My 05’ 2500’s automatic transmission seems to be irritable. There is appx. 96K on the odometer and I have no reason to believe it is not the original transmission. Ever since I’ve had the truck (right at a year now) it has always been reluctant to “fully lockup” in overdrive. Scratch that… It always does, just seems to be ‘late’, for lack of a better term. From a stop, accelerating “grandma speed”, on flat ground, without any load, the transmission will not fully lock –up, in overdrive, till somewhere above 55 MPH. It seems odd and ‘late’ to me.

I’ve played with the tow/haul mode and under identical conditions, it still seems to be late, for the full lock-up in overdrive, but just seems a little more abrupt. I would have thought (don’t know though) I would have been able to feather the accelerator pedal and encourage it to go ahead and fully lock-up, in overdrive around 45 MPH (no load, flat ground).

I replaced the transmission filter and appx. 6 quarts of ATF +4 about 3K miles ago. I have no way of knowing if it was ever serviced before. This service had no positive or negative effect on the late lock-up, of overdrive.
Can the shift points and lock-up points be altered/changed or are these symptoms of a tired and worn out transmission?

 

That sounds about right for a stock unit, 55 mph with TH off. It should hit OD and lockup at 45 or so with TH engaged. If it doesn't could be a computer thing or possibly just wear. As long as it goes into OD and lockup its pretty normal. The stock engagment was not very positive unless you were getting after it.

 

Yep my 05 does the same... when you step on it it seems to overspeed at 55 like wont lock up, i have to get off of it and then she locks in...

 

Perfect description, engine overspeed. Like the engine is begging the transmission, "Hey... A little help here?" Sounds like the answer is Drive On. Thanks for the input guys.

 

My 03 was behaving similar, new APPS, problem solved. No 6 oh no has a better understanding of 05's than me, what do you think? Adjustment?

 

Rebuild or drive it. Everything they are describing is typical stock trans reactions under power. One can play with adjustments a bit but a good TC, shift kit, and a few other pieces is really the only "fix".

 

Man I wished my T/C would lock up in the higher range.. Mine locks up around 45-50. Not so fun when I've got 15,000 on the back

 

Me too, I am easy on the throttle rolling into it after it hits 4th trying to keep it unlocked until 50-55 mph when I am towing....LOL

 

Sounds like it's time for band adjustments. That may make a difference, bedsides the fluid replacment will good for it anyway.

 

My '03 locks up at 50 mph unless you have your foot into it and it may go a little higher. When towing if I don't want it to lock up at its normal speed I just turn off O/D until about 55 or 60 and then turn it back on. 194K without any problem of over rev or slip. Bands were checked at 130K with only a very minor adjustment.

 

Dodge seems to have gone out of their way to *avoid* T/C lockup, or at least to unlock at the slightest torque provocation. I get the sense they don't trust their warmed-over 727 behind a diesel. Then again, I have M/T envy.

That said, I get lockup in 2nd with shifter in (2) at 30MPH, then lockup in 3rd at 40-45ish with shifter in (D). O/D lock kicks in about 55.

I will say the BD valve body has been a godsend. The tranny shifts hard like a tranny should. I always run in T/H mode in my '05. Shift points are much better in T/H mode.

The real problem with all this is that below 30MPH there is NO T/C lockup so pulling up a long twisty hill out of the lake where you just can't get to 30MPH about cooks the transmission. Backing the trailer up my 300ft somewhat uphill driveway is another balancing act between throttle pressure and transmission temperature. I've gone from 165* to over 200* when I didn't just baby the throttle in reverse. Did I say I have M/T envy?

I've got the parts for a mystery switch that will hopefully help by allowing me to force the lock-up to occur at lower speeds. I wonder if the switch will allow lock-up in reverse?

 

Not on the 05 and newer trucks it isn't. Way more aggressive than anything else in TH which is what it is for. Normal mode is NVH mandated for people that do NOT want to feel a shift and lock. The cure for that is a tighter TC.

Spend some time in 2nd gen and THEN you will know what a crappy lockup algorithm really is.

Low range and TH works really well in those conditions. A lockup switch does also, even in 1st. Since you over sized the tires and did not regear you pooched the ratios that work well and changed the way the trans works. Need to fix it so it works as designed.

Nope, not unless you modify the VB extensively.

 

I see billet shafts in your future..