4R70W or 4R75E

[Granddaddy Marq]

I'm about to do a motor swap. The motor I'll be installing has (what I was told) a 4R70W transmition built by 88grandmarq. The transmission that's in the car now I believe is a 4R75E. The donor car was an 03 300B, the recipient is an 04 300B. I don't know how to determine the difference between the two transmissions. What are the pros and cons in swapping these out? Should I swap them at all? The 4R70W has 115000 miles and been rebuilt, the 4R75E has 138000 miles and hasn't been touched. I know once the swap is made there will have to get some tuning done. Will there be a tuning issue with this swap? Or wiring issue?

Tag on 03 trans.

[martyo]

Swapping the trans will require a new tune.

[Bad_S55]

I'm a little rusty, I haven't dealt with this since August, but I believe it was the vehicle speed sensor reluctor wheel that needed to be changed. Otherwise, you won't really notice a difference. You won't need a tune. When the trans blew apart in my friend's '03 300A, we put in a 4R75. Aside from more crisp shifts from the new clutches, no difference we noticed, & his is a Trilogy car.

[Granddaddy Marq]

Swapping the trans will require a new tune.

Marty your at the top of my list for tuners. But it's a short list. Your also at the bottom. I will be contacting you and Jeff for custom tuning when we get this project going. We've had a very busy winter, my son's and I just haven't had the time to tackle this yet.

[martyo]

Marty your at the top of my list for tuners. But it's a short list. Your also at the bottom. I will be contacting you and Jeff for custom tuning when we get this project going. We've had a very busy winter, my son's and I just haven't had the time to tackle this yet.

We are ready when you are!

[88grandmarq]

The main difference between 2003 and 2004 transmissions is the output shaft ring gear and how the OSS reads the speed signal. 2003 and older transmissions have 6 holes in the ring gear. 2004 and newer have 24 teeth on the ring gear. I am told you can change this setting in the PCM with a hand held tuner, but I have never personally done it.

Its a very strong transmission and will shift VERY firm and unless you abuse it severely (IE run it out of fluid, try to tow 30,000lbs with it, etc) it shouldnt break any time soon.

[Granddaddy Marq]

Thank all of y'all for the responses. I'm going to put the 4R70W in as long as the tuning isn't problem. One more question has anybody pulled motor and trans out the top with them together? Or should I separate them? Motor out the top trans out the bottom.

[Chayton]

Thank all of y'all for the responses. I'm going to put the 4R70W in as long as the tuning isn't problem. One more question has anybody pulled motor and trans out the top with them together? Or should I separate them? Motor out the top trans out the bottom.

From what I recall it is suggested to pull motor out the top trans out the bottom.

[jwibbity]

Just an fyi marty this is my wrecked vehicle granddaddy now has. He has in his possesion the handheld tuner I got when I did the eaton swap with you guys.

[martyo]

Just an fyi marty this is my wrecked vehicle granddaddy now has. He has in his possesion the handheld tuner I got when I did the eaton swap with you guys.

Roger that good buddy.