Do I have a 48RE shift problem ?

[RonD]

I have a 2005 3500 with a 48RE auto trans, the truck has 65000 miles, the trans was rebuilt at 57000, and the truck is stock, including tire size. Here is the issue, I am towing the 5th wheel, it weighs about 14000 pounds, the truck is about 7800 loaded. On a hill, say about 4% grade, I am at 55 mph in 4th gear flat ground, I start up the 4 % hill, it down shifts at about 50 mph, I am now in 3rd gear, the truck continues to slow down, I have my foot to the floor, it is now at about 1400 RPM's, and 45 mph, I pull the lever down to 2nd, nothing, I put it back in Drive, when it reaches 42 MPH it shifts down to 2nd, then it also sometimes jumps between 1st, and 2nd. I have tried tow-haul, no tow haul, it doesn't effect it. Is this normal,? pulling hills is no fun watching the speed drop down, then jump into a lower gear. Now I have a good idea why they came out with a 6 speed.

 

[cerberusiam]

First off, these things really don't like WOT throttle and shifting, try lifting off the throttle a bit before going for downshifts.



Manually downshifting you should get 2nd gear anywhere under 50 mph, thats holding a bit to long to 42. Could be the WOT causing it or the typical gov solenoid and transducer problem.



In drive mine will gain speed on a 6% grade even with stock programming, the fact you keep slowing down is a bit strange. You should be at more than 1400 rpm's in drive at those speeds especially with stock tires.



You have checked/changed air and fuel filters lately?

 

[RonD]

Fuel filter is new, air is 80 rear, 70 front, level ground is maybe 1600 rpm towing at about 55-60, I really haven't pain much attention to that, but the RPM's decrease with the speed decrease as it should, the big complaint why it won't go from 3rd to 2nd. I am really looking for the correct numbers to compare mine to, than if I do have a problem I can get it fixed, I will try backing off on the throttle a little, but I don't think that is the problem, thanks

 

[HBarlow]

Ron,

The previous poster was inquiring about your air filter not air pressure in tires. Is the air filter clean?

Your truck may have 3. 73 differential gears which is not the ideal choice for a heavy trailer. The tall gear provides less torque multiplication for the steep grades.

The 2005 48RE differs from other years. IIRC the 2005 is the only year when Dodge made a programming mistake. The 2006 I had could be run with OD locked out OR in Tow/Haul mode selected by a button on the end of the shifter. The 2005 may not have "OD lockout" feature but can be run in Tow/Haul mode.

If your transmission allows, lock OD out and run in 3rd gear. With the road speed you are pulling and 3. 73 gears it would help to be towing with OD locked out to get the rpm up a bit. The 48RE programming of your '05 may not allow this.

Anticpate the approaching grades by speeding up a bit then allow speed to fall off on the grade. When your road speed declines to 1600 rpm, back off the accelerator pedal, pull the lever down to 2nd gear, and put your foot back in it. The transmission has electrical interlocks designed in to prevent overrevving the engine. It may prevent downshifts to second gear at road speeds higher than 42mph. What engine rpm does your truck run at 42mph in second gear?

 

[cerberusiam]

the big complaint why it won't go from 3rd to 2nd.

When you are at WOT the TV pressure is ramped as high as possible, this tends to defeat the shifting patterns and hold gears both up and down.



I can pull the shifter into 2nd at anything above 50 mph and it will stay in drive, thats the OD lockout on an 05.



Once it drops under about 48 mph it will always downshift to 2nd, but, I never go WOT when doing this. As I said before, WOT causes some issues with gear hang both up and down so try avoiding that when you want a shift to happen.

 

[RonD]

OK, I think I have it now, thanks to both of you. The air filter is clean, I understand the trans TV cable, and how it works, I just am not familiar with Dodge, I do have 3:73 gears, the next truck will have 4:10 for sure, mine does not have a OD lockout, only Tow Haul, I have pulled the lever down into 2nd prior to the rpm drop, that works most of the time, I can live with this for now, when I bought this truck in 2005 I didn't have a 5th wheel, that happened a few months ago, the truck really isn't setup for what I now use it for, a 6 speed would be great, the next truck will be ordered for the mission, thanks Ron

 

[cerberusiam]

OK, I think I have it now, thanks to both of you. The air filter is clean, I understand the trans TV cable, and how it works, I just am not familiar with Dodge, I do have 3:73 gears, the next truck will have 4:10 for sure, mine does not have a OD lockout, only Tow Haul, I have pulled the lever down into 2nd prior to the rpm drop, that works most of the time, I can live with this for now, when I bought this truck in 2005 I didn't have a 5th wheel, that happened a few months ago, the truck really isn't setup for what I now use it for, a 6 speed would be great, the next truck will be ordered for the mission, thanks Ron

FYI, these trucks don't have TV cables anymore. They now use a TV motor that is set by the ECU based on wheel speed, the same as the gov pressure. Partial electronics are partially problematic at times. :-laf



FWIW, I pull a trailer at about the same weight as you and after some tweaks to the transmission and adding a Smarty its a different beast. As I said mine will gain speed on a 6% grade in drive and with the extra power it almost never comes out of OD at hiway speeds. Shift problems were solved with a shift kit and shift enhancer. I even run taller tires than you and it performs flawlessly.



The 3. 73 are about the best all around gear you can get if it does double duty.

 

[RonD]

I think you hit the nail on the head. With a little more power the trans can hold 3rd gear in most cases, or 4th. What Smarty do you have ? and at what level do you set it at for towing ?, I know the trans may take a beating, but I could keep the settings down as low as will work, thanks Ron

 

[HBarlow]

I had a similar gear choice experience several years back. I ordered a new '01 HO/6 spd w. 3. 54 gears in early '01. It was perfect for towing an 8,000 lb. Airstream. In late summer of 2003 I got the bug for a fifth wheel and bought a nice used Travel Supreme that weighed 14,500#. My 3. 54 gears were no longer perfect. Sure, the Cummins will pull twice that weight but it just wasn't as well matched as it was with the previous trailer.

Since then I've owned two more Dodge Cummins w/4. 10 gears. With the modern six speed automatics and 4. 10 gears you can almost pull a house and still have low rpm highway cruise.

 

[SSell]

Sounds similar to my situation earlier this year (read: bigger tires, now down on power? thread for the gory details) '05 4x4, loaded/towing, mountain grades, previous years I was doing the passing, this year had school buses & mopeds giving me the finger for holding them up... Pretty sure trany was doing it's job, motor just wasnt fueling correctly. Some good suggestions in that post, I"ve redone air & fuel filters (both were fairly new), had 5star scan for faults, overcharge me for "injector flush",flash ecm for correct tire rpm, looked for intercoler leaks, etc,etc,etc. Don't know if fixed yet, havent had the trailer out yet. Really hoping the fuel filter does it, there was nothing wrong with it until a long heavy pull uphill.





good luck!

 

[cerberusiam]

I think you hit the nail on the head. With a little more power the trans can hold 3rd gear in most cases, or 4th. What Smarty do you have ? and at what level do you set it at for towing ?, I know the trans may take a beating, but I could keep the settings down as low as will work, thanks Ron

I am running Smarty SO6, have not upgraded to the POD yet. I usually run SW #3, TM 3, Timing 3, RP 3. Grossing 23k will roll all but the long steep grades at 70 mph without dropping OD. I try to hold the rpm's at 1900-2000 and thats about where it is with 33" tires and 70 mph.



I also run a bilet cover lower stall TC, shift kit, and some other billet internals. All you really need to hold the power is a shift kit. The other billet parts nice but if you are not looking for big power they can slide.

 

[RonD]

The S06 I got all the info on, great unit, I think I will go ahead and get one, as far as the shift kit, I have a few questions, I have a deep Mag-Hytec trans pan, are you running a Transgo SK48RE shift kit, ? and if so is this a do it yourself install?, I have built a couple street rods, and do all my own service work on the Dodge, I also have a 2 post lift and all the tools. If it's real complex I may want to have it done, if it's follow the instructions I should be ok, thanks Ron

 

[cerberusiam]

The S06 I got all the info on, great unit, I think I will go ahead and get one, as far as the shift kit, I have a few questions, I have a deep Mag-Hytec trans pan, are you running a Transgo SK48RE shift kit, ? and if so is this a do it yourself install?, I have built a couple street rods, and do all my own service work on the Dodge, I also have a 2 post lift and all the tools. If it's real complex I may want to have it done, if it's follow the instructions I should be ok, thanks Ron

Yes, the new TransGo shift kit is what I am running, and DTT Shift Enahncer to allow the us of TQ management removal. The TransGo kit is not bad to install and the instructions are fair. If you do your own work you should be good to do it. Take your time and keep things clean and they are really not that bad.



I smoked the direct clutches by not doing the shift kit early enough with the Smarty so did a complete rebuild. All but the direct clutch pack was in great shape at 100k. I also added a billet cover to the front servo to address a potential leak spot, billet band strut, billet input shaft, and a billet single disk TC. The input shaft and TC was safelt reasons when I rebult it but ran the stock setup for over 10k with just the shift kit, billet servo cover, and band strut with no problems.



The one caveat is the TC to flex plate bolts need to be checked periodically with the stock TC. They do flex a bit under higher pressures, power, etc, and can cause a problem if the bolts come loose.

 

[RonD]

I ordered the new Transgo kit, I don't think it will be a problem to install, I am also going to get a Smarty S-06 to get a little more power, as far as the shift enhancer, I will see how it shifts under my type of driving, then add it if needs it. As far as the Flex Plate bolts, I will remove them and add some Torque Lock (blue) to them and re install, then check them at oil changes for looseness, or cracked tabs at the attachment. My stock trans only has 8000 miles on it after Dodge rebuilt it under the 7/70, it also has a new valve body, and torque converter that they installed during the rebuild, so I am starting from almost new, I won't run the Smarty without the Transgo kit installed first, thanks for all the help, Ron