- Joined
- February 8, 2003
- Messages
- 9,824
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- City, State
- Sacramento, CA 95827
- Year, Model & Trim Level
- 1992 XLT
One of our members was kind enough to send me an article on some of the changes made to the 4R70W in 2004. I have not had a chance to get my hands on that recent a model to look at, but was aware thatsomething was up when they increased the torque handling capacity and came out with the 4R75W.
To back up, for those unfamiliar, somewhere along the way FORD started to standardize their naming of transmissions. The first number (4 in the case of 4R70W) stands for the number of forward gears. the R stands for rear wheel drive, the 70 (or 75) is torque handling capability [add a zero at the end and you have the torque capacity in foot lbs - 70 = 700, 75 = 750] and then the W in the case of the 4R70W stands for Wide ratio gearing. Initially FORD used an E on the new all electronic versions of older trannies when they were introduced (AXODE AODE 5R55E etc). The return to a 4R70E and 4R75E is still somewhat a mystery, unless it was designed to denominate a standard gearing ratio tranny as opposed to the wide ratio 4R70W. But I digress...
In 2004 the venerable 4R70W got some significant changes made to it. Remember the 4R70W traces it's lineage to the AOD, which has been around nearly 30 years. the 4R70W was born in 1996 from the AODE. Significant changes occurred in 1998, and some smaller ones since, but nothing like this.
The changes are as follows:
1. redesigned pump and stator assembly
2. redesigned intermediate clutch assembly
3. redesigned forward-clutch drum (with a new Sun shell as well)
4. redesigned center support
5. new style anti clunk spring (now called an anti rattle clip)
6. redesigned transmission case
7. shorter output shaft speed sensor
8. redesigned ring gear
FORD says none of these parts are reverse compatible. While I understand what they say, I do know that in the past they have said that and ingenuious folks have found ways to work around and MAKE them reverse compatible. Still, at this juncture I'll take them at their word.
One of the interesting things about redesigns by the manufacturer is that they highlight problem areas - usually already well known and with existing aftermarket fixes.
Here is what we know about the 4R70W in terms of weak areas. The pump sealing rings have been a minor problem area and often that has led to problems in the forward clutch area due to inadequate pressure. Aftermarket one piece teflon seals have appeared in an effort to solve this. Also drilling the feed hole to the forward clutch circuit is also not uncommon. The direct drum had similar issues with scarf cut type sealing rings on the output shaft feed, and that was fixed in the aftermarket by adding one piece sealing rings (which FORD even includes now in their rebuild kits as well.) The intermediate clutch was not a problem area to my current knowledge, but FORD has upped the size of the apply piston in their upgrades.
Let's look at the upgrades one by one.
1. Intermediate piston
The old intermediate piston design had a piston that was .550 inch wide and that used lip seals. The new one is .690 wide and has a bonded seal. The old piston had a bleed hole, and the new one uses a checkball capsule. The old spring retainer has been eliminated, and in its place there is a case mounted wave spring used as a return spring.
2. Pump
The pump stator has a deeper sealing ring groove and FORD has gone to a plastic butt cut sealing ring. The pump body was redesigned to accomodate the larger piston for the intermediate clutch and elimination of the return spring assembly.
3. Forward Drum
The forward drum was changed to provide a triggerring mechanism for a new speed sensor.
4. Sun Shell
The sun shell was changed from a ferrous material to aluminum to allow operation of the forward clutch sensor. This meant using some rivets to retain the shell to the sun gear (I openly wonder the strength of this setup).
5. Center Support
The center support has yet another notch cut in it to accomodate the new speed sensor. In 2002, FORD apparently eliminated the old style "clock spring" anti klunk spring in favor of a new style "clip" looking thing. I plan to investigate the reverse compatability as I HATE the old style. For those interested the new style is FORD P/N 2L3Z-7F277-AA.
6. Output Shaft Speed Sensor
The old output shaft speed sensor was made .100 shorter, and instead of triggerring off the holes in the ring gear, it now triggers off the parking pawl teeth, which have been made longer. I suspect the days of ruining the output shaft sensor on disassembly are now gone.
7. Case
Finally, the case has been slightly redesigned to accomodate the added sensor (turbine shaft speed sensor) on the forward drum.
I do not know exactly how the 70 became a 75, but someone earlier claimed there was a running part change in the planetary assembly that they attributed the increase in torque handling to.
I am not sure how long this link will work, but here is a link to the article:
http://www.atsg.biz/articles/pdf/4R70W Supplement.pdf
To back up, for those unfamiliar, somewhere along the way FORD started to standardize their naming of transmissions. The first number (4 in the case of 4R70W) stands for the number of forward gears. the R stands for rear wheel drive, the 70 (or 75) is torque handling capability [add a zero at the end and you have the torque capacity in foot lbs - 70 = 700, 75 = 750] and then the W in the case of the 4R70W stands for Wide ratio gearing. Initially FORD used an E on the new all electronic versions of older trannies when they were introduced (AXODE AODE 5R55E etc). The return to a 4R70E and 4R75E is still somewhat a mystery, unless it was designed to denominate a standard gearing ratio tranny as opposed to the wide ratio 4R70W. But I digress...
In 2004 the venerable 4R70W got some significant changes made to it. Remember the 4R70W traces it's lineage to the AOD, which has been around nearly 30 years. the 4R70W was born in 1996 from the AODE. Significant changes occurred in 1998, and some smaller ones since, but nothing like this.
The changes are as follows:
1. redesigned pump and stator assembly
2. redesigned intermediate clutch assembly
3. redesigned forward-clutch drum (with a new Sun shell as well)
4. redesigned center support
5. new style anti clunk spring (now called an anti rattle clip)
6. redesigned transmission case
7. shorter output shaft speed sensor
8. redesigned ring gear
FORD says none of these parts are reverse compatible. While I understand what they say, I do know that in the past they have said that and ingenuious folks have found ways to work around and MAKE them reverse compatible. Still, at this juncture I'll take them at their word.
One of the interesting things about redesigns by the manufacturer is that they highlight problem areas - usually already well known and with existing aftermarket fixes.
Here is what we know about the 4R70W in terms of weak areas. The pump sealing rings have been a minor problem area and often that has led to problems in the forward clutch area due to inadequate pressure. Aftermarket one piece teflon seals have appeared in an effort to solve this. Also drilling the feed hole to the forward clutch circuit is also not uncommon. The direct drum had similar issues with scarf cut type sealing rings on the output shaft feed, and that was fixed in the aftermarket by adding one piece sealing rings (which FORD even includes now in their rebuild kits as well.) The intermediate clutch was not a problem area to my current knowledge, but FORD has upped the size of the apply piston in their upgrades.
Let's look at the upgrades one by one.
1. Intermediate piston
The old intermediate piston design had a piston that was .550 inch wide and that used lip seals. The new one is .690 wide and has a bonded seal. The old piston had a bleed hole, and the new one uses a checkball capsule. The old spring retainer has been eliminated, and in its place there is a case mounted wave spring used as a return spring.
2. Pump
The pump stator has a deeper sealing ring groove and FORD has gone to a plastic butt cut sealing ring. The pump body was redesigned to accomodate the larger piston for the intermediate clutch and elimination of the return spring assembly.
3. Forward Drum
The forward drum was changed to provide a triggerring mechanism for a new speed sensor.
4. Sun Shell
The sun shell was changed from a ferrous material to aluminum to allow operation of the forward clutch sensor. This meant using some rivets to retain the shell to the sun gear (I openly wonder the strength of this setup).
5. Center Support
The center support has yet another notch cut in it to accomodate the new speed sensor. In 2002, FORD apparently eliminated the old style "clock spring" anti klunk spring in favor of a new style "clip" looking thing. I plan to investigate the reverse compatability as I HATE the old style. For those interested the new style is FORD P/N 2L3Z-7F277-AA.
6. Output Shaft Speed Sensor
The old output shaft speed sensor was made .100 shorter, and instead of triggerring off the holes in the ring gear, it now triggers off the parking pawl teeth, which have been made longer. I suspect the days of ruining the output shaft sensor on disassembly are now gone.
7. Case
Finally, the case has been slightly redesigned to accomodate the added sensor (turbine shaft speed sensor) on the forward drum.
I do not know exactly how the 70 became a 75, but someone earlier claimed there was a running part change in the planetary assembly that they attributed the increase in torque handling to.
I am not sure how long this link will work, but here is a link to the article:
http://www.atsg.biz/articles/pdf/4R70W Supplement.pdf
