I have a 2004.5 RAM with the 5.9L and the 4 speed automatic. I tow a 10,000# trailer for 18,000# combined. I find the transmission has awkward ratios at 55-60 MPH:At 55MPH - In drive, 1,500 RPM, Exhaust gas temperature in the 800'sAt 55 MPH - in Tow/Haul, 2,200 RPM, EGT in the 600'sAt 60 MPH - In drive, 1,700 RPM, Exhaust gas temperature in the 800'sAt 60 MPH - In Tow/Haul, 2,400 RPM, EGT in the 600'sWhat gear should I be driving in while towing at these speeds? It seems like it is lugging when in OD. I am thinking in terms of engine longevity, transmission longevity, fuel economy. The truck is perfectly content at 65 MPH in OD.

Towing keep speed high enough to allow the engine to spin around 1900 RPM

I would go with 60 in OD. 800 pre turbo isn't too bad.The thing I disliked about my 01 the most was the gap between 3rd and OD is too big. I switched to 4:10 gears which really helped but it was either cruising nicely in 4th or screaming in 3rd.The thing I like most about the 6.7 isn't the engine, it's the 6 speed transmission.

I tow with a 1996 Ford diesel with a 3.55 axle and have about exactly the same rpm vs speed ratio as your Dodge, and with about identical egts at those speeds. For the past 20 years I've been towing in overdrive at the 55 to 60 mph range and have experienced no mechanical problems with either the engine nor the auto tranny.Of course, when I get in the hills I shift it out of overdrive into third when the tranny starts "hunting," which is what Ford recommends. On long mountain grades, the gear I select is determined by my EGTs.

What RPM is peak torque? Probably around 1,900 or so. That's where you should be running it.The worst thing about those trucks was the 4 speed automatic.

^That. Not enough gears, but 6-800 deg egts are super low if pre turbo. That seems like post turbo temps. Can't imagine 600deg pre turbo pulling 10k even on a flat road. However, IMO I like my 5.9 running close to 2krpms or over when towing. Lower rpms makes my pre turbo egts go up quite a bit, but I'm adding extra fuel.

When is my Cummins the happiest? | Good Sam Community

DirtyOil
Explorer
Nov 12, 2016
My Ram is happiest when not towing Fish's Ford... :B
john_bet
Explorer II
Nov 12, 2016
I have the same truck with a 3.73 rearend. I tow a 12K 5th. I put the selector in "D" and drive. I have towed in all kinds of traffic and all kinds of roads including some in your state. On Interstates it is 1800 rpm at 65 mph. I let trans do it's thing. Very seldom touch the T/H button.
transamz9
Explorer
Nov 09, 2016
wilber1 wrote:
transamz9 wrote:
wilber1 wrote:
Yup. Peak torque at 1600 RPM so 1700 RPM would not be lugging, you just make less HP than at 1900 RPM. Don't know about the 48RE but my 47RE did not have tow haul and would not run in 4th with the torque converter unlocked.

On the first 48's 04.5-05 the torque convertor will only lock in OD (4th) when the tow/haul is off. With tow /haul on it will lock in 3rd and 4th. It will also lock in 2nd if you put the gear selector in "2". Tow haul was the only option on the 48's in 04.5-05. In 06 they started offering tow/haul and also OD lock out.

That's odd. No wonder they only did it for a year.

Yeah,it's kind of stupid if you ask me. What just as stupid is in 06 when they started offering both options they put it on the same switch, the button on the end of the shifter. Push it once for tow/haul. Push it a second time to lock out OD. Pusher it a third time to go back to normal. There are times on the back roads that I wish I could easily lock out OD when running 35 - 50. I can lock it out on my tuner but is not as easy as pushing one button but you get the point.
wilber1
Explorer
Nov 09, 2016
transamz9 wrote:
wilber1 wrote:
Yup. Peak torque at 1600 RPM so 1700 RPM would not be lugging, you just make less HP than at 1900 RPM. Don't know about the 48RE but my 47RE did not have tow haul and would not run in 4th with the torque converter unlocked.

On the first 48's 04.5-05 the torque convertor will only lock in OD (4th) when the tow/haul is off. With tow /haul on it will lock in 3rd and 4th. It will also lock in 2nd if you put the gear selector in "2". Tow haul was the only option on the 48's in 04.5-05. In 06 they started offering tow/haul and also OD lock out.

That's odd. No wonder they only did it for a year.
transamz9
Explorer
Nov 09, 2016
wilber1 wrote:
Yup. Peak torque at 1600 RPM so 1700 RPM would not be lugging, you just make less HP than at 1900 RPM. Don't know about the 48RE but my 47RE did not have tow haul and would not run in 4th with the torque converter unlocked.

On the first 48's 04.5-05 the torque convertor will only lock in OD (4th) when the tow/haul is off. With tow /haul on it will lock in 3rd and 4th. It will also lock in 2nd if you put the gear selector in "2". Tow haul was the only option on the 48's in 04.5-05. In 06 they started offering tow/haul and also OD lock out.
wilber1
Explorer
Nov 09, 2016
Yup. Peak torque at 1600 RPM so 1700 RPM would not be lugging, you just make less HP than at 1900 RPM. Don't know about the 48RE but my 47RE did not have tow haul and would not run in 4th with the torque converter unlocked.
transferred
Explorer
Nov 09, 2016
KD4UPL wrote:
What RPM is peak torque? Probably around 1,900 or so. That's where you should be running it.

No, peak torque is at 1,600rpm in the Cummins 600 and 610.

edit- added both 600 and 610 variants
transamz9
Explorer
Nov 08, 2016
Durb wrote:
Thanks for the feedback. Sounds like revving over lugging is preferable. I would like to drive 65 (1,900 RPM) all the time but sometimes traffic won't let me. Last trip I followed a friend with a Motor Home and apparently his sweet spot was 59-60.

Your truck is happiest when the torque convertor is locked. This happens the most in tow haul mode. ;)
DakotaDad
Explorer
Nov 08, 2016
Edited in the spirit of discretion...
Durb
Explorer
Nov 08, 2016
Thanks for the feedback. Sounds like revving over lugging is preferable. I would like to drive 65 (1,900 RPM) all the time but sometimes traffic won't let me. Last trip I followed a friend with a Motor Home and apparently his sweet spot was 59-60.

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