Need Ideas

[imaybail]

Background:
I have been driving a 2007.5 truck for about 10 years. It is a manual truck, crew cab, and is deleted with a Smarty S67ME. Has really been a good truck and does everything I need it to do, but I wanted to trade for an automatic truck with a long bed. I tow about 8500 lbs. on a regular basis.
So shopped around for a while and bought a 99 3500 Auto, long bed dually. Very good condition and well taken care of.
Today I towed my tractor for,the first time and was kinda disappointed in the truck’s lack of power on the hills. It has 4.10 rear end and it just doesn’t seem to hold its speed well on hills. There is no throttle response until you press the pedal all the way to the floor and then it shifts down and really winds up the rpms. This is on a road where the speed limit is 55. 55 is really too fast to run with O.D. off so I’m running in overdrive with the TC locked. Rpms are around 1600. If the truck would shift down out of overdrive or unlock the TC I think it would hold its speed better, but it won’t respond until you mat the pedal.
On the interstate I usually drive 65 max and the truck holds its speed well on the hills. Rpms at 65 are about 2000.

Fuel mileage seems poor as well. Overhead calculator is indicating 16.2, but I’m guessing it’s closer to 10 mpg. No boost gauge or egt gauge on the truck.

So is this what I should expect from this truck or is there something I should check to see if performance can be improved? I believe a more responsive transmission would improve performance on hills.

 

[JR]

The 4 speed is a big negative with the auto, if the trans is stock the loose TC makes it even worse. A tighter converter, some mild injectors and a programmer like a Smarty or Edge will make a big difference. But again if trans is stock be ready to put some coin into it. They will not hold much above factory power levels.
If you really are planning on keeping the truck on the long term imo the 47 just isn't worth investing money into. I had a built 47 in my 98, it improved the driveability ten fold but at the end of the day there just isn't enough gears for towing heavy. If I had it to do over again I'd have just spent the coin on an NV5600 or a G56 and been done.

 

[DavidC]

JR is right on. My 99 was a dog towing the 5ver on grades so a DTT trans, DTT trans controller and a Edge Comp woke her up. Mine has 3:54's so that did not help the uphill battle.

Dave

 

[imaybail]

Well I already have a manual truck, I want an automatic now.
So, is the truck just that underpowered? I really think the transmission is not working properly. It should shift out of overdrive, or unlock the TC before you have to floor the pedal. You would think that with 4.10 gears it would pull better without so much drama. Probably won’t keep it if it has to be bombed to get the performance I need. I think there are stock trucks out there that are more capable.

 

[JR]

Not trying to sound condenscending, but youve been driving a truck for a lot of miles with a solid +125 hp to the good and 2 extra gears to boot. Even with some minor mods your not going to get the same performance you've become accustomed to.
If you really think something isn't right with the transmission, try to find a good diesel repair shop and take someone for a test ride. I suspect your just going to be disappointed either way.

 

[imaybail]

Not trying to sound condenscending, but youve been driving a truck for a lot of miles with a solid +125 hp to the good and 2 extra gears to boot. Even with some minor mods your not going to get the same performance you've become accustomed to.
If you really think something isn't right with the transmission, try to find a good diesel repair shop and take someone for a test ride. I suspect your just going to be disappointed either way.

I had a 2004 with a 48re and it was a strong truck too. You may be right, but I’ve never heard anyone complain of the symptoms I’m experiencing, just good reports about how their truck runs. I think the ‘99 has 215 hp, and 400 ft/lbs torque. Am I unrealistic thinking that this truck with 4.10 gears should hold its speed on a hill at 55 mph and not rev its guts out doing it?

 

[JR]

Am I unrealistic thinking that this truck with 4.10 gears should hold its speed on a hill at 55 mph and not rev its guts out doing it?

Empty or hauling a load?
If I had much over 6-7k lbs on the hook I'd leave OD locked out at those speeds, but I also had 3.54's .

 

[DavidC]

We have some pretty steep long grades in Az. Pulling the 5ver ( about 10k) I lock out OD at the start of the incline and the comp set on 4/5 I can usually climb at 60-65mph. I can probably do more but with tires rated at 65mph I am fine with that. When stock maybe40- 45mph. I read where a set of RV 275 injectors really bring them to life also. The truck is also carrying the Wife, 80lb German Shepherd and 45 gallons of fuel in the reserve tank. If I forget to lock out the overdrive it will kick out about 50mph and 1/2-3/4 throttle and maybe unlock the TC (not real sure of that one). When it does that it actually feels like it lost power and I unlock manually and ease off the throttle until things return to normal with out OD which then appears to have the power back. Maybe that has to do with the DTT 89% TC.

Dave

 

[imaybail]

Empty or hauling a load?
If I had much over 6-7k lbs on the hook I'd leave OD locked out at those speeds, but I also had 3.54's .

I was towing about 8000 lbs(3600 lb trailer with a compact tractor). To leave OD off would limit my speed to about 45. Just need to know if this is all the truck has. Remember with 4.10 rear gear I run about 1600 rpms at 55 mph. Forgot to mention, truck has 17” wheels and tires from a 4th Gen dually. So I guess that would lower the numeric ratio some, but not much I would guess.

 

[DavidC]

I have read where members installed a Edge EZ (65hp) I believe (no pump tap) and a simple install. That may be all you need to be happy.

Dave

 

[imaybail]

Gonna have to get used to running more rpms than 6.7 and maintain my speeds with no problem.

 

[JR]

At 1600 rpm your in the basement on the torque curve. I regularly ran my 98 up to 2400 rpm sustained when towing depending on load, the 4 speed auto is just that mismatched your either running high rpm or lugging it. Running too low of rpm is not only harder on the engine but also the transmission.

 

[gtwitch]

The same engine that Cummins has designed and sold for years was and has been used in marine use and was designed to run at 2500 rpm in a marine application at a full power demand and do it all day/every day so don't worry about hurting that engine and your not over revving it at 2500 rpm
gtwitch in wyoming