I have been towing fairly heavy lately and I love the power, but I have one question for you all. If I keep the truck in overdrive when towing, when I get up to 50 mph the o/d kicks in and the truck seems to "lug" down the road. If I'm on the highway going 55-60 mph, it also seems to be lugging. Of course I can go faster, but sometimes traffic doesn't allow that.

If I take it out of o/d, then the rpm's at 55-60 mph are too high and it kills my fuel mileage. Also in tow/haul mode, the truck also seems to lug down the road at those speeds. By lugging, I mean that the rpm's are approx. 1600 rpm and the truck just seems to need to downshift....

What mode do you guys tow in??? Anybody have any suggestions? I know some of you are going to say just drive faster, which alleviates the issue, but most of the time traffic doesnt allow it. TIA.

 

I got my dodge just so I wouldn't have to tow at 55 or 60. If I wanted to tow at those speeds I would have kept my GMC. I guess you could change gear ratios either with gears or tire size, or put in a shift kit to alter the shift speeds.

 

No Worries. 1600 isn't going to hurt your truck at all. Just keep running it and if you start to lose to much speed on a hill or something then downshift. I have found that my truck gets better mileage the lower I run the rpms under all conditions. Not all trucks may be this way but mine is. Just watch the egt's if you lug it too much because obviously the turbo won't push as much air at slower speeds.

 

Yeah, I have towed at higher speeds too, but I tow on back roads and slower posted roads where you can't safely drive faster than 50-55 mph.

At 1600 rpm's, the truck just doesnt seem to have the "oomph"(for lack of better words). Like I said, it just seems to lug and it just doesn't feel good.

So running at 1500-1600 rpm's with a load isn't gonna hurt anything? How about running 2500 rpm's with O/D locked out, other than fuel mileage, is that gonna cause anything bad?

Going up in tire size would only make things worse, correct?

 

I guess I'm just used to the torqshift tranny that I had in my previous truck, which was actually a decent tranny(when it ran right).

 

I have not towed with my truck in quite a while but when pulling a heavier load such as my TT and it's not that heavy maybe 6800lbs fully loaded I would always start out with OD off selected once I was out on the highway I would run it up to say 55 mph and then manually push the button to go to OD. Now I know exactly what your saying, differences in the enviroment play a big role in which gear to be selected. Sometimes you have plenty of momentum to go over hills or pass easily other times some jerk my pull out in front of you and cause you to loose that momentum. I've kinda learned to listen to the sound of the motor and glance at my tach to determine when to shift, (turn on or off the OD button) and usually I beat the transmission from automatically down shifting for me like if I'm pulling pretty good hill. If you choose to let the transmission do it and it becomes what they refer to as hunting like 4th to 3rd, 3rd to 4th and so on back and fourth go head and select your OD off button. Now the Tow/Haul button maybe bascially the same as the OD off, but I'm not for sure on that one. Also usually running through a town I'll select the OD off most of the time because my OD kicks in at 42 to 44 mph. Even though my truck is stock I still opted for a set of gauges for it Pyro,Trans,Boost to keep a eye on those temps. With OD off on my truck it's taching above 2000 RPM probably 2300 to 2400 RPM running close to 60 mph I really don't understand you saying it seems to still be lugging with your T/H turned on What sort of mileage are you seeing while towing, the average on heavier loads will usually range from 10 to 13 mpg.Each truck is a little different mileage wise even though there spec'd out the same but usually pretty close in mileage.

Tony

 

Personally, I don't think youre hurting it. On a reated subject, does anybody know what the torque check speed on the CTD is? I remember hearing somebody saying that a dealership saying they were going to void their warranty for having a larger diameter tire on the the truck due to what the dealership said was putting the engine into a lug condition. Maybe it puts it below TQCK speed with a slightly larger tire????...

 

Bigger tires are worse, smaller ones would up rpms.

 

My truck had two selections...tow/haul AND O/D off. With O/D off selected, the truck doesnt lug, but at 50-55 mph the rpm's are too high which kills fuel mileage. With tow/haul selected, there is trans braking involved when stopping, but it doesn't really do anything for the lugging issue.

Tony T., you say you that you start off with O/D off selected and push the selector button off and on as needed. I have done that also, and it alleviates the issue(shift gears when I want it to shift), but I was told that it is very hard on a tranny and could cause damage to it if you constantly push the button off and on while on the fly, especially when towing a load. Has anybody else heard this??? If that is a myth, and I can just keep turning off O/D when I need to on the fly, then my problem is solved. I always thought that would cause damage....

 

I had a '99 1500 Quadcab gasser, and I always pushed the overdrive button on the fly. I kept O/D off until I hit at least 45mph. I towed heavy for only having a 1/2 ton, and akmost always locked out O/D when towing. I had 125,000 hard miles on it when I upgraded. Never heard that pushing the tow/haul was a bad thing.

 

I'm with 05hdram, I have never heard that it was bad for it. I thought that was what it was there for. Its the hunting back and forth for gears thats bad for it I thought.

 

I pull a 13k 5er alot. I run allways in od, until I am going up a big hill, then I watch my rpms, and when it gets down to 1950 rpm (if i have had the opportunity to go faster) I will manually switch off the OD. This will not hurt your tranny as it is just doing the same thing your tranny will do in a few more seconds, but letting your engine keep its power flowing.

Kevin

 

At 50-55 MPH I lock O/D out. I would rather have higher RPMs than lug the motor. Long term it can't be good for the tranny either. 55-60 MPH depends on the terrain, if it's hilly and I'm towing I keep O/D locked out. 2500 RPMs is not gonna hurt the Cummins, it likes it. Better than lugging it in my opinion.

 

Even if the engine has to steadily pull somewhat hard at 1600 rpm you will not hurt the engine unless you are on a hill and engine rpms are dropping fast, or you push the fuel feed down fully to gain rapid acceleration on the flat when pulling a heavy load resistance. If the engine is easily pulling at 1200 rpm on the flat at low velocity and you are light on the fuel feed the engine is not being harmed. The engine components are of a heavy design and can take substantial stress, but demanding high torque faster than practical at low rpm is risky. I have had mechanically injected diesel engines down to 1200 to 1400 rpm while pulling a load on the flat and I can slightly lug them to a higher velocity and engine speed by adding the fuel very gently over a substantial period of time without gearing down. That way the components are not severely stressed. Imagine how much stress the components take even in a lower gear when a hot rodder from a standing position stabs the fuel feed and holds it on the floor until the laboring engine rpm increases. Pulling any load, or just the heavy truck curb weight adds stress to the engine components on hard acceleration. Half coasting and slightly pulling now and again down the flat or slight down grade road will not hurt the engine even if the engine speed is 1000 rpm. Cummins I-6 is not a gasoline V8, but drivers are used to driving V8 gas engines that have to be kept humming to be happy the same as a V8 diesels. If a laboring Cummins starts to shudder the cab, then you know you are more than likely hurting the severely stressed engine if you do not gear down immediately to raise the engine rpm. Use common sense and not the experience you developed from driving gasoline engines. The I-6 Cummins is a truck engine designed to take hard stressful work and abuse and keep going. The modern computer injected engines will not let you lug an engine dangerously as they will add fuel to keep the rpm within reason according to the gear selected and load sensed so as not to lug the engine. I like low engine rpms, but I have developed a feel for what is taking place within the engine by listening to its operational sounds. The computer sometimes adds fuel to increase the engine rpm when I would like no more fuel.

 

Actually, I'm more concerned about my auto tranny than the Cummins.