48RE Delayed 1-2 Upshift, Advanced 2-1 Downshift

[RFogarty]

My 2003, 48RE trans has 64K miles on it after a rebuild during the Dodge trans-cooler recall several years ago. Total vehicle mileage is 77K, the bulk of which are about 60% lite miles with no towing or heavy loads in the bed.



The trans shifts normally until the engine and trans have come up to full running temperature. Once heated up, the trans will not shift 1-2 until I press the accelerator past a point where I can feel a resistance, or binding, of some kind in the acclerator travel, usually around 20 mph and then the truck will upshift through the rest of the gears normally.



I should note that the spot where it feels like the accelerator pedal binds up only occurs after the engine and drive train have fully heated up. When the truck is cool after starting it for the first trip of the day, or it has set for a few hours, the accelerator pedal will travel smoothly with no binding for the full length of its stroke.



I can get the trans to do a 1-2 upshift sooner during a gentle accleration if I back off the throttle, shift into neutral, quickly stomp on the accelerator to get it past the spot where the binding is felt and not over rev the engine, go back to "D"rive, and then the truck will shift normally until I reduce speed as in coming to a boulevard stop.



When I start slowing down, say 20-30 mph, the trans will do a hard downshift 2-1 as if the gearshift lever was used to force a manual downshift.



Now, whether I come to a complete stop or slow to 10-15 mph and the truck has downshifted to first, I still have to do the accelerate, shift to neutral, stomp, shift to "D"rive, and continue on acrobatics to get up to speed without getting the rpm's to the point where the truck feels like I'm doing a wide open acceleration.



Makes the grandkids giggle but I'm not amused.



I took it to the local Dodge dealer yesterday and they diagnosed it as a shorted Transducer Pressure Sensor. When they test drove the truck after replacing the sensor it continued to do the same thing.



Then they concluded it was something inside the trans and the trans was going to have to come out of the truck ($2,100 for R/R), and when I asked how much further that price would go if they found the failed part, I was told it could go to $4,500 - $4,800 for the total repair if it was necessary to rebuild the trans.



Beings that the sensor was shown as shorted, they left it in the truck and I decided to do some research before committing to $4,800 for a rebuild.



I would appreciate any suggestions on what may be causing this problem, and is the trans with 64K on it really due for a rebuild?



Thanks for your help.

 

[cerberusiam]

Pretty good chance the binding problem is causing all your issues and its one of the failure points. So much so Sonnax makes a kit specifically to address the problem.



Shifting is an interplay between governor pressure and throttle valve pressure controlled by how far you depress the throttle. What happens is the throttle pressure valve wears in the VB and when it warms up it will stick in the bore, the resistance your feeling. Cool the clearances or ok and it works smoothly.



Could also be you have a short in the gov solenoid or transducer that shows up when it warms up to temp also. Either way, pretty sure all you need is the TV pressure fix kit from Sonnax and the obligatory gov solenoid and transdcuer.



Your biggest problem will be finding a shop that will do just what is needed instead of wanting to empty your wallet. As you have already experienced. .

 

[BIGNASTY]

They must have changed things in 04. 5 mine has 98+K on it and have towed somethings I know I shouldnt have pulled and the TT all over the west and have had no problems except that it wont back a load up hill but Ive been told that its not a problem its just that way. All I have ever done is what Cerberusiam has told me to 1 change ATF 2 change filter 3 have adjusted the bands a couple of times but I dont think that it really need the adjustment. I change the ATF more than I think is needed but its just cheap insurance to my thinking

 

[cerberusiam]

They must have changed things in 04. 5 mine has 98+K on it and have towed somethings I know I shouldnt have pulled and the TT all over the west and have had no problems

Not really, its just hit or miss on the VB's wearing like that. Its the same thing with the detent ball wearing in the top of the VB and causing it to stick in park. Soft castings and they wear faster than others. The QC on the VB's is really crap when compared to the older trucks.

 

[RFogarty]

Pretty good chance the binding problem is causing all your issues and its one of the failure points. So much so Sonnax makes a kit specifically to address the problem.

Thanks for the info. I think you're on the money. I've been to two other trans shops after the Dodge dealership and they both focused in on the solenoid and pressure sensor after I gave them all the background. When I mentioned that Dodge replaced those and it didn't fix the problem, they still seemed fixated on the solenoid and sensor.



My limited experience with transmissions goes back to the 60's when I put a 4-speed hydro behind a Pontiac mill in a '37 Willys, and helped some friends that had the Torqueflight's. Played around with the governors, springs, and porting to some degree. Ancient history, I know, but the issue of the throttle pressure valve brought back memories of when we would monkey with the TV linkage on the carb along with the governor to raise the setting of the shift point up into the higher RPM range. At least I think that's what we did. It's been awhile.



Now I need to find someplace in Southern Cal that has above average experience with 48RE's and see what diagnosis they come up with in hopes that one of them will turn to the TPV without coaxing.



Thanks for the help.

 

[RFogarty]

The QC on the VB's is really crap when compared to the older trucks.

Seems to be the case across a number of makes. The older stuff just seems to last longer in some cases.



I have an '89 Camry with 340,000 on her and it won't give up the ghost so I have an excuse to get something newer.



Of course everytime she shifts I wonder if it will be the last, but it keeps on going. The grandkids call her the Timex.