Occasionally while towing in OD it will become necessary to lock OD out in order to essentially downshift to maintain speed and power, esp. when taking on the grades/hills. I have been doing this by simply turning OD off using the button on the gearshift, which will drop the gear down on the truck, and the rpms will really surge.

Does anyone else do it differently? I'm just wondering if dropping out of OD like that is going to cause me some problems or damage down the road.....

 

No, it won't cause any problems. You can tow forever with the OD off. It just uses a bit more fuel.

 

only time i turn off o.d. isdownhill or if trans trys to upshift going uphill (hunting)

 

New superduty there isn't a button to turn off o'drive. Tow/Haul took it's place. I can drive all over the east coast and let it stay in cruise.

 

Again I was told today to turn OD off (9000# trailer,4r100 trans) otherwise will build excessive heat.

Is this truth or myth?

 

Who told you? Do you have a good trans cooler on your truck? If you don't, I wouldn't even tow!! Put on the biggest cooler you can get on it and tow in o'drive to your hearts content! Or at least until the hills make you slow down and take it out of o'drive to keep it from from dropping out on it's own.

 

I have a rather large cooler and a large-ish trailer (9/10k loaded)
Yes, hills tend to kill me a bit but you know steady as she goes.

 

Mostly myth, but if the trans is frequently shifting in and out of overdrive, then it's true. If the trans is not shifting often it won't make any more heat in overdrive.

 

I tow in OD, but when I approach a good hill I usually drop out of OD and pick up a little speed. If you get the speed up and get the RPMs into a good range before the hill, it is easier to maintain speed and stay in gear. If you let the tranny downshift instead, it will wait too long and then you will be out of the power band and will probably wind up in a lower gear/higher RPM and slower speed than if you dropped into 3rd before your speed drops.

If your tranny hunts gears, drop out of OD until you get to flatter terrain again, is the general rule.

Get a tranny temp gauge and make your decisions on a cooler from that. Do not buy the biggest cooler you can find, you can overcool the tranny, although that is not nearly as bad as overheating.

On my 94 F250, the factory aux cooler is the right size according to the tranny shop and my temp guage says probably right. My towing temps usually stay in the 180-190 range. If I am in hills in hot wetaher or have head winds it can get to 200. I have seen it spike a few times to 210 and once to 230 when I pushed the trailer up a slight hill slowly in reverse which is perhaps the worst case situation.

I am from the old school "bigger is better" and am always tempted to get a horking big cooler, but the tranny shops I trust and several magazines and I think the Ford Truck Owners Bible and Trailer Life Magazine say to get only the cooler sized appropriately to your expected load. For example if your truck and trailer weigh about 15,000 pounds I would go with say a 15-20K cooler. I would not get the 36K cooler since you can over cool. This leads to delayed shifting and a slight chance of additional wear and tear, especially in cold weather. My temp guage used to take and hour or two to get past 130 when it was freezing outside, and it would delay shifting from a cold start longer than when it was warm.

Just my experience and opinion.

Jim Henderson

 

The problem with the 4r100 and towing in O/D is there are fewer clutch plates for o/d. Less torque holding capacity than in 3rd. You can tow in o/d, what I have found is the EGTs start to climb much more than in 3rd, So I usually base my taking out of o/d base on my EGT reading or if I am starting the next hill.

 

I talked to BTS and they told me that it was ok to tow in OD. However, his tranny is definately good for OD towing. After all, he is fixing it if it breaks under warranty. Further to that, there was someone who got his tranny rebuilt for $150 after the warranty expired. From what I have read, how could you go wrong following his advice?

I have towed for a bit in OD before my tranny crapped out. Being that it was used and I got it with a black fuel filter, I am not sure how the previous owner had maintained it but it was used by a transport company. Anyways, I never noticed any difference in my trans temp. With the 6.0L cooler it was about 60-80 degrees above ambient and with the stock thingy it was about 100 above ambient towing.

I have had a couple Ford Techs tell me you cannot tow in OD and it is stated in the manual but I haven't seen that line myself.

 

That is the correct method. I tow in OD all the time then drop it back to 3rd for climbing the steeper/longer hills/mountains using this exact method. Worked fine for 200,000+ miles.

That you can't/shouldn't tow in OD is a leftover from the early days of OD transmissions. If you are geared correctly and have enough motor to pull the load and are not overloaded, you can tow in OD just fine as long as the torque converter clutch doesn't hunt in and out of lockup.

Steve
'95 Clubwagon XLT

 

I tend to agree with that. However, what puzzles me is that 2 Ford Techs tell me the same thing. You cannot tow in OD because the weight AND the wind resistance of the trailer (Toy Hauler) creates too much drag and overworks the tranny. Funny, I never saw my trans temp rise. Also the manual just says to downshift out of OD if you are going up steep hills or need engine braking. Nothing about going out of OD when towing. When I had an 99 Ford Ranger, that was what the books said. Get out of OD for towing.

 

There is some truth to that. On level ground, aerodynamic drag is a bigger concern than weight. The answer comes down to the same thing; load and gearing. If you can pull OD comfortably, then tow in OD.

My van doesn't have a big motor (its just a 5 liter) but I use it to tow my racecar (on an open trailer) all over the US. I have 200,000+ miles towing it since '97. When climbing mountains I cancel OD at the bottom and use the power from the additional rpm to climb.

I once had to tow an enclosed car hauler (a 22 ft Pace) when a friend had the transmission (in his Chevy truck) take a dump 250 miles from home. My van could handle the weight but the aero drag meant I had to tow in 3rd gear. It wouldn't pull OD on level ground. 3rd gear worked fine but because of the shorter gear, I had to drop my speed back rather than run the motor at an rpm that was higher than I was comfortable with. I knocked my cruise speed back about 10 mph and it did just fine.

So yes, aero drag is an issue. I have seen some travel trailers that are very tall, like towing a barn, I know the drag is enormous. But if the motor will pull it the transmission should be OK. Now there are limits. If you do a bunch of power adders and don't upgrade the transmission too, then you can overpower it.


Well yeah. That's a Ranger. The 5R55E automatic in it I wouldn't tow a jet ski with in OD. They are not very strong transmissions at all.

Steve
'95 Clubwagon XLT

 

My trailer is definately a barn door, my tran temp stays pretty much the same in either gear, it mainly depends on how much wind and hills that determine o/d or not. I base that on how hard the engine is working which is easily seen by the exhaust gas temperature. No wind or hills it is about 850 in 3rd at which point I will go to o/d. If it is hoovering around 1000 or higher I stay in 3rd. I know we all have different vehicles all of which are great, and not everyone has a pyrometer. I do so this is what I go by and so far it has worked great for me.