OT overdrive

I have a Toyota Tundra pickup. Should I lock it out of overdrive when pulling a trailer, about 4,000 lb, when driving the interstate at 70-75 mph?

I would use the OD on flat or near flat ground. Hilly, no. Jim

The owners manual will cover that.

If it's missing, look online.

But you can pretty much tell, if it's struggling to maintain level ground speed, it needs to not be in overdrive. Wind resistance can also be a factor, even more so than weight.

i would be using it if your pulling 4000lbs at 75 mph with a pickup on flat highway.

I assume this is an automatic. If so, the issue isn't the overdrive gearing so much as the locking torque converter. I'm not sure about your Toyota, but with the GM 700R4 transmissions, shifting out of overdrive into drive also stopped the converter from locking. Check your owner's manual.

Hi, I would never pull 2 ton at 75mph with a pickup. 60 mph would be my limit. Ed Will Oliver BC

The truck will tell you if it can handle, if kicking in/out, then no.

Your tires are probably rated for 65, so I think 70 is probably limit.

Yes unless you want to burn up the tranny

If you could put a temperature gauge on transmission and keep temp between 180 and 210 your ok but when it gets about 220 and up you burning the oil and breaking it down. Heat is the killer of automatic transmissions.

I wouldn't use OD under those conditions, unless you want to be the proud owner of a new transmission.

When I was a Ford Service Manager, a Crown Vic was towed in with the engine locked up. Only it wasn't the engine that was seized, it was the transmission. It turned out the guy had been towing a 28' camper on the Interstate with the trans in OD, and some of the aluminum internal parts of the trans had gotten so hot they were welded together. He actually made it from Minnesota to Nebraska doing that. We played Billy Hell getting to the bolts on the flex plate to get the trans pulled.

I was dumbfounded when Ford covered it under warranty.

That being said, my Chevy pickup has a "Tow/Haul" button the shifter that reprograms the trans for towing. The only time it goes into OD is maybe going downhill. Anytime the pickup is pulling, it's out of OD.

Pat, I think that you should leave earlier and lock it out and stay under 65. That is better all the way around.

I second the idea of reading the manual, maybe talking to a transmission shop would be a good thing to do too. My story is comparing apples to oranges so take it for what it’s worth.

My 98 1/2 Dodge Cummins five speed locked up the transmission for the previous owner when it was pulling a large load in overdrive. The tranny was still under warranty from Inland parts, Inland told them overdrive should not be used under a hard load. The owner thought Inland was trying to weasel out of it but Later on I heard the same thing from another person. This rebuilt tranny had been in the pickup three days before this happened. They said overdrive is in the tail of the tranny and is undersized for the torque from the Diesel engine. Later that summer overdrive quit, you could put the shifter in overdrive but it was in neutral. They ran it without overdrive till after warranty was gone. Finally I pulled the tranny and found a worn snap ring had come out of a groove. A new snap ring fixed it but when I had it apart I did notice the gear isn’t all that big and I suspect the lubrication isn’t the best either. Again, I’m talking about a completely different vehicle but this is just an example of what can happen.

Does yours have the factory tow package? If so, use the tow/haul button and keep an eye on the trans temp gauge. The tow package will select or deselect OD as needed. That also sets the shift points to provide better power. If the temp starts to get to high, then maybe drop out of OD. I seldom pull very far with heavy loads with my 5.7L 2013 model, but never have needed to manually do that.