3.5 rear axle

[AHuber]

Hi, my question is ; My 2001, 2500 quad cab SLT 4x2 long wheel base, four speed Automatic 47RE , Rear Axle 3. 5 Truck has a gross COMBINED weight of 16,000 lbs. I weighed my truck and 29 ft. travel trailer on the co-op scales and weighed 15,300 lbs. clearly within truck specs. The Dodge weighing 6,750 lbs. and the trailer weighing 8,550 lbs. The truck seems to pull very well in overdrive from about 60 m. p. h. up to whatever speed you deem safe. When driving on two lane highway's under 60 or 55m. p. h. it seems to work harder or lug the engine dropping into third gear. Also the cruise control wont stay enguaged in overdrive when pulling the trailer but will in third gear.

All in all I'm satisfied with the truck's preformance except for the drag on the engine under 60 or 55 m. p. h.

I really dont want to do anything to the Cummins for fear of voiding the warrenty but wondered if changing the rear axle to a 4. 10 would enhance my pulling power . How much would this cost and would it be a good idea to have the dealer do it ? Also would the computer have to be reflashed with the change ?

I have asked around and get many different answers but posting my question here i can count on reliable ones.

Thank's

Al

 

[Lsfarm]

Towing in Od

Hi Al. Your truck may have the 'reduced power in OD' ECM [?] program. My 2001 had no power in OD, and my 2001. 5 was much more powerfull in OD. The trucks were identical except for the ECM program.



I don't know the TSB # but I know there is one for a reflash to remove the 'reduced power program'. The reason for the program was to prevent damage to the auto transmission with the higher output engines.



I wouldn't recommend towing your load at less than 55-60 mph in OD anyway. Punch the OD off, the revs will be a bit higher,but the transmission pressures will also be higher, and your transmission will last a lot longer. The other side effect is that your EGT's will be a lot lower when you aren't lugging the engine.



I wouldn't change to 4. 10 gears unless you are planning on using this truck at least 50% of the time for towing, most people only tow about 10-20% at most.



But many owners wouldn't think of towing with 3. 55 gears. However, when stock I towed many times at 17-18K GCVW, with no problems.



I hope this helps, Greg L

 

[BigMike]

Al, Your GCWR is more than 16000lbs. My sticker said the same thing. I couldn't believe it, so after much TDR discussion, I called DC, gave them my VIN number and they told me my GCWR was 20000lbs. That will be important information to know if you decide to upgrade your trailer and pull something heavier.

 

[Steve M]

That's exactly what I like about the 3. 55 ratio. I had a '95 auto/3. 54. Traded it for a '98 5spd/4. 10. With almost 90k on it, I traded it for another auto/3. 55. I like being able to lock out O/D and tow in direct gear in the hills at 55-65. I couldn't do that with the 4. 10. RPM was too high to use direct over 55mph. So I was using O/D to pull the grades. Not good for the standard or automatic transmission.

I use overdrive while towing at any speed that feels comfortable. If I feel like I'm lacking power from too low rpm, or I'm fixing to head up a grade, I lock out O/D.

With a 4. 10 in O/D, you're the equivelant of a 3. 07 ratio in direct. Too tall and in direct with 4. 10s, to high rpm. I realize my opinion is unpopular but I've owned and towed with both. I prefer the 3. 55.

 

[Blair]

Mike the 5 speed trucks have higher GCWR and so do the 4. 10 trucks. Check out the DC towing guide it's a small book that gives you all towing and haulling specs.

 

[Chipstien]

The cost for 4. 10 is very high. Spend that money on a mild box and be done with it. JMO

 

[Big White Beast]

Gear change is costly.......

I know I did it twice. My advice if your really want to change gears is the 3:73. 300 RPM difference vs 600 to go to 4:10.



If you go from a 3 series gear to a 4 series you will also have to swap the carrier and that's another $500 or so. 3:54 to 3:73 will run you about $500 and up depending on installer or doing it yourself. Even with the power mods for me the gearing was essential to keeping it in the powerband.



Garrett