Step-by-Step 4R70W Automatic Transmission Installation

[chuzie]

****ATTENTION potential 4R70W installer**** If you intend to reference this thread in accomplishing your installation, I STRONGLY urge you to carefully read through the ENTIRE writeup. Modifications were made along the way so everything is not necessarily is perfect operational order.

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This article will guide you, step by step, through the installation of a 4R70W automatic transmission into a Early Bronco with a C4 automatic, D20 J-shift transfer case, and 302 engine.

I used info in the following threads to gain general information regarding different aspects of the swap.

http://www.classicbroncos.com/forums/sho...t=4R70W+ZF

http://classicbroncos.com/forums/showthr...p?t=184809

http://classicbroncos.com/forums/showthr...915&page=3

http://classicbroncos.com/forums/showpos...tcount=194

http://classicbroncos.com/forums/showpos...ostcount=1

The C4 has served me well but with the 35" tires, 4.56 gears and my personal requirement to make this rig drive to events, I was forced to install something with overdrive. With the C4, my RPM sat around 3,000 @ 60MPH which was unacceptable to me. I have no desire to travel faster than 60 because this huge rolling brick becomes a massive drag device and MPG go even further down the toilet. I prefer to see my RPM cruise around 2300 RPM and with the 0.7 gear ratio of the 4R70W, I was able to achieve that goal.

Below is my list of parts which I have added as of the conclusion of the project which totaled $1,980.00

4R70W-junkyard-'99 AWD V8 Mountaineer -$320 + $30 core
starter-junkyard-'99 AWD V8 Mountaineer-$ Included w/ transmission
converter-junkyard-'99 AWD V8 Mountaineer-$ Included w/ transmission
flexplate-junkyard-'99 AWD V8 Mountaineer-$ Included w/ transmission
ZF crossmember-BC Broncos-ZF-$125.99
ZF adapter-BC Broncos-50-4303-$441
controller-Baumann-OS1-$565
harness-Baumann-HPF2 or HPF2A-$ Included w/ controller
shift cable-Lokar-ACA-1808-$52
Lokar Dipstick -$$105.90
JB Fab Twin Sticks-$149.03
Aux cooler lines-$23.99
Adapter seal 471950-$18.36
Misc fitting, bolts, and other crap-$59.61
14 quarts of trans fluid and trans filter:$90.00

Got the 4R70W from a 1999 Mountaineer AWD (also referred to a 4WD or 4x4) 5.0 with 100K miles from a local salvage yard.








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To prevent having to gut the transmission to replace the output shaft as required for other 4R70Ws utilizing the Advanced Adapters 4R70W to D20 adapter, I specifically utilized the AWD 4R70W variant as its shaft length is sufficient to use the ZF to D20 adapter while only needing to cut 1/2" from the end. Eliminating the transmission dissasembly is very appealing as is the flexibility of using a ZF adapter for potential future upgrades if need be. The other advantage of using the ZF variant is the cost being less than the other adapter.

I measured 1/2" from the end of the shaft and used some blue painter's tape as a guide. My cutoff wheel worked well but I was careful to constantly rotate the shaft as I was cutting so as to prevent an angled cut.



After the cut, the shaft came to 5.938"




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I chose to do the cut first before pulling my C4 from the Bronco in case I botched something up and had a useless transmission. With the cut successful, the dissassembly could commence.

I measured the distances of the front and rear driveshafts for reference before and after the installation of the 4R70W. My lengths are different than stock as I have a 4-link in the rear.

Front: 24-3/4"
Rear: 35-7/8"

Since I don't own a transmission jack, I just used cargo straps on the front and rear to lower the transmission assembly to the floor.

Next, I pulled the flexplate only to find that, after doing so, it was actually an AOD plate as depicted by the AOD stamp on the back. This makes sense as my motor was from an 89 Mark VII. Just wish I had noticed this before I removed the flexplate. Now I have a spare if anyone is interested.



Here is my C4 next to the 4R70W



Since my 4R came already pulled, I do not have mounting bolts for transmission to engine nor do I have a dipstick. The length of the 4R mounting bolts is different than the C4 by about 0.465" which is due to a difference in the bellhousing thickness. This means you need to pickup six 7/16 x 2.25" bolts and start figuring out what you are going to do about a dipstick.