[Jackpine]

RGSMDNR, I'm going to move this thread into the Towing forum when I finish this reply.

Tell me though, what rear end do you have on your truck? And, is it equipped with the factory tow package? I'm guessing you have 3.73 gears with the tow package, but I just wanted confirmation.

Now, as you probably know, I tow too, not as much weight as you (about 3600# in the trailer) but by the time we factor in all the other crap that's in the bed plus the bed cap, I'm easily pulling 4000#. I've pulled this all over the Colorado Rockies and over some passes above 11,000 ft and up grades over 7% for 7-10 mile distances. I almost always have to do this pulling in 2nd gear, and the transmission fluid will get up to abut 220F. I can maintain 60-65 mph doing this, but my engine is screaming at 4000 rpm.

There's no way I can do this in 3rd gear. It simply does not have the power in that gear range. I have to be in 2nd. If the transmission doesn't "hunt" between 2nd and 3rd, I'll usually leave it in Drive (with the overdrive turned off). If there's any tendency to shift up and down though, I lock it in 2nd.

I find as soon as the rpms increase above 2500, the TFT starts going up. If you set the shifter in 2nd, there is a power reduction (probably for slippery starts) that is applied until you reach a certain speed. This was discussed in another thread quite a while ago. Supposedly, this reduction is not applied as long as the shifter is in Drive.

The towing tunes are designed to give you more low end torque and are not really designed for high speed torque. Since I try not to exceed 65 mph (about 108 kph, I think), this is not much of a factor for me.

I have not noticed any power reduction caused by high fluid temperatures though.

I try to not let the speed fall off in a hill climb, so I don't have to make it back up, and I've never seen the transmission drop into 1st. I monitor "Comm Gear" when towing and the torque converter is usually always locked up under these conditions too.

It's possible you MAY be expecting too much out of a 150? And, you may have a much higher "combined weight" than you realize. I know I did. When I weighed my truck trailer combination on a scale, I found I was about 60# over the weight limit for the rear axle. I've since made an adjustment to the equalizing hitch to correct this.

Somebody else recently said somewhere that about the most you can "comfortably tow" with a 150 is about 5000#. I know there are people who tow more, and I know having higher rear end gearing will help with that too.

I can't give you any more to address your concern than this. And again, I've never seen the pulling power drop off with higher TFTs.

- Jack