I'm keeping up with Gabba's post here cause I'm considering doing the same thing to my 70. So I am wondering about driving around town in 3rd gear and in OD on the hi way? Is that feasible? I heard from elsewhere that, that wears out the OD band. Fact or fiction? I already have the OD out of a T-Bird but am considering going with a T5.

HudginJ3 wrote:

I'm keeping up with Gabba's post here cause I'm considering doing the same thing to my 70. So I am wondering about driving around town in 3rd gear and in OD on the hi way? Is that feasible? I heard from elsewhere that, that wears out the OD band. Fact or fiction? I already have the OD out of a T-Bird but am considering going with a T5.

HudjinJ

That’s a great question .. i will do some research there .

As far as I have heard , the OD comes in after 40mph

I am definitely thinking of upgrading the low reverse drum and OD band to a 2” instead of the 1.5”  , giving it more grab and reliability in OD gear (same setup as a 4R70W)

Also if I can source a planetary gear set from a 4R70W , I can have even lower gear ratio on first gear ... adding more Umph out of the hole.

But if not I’ll be happy as a clam with the standard AOD (C4) ratio just as well

I'm not totally familiar with the AOD, but from other overdrive automatics I've worked on and rebuilt I can say that the odds that it shifts to OD at a certain MPH is highly unlikely.  The trans has no idea what road speed you are going.  Shifting is accomplished based on shifter position (manual valve) and various other valves related to throttle angle, and pressures in the valvebody that are related to engine load.

Now its entirely possible that 40MPH in most vehicles just happens to be the MPH where when cruising under light load the conditions are right for the trans to shift into OD.  BUT, like anything else about how an automatic shifts that's dependent and can be altered if you know what you're doing.

I can say that running with the trans is D (3rd gear) instead of OD (4th gear) is not going to hurt anything.  In fact, when towing that's what Ford advised with its trucks for decades, because THAT would definitely wear out the OD band, because it doesn't have enough surface area, or a strong enough apply pressure to last under heavy load. 

I'd seriously look at weighing what swapping the planetary gearset does overall.  Its not just about first gear ratio.  What does it do to the drop between 1st and 2nd?  If that drop gets wider you end up with a car that screams off the line, then falls on its face at the 1-2 shift.  If that's not a concern then it could be worthwhile.  I'd have to know what ratios we're talking about to say one way or the other. 

So it’s PRN-4-3-2 or 4-3-1 whatever that lowest gear is.. I can work with that, esp for now till someone has a 3.25 for me or I rebuild that third member to have a 3.25 gear and pinion in it .. I may have to manually shift to OD on highway. I can work with that.

Bullet Bob wrote:

red351 wrote:

Maybe I should mention,  (if BB didn't), that maybe your shifter notches will not match the AOD in some positions.

Actually, the C4 shifter notches are fairly close to the AOD but the shift rod travel is off.  To  cure the problem I ended up shortening the shift arm on the shifter and moving the rod attachment point to the rear to make the shifter arc more closely match the arm on the trans.  That's why I said it was the hardest part.  Spent a lot of time making that shifter work.  There are reasonably priced and way less time consuming ways to go but I'm one of those guys who figure why spend $150 if I can make it myself in only three weeks.

BB
 

X-2!!
 

FYI, governor weights and springs can be changed to change the RPM at which the trans shifts.  Its a bit of trial and error, but works well once you hit upon the right combination. 

Definitely get the ASTG manual in one form or another.  I have one for every automatic I own, including ones I've never had to rebuild, just because the troubleshooting section is worthwhile.  Its especially important for later model, fully electronic transmissions, because another layer of complexity has been added with the solenoid pack and system that controls them.

A 700R4 was the first automatic I rebuilt.  I couldn't find anyone locally who seemed to know anything about them other than to claim they were junk and I should just put a TH350 in the truck.  Interesting that a 700R4 is basically a TH350 with OD.  I found a guy online (Dana from Probuilt) who seemed to know all about them and had helped design some of the parts he was selling in his rebuild kits.  He also had some tricks he gave me for various stock parts, and I called him and spent about an hour total time on the phone with him over several calls during the build.  Really, really good guy, unfortunately only does GM stuff.  BUT, the important take away for any auto trans rebuilt is to seek out the knowledge first and build second.  I built that trans 15 years ago, and the internet was good, but nothing compared to what it is today.  The knowledge is out there if you look. 

Ok.. so the 87 AOD is fully apart .

For anyone doing this rebuild/ tear-down.. two thing have been the most tricky to figure out..
1) Roll pin that holds the manual shift lever in the tranny case (i know you figure that'd be an easy part) LOL ..  Make sure to have good quality diagonal cutters. most manuals recommend having that tool
2) Taking the pump off the front of the transmission without the recommended special slide hammer and adapter tool

So ,there are two threaded holes 180 degrees apart in the pump housing itself which are there for you to screw an adapter in, which then adapts to a slide hammer, then you use two slide hammers simultaneously to slide hammer that pump out. Well.. .I didnt have that adapter or a slide hammer (i could rent a slide hammer from oriellys)

So I put chain around the heads of the two bolts and tried using a big hammer to yank on it, to have enough intertia to slide the pump out. Well.. I tried and tried and tried.. NOPE..

Then a friend of mine who was over, just for fun of it took my crwobar, and gently leveraged against bell housing and was trying to lift those screws, and saw some movement.. Well.. that was it, going back and forth between the two screws, I walked the pump out with a crowbar.. PHEW!! LOL

After pump came out, the drums, and clutches, bearings, and everyhting came out of the transmission within 10 minutes. It was the easiest thing I have ever disassembled!! The 87 is now fully disassembled. The housing is going to recycle. Parts I dont use will be sold later. I have all the parts in order laying on a table, and I am going to label them, count the clutches in each drum, and then bag it all up for parts.

Then I will start on the '90 transmission, and having learnt the lessons I did from taking the 87 apart,I will now take apart the '90 :D yaay!

FUN FUN FUN :D
 

I have a 4L60 tranny in my S-10 partz chaser. I put a shift kit in it yeeeeears  ago AND used the B&M Trick Shift fluid in it. Shifted MUCH firmer and stopped the constant sliding in&out of OD @40mph.(right where I drive in town!!!) Prolly put over 100,000 on it before the "sun gear"?!@?? broke and left me on the side of the road.
Had it towed yada-yada. The mechanic rebuilt it and installed Corvette servo and some other parts.
(here's the end of the story)
It always has and always will  shift from 1st to 2nd at 15mph! Into OD by 40mph!! (normal round town drive) Now when you "pin-it" is when it barks 2nd and goes into 3rd at 70mph. OD after that.

Sooooo the shifting between gears sux around town butt...........dats OK cause I'm just scoot'in....around town!!
Play with the governor & weights and stuff to make it more performance shifting IN ADDITION to a shift kit.
(I wasn't kidd'in about the manual valve body!!)
6sal6

Bullet Bob wrote:

Hey Gaba, I just thought of a new tool to add to the "tool kit".  How about a couple of bolts to go into the pump, a length of square tube or angle iron that spans the bell housing, two lengths of all-thread with nuts, and two pieces of chain to go between the pump bolts and the all-thread.  Pulling the all-thread from nuts on the front of the angle iron, and working from one to the other, would pull the pump evenly.

BB

Bob

That is what I was trying.. but looking at the pump now, I see why that didn’t work..
while using a chain and a trying to pull by it, the pump got wedged for me .

The two threaded bolts are not exactly 180 apart. They are offset a bit favoring one side . I’ll post a pic.. but may be also I was just doing it wrong too haha

hey my crowbar trick works well too (very gently) . I will try to video it, when I take the '90 apart. lol .. see if it works. :D

The only special tool I've ever used for rebuilding an automatic trans was a clutch spring compressor I bought at Carlisle one year for $20.  Everything else I've improvised or made.  Long bolts with the heads cut off for guide stud for installing the pump, a polished, rounded old feeler gauge for a lip seal tool, etc.  I do use Transgel for assembly lube.  Some guys use petroleum jelly, etc., but its cheap, NAPA stocks it, and its made for the purpose. 

Here are some detailed parts pics of the '87 AOD parts all laid out, and bagged up for going into a storage bin.

I love looking at these pictures , and wanted to share with y'all.. its really not much to take apart this transmission
Overview:


Now some parts pics.. labelled then as to what they are just for my info. The number in the circle 4 or 5 or whatever is how many clutch fibres does this drum contain.

Last edited by Gaba (6/01/2018 9:38 AM)