to put it in tow haul as it helps save the transmission.
 
   / Trailering with automatic overdrive transmission #4  
It all depends on the year/brand ect. of your pu.. Read in your owners manual what the mfg. suggest you do.

My pu says it's just fine to pull a trailer in OD, but if in hilly country and it's shifting up/down excessivly, I can leave it in drive to stop that.

SR
 
   / Trailering with automatic overdrive transmission #5  
I pull in OD but keep an eye on my trans temp gauge. If I am coming to a hill I just pull it into D before I get there.
 
   / Trailering with automatic overdrive transmission #6  
My Ford F-150 manual says to run in direct for anything over 1500 pounds(trailer + load combined).
 
   / Trailering with automatic overdrive transmission #7  
In my '03 Dodge I tow my fifth wheel camper that weighs about 14K in OD all the time. If I don't I am limited to about 80km/h. Any faster and I will be over-revving the engine. The only time it comes out of OD is when I am climbing a hill.

The best advice would be to read the owners manual. What the manual recommends is the best fir the longevity of your transmission.
 
   / Trailering with automatic overdrive transmission #8  
If your vehicle comes with a lockout button, I would think the manufacturer would want you using it when necessary. What does your owners manual say ?
 
   / Trailering with automatic overdrive transmission #9  
I always used the OD lockout on my 04 Tundra. With my 2015, I hit the tow/haul button and put the 6 speed transmission in 5th gear.

Will
 
   / Trailering with automatic overdrive transmission #10  
As has been mentioned, keeping the trans shifting at a minimum is key. Constant shifting and gear hunting is both hard on the trans and doesn't necessarily allow the engine to remain in optimum RPM range for either pulling or downgrade braking. That is why I like the newer autos with manual mode that allow one to have more control over things. It is not unrealistic to allow the trans into the OD's when the pull is not so extreme like on flatter terrain. Hills, high wind causing hard pulling, etc, of course it would be more advantageous to keep it out of the OD's. Healthy dose of common sense will go a long way.
 
 
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