96 5.0 explorer 2wd 4r70w transmission swap to 2002 4r70w from 3.8 v6 mustang

[TelMinz]

Is this swap possible? I know the transmission will bolt up and that the wiring harness on the truck will need to be repinned. But will the speed sensor work, or would a signal converter like the Dakota digital work?

 

[410Fortune]

should work yes
Whay year was the 3.8 stang? EDIT i see its a 02

3.8 and 5.0 have same bellhousing
You could add the speed sensor drive wheel from the output shaft of your 96 to the output shaft of the newer 3.8 trans
I did it with a dremmel and diamond grinding bit, basically the drive wheel is held in place by a bb
Then bolt on your 96 tailhousing and you can keep the VSS

You will want to use the DTRS from your 96, as the 98+ transmissions use a digital sensor, the 96 uses an analog sensor

Rewiring the solenoid pack from the 94-97 4r70w to the 98-04 setup is straight forward, easy enough to do while the trans is out.
I like to upgrade the older 4r70w to use the 98+ style internal wiring harness and solenoid pack anyways.

 

[boominXplorer]

^^^ what he said. The VSS on the tailshaft is necessary for the 96 computer to tell the trans to shift.

 

[410Fortune]

you COULD use a dakota digital device to take the place of the now missing VSS, but its easier and better to just re use the 96 unit when possible

 

[TelMinz]

Rewiring the solenoid pack from the 94-97 4r70w to the 98-04 setup is straight forward, easy enough to do while the trans is out.

You’re talking about repinning the body harness, correct?

So all I need to do to make this work is add the speed sensor drive wheel from my old transmission, install the old tail shaft housing, use my old dtrs, and repin the harness?

 

[410Fortune]

yes and yes

I am talking about re pinning the harness on the truck side of things
Basically it works like this, the 94-97 version of the 4r70w had three separate power wires entering the transmission, 3 ea 12V + feeds. In 98 they did away with the multiples and used a single 12V+ feed into the transmission wiring harness, they also moved some pins around.
On my personal vehicles whenever I have a 96-97 4r70w I upgrade them to the 98+ style solenoid wiring harness and do this re pin. It can even be done in the vehicle with the transmission in place, but it is a PITA. I would rather do it while the transmission is out

Next remove the tailhousing from your 96 transmission and pull the speedometer drive wheel off
You will see the check ball (stainless steel bb) that is used to retain the drive wheel
Measure the location and duplicate the hole/dimple in your new 02 trans, I used a dremmel when I did one of these years ago, it worked perfectly.

Now you can slide the speedo drive wheel ontol the 02 output shaft and re use your 96 VSS drive gear, thus giving you a 96 style VSS and tailhousing on a 02 transmission

Swap the DTRS to the 96 unit and you are good to go!!!!!!!

 

[TelMinz]

yes and yes

Thank you for all the great info, I will be using all this in the near future so thanks again.

 

[CDW6212R]

All good stuff, but also make it a new DTRS. The original range sensors were poorly weather proofed, moisture got in and caused malfunctions. Replacements should come with a better design of the sealing perimeter, but always replace the older pre-98 DTRS units.

 

[TelMinz]

A direct write up on the harness rewire for anyone that might need this in the future.

 

[CDW6212R]

yes and yes

I am talking about re pinning the harness on the truck side of things
Basically it works like this, the 94-97 version of the 4r70w had three separate power wires entering the transmission, 3 ea 12V + feeds. In 98 they did away with the multiples and used a single 12V+ feed into the transmission wiring harness, they also moved some pins around.
On my personal vehicles whenever I have a 96-97 4r70w I upgrade them to the 98+ style solenoid wiring harness and do this re pin. It can even be done in the vehicle with the transmission in place, but it is a PITA. I would rather do it while the transmission is out

View attachment 422671

Next remove the tailhousing from your 96 transmission and pull the speedometer drive wheel off
You will see the check ball (stainless steel bb) that is used to retain the drive wheel
Measure the location and duplicate the hole/dimple in your new 02 trans, I used a dremmel when I did one of these years ago, it worked perfectly.

View attachment 422672
Now you can slide the speedo drive wheel ontol the 02 output shaft and re use your 96 VSS drive gear, thus giving you a 96 style VSS and tailhousing on a 02 transmission

Swap the DTRS to the 96 unit and you are good to go!!!!!!!

That's really good to hear, that the VSS drive gear can be fitted to a newer shaft. How deep does that hole need to be for the BB, the radius in depth or what?

 

[410Fortune]

half the depth/height of the bb
The pic above shows when I did this, but my truck was a 4x4 and that tailhousing is on the 4406 t case
His tail housing will be similar on the back of the rwd transmission

 

[CDW6212R]

Thanks, I have just one 97 4R trans, but will likely need another one for my older Ford projects. I wonder what the 6R output shaft is like, splines and size. I don't plan to use one of those for an older car except my 98, but it's interesting to see what changes Ford made over the years.

 

[TelMinz]

Update on this swap for anyone interested in doing something similar and they find this info. It’s in and working great now. For some reason I did not have to add the output speed sensor to the new transmission. I guess the 96 5.0 explorer used the same speed sensor as the later models? I had to open the transmission and swap out the shaft for the rooster comb/shifter with the old one. I repinned the harness for the new electronics. The torque converter felt funny the first trip, but it’s been doing great otherwise, no weird shifts or anything else.

 

[TelMinz]

Update: All is not well. I got in the truck today to go and get a new windshield installed, and the transmission started slipping. Im looking at the scan tool, it says it’s calling the torque converter for lock up, but the torque converter just slips. I can get up to about 55, then the slipping takes over and the engine just revs when giving it gas while the truck coast to about 30. But I can put it in 2 manual and it does not slip. I’m not sure where to go from here, any advice would be appreciated. I checked fluid per the manual and the level is sufficient. I’m thinking about swapping the old electronics back in and repinning the harness back to stock. Maybe even use the old valve body? The previous transmission worked great, but wasn’t flowing fluid for some reason so it would over heat, which I believe was due to lack of flushing the coolant lines out when the original trans died. So maybe the valve body will work in this new transmission?

 

[C420sailor]

I’m not a trans pro, but even if the TC lockup clutch fails, it shouldn’t slip/false neutral like that. It should drive fine, just without lockup…which means slightly higher cruise rpm, higher fluid temps.

I wonder if this trans was on its way out, but was handling the light ‘stang. Putting a worn trans in a 5,000lb truck behind a 302 may have exposed its weaknesses…

 

[C420sailor]

I’d drop the VB and check everything. VB, accumulators, servos, solenoids. Double check your pinning, obviously.

 

[CDW6212R]

If the trans was not worn out before and the pan isn't full of friction material, or parts, then the problem should be fixable. But stop driving it now, diagnose it now and do whatever can be done, now. If the pan and fluid still seem to be clean, then go back at it with some new user serviceable parts. The valve body is usually the cause of any symptom of an old transmission. Something is wrong with the VB, or else the accumulators, their springs, or the PCM control. It's almost never the hard parts, which will be killed/ruined if you keep driving it with a bad symptom.

It is not very expensive to replace the solenoids, accumulators, those springs, and a few internal VB parts. Sonnax makes several VB part kits that improve overall performance, and durability(correcting wear items). Installing all of those is not quick and easy, but a very good mechanic can do it all, and any trans shop can if they are willing to. Most don't want to help to do those things, because they want the big bucks from a full rebuild. A rebuilt VB may often just be a used VB which passed a fluid function test, so they sell it with very little guarantee.

 

[C420sailor]

take a good look at that OD servo

 

[TelMinz]

The trans is brand new rebuilt monster transmission, I bought from a guy and he never installed it in his project as he went with a manual transmission instead. I dropped the valve body and found two valves stuck, the “bypass clutch control plunger valve” was stuck, I managed to free it up, but the “converter pressure limit valve” is fubar, no movement at all. I’m going to swap my valve body from the old trans in after I clean and check it. Hopefully that will fix it and be the end of my problems with this transmission

 

[Mbrooks420]

The trans is brand new rebuilt monster transmission, I bought from a guy and he never installed it in his project as he went with a manual transmission instead. I dropped the valve body and found two valves stuck, the “bypass clutch control plunger valve” was stuck, I managed to free it up, but the “converter pressure limit valve” is fubar, no movement at all. I’m going to swap my valve body from the old trans in after I clean and check it. Hopefully that will fix it and be the end of my problems with this transmission

Brand new and rebuild are two ENTIRELY different animals. I’d not be confident in its build quality if two things were hosed from the beginning.