I have a 2003 Durango with the 4.7 engine and the 545RFE transmission. Is there a way to add a switch or otherwise mod this transmission so that the lockup clutch can be made to STAY engaged?

I really dislike the way this transmission goes in and out of lockup when using cruise control on the interstate. The slightest of grades and the lockup disengages, only to re-engage when the vehicle crests the hill. Even if I had to remember to turn a switch off when coming to a stop, that would be OK with me.

I have an electronics background, so if this involves soldering wires, adding components or performing other electrical procedures, I'm fine with that.

Any help will be greatly appreciated. Thank you.

 

On this rig I know of one person that did this. Not sure how he did it but I know it can be done. The problem with this mod is that the user in question did it and messed the trans up. He had to do a complet build up and install a shutter on the torque convertor. Even after this mod he still didn't get it done because he didn't lesson to this!

There is a OD off button on the shifter that does just that function. It locks the gearing out of OD but locks the torque managment which keeps the torque convertor locked.

It's all ready in the truck. But I read a different question here. You want to also use OD so in this case I would tell you to do the TPS mod and that should help. Also, you can have the PCM flashed and with some upgrades have the torque management removed. Also installing a shift kit from Transgo will help.

All this information is on here if you search the 1st generation Durango Section using this Advanced Search.

Also check here: Do It Yourself (top questions and answers)

Have a great day and hopefully I helped....

 

cruise at a higher speed ont he highway, i run at about 2k rpms on the highway (about 80) and the cruise hold its just fine up/down hills, its when i run aroun 60-65 at about 1.5k RPMs that i have this issue, and as said turning off the OD does this, but is only good until about 45 at the top of the range, otherwise i wouldnt mess with it because as hydra said, if you dont know EXACTLY what you are doing you will likely screw up the transmission

 

It's not really a 5th gear versus 4th gear issue, it is a Lockup Clutch issue...no matter what gear it may be in.

When driving with the clutch already locked up, the SLIGHTEST pressure on the accelerator and the thing will unlock! That's what I'm trying to change. I want to be able to go almost WOT and have the clutch stay locked up.

Hydrashocker, if you could find out more about the fella that you know of who did this, I would at least like to learn what he did to see if I want to try it. If his solution looks to radical, I'll pass. I have already ordered the Transgo shift kit but it has not arrived yet. As for your other suggestions, they sound interesting but I don't know where to go. For example, where can I get the PCM flashed?

I've done some reading here about the TPS Mod and there seems to be varied opinions as to whether it is worth messing with.

I appreciate any additional information.

 

the OD off unit also keeps the transmission TC in lock up longer, it was put on there for towing so it does this to reduce slip in the transmission which will reduce heat, and extend the life of the transmission, so it essentially does -what you are looking for, i know that i can pul some hills where i live at 1500 RPMS w/ OD off but it jumps to like 2200 w/ OD on i usually drive around town w/ OD off

 

No, it really doesn't. I am very familiar with the OD OFF function, having driven an '04 HEMI RAM for several years with this same transmission. Also did a lot of towing with that rig and used the OD OFF function quite a bit.

I can't cruise the interstate with the overdrive OFF...the RPM is too high. Besides, it sort of defeats the whole purpose of having the 5th gear overdrive. And even with the OD off cruising in 4th gear, the same thing happens - the slightest grade or a little extra pressure on the accelerator and she unlocks.

I am looking for something that will allow me to engage the lockup clutch and keep it engaged, no matter whether I am in 3rd, 4th or 5th gear. If it is a switch, I'll have to remember to shut it off when coming to a stop, but that's OK.

 

Buy another D with the 5.9. That will do it.

Otherwise, you have a 4.7 with an ELECTRONICALLY CONTROLLED transmission. You are getting exactly what the computer is telling the trans to do. An Hypertech or Superchips for the 4.7 MIGHT change shift points and responses to your liking. MIGHT.

IndyD

 

i agree, with Indy, the OD off does what you want around town (im pretty sure i said that its only good up to 40 or 45 ) and on the highway you just need to cruise at a higher speed to keep the revs up a little higher, or like indy said, get a 5.9

 

www.bgperformancepcm.com or you can try www.sctflash.com/ but I can't remember if Torque Management is removed from sct.

Get a TPS and do the Mod.

Also, do a fluid filter change to ATF+4 when you do the shift kit whick you will do anyway.

 

BTW<--------- This guy was years ago and like I said he messed the trans up.