5.9 Cummins Diesel Towing capacity

fj12ryder wrote:
So I'm unsure what you're asking. The automatic transmission on these years' trucks is a known issue. The only way to solve that is to pull the transmission and have it beefed up to handle the load/weight.

I have a 2001 Dodge Cummins dually with the six speed transmission. I'm pulling a 15,000 lb. toyhauler which it does very well. It's pretty much at its max since I have to keep a close eye on the EGT. But I pulled a 12,000 lb. 5th wheel before this one and it pulled that thing with no issues at all. The truck can do it, it just depends on if you want to spend the money to enable it to continue.

This ^^^^.

If you like your truck just get a good builder like: Firepunk, PDD, Commercial Powertrain, Sun Coast, bla, bla, bla…….Have them build a good tranny, slam it in your truck and forget about tranny problems. My guess is around 5 to 7K for what you want to do.

Not cheap but new trucks aren't either and after you get it done you can forget about tranny problems forever.

https://www.tstproducts.com › Torque Converter Lockup Switch

Could someone smarter than me please make a link out of this. Grit Dog this is what I did. ZERO valve body mod. Truck was stock.

^ I believe that the valve body also has to be modified to lock up 2nd and 1st gear. In any gear, a circuit must be completed for lockup (the switch), but in stock form the valve body only has the ability to lock 3rd and 4th gears.
IIRC from back in the day, there's a cheap "hack" to accomplish this or of course purchasing a modified valve body. Has something to do with drilling out or plugging a certain port to allow the right flow path for converter lockup in the lower gears.
ICBW though.

"Correct, a modified valve body and a lock up switch are required for any more than 3rd and 4th gear lockup"

On my 98 12V I has a simple light switch taped to my shifter that once rolling I flipped that would cause "ALL" gears to lock! Only negative if you forgot to unlock it would stall the engine when coming to a stop.

Grit dog wrote:
^ Correct, a modified valve body and a lock up switch are required for any more than 3rd and 4th gear lockup.
Seeing you have 3.55 gears as well, stock 03 power and 47re trans ratios are not a very good combo power or gearing wise for heavier towing. When towing, I'd run the smallest tires you can put on it with adequate capacity. Like 245 75 16s, re-gearing is expensive. Power is low, so gears or a tune are the easiest power solutions for moderately more power. If your tans is built a little bit, tow tune will do wonders, for 1/4 the cost of gears.
Synopsis for towing 12k+ high profile like a boss and not getting killed on the uphill runs.
-Tune
-Built trans
-VB and lockup switch
-Little tires

Add an exhaust brake, only if you have a manual lock up switch and only in the gears that it will lock in.

Bottom line, assuming your trans is stout enough to handle a little power and e brake, you have some work to do to get it to tow anything like a newer truck.
Only about $1200 in parts for a cheap tuner and a VB/switch if you do the work yourself, otherwise closer to $2k.
Exh brake, $1200 diy, over $1500 installed.
Tires...however much they cost.

I was going to say my BIL had the same truck, it was no power house towing his 12000lbs trailer. You need modifications and a good transmission cooler.
You are what 235HP and 460Ft/lbs of torque? How do you expect it to tow that much weight with a 4 speed and those gears? You could get out of the go pedal a bit. I ended up putting a Tru cool 40k in his truck and no more over heating, but there were plenty of times where he would slow down on hills. He worked for the carnival with that truck for years, and with the cooler and rebuilt trans it was really reliable.

^ Correct, a modified valve body and a lock up switch are required for any more than 3rd and 4th gear lockup.
Seeing you have 3.55 gears as well, stock 03 power and 47re trans ratios are not a very good combo power or gearing wise for heavier towing. When towing, I'd run the smallest tires you can put on it with adequate capacity. Like 245 75 16s, re-gearing is expensive. Power is low, so gears or a tune are the easiest power solutions for moderately more power. If your tans is built a little bit, tow tune will do wonders, for 1/4 the cost of gears.
Synopsis for towing 12k+ high profile like a boss and not getting killed on the uphill runs.
-Tune
-Built trans
-VB and lockup switch
-Little tires

Add an exhaust brake, only if you have a manual lock up switch and only in the gears that it will lock in.

Bottom line, assuming your trans is stout enough to handle a little power and e brake, you have some work to do to get it to tow anything like a newer truck.
Only about $1200 in parts for a cheap tuner and a VB/switch if you do the work yourself, otherwise closer to $2k.
Exh brake, $1200 diy, over $1500 installed.
Tires...however much they cost.

I had a 01 and enquired about a lock up controller to keep the converter locked in second. I was told I would also need a modified valve body, a switch wouldn’t do it on its own. A worthwhile thing to do though because if you can keep the converter locked, temperatures won’t go up much at all. You will also need a way to keep the converter locked if you install an exhaust brake.

billy1davis wrote:
My owners manual tells me the max pin weight is 1200 and the 5vr (2007 Arctic Fox 27 ft) has pin weight of 1500lbs. On top of that the trailer is max of 12000 and the truck is rated at 9600lbs approximate. I could change out the rear end to make it max out at 13000lbs. I have a chip and an extra cooler on the tranny which I had rebuilt. But coming up on steep and slow 2 lane roads i top out the temp on the tranny. Engine is fine but the tranny isn't.
NOt sure about getting a new truck or lightly used ot stepping down to a bumper pull'
Truck is 2001 Dodge dually 5.9l
Suggestions?

So if you want to pull that with your Ram it will need a lower gear ratio. I see that with a 4.10 gear the 3500 is rated at 12,900# towing. If you care you will likely be over the ridiculously low 10,500# or 11,000# GVWR of the Ram.
don't state if reg cab or Quad cab, 4X4 or 4X2?

These are the towing charts from the manual of our old 2001 Ram.



The best you can do is get a quality rebuild on the trans, with good additional coolers, and go with 4.10 gears and you should be ok. You might also put a small chip on the engine for a few more HP and lb. ft.
We towed a 12,500 5er with our 2001 Ram 2500, small chip and Bosch RV275 injectors, 5 speed manual and 3.55 gears. I would also add a PacBrake exhaust brake for extra stopping power.

I did have a radiator shop clean mine and test.

I had an 01 and pulled a similar trailer pin weight was closer to 1800lbs. It handled it fine. As mentioned the trans is the weak link in that truck (I had mine rebuilt well so it was no longer an issue for me). The cooling system is adequate if as someone mentioned the radiator is clean on the front. And as he mentioned pulling it out is the only real way to clean it as you just cant get to it good enough when it is in the vehicle. I used to pull mine about every 5 years.