Hey guys. This weekend I'm going to replace the transmission in a 1997 Econoline with a 4.6 liter engine. Research tells me this this is a 4R70W transmisison. Further research tells me this is nearly identical to the AODE except for lower gear ratios and 7/8" in length... Here's the story. It's a delivery van for a flower shop. It has 320,000 miles and doesn't smoke or leak a drop. Really a great van, but they will be replacing it soon with a new one. The transmission died this week. They don't want to spend the money on a full rebuild as they only need the van to last them about another 8 months, so I'm going to get a trans from Pull-A-Part this Saturday and install it for them Sunday. I just need some info for my hunting... First, I'm going to look for a donor vehicle that's either been in an obvious wreck or has detectable engine damage, blown head gasket, etc. and something that doesn't have insanely high miles. Basically I want to improve my odds by finding a vehicle that wasn't scrapped because of a bad transmission. When I find a likely candidate, I'll drop the pan and look for shrapnel, see if it smells burnt, and if not, that's my transmission. I know the 4R70W came in E150's, F150's and even a few cars. I'm hoping to find a van simply because it will be so much easier (I think) to pull, but I'm open to other ideas. Where else should I look? There are a bunch of Cougars, Vic's and Thunderbirds at the yard... Is there any reason why I might run into trouble getting a trans from something besides a van? Different tail housings, wiring, anything like that? And what about an AODE? Is there any reason an AODE wouldn't be a plug-and-play swap, other than maybe driveshaft length? I am under the impression that they have all the same mechanical and electrical connections and are no different except for gear ratios and length. Am I right? Flowers aren't very heavy, so I don't see the gearing being a problem... Finally... I assume it's mandatory to find a donor vehicle with a 4.6 liter or other mod motor, because the bolt pattern is not the same as a Windsor. Correct? Thanks for any help you can provide...
Yes, you need a transmission from a modular engine car/truck. I don't believe that an AODE is either "plug and play" or a good substitute - they are NOT as strong - many internal differences. Get a 1997 or later 4R70W trans from as similar vehicle as you can. It is likely that the truck transmissions are stronger than those in a car - maybe not on the later model 4Rs.
I looked for hours, unfortunately there were absolutely no 4R70W's anywhere in the yard, let alone one from an obvious wreck. What I did get though, is an AODE from a Town Car. Not too many miles on it, and the car had obviously had been ground up on a guardrail like a cheese grater, so I think the trans is probably good. Fluid is a nice bright red, doesn't stink... I'm gonna try this. I don't think the strength will be an issue as this van never carries significant weight. (The original trans did last 320,000 miles) And as I said the thing doesn't need to last or else I'd be getting it rebuilt. The electrical connections seem to be identical, trans lines and dipstick tube are the same, linkage is the same... The AODE is 7/8" shorter and I think that's in the tail, which is the only part that appears to be any different at all. So I'm unsure as to whether the driveshaft is going to fit, but everything else is a go. I might end up having to get another driveshaft or might try to change the yoke. I'll report my progress tomorrow...
EVEN IF THE CONNECTORS ARE THE SAME IT DOES NOT MEAN IT IS WIRED THE SAME!!! You may just fry your trans module.... or at minimum it will shift at all the wrong speeds.... You should get one that comes out of an e150.... it's better to be safe than sorry.... jmo
Noticed that... I think I'm covered there. This is a 1994 transmission replacing a 1997. In 1998 they changed to a different pinout with the same connector. 1992-1997 AODE and 4R70W's are electrically the same, although it might throw a code due to the different gear ratios. But I think that's an issue when you swap the other way - 4R70W in an AODE car. Computer thinks the trans is slipping or something. Anyway, apparently the spline count and length of the output shafts are all the same too, it's just the tailhousings that differ between these two. I think I can swap tailhousings to accommodate the bigger slip yoke. Will find out tomorrow... I guess I'll either get lucky or do some more junkyarding...
I do see one potential problem - because the gear ratios are lower in the '97 trans, I could see the possibility of it shifting too early. If that happens, I'm thinking I might try to swap the ECM from the donor vehicle, if it's compatible...
Research continues... I think I'm gonna swap the shift and TCC lockup solenoids along with the internal wiring, from the '97 trans into the '94. Pinouts may be the same but impedance on the solenoids likely isn't. Might swap the valve body too. Apparently people do this in Mustangs. Damnit, how do I let myself get into this stuff?
Update: Last weekend I did go ahead and put the AODE in there. I swapped the valve body, solenoids and wiring from the 4R70W into it. You may now commence the chorus of "I told ya so." I don't know if the junkyard AODE was bad, or if the (meticulously compared, seemingly identical) valve bodies were incompatible, but whatever it was, I didn't get the chance to see it throw codes, 'cause it didn't move an inch. I had theorized that although going from AODE to 4R70W throws ratio codes because the output is moving at a lower RPM than the PCM expects, going the other direction might not throw codes, because the output shaft moving faster than (engine RPM x gears) happens all the time in normal conditions. I mean the PCM doesn't freak out when you're driving downhill, does it? Anyway... I will never know, and I don't care. I went and got a '97 4R70W, spent about 5 hours installing it, then drove all over the place today. Job done, lesson learned...
