I have a 2004.5 with HO, 48RE, 3.73 on order (don't have the owner's manual yet) and will be towing an enclosed utility trailer most of the time. The trailer is 6.5' tall and 7' wide so it has some pretty good wind resistance. Also, most of my driving will be around town (handyman repair business). The trailer will weigh approx 4000 lbs total.

1. What does the owner's manual of a 48RE truck say about using the overdrive? I assume it says to NOT use it when towing but is there a time when it's OK? At cruise? Or below a certain trailer weight?

2. What do you guys do?

Thanks!

 

Although I do not have a 48re I think the idea is still the same. I would not use OD empty around town if your RPM's are not at least 1700. If OD id going to put you below that I would stay in D. I think it is fine to tow in OD, especially 4000 lbs, as long as your RPM's are up and the truck is not hunting between lockup and non lockup. Again, I would try to keep them at least 1700 when towing or maybe a little more. The low line pressures created in the transmission due to the low RPM's combined with the torque of the Cummins is what is killer on the autos.

 

Hey Tim,
I don't know what the owner's manual will say about this, but I think the rule of thumb for the previous 47RE was staying out of OD until you were up to highway speed when towing. Personally I will leave my OD locked out if I'm towing the 5er in city traffic. The reason is, that it tries to shift from 3rd to OD (at speeds above 45mph), but ends up staying in unlocked OD which builds up heat in the tranny fast.
This is just my opinion, but I believe that in your case, I would leave OD locked out while in town and only engage it when you can get the rpms up to around 1700-1800 and stay above that. You should be able to tell after you get your truck and trailer and do a little driving wiith it. Number one rule is to NOT let it hunt back and forth between 3rd and OD.
When out on the highway, I tow in OD all the time pulling a 10,000 lb. 5er and only lock it out when it downshifts climbing hills or in the mountains. I'm sure others will chime in with their opinions also.

 

Very good advice here. The key to working a diesel is keeping the revs up under a load. Don't let the motor bog down, and the motor and everything behind it will be better off. Hunting between gears or lockup/unlock will kill a trans fast. Sometimes you will have to think for the computer to keep it from melting the trans.

 

Like the others here I shift out of OD when towing at low rpms. The 373 gear will help to get the rrrs up to where you can put it in OD. When I drive in snow and on the dirt roads I take it out of OD as it will sift in at about 40 mph and possibly heat the tranny. I don't know just try to play it safe.

 

Thanks for the info!

What an amazing truck! 10,000lbs with OD? That's cool!

Sounds like 1700 RPMs is the key with a little human intervention watching out for up/down shifting.

Thanks again.

 

As long as I am towing on level ground or moderate hills, she has no problem as long as I can stay in the "sweet spot". The "sweet spot for my rig is 2000 rpm. It seems to pull like a completely different truck @ 2000 and above. I purposely kept the 245 size tires because I didn't want to change the ratio any being that I have the 3.54 rear. The 4.10 would probably been better for towing, but 90% of my miles are back and forth to work empty and the 21mpg is nice.

This was before I added the Edge EZ. I haven't had the chance to tow with the EZ yet,,,,,,,,, and I can hardly wait!

 

The AT mechanic at the Dodge dealership told me to lock out OD when towing at 55 mph and below. The key to the entire OD in/out topic is = Don't allow the AT to hunt for gearing, this builds up tremendous heat rapidly and heat is the mortal enemy of AT's.

 

I haven't towed yet with my CTD,but I had a gasser GMC before this truck and towed an 8k (wet) TT. I put about 45,000 miles on it towing the TT all over the U.S. including the nose bleed passes of Colorado! I towed in OD 80% of the time. Like the others said, when it started hunting, or the RPMS started dropping, I would go into tow/haul mode. I had the tranny flushed and synthetic Amsoil put in at 50,000 miles. I didn't have the old fluid analyzed,but it still looked and smelled good, no shavings in the pan. Since I tow pretty frequently, I have always tried to do a tranny flush well before manufacturers recommended mileage. Cheap insurance

 

i have 92 automatic ctd of course and i dont use overdrive period unless im driving flat ground on interstate. i live in mountains and sustained speeds of 55 or greater are rare so i just dont use it. transmission repair people have told me that also. 350,000 on truck and still clicking

 

I have a trailer similar to yours, a 23' enclosed traiker that weighs about 5000# loaded.
The only time I turn the OD off is before I get to the highway, after that I leave it in OD.
I tow in some fairly hilly terrain, not big hills but a lot of medium size hills it's only downshifted once.
as long as it doesn't hunt for gears your OK.

 

Our truck is a 2001 with the automatic and 3.73 gears, all stock. We pull a fifth-wheel that maxes out at 10,200 but we hardly ever get that close in weight. In hilly terrain it will drop out of OD and I try to keep it around 2,000rpm to hold it at 55 mph or so. Although it sounds like it's running hard it pulls easily at that rpm. Is this a reasonable speed/rpm to maintain for long periods? The temp rises just a little, nothing I worry about. Any opinions? Or should that be how many different opinions?

 

I will use OD as long as I can keep the RPM's at 1800 or higher.
If not, I drop it into 3rd and let the RPM's get to 2400-2600. It will run all day like that.

 

I'd stay out of OD until after about 60 mph. After that, you should be fine. That's how my family and I have always done it.