Towing and transmission issue

RGSMDNR · #1 Tue, September 15th, 2009, 08:07 AM

I have an 07 f150, 5.4 supercrew...

I tow a 25' travel trailer that weighs about 5000lbs. My issue im having is maintaining highway speeds when the tranny heats up. Its fine around 150 or so... but anything above that the truck seems to run like a dog. It doesnt matter if im using the towing tune or running stock. To be honest i dont run the towing anymore because it doesnt have any top end. It seems to run better stock. Any thoughts on why the truck doesnt make any power when the tranny heats up?

thx

***88Racing*** · #2 Tue, September 15th, 2009, 08:15 AM

How many miles on the truck and last time tranny fluid changed?
Also what's the highest temp the fluid has gotten to?

Lars

RGSMDNR · #3 Tue, September 15th, 2009, 08:18 AM

There are about 34000 kilometers on the truck. Ive never had a tranny service done. I think the highest temp Ive seen is about 200.

***88Racing*** · #4 Tue, September 15th, 2009, 08:27 AM

If you have done a lot of pulling with the fluid from the factory I would suggest getting it changed.
Probably a synthetic like royal purple might do a better job than motorcraft if you pull a lot.
But just in case I wll post a note on the mod board.
200 is getting close to break down temp. Let me find that number and get back to you.

Lars

RGSMDNR · #5 Tue, September 15th, 2009, 08:30 AM

I guess im just disappointed in the lack of power this truck has while towing. I wasnt sure if it had anything to do with the tranny temps or not. I dont pull all that often, but when i do its just frustrating trying to maintain highway speeds without having to step on it every so often to get it back up to speed. Would the hotter tranny temp be robbing that much power??

***88Racing*** · #6 Tue, September 15th, 2009, 08:40 AM

I am going to have to try and draw Bill's attention to this issue.

Lars

***Jackpine*** · #7 Tue, September 15th, 2009, 12:25 PM

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

***88Racing*** · #8 Tue, September 15th, 2009, 01:31 PM

Here's a thread with some good info for everyone.

http://dygytalworld.ehost-services13...ht=temperature

Jack has posted some good numbers in it.

Lars

RGSMDNR · #9 Thu, September 17th, 2009, 09:06 AM

Yes im sure I have the 3.73s. Next time I tow Ill hit a scale and see what the actual weight is. Maybe I am expecting too much but even on level ground I find the truck slowing down and am having to step on it (to shift it in 2nd) to get back up to speed.

TXWolf · #10 Thu, September 17th, 2009, 01:21 PM

RGSMDNR, I recently bought a 36' travel trailer. When it's loaded with everything we just HAVE to have for camping,

, I'm sure the weight is around 8000 lbs. We just came back from a trip to the Texas Hill Country, and I am SO impressed with the pulling power of my 2008 F150. I was able to maintaing 55-65mph very easily. Now, when I hit a long, gradual uphill grade .... I'd have to mash the pedal, the rpm's would jump up to 4000-4200, but I never felt like the truck COULDN'T handle the weight.

I know that my TFT has been around the 230 degree mark area a couple of times, so I'm going to flush the fluid and go with full synthetic. But even with the TFT up quite a bit more than yours is indicating, I still had plenty of pulling power.

Just my