48 RE operation/personality question from an auto newbie

[JCleary]

After 1k miles on my new truck I've noticed a few things about my auto.



- The shifts are smoother than new, but still hard when over 1/2 throttle

- It works pretty well for a 4-speed in tow/haul (but does not shift nearly as smoothly as an Allison or Torqshift). I do especially like the fact that it will stay in gear down to low rpms and actually use the CTD's torque. Not like the Torqshift that downshifts at the touch of a feather.

- It hangs a bit at 3200 when shifting from 3-4. Not too long, but longer than it should. I haven't timed it yet.

- It has a personality, it seems...



When the truck is parked for more than a couple of hours and restarted, it will take a few seconds to move when the trans is put into gear. Same thing, forward or reverse. If I let it idle in neutral it will go immediately when put in gear.



It also seems like the transmission shifts into OD randomly. Sometimes at 35, sometimes at 45-50, but I have yet to see a trend based on throttle position, engine temp, run time, etc.



I have experienced a similar problem in my pop's '97 gasser. In fact, he still has it. If it's parked for a while, it will not move for several seconds, even with throttle. The truck is now on its second transmission, and it only has 52k miles. It still behaves the same. The original trans had the VB replaced under warranty at 30k miles, but it only improved the shifting while in motion, not the lack of movement at startup.



I was told it's some type of check-valve (on the '97) that's allowing fluid to drain back into the pan. I was also told that the pump doesn't circulate ATF in Park, only in N, so it's not recommended to idle in Park due to a bushing not receiving lubrication.



So I start my truck in Neutral and let it idle, not knowing if it's a bad thing to idle in Park.



I would have thought that 10 years later they would have fixed a seemingly common problem.



Sorry about this "newbie" question, I just don't know squat about automatics. My last truck had a NV5600.



Any advice?



Thanks in advance for your replies.

 

[JValdez]

I have an 05 and what you describe is exactly what mine does. I guess they haven't changed. They do some weird stuff at different times but they always keep going. If my truck sits for a while at home I will start it and let it idle in nuetral for a minuet. If I don't it will take a few to get it going. The only problem I've had is the band adjuster bolt started leaking fluid. The dealer had that taken care of in less than an hour. Sounds just like my transmission though.

 

[cerberusiam]

No, they have not fixed the fluid circulation in park. Sometimes ya really gotta wonder.



You should not be getting the hesitation when you put it in gear. The check valve is supposed to stop the drainback and give positive engagement immediately. I suspect it stuck open and leaking back. My 05 will roll out immediately after starting and putting into gear. Most of the newer act this way so it is not what I would consider normal.



Shifting to OD is a computer controlled thing based on multiple parameters. Throttle position plays a part, so does load, speed, and TH. Hanging at WOT throttle is normal as is the late shifts. The TV pressure controls the shifts and it is computer controlled. Its program is defaulted to safe mode to save the parts. You have to work the throttle to get a better reaction.



Run it it TH all the time for better shifts and more predictable actions.

 

[JCleary]

No, they have not fixed the fluid circulation in park. Sometimes ya really gotta wonder.



You should not be getting the hesitation when you put it in gear. The check valve is supposed to stop the drainback and give positive engagement immediately. I suspect it stuck open and leaking back. My 05 will roll out immediately after starting and putting into gear. Most of the newer act this way so it is not what I would consider normal.



Shifting to OD is a computer controlled thing based on multiple parameters. Throttle position plays a part, so does load, speed, and TH. Hanging at WOT throttle is normal as is the late shifts. The TV pressure controls the shifts and it is computer controlled. Its program is defaulted to safe mode to save the parts. You have to work the throttle to get a better reaction.



Run it it TH all the time for better shifts and more predictable actions.

Where's the check valve located?



I have noticed that T/H seems to work better.

 

[JoelMartin]

One thing I have noticed with mine is it really clunks when shifting into 4th under lots of throttle. Anyone else notice this?

 

[cerberusiam]

Where's the check valve located?



I have noticed that T/H seems to work better.

IIRC, return line close to the cooler output fitting. They move the stupid things around too much to remember. Its relatively easy to fix the drain back and circulation problem. That check valve is a POS problem so most toss it and change 2 valves in the VB to solve the problem. Plus you can idle in park and not worry about toasting the trans.

 

[cerberusiam]

One thing I have noticed with mine is it really clunks when shifting into 4th under lots of throttle. Anyone else notice this?

No, mine is smooth and positive even with the Smarty turned up. No clunks, bangs, or rattles.

 

[JCleary]

IIRC, return line close to the cooler output fitting. They move the stupid things around too much to remember. Its relatively easy to fix the drain back and circulation problem. That check valve is a POS problem so most toss it and change 2 valves in the VB to solve the problem. Plus you can idle in park and not worry about toasting the trans.

I'm debating postponing my suspension lift and doing the transmission first. Just a TC, VB, billet input and maybe a flexplate. Right now I can't see building the whole thing with only 1k on the clock.



But I could easily see myself killing the stock auto in short order with 35" tires, 3. 73's and a Smarty.



Boy, my girlfriend will be po'd if I mod the trans instead of getting a suspension.



Direct quote from my girl:



"I fully endorse you buying rims, tires, and a lift. But thats IT!#@$%! You are NOT going to do this aGAIN!"



Apparently she wasn't too happy with the expenditures on my '03. She did like the truck on dyno days, though...



He he. Gotta love her.

 

[cerberusiam]

But I could easily see myself killing the stock auto in short order with 35" tires, 3. 73's and a Smarty.

Yep, the stock setup does not like that unless one is VERY conscientious. :-laf



At least do the VB and get some more pressure in it to minimize the wear.



Oh, and good luck with GF.

 

[wantabe351]

I notice at times my trans will clunk,almost like bang into 4th at times,,but it might be the edge box causing this problem,it controls the map signal and that reflects engine load and computer adjust by what it gets... .

 

[JCleary]

Yep, the stock setup does not like that unless one is VERY conscientious. :-laf



At least do the VB and get some more pressure in it to minimize the wear.



Oh, and good luck with GF.

Thanks



Last night I spoke with the guys at Suncoast (John and Ron, I think)



I was told by them to swap out my converter, flexplate and input shaft, and I did not need to swap valve bodies. They said the 48RE has good line pressure, and the only reason I would want to change the VB is to get firmer shifts. If I like the shifting now, leave the VB alone.



The TC/flexplate and input shaft are supposed to hold mid-400's in the hp dept.



He said that it's easy enough to swap the VB out at a later date anyway.



This auto-trans mod decision making is difficult...

 

[cerberusiam]

Thanks



Last night I spoke with the guys at Suncoast (John and Ron, I think)



I was told by them to swap out my converter, flexplate and input shaft, and I did not need to swap valve bodies. They said the 48RE has good line pressure, and the only reason I would want to change the VB is to get firmer shifts. If I like the shifting now, leave the VB alone.



The TC/flexplate and input shaft are supposed to hold mid-400's in the hp dept.



He said that it's easy enough to swap the VB out at a later date anyway.



This auto-trans mod decision making is difficult...

The stock pressures are not bad if you stay stock. The problem is a lower rpm's they don't hold as well and with a lot of stop and go driving plus big tires it tends to slip the clutches a bit. Of course if you raise the pressures you have to change other things to maintain the same shift charachterisitcs. Its a never ending battle.

 

[JoelMartin]

I notice at times my trans will clunk,almost like bang into 4th at times,,but it might be the edge box causing this problem,it controls the map signal and that reflects engine load and computer adjust by what it gets... .

Mine is stock and does the same thing.