towing rpm

john&bet wrote:
I tried it yesterday afternoon and it does not shift into 4th. The torque convertor locks up and it stays in 3erd. If I hit the button at speed it shift down to 3erd and torque convertor unlocks, then a few seconds later the torque convertor locks up again. Just how mine works. Others may be different. I have a Jan.'04 build date, with 325hp,600tq.

45Ricochet wrote:

2500 Grunt wrote:
The 2005 year Cummins is the only year where the tow/haul button once pressed only alters the shift points in gears 1 thru 4 or raises the rpm shift points. It will not lock out 4th gear (overdrive) unless you purchase an aftermarket OD lock out switch/box. Don't know why Dodge engineers did this but they switched back to the other way in 06? To the OP, sounds like you are running in 3rd gear at 2500 rpm's unless you are running 4.56 gearing in 4th? With stock tires with 4.56 gearing in 4th gear you should be around 2300 rpm's at 65mph +/_ (can't find the gearing chart).

Just to clarify, 06 here and the button is a three way switch. Yes push it once for tow/haul which changes shift points, twice it will lock out over drive, third push will be normal operating condition. I believe 2004.5 back they were only a two way switch which would lock out over drive.

Got it! I knew the '03-04 was an OD lockout. I thought the '04.5+ was the same as the '05 but it is not; The '04.5 325 still locks out OD. Strictly '05 models get T/H and get to use OD but do NOT have the ability to lock out OD. '06-07 get T/H AND OD lockout as separate selections.

Thanks for the clarification!!!

2500 Grunt wrote:
The 2005 year Cummins is the only year where the tow/haul button once pressed only alters the shift points in gears 1 thru 4 or raises the rpm shift points. It will not lock out 4th gear (overdrive) unless you purchase an aftermarket OD lock out switch/box. Don't know why Dodge engineers did this but they switched back to the other way in 06? To the OP, sounds like you are running in 3rd gear at 2500 rpm's unless you are running 4.56 gearing in 4th? With stock tires with 4.56 gearing in 4th gear you should be around 2300 rpm's at 65mph +/_ (can't find the gearing chart).

Just to clarify, 06 here and the button is a three way switch. Yes push it once for tow/haul which changes shift points, twice it will lock out over drive, third push will be normal operating condition. I believe 2004.5 back they were only a two way switch which would lock out over drive.

We have a 2012 GMC 2500HD D/A Crewcab and when towing our FW at around 65 we are pushing 1,600 rpms. We do have the six-speed auto but I find no difference whether we use the "tow/haul" button or not while cruising down the road. Usually we are also towing a 19' boat behind the FW as well.

john&bet wrote:

boogie_4wheel wrote:

john&bet wrote:

boogie_4wheel wrote:
If this is an early 04, try running with the T/H off. This will allow it to drop into 4th and would probably net you some fuel economy. Save T/H (OD lockout) for the hills.

The 04.5+ T/H allowed 4th gear operation, but 04 and older was an OD lockout feature. I don't know the specs on your FW but would at least try to pull it in OD.

With reguard to the t/h mode, if I push the button I run the ops' rpm. I put my '04.5 in D and go. I very seldom push the button. I generally run 1800 rpm on the interstate with very little down shifting and 55 mph on other roads.

Maybe I'm wrong... The T/H on the '04.5 is still only a lockout :? When you first enable T/H while under way, the truck will downshift to 3rd, but after a few seconds it will upshift back to 4th. Try it from a stop empty with T/H enabled, truck should go into 4th at ~45mph with light throttle. If it doesn't then I was wrong and the T/H with 4th enabled is an '05+ thing (not an '04.5+ thing).

For the OP, I would still try running without T/H enabled and pulling in 4th.

I don't notice mine shifting back to 4th under load. I will try what you suggested after bit when I have to go to town just to see.

I tried it yesterday afternoon and it does not shift into 4th. The torque convertor locks up and it stays in 3erd. If I hit the button at speed it shift down to 3erd and torque convertor unlocks, then a few seconds later the torque convertor locks up again. Just how mine works. Others may be different. I have a Jan.'04 build date, with 325hp,600tq.

The 2005 year Cummins is the only year where the tow/haul button once pressed only alters the shift points in gears 1 thru 4 or raises the rpm shift points. It will not lock out 4th gear (overdrive) unless you purchase an aftermarket OD lock out switch/box. Don't know why Dodge engineers did this but they switched back to the other way in 06? To the OP, sounds like you are running in 3rd gear at 2500 rpm's unless you are running 4.56 gearing in 4th? With stock tires with 4.56 gearing in 4th gear you should be around 2300 rpm's at 65mph +/_ (can't find the gearing chart).

I think the OP will be happier at the fuel pump after a day driving in high gear. Good luck.

Hannibal wrote:

Mote wrote:
My old Dodge with the Cummins won't even turn 2400 rpm. The govenor limits it to 2200rpm which is around 55mph with overdrive locked out. At that rpm it sure is loud.
I can run overdrive when pulling the camper most of the time when on the highway. I do have to be carefull pulling hills thou as the torque of the engine is to much for the trans to handle and it will slip.

Something is wrong there. Peak HP is at 2600rpm. My '95 and 98 12v would both run to just above 2600rpm before the governor would reel it in. Even then it felt very ornery compared to the ISB and ISBe. They started to run out of breath just over 2900rpm but I believe if I remember right they were governed at 3200rpm.

Maybe/maybe not. There were changes from year to year and auto vs manual. With the 96-early 98 manual being the strongest.

I use the T/H on take off when towing my 14K fiver.The truck seems to like the shift pattern better.Once up to speed,about 50 mph,I'll shift out of T/H,and stay in 4th till the rpm drops down to around 1700-1750.
I have found that everything just purrs along at close to 2000 rpm,I "think"
my MPG may be a little better holding close to 2000 rpm
My 04.5 Dodge CTD 4 speed 48RE tranny has the 4.10 rear end,and at 2K rpm in 4th it is right at 65mph

Mote wrote:
My old Dodge with the Cummins won't even turn 2400 rpm. The govenor limits it to 2200rpm which is around 55mph with overdrive locked out. At that rpm it sure is loud.
I can run overdrive when pulling the camper most of the time when on the highway. I do have to be carefull pulling hills thou as the torque of the engine is to much for the trans to handle and it will slip.

Something is wrong there. Peak HP is at 2600rpm. My '95 and 98 12v would both run to just above 2600rpm before the governor would reel it in. Even then it felt very ornery compared to the ISB and ISBe. They started to run out of breath just over 2900rpm but I believe if I remember right they were governed at 3200rpm.

my chevy 6.0 gasser w/ 4:10's pulling @8000lb TT runs about 2500rpm at 65mph on slightly hilly north east hits 3000rpms at 7% grade 45mph with or with out tow haul. for me it just streches out the shift point on my 4spd tranny. I use synthetic oil and tranny fluid if that matters.