Towing Woes and the Torque Converter 5.4L

andymaan · #1 07-21-2010, 06:12 PM

I'm looking for some help regarding towing with my 5.4L 1998 F-250 LD. I tow a 6500lbs Travel Trailer and have had no issues locally. Recently we have been towing up mountain Roads (Big Bear, CA), and have noticed an issue. 1st gear pulls great, then 2nd takes over and starts to pull with power. Within 400rpm, the truck feels like it shift to 3rd gear. Reading the info on this board leads me to believe that it's really not shifting into 3rd, but is locking the Torque Converter. When this happens, my truck battles to hold 30 miles per hour up the road. My understanding is that the reason why the TQ locks is to reduce the temperature of the trany. Is there anything else I can do to get more towing performance?

Thanks for your help,
Andymaan

glc · #2 07-21-2010, 06:42 PM

What happens if you pull it down into manual 2nd?

andymaan · #3 07-21-2010, 06:52 PM

Quote:

Originally Posted by glc

What happens if you pull it down into manual 2nd?

Hey glc,
It acts the same when I manually put it in 2nd. I thought it was shifting into 3rd, but now believe that the TQ is locking....

thx,
Andymaan

glc · #4 07-21-2010, 08:14 PM

I didn't think the TC locked in 2nd - just 3rd and OD.........

It doesn't unlock when you stomp it?

andymaan · #5 07-22-2010, 12:24 AM

No it doesn't do anything when I stomp down. It just waits until I slow down to approx. 30 mph and shifts into 1st gear.

Thx,
Andymaan

Galaxy · #6 07-22-2010, 09:31 AM

Yes, the converter does lock in second...will not lock in first. This is a good thing. It may rob a little bit of power but it's much much better for the tranny and the converter. The thing you need to do to reclaim your power is manually put it in 2nd and keep the rpm's up...3,000 ish is pretty good. Holding 30 mph is too slow for second gear. My truck wont even keep the converter locked (a bad thing) if I get that slow in second.

If I'm pulling a hill that drags me down that slow while in 2nd (which usually doesn't happen but on rare occasion), I then slow down further so I can go to 1st and pull it easier. But in this scenario, gotta watch the temps cause like I said, the tranny will not lock in 1st.

glc · #7 07-22-2010, 02:07 PM

If it doesn't unlock when you stomp it, something is wrong.

MitchF150 · #8 07-22-2010, 03:32 PM

Quote:

Originally Posted by glc

If it doesn't unlock when you stomp it, something is wrong.

If you have the gear shift pulled down into "2" and stomp the pedal, that's when the TPS tells the trans to lock the TC.. That's how I get mine to lock on most of the grades I pull.

If you have the gear shift in "D", and stomp on it, if you are going slow enough, it should then downshift into 1st. If your speed is still above 30 or 35, then it should stay in 2nd, but it can still lock until you bog down enough for it to shift into 1st.

I have a 12% or so grade in my neighborhood and the few times I've towed my trailer up it, I bog down if I have the gear shift in "2". I limped my way up the rest of the hill going about 25 mph.... I didn't want to pull it down into 1st while I had the pedal to the floor and still going 25 mph....

The next time I took the hill, I left it in "D" and it downshifted on it's own into 1st when it bogged in LOCKED 2nd. I still slowed to around 25 mph, but I was screaming at over 4000 rpms!!

To the OP, you need to make mods that will get you more low end power, or keep your peak rpms in the 3000 rpm range. That grade in my neighborhood is in a 35 mph speed zone... I was able to speed up to 45 mph at the bottom of the grade, but it slowed down really fast! It's probably a mile long too.

You probably already have 3.73 gears since it's a LD 250.. Going to 4.10 might help you be able to hold locked 2nd? How tall are the tires on your rig? If they are taller then stock, you may have to go all the way to 4.56 to make a difference as the 4.10's may still not be enough to hold 2nd..

You can try to 'feather' the pedal to try to keep it in unlocked 2nd. I found that if you let up on the gas, it'll stay unlocked... But that's gonna heat up your trans fluid pretty quick, and once you have to mat the pedal, it'll lock up and if you can't hold the rpms in that state, it'll bog pretty fast....

Good luck!

Mitch

andymaan · #9 07-22-2010, 04:20 PM

Thanks Mitch,
You have described my situation exactly. I believe I do have 3.73 gears and stock tires. It tows great except on the winding mountain roads. 1st gear has quite enough power to get me going, but when the TC locks in 2nd, I bog. I believe that the real solution is to just deal with the slow speed towing up the mountain (approx 3 times a year). What would the approx. cost and negative reason for going with the 4.56 gearing be in my truck?

Thanks again,
Andymaan

MitchF150 · #10 07-22-2010, 04:34 PM

If you have a 4x4, it could run upwards of $1500 for a gear swap. Downside is that when you are not towing, you'll be pulling some high revs just to cruise down the road... With stock size tires and 4.56 gears, you'll be pulling around 2000 rpms in OD going 60 mph. In third, you'll be pulling some 2800 rpms going 60 mph..

For only 3 times a year, I'd just put her it "D" and drive it however it wants to go up! It might be slow, but that's what the right lane is for!

Back in the day, that's how it was done without even thinking about it.. Back then, they didn't even have lockup converters or OD.... My Dad's 1971 F250 with a 390 and automatic and I'm pretty sure 4.10 gears would be crawling up the grades in 1st gear with the pedal to the floor towing our #6000 or so TT in the late '70's on our family vacations up and around Shasta and the Kern River and Big Bear and all the other places we would go when we lived in Cal.. Did the Grape Vine a lot too..

Mitch

andymaan · #11 07-23-2010, 01:48 PM

Thanks again for your input. I agree, I will put her in "D" and head up the hill.

Happy Camping to all,
Andymaan