I did a bunch of research and decided to have this done in my Maverick. I want an overdrive trans, I don't want any electronic controls, and it needs to bolt to my 99 Explorer 5.0L. That is why I need the pre-93 AOD but AOD's have a bad reputation.... I have an AOD from a 1991 Mustang GT 5.0L and a 4R70W from a 93 Mark VIII. (old c-4 from my Mav in blue next to AOD) Mk.8 4R70W I talked to my trans builder and he said it would be $500 to build it and give a warranty. My trans shop will use the case, torque converter, 0.67 O.D. and valve body from the AOD, and they will use the much stronger gear set with a lower 1st and 2nd gears, steel drum (instead of the cast iron drum in the AOD) and the wider O.D. bands from the 4R70W. They will also modify the 3-4 shaft to prevent lock up in 3rd gear. That should get me good acceleration from a stop and still get maximum mpg on the highway. I'm not sure how to figure out what rear gears I need. A 0.67 OD is really steep and I don't want to be stuck in the carb's idle circuit at any speed below 70. I currently have a 8" 3.00:1 open diff. My dad thinks a 3.50 rear gear would be good, but I think I'll need something closer to a 3.80. I also want a trac-loc installed when I swap the gears.
That's a very reasonable price, I'm assuming for that they are just going to re-use all the clutches and such. One thing to note, with the stock valve-body you may have some gears holding too long before they shift, and others too short. I forget which ones do what. Silverfox offers an excellent valve body, that I believe can be suited to such a swap. Just something to consider while doing this. If it was a stock AOD I'd say go with the 3.80, but with the wider ratio, especially torquier 1st and 2nd gear of the 4R70W, I think you'll be satisfied with the 3.50, but that all depends on what you are doing with the car, and personal preference. AOD's tend to get a bad rep because the TV grommet goes, people don't realize it, and it burns the transmission up...in general the later model AOD's were pretty decent transmissions, and with a decent valve-body can be made to shift nicely.
Yep, I have over 700 drag strip passes some with nitrous on the AOD that was in my Bird... It's only mods are Trans-Go shift kit and hardened input shaft(broke orig on 2nd pass 1st time at track)... I may stick it in the Comet one of these days, have a fresh one for the 331... With a 3K or so stall, I doubt most can tell the difference between the 2.40 & 2.84 1st gear... May give you a tenth at the strip...
I also got a TransGo AOD HP shift kit for it, new in the box, plastic still sealed, off CL for $30, it lists on Summit for $89. I was going to have the trans shop install the shift kit when they do the build. Will that do it for required mods on a grand touring car? I'm not gonna pound on it. I want better reliability through use of heavier duty equipment like the 4R's gears and bands. The lower gearing is just a bonus. The guy I bought the trans mentioned something about a mod that adds an oil tube to the output shaft bearing....? or something like that. Any of you guys know about that? We have ordered the Lokar AOD TV cable for carbed Edelbrock intake. We will have to test fit the engine and trans together to figure out how much beating, I mean ADJUSTING I will have to do on the trans tunnel. I'll bolt up the AOD without the converter installed just for fitment adjustments to the trans tunnel before I give everything to the trans shop for the custom build. i want the trans shop to do the final install of the trans in the car for proper TV cable adjustment anyway.
That will be a big improvement, it won't change shift characteristics though, you may experience under light/medium throttle that the car wont even shift out of first until it gets to 3-4000RPM (using this RPM as an example, may be less) , and at WOT you will be over 6K RPM (which might be ok if your engine is built decently) Second gear then tends to get a very short amount of time, quickly shifting into third. Talk with your trans guy, hopefully he has experience with it, I know you can get custom valve bodies tuned for this swap that makes it behave "normally". If you do a google search plenty of this info will come up on various car sites with guys who have done it.
I never had any issue with late/high upshifts, one in the Bird would shift approx 5500 at WOT(or approx 1K over stock)... That's with the TV cable as short as possible and governor mod installed, without it shift points were approx same as stock just much firmer... One thing the kit will do is prevent slip if the TV cable breaks or comes loose, will just shift very early and go on without issue...
My trans guy mentioned something about also modifying the 3-4 shaft to prevent lockup in 3rd gear when he does the build. I got the shift kit after I talked to him. Think there will be any issues with the shift kit I got?
No a std ratio... I could see a wide ratio maybe giving a issue, solution would be NOT to install the governor mod that raises shift points... I dunno about any mod that effects third without also effecting O/D... Normally a AOD is approx 60% locked up in 3rd & 100% in O/D... I liked that arrangement in the Bird, but some eliminate lockup all together...
Not to be the negative Nancy here and no offense intended.. but I've driven and ridden in many performance cars/trucks with both transmissions and I would take the added benefits of an elctronically controlled valvebody and the improved front shaft design of the 70 over an AOD any day of the week. The added cost of a decent stand alone controller is well worth it once you start tuning over the longer run. Much more calibration flexibility to increase performance AND comfort. AFAIK, the lockup delete mod is primarily intended for those racers who want to "stay on the converter" through the lights. Lots of guys have done this same mod through the years but that was primarily before we had much more affordable controllers like we do these days. As for the rear gear choice. For mainly calm street and highway cruising.. 3.55 will be more than fine because the car is light. If you want to race around a bit more than the average Joe?.. no less than 3.70-3.80 rear gear and you'll still have nice mellow highway rpm's. If you're a nut like me on the roads?.. go to +4.00 ratios to allow you to reach the top of 3rd gear. Only ever used at the track with proper safety precautions, of course. lol
Rear tire size will be a factor also in gear choice to consider. Most don't realize it but a 3.50 gear with a 26" tire gives you a very similar rpm on the highway as a 4.11 on a 28" tire.
yep.. very true. you can also gear more mellow for daily driving and find yourself some short-walled 14" drag tires" for an occasional strip run too. Stickier 24" tall tires really wakes these little motors right the hell up. Have even seen guys running 13" slicks too. Sinfully ugly looking and you'll feel the air getting under the chassis a bit more on the big end.. but well worth the time for a simple bolt on you can store in the trunk for the ride home.
I have the AOD with EFI and 3.55. I wanted to retain the converter lock up for better fuel mileage. I do not intend to race it and my FWHP is probably 400 hp. I let my trans and converter builder talk me into a non-lock up converter. I regret it. I probably have 300-400 RPM slip at 70 MPH in OD. Not at all what I was looking for. Micah
I will definitely keep my stock 91 Mustang AOD lockup torque converter. (on the right) Having a lockup converter is almost like having another gear, In my truck, I can see and feel the 500 rpm drop when the TC locks up after it's been in od for a minute and a steady speed has been reached. In my truck, lockup usually happens at any steady speed over 40. And its already paid for...
The thing with a AOD is lockup and O/D are one in same, so gives a rather large drop in RPMs when it engages... In my stock Super Coupe AOD, I ran a 2600 lockup converter with 3.73 gears(a just about minimum in my opinion) and was basically happy with it's performance... This is reason I chose to retain the 2.40 1st gear... My new setup up features a 3500 stall converter but is still lockup... I can tell you this, even with the 2.84 1st gear, a stock converter will suck...
