What AOD Trans to use

[triggers68]

Am building a '77 with 302. Want to change from 3 on tree to AOD to make it more user friendly for my wifey. Whats a good inexpensive salvage yard trans for me to look for and what does it take to install to t-case?

 

[WyleCoyote]

89 or later AOD is the better one to get - I had the 4r70w gearset swapped into mine while it was in for rebuild gave me a lower 1st gear. the AA adapter for the D20 runs $500+ and has a new spud shaft that you have to disassemble the transmission to install, then you have to modify the crossmember because it moves back about 1.5", and has to be clearanced in the middle.

Since I had a shop do the rebuild and install the adapter parts to the transmission, the work I had to do wasn't much - and there are good write ups for it in the AA Adapter instructions. I got my tranmission from a Mercury Grand Marquis, but you can find them in many 90's vintage fords.

 

[needabronco]

Do a thorough search for one with an adapter already on it if you can. There are occasionally deals to be had. I happened to 'stumble' across one that had previously been in a Bronco before, so I know those deals exist.

I would also research what it will cost you to have an AOD rebuilt, or buy the book and learn how, they seem to be pretty expensive to have a shop build.

I would get an 89 or newer, they are the better of the AOD's. If don't care what transfer case you use, get one from a 4X4 and then install an NP205 and spare yourself the adapter expense.

The low gearset (4r70W) can sometimes cause the need for a modified valve body due to incorrect shift calibrations, but there's a guy called 'silverfox' on www.clickclickracing.com that modifies and sells custom valve body's for this swap for a very reasonable cost.

I'm in the middle of this swap right now and it looks like it will be easier to do a twin stick swap at the same time. The cross member does need a minor cut and box modification also.

 

[kjbronco]

I've been researching the same thing and apparently with a few mods to the governor the later model output shaft can be used which I am told improves lubrication and wide open throttle upshift.

I was seriously considering the later model wide ratio gear set..but haven't been able to find a source for the gearset for a reasonable price, and right now will likely use the stock gears. Any feedback on the performance difference with the wide ratio gearset?

The AOD doesn't appear that hard to rebuild but there is a cost, about $250, in transmission specific tools (drum spring press and seal installation protectors. There are good discussions regarding weak spots in the AOD, early and late, on the internet these focus around necessary upgrades to the OD servo and band and recommendations to use high quality/high number drive clutches and steels. Also the OD lockup shaft has aparently been observed to suffer under high horespower/torque loads and there is an upgraded shaft for $180 of so. Best I have been able to find so far is about $1000 for parts including new torque converter and upgraded OD shaft but not tools. Good luck..

 

[triggers68]

Thanks for all your info. I plan on hitting the U-Pullit soon and look around. I have two Dana 20 t-cases, one thats in my 77' and one from my 69' donar bronco. The one out of the 69' has the t-shift and I like that look and its simplicity. Can I just swap the top of the t-shift case with the newer t-case from my 77'? This is going to be a daily run around the roads and trips to Sonic type build and dont plan on ever using the 4 wheel drive option but would be nice to have it work and work like I want. Also does anyone make a cover plate for doing away with the PTO shaft?

 

[needabronco]

The weak points of an AOD seem to come from the high performance/street mustang crowd. I've talked to ALOT of people that run AOD's in Bronco's and BAX is the only one I've ever heard of that's had any problems. Most seem to think it's a pretty decent trans.

As far as sourcing a low gearset, scavange a cheap 4R70W for the gears and upgrade parts.

After searching for a builder for the AOD I finally found an old school biker type, that was highly recommended by several people. He told me the AOD is nothing special as long as you keep the tolerances within spec (he means use the book) and use the seal install tools (or be careful with a pick and dentist tool), other than that standard tools and feeler gauges. The seal tools are usually on ebay for $40-50. A one piece output shaft might get you strength for full throttle 6,500 rpm, 500 horsepower, 400ft lbs of torque shifts, but who really does that in a Bronco(besides BAX)? And you loose the 'locked' torque converter in overdrive, which means more heat on the highway... Plus then you have to buy a new torque converter.

If you think your confident enough to think you can tackle an AOD you probably can. I was all about doing my own, then found a fresh one with about 1000 miles on it, so I don't have to rebuild mine until I do the low gearset swap myself...

 

[triggers68]

My main reason for the aod is to try and improve the fuel mileage when the wife and I take trips in it. Its going to be strictly a highway runner. Looking at EFI and an AOD to try and squeeze at least 17mpg's out of it.

 

[needabronco]

I've talked to several people who claim 16-17 mpgs out of their efi'd Aod'd rigs, both had 4.56 gears and 35's and drove 65 on the highway. I think it's doable but I'd realistically expect more around 15.

 

[triggers68]

I've talked to several people who claim 16-17 mpgs out of their efi'd Aod'd rigs, both had 4.56 gears and 35's and drove 65 on the highway. I think it's doable but I'd realistically expect more around 15.

Glad Im splurging on 23 gal. tank. Want to make it from station to station.

 

[RenoBuc]

I'm currently doing the same swap. It sounds like I took a bit of a more conservative route as my mechanical skills are probably less than 90% of the contributors to this forum. I went with a local tranny guy who had experience with this swap. He had an AOD (88 and newer were said to have improved oiling capabilities) and rebuilt it for me. I purchaed the conversion kit from Tom's (made by advance adaptors). So, I provided the t-case and the conversion kit and for $1400 I got a rebuilt AOD already sandwiched to the t-case with a new torque converter. 2 weekends ago, I hung it in place with the conversion crossmember from Toms (has a cutout and brackets that move the tranny further back). A decent website for all things AOD is: http://www.ford-aod.com/. Right now I'm installing the special kickdown and shifter linkage. Still need to figure out how to deal with the neutral safety plug.