4R55E to 5R55E swap possible?

[A Quiet Boom]

Can a 5R55E trans be swapped in place of a 4R55E? I know that it will physically bolt it the question is will the computer work with it etc. Vehicle is a '96 Explorer Limited 4wd. Thanks in advance.

 

[Jason_25]

I am relatively sure everything will work, as two tranny "experts" have told me they are identical trannies. But if I were you, I would try to confirm it with a dealership maybe or try to take a look at the wiring diagrams in the factory service manuals.

 

[A Quiet Boom]

I'm still trying to determine if the 4R I have is bad yet, if it is my brother (tmsoko) has a 5R. I bought the truck from a guy on the board who said the motor had locked up well when I got it I could turn the motor by hand but the was a "bad spot" that the starter couldn't spin past. Anyway I removed the motor to find that the flexplate was badly cracked and pulled away from the engine causing the torque converter to rub the back of the bell housing and the flexplate is bent such that the "bad spot" is really far from the engine and the starter gears won't engage in that area. My concern is that the tranny not the engine is what locked up possibly due to a bad mainshaft or something. I'm gonna put the motor in and see what happens and go from there. My brother was thinking that the computer wouldn't know how to shift the 5R since they didn't put those in until '97. I'm swapping a '99 long block into the truck to replace the "bad" engine that was in it. Maybe a computer from a 5R '97 OHV would work?

 

[yob_yeknom]

Your brother is correct. The transmission is completely computer controlled and a '96 computer couldn't control a '97 transmission.

I don't think swapping the computers would work either. The 4wd system was changed from '96 to '97, which would effect the computer.

 

[Jason_25]

John. the GEM controls the 4x4 system, not the PCM. What I'm saying the sensors and parts (are supposed to be) identical in both trannies. Like I've said before the reason the 5R55E is a 5-speed is that it adds O/D to 1st gear in the tranny there-by making it a higher ratio.

I'm not guaranteeing it will work, but it's definitely worth looking into.

 

[Majisto]

Originally posted by Jason_25
John. the GEM controls the 4x4 system, not the PCM. What I'm saying the sensors and parts (are supposed to be) identical in both trannies. Like I've said before the reason the 5R55E is a 5-speed is that it adds O/D to 1st gear in the tranny there-by making it a higher ratio.

I'm not guaranteeing it will work, but it's definitely worth looking into.

How do you add overdrive to the 1st gear? I thought overdrive was its on seperate high-range gear?

 

[Jason_25]

Just like you would add it to 3rd gear to make 4th on the A4LD and 4R55E.

 

[A Quiet Boom]

So is it possible that a 5R being controled by a 4R computer just wouldn't engage OD in first and therefore just operate like a 4R? I'm assuming 1st and 2nd gears on the 5R are farther apart than the 4R to "make room" for the new 2nd gear which is an overdriven 1st is this correct?

Lastly does this swap make any sense? If my tranny is bad should I just replace it with another 4R or would the potential hassle involved with installing a 5R be worth it? I'm assuming I could just plug in a manual computer and use a tranny controller at worst or possibly the '97 5R computer or even just the 4R computer at best.

I checked and found that both the 4R and 5R where available in '97 the question is how similar where the engines systems between '96 and '97, if they where identical this seems like a no brainer.

 

[Apten]

Since you are pretty close to St. Louis, I may be able to flash your EEC with a program that runs the 5R55. I'll check on that monday.

Brian

 

[Jason_25]

Brian, if you find out, please post and let us know. I want to see if you can make me a chip that makes my 4R a 5R.

 

[A Quiet Boom]

Who lives close to St. Louis? I'm in Ohio LOL

 

[Apten]

I'm in ohio all the time, it's not that far

 

[A Quiet Boom]

Well, I'll let you know how it goes on Tuesday, that's when I expect to be down with the engine swap. If indeed you could flash the computer that would be great and I greatly appreciate the offer. Would you need the whole truck or can you flash the computer if I sent it to you?

 

[yob_yeknom]

Originally posted by Jason_25
John. the GEM controls the 4x4 system, not the PCM.

But they feed off each other.

The 5R55E has slightly different gear ratios than the 4R55E.

The 4R55E offered in '97? I don't think so, nothing I have shows it. The 4R44E was in some Rangers, but not ones with the 4.0.

 

[Jason_25]

Yes true, I don't know the relationship between the two computers.

The reasons the ratios are different is because the O/D is applied to the gears. If you do the math, you'll see that it all works out. You have the 5R55E.

 

[Jason_25]

Here's an example.


5R55E and 4R55E 1st gear: 2.47:1
5R55E and 4R55E O/D gear: .75:1

5R55E (published) 2nd gear:1.87:1

You can make that number by multiplying 2.47 * .75 which equals 1.85.

Hope that helps.

 

[yob_yeknom]

I can't verify any 4R55E numbers (but I'm 99.9% positive it is the same with the exception that the 2nd gear doesn't exist), but I have a list of 5R55E numbers.

1st 2.47:1
2nd 1.87:1
3rd 1.47:1
4th 1.00:1
5th 0.75:1
R 2.10:1

Just in case anyone was wondering.

I remember reading a page by a member here of compiled info, but don't think the two sets of numbers matched up. I did some searching of information from Ford that I have and did come up with the numbers being the same though, so I take back my earlier statement of different ratios.

Brian, I hope you can make a 4R55E a 5-speed. I'm sure a lot of people here would pay for that.

I'm searching right now to see what I can come up with.

 

[yob_yeknom]

Didn't come up with much. Only thing I learned was when the selector is on the 2, with the 5R55E you're actually in 3rd gear.

 

[Majisto]

Does this link help anyone? Dead Link Removed

 

[Jason_25]

Originally posted by Majisto
Does this link help anyone? Dead Link Removed

That's actually the site I got my numbers from. Very helpful.