Running in 5th gear

[RPreeb]

Originally Posted by crossup

Call me paranoid but after a couple hundred miles of towing its obvious my rig is going to spend most of its time in 5th gear instead of 6th. I guess nearly every one towing is in the same boat so just looking for anecdotal info as to what to expect the impact on vehicle life, maintence etc to be.
'016 Chevy 3500 van 6.0 6L90 3.42 towing just under 6k gross trailer weight.
While we are at it, anyone know the cost of regearing to 3.91 etc?

I run in tow/haul in the mountains, but out on the plains I use standard mode. I will occasionally lock out 6th gear myself if running through some hills, but I rarely have to do that. In the mountains I will even manually lock out 6th, and sometimes even 5th, running in 4th or lower. Towing 5500 lb max with 2016 F-150 3.5 EcoBoost and 3.55 gears.

Had a long downhill run from Cameron Pass down the Poudre River coming home yesterday (Northern Colorado). Locked out 5th and 6th and used 4th, 3rd and even 2nd to help save the brakes. Tranny shifted when it was supposed to in tow/haul. That's 58 miles, almost all downhill on a twisty, winding road. Whenever I had to use the brakes, the tranny would down shift at least one gear, sometimes down 2 in quick succession. Engine never went over 4500 rpm and it went a long way to minimizing brake usage.

[mrgrayaz]

Remember 5th is a direct drive usually in a 6 speed transmission. So that is the "gear" that will last the longest and run the transmission the coolest. There is no torque multiplication in play in 1:1 - its straight in, straight out - the transmission isnt doing anything. So it runs the coolest and the longest in that gear - most vehicles will drop to 1:1 (be it 3rd in a 4 speed, 4th in a 5 speed, 5th in a 6 speed, etc) when put in tow haul - as its the easiest on the transmission.

With that kind of trailer I WOULD use tow haul, which most likely WILL lock out OD and leave you in 5....which is what you want anyway? Why fight it?

[09 harley]

Originally Posted by mrgrayaz

Remember 5th is a direct drive usually in a 6 speed transmission. So that is the "gear" that will last the longest and run the transmission the coolest. There is no torque multiplication in play in 1:1 - its straight in, straight out - the transmission isnt doing anything. So it runs the coolest and the longest in that gear - most vehicles will drop to 1:1 (be it 3rd in a 4 speed, 4th in a 5 speed, 5th in a 6 speed, etc) when put in tow haul - as its the easiest on the transmission.

With that kind of trailer I WOULD use tow haul, which most likely WILL lock out OD and leave you in 5....which is what you want anyway? Why fight it?

On the newer Ford 6 speed 4 th gear is 1 to 1. Don't know when the change was made but probably in the switch from 5 to 6 speed. Last two gears are overdrive for mileage.

[Ray,IN]

Originally Posted by mrgrayaz

Remember 5th is a direct drive usually in a 6 speed transmission. So that is the "gear" that will last the longest and run the transmission the coolest. There is no torque multiplication in play in 1:1 - its straight in, straight out - the transmission isnt doing anything. So it runs the coolest and the longest in that gear - most vehicles will drop to 1:1 (be it 3rd in a 4 speed, 4th in a 5 speed, 5th in a 6 speed, etc) when put in tow haul - as its the easiest on the transmission.

With that kind of trailer I WOULD use tow haul, which most likely WILL lock out OD and leave you in 5....which is what you want anyway? Why fight it?

Not that way for his Chevrolet; 5 and 6 are both overdrive gears.

[crossup]

Since it seems people aren't reading the whole thread, the question is basically is it ok to tow long term in 5th or should I regear. If you have long term towing experience in 5th with a 6L80/90 good or bad let's hear about it.

[lynnmor]

Originally Posted by crossup

Since it seems people aren't reading the whole thread, the question is basically is it ok to tow long term in 5th or should I regear. If you have long term towing experience in 5th with a 6L80/90 good or bad let's hear about it.

It is better for a transmission to do less of the gearing increase or decrease and let the rear end take care of the needed gearing. That said, 5th should be actually better than 6th as it is closer to 1:1. I don't have long term experience because my 6 speed diesel doesn't need to run lower gears. My son has an F250 with the 5.4 engine and he has towed cross country with using 3rd gear much of the time.

Back in post #26, I showed the gear ratios, and the 1:1 figure is still being used in recent posts.