I keep gettin mixed reviews from people, is it ok to click the overdrive back on when I get up to cruising speed on the highway? I have an '03 F250 SD Lariat FX4 w/ 5.4L V8. I just got the truck a couple months ago and haven't had to tow with it yet cuz i'm in the process of changing some things up on my racecar, but it will be running again soon and I also told a buddy i'd go pick up his boat for him this weekend, so I just wanted to get this settled for sure of what's right. Thanks for any help guys!! Also, i've been told that going cruising over 70 with a trailer on the back is really bad for the trans, is this a myth or what (I had a problem with the trans in my '04 F150 Lariat I had before this truck after only 40,000 and these are things people were tellin me, cuz I used to click the o/d back on when I reached cruising speed and towed between 80 - 90 most of the time on long highway trips)?

 

I generally leave it on unless im in the hills or mountains, or if it keeps shifting back and forth. I dont know how a gas tows, but to tow at 80 to 90 in my pickup you have no choice but to be in OD. The only thing the speed has an affect on i believe is tranny temp. I tow all the time with the cruise on 80 to 85 and have over 150000 miles on my stock tranny.

 

You can tow all day long in O/D and it won't hurt the trans. What you have to watch for is gear hunting. If it's shifting in and out of O/D, that's adding lots of heat which will reduce the tranny life. In that situation is when you lock out O/D until you get to flat ground and an even speed.

 

I usually use turn the od off until I know that I am going to be above 55 or 60 mph for at least a mile or so and I know that it wont be dropping back down to 3rd.

 

Thanks guys, that's what I was hoping to hear! Guess I must've just had a turd in my '04 150, cuz we got that truck at 28,000 miles and at 46,000 the trans went out on it, lost overdrive and reverse and had to pay $1500 to rebuild the trans cuz it was out of warranty cuz the place we bought it from told us it had an extended warranty, but we came to find out they never transferred it over from the previous owner or some bull**** and basically we got screwed and had to pay to get the tranny fixed.

 

I've towed with and without the OD. I save about 2mpg's while pulling if I leave the OD on, and I rarely see a difference on the trans temp gauge. I maily know only shut off the OD in the hills and mountains

 

Check the local laws before deciding you can tow at 70 or 80 MPH. A lot of states have special speed limits for any vehicle towing a trailer.

In Illinois, it is 55 MPH, although the State Police will usually let you get away with 60 MPH if conditions are good.

 

Driving across Illinois at night, with a trailer is very dangerous. Driving that slow, I almost fell asleep...

 

Last I checked, anywhere 80 or 90 mph is illegal....

The trans in the f150 probably had issues because it was a 4r70w. They use a band for od, which is probably why reverse went out too. The bands can't hold much power or load, so no od on them.

However, the 4r100, uses a large clutch at the front of the transmission so towing in OD is ok. Pretty much the only reason to lock it out is if you notice heat, or it's hunting on hills.

 

Have you ever started off in OD from a full stop? No, of course not, at least not in an automatic. Running in OD with a "non-normal" load and especially at HIGH speed is a lot like having a stick shift and trying to start off in an inappropriately high gear ratio.

Don't, DO NOT.

And yes, your engine may be able to produce enough torque in a "minus" gear ratio (the transaxle output shaft turning FASTER then the engine), but the torque converter lock up clutch was not designed for such abuse. Basically it was designed to operate in the torque range wherein the engine would provide the best FE under NORMAL operating conditions.

 

Maybe back when the first od auto trans came out in the 80's that was true, but has not been the case for many years. I have always towed in OD when the road conditions allow. If you did any seriuos towing you would know this to be true. In our freight company we tow 18,000 lb trailers in OD quite frequently and never have problems. We have 8 guys that drive for us and none of them have any problems towing in OD. I just about always tow at 70 mph in Illinois and have never been stopped, but you have to use your judgement. I can actually get better economy at 75 mph than 70, because I think it has to do with being in the powerband of the engine moreso than at 70 mph. The key to long trans life is to keep temps down, and to flush the fluid every 50,000 miles or a year. I have 220,000 on mine now and the original trans is doing great.

 

I hear that! I am doing the Appleton WI - Rockford IL - Normal IL - Champaign IL - Danville IL - Terra Haute IN - Evansville IN route this weekend. It can be a struggle to stay awake.

 

I've towed in a Dodge Ram 1500, and a F150 w/ 4.6. Both of which if I was on flat ground, with little hills I kept overdrive on. But if I was in city or in hilly country, I left it off.

I don't know if its different for SD's though.

 

I'm not sure I understand what you are trying to say, if you have an automatic it will always start off in 1st gear it would be impossible to get it to start off in 'overdrive' all overdrive is is a 4th gear so it is fine to tow in overdrive. But, like someone else said if it starts hunting back and forth between overdrive (or 4th gear) and 3rd gear then you want to shut it off so it will stay down in 3rd gear. Same as if you are going up a hill in 3rd gear and it starts going back and forth between 3rd and 2nd you want to downshift to 2nd to keep it in one gear to help save your tranny. overdrive does not affect 1st thru 3rd gear at all nor does it affect starting from a stop.

 

This post makes no sense