A4LD vs. 4R70W - unfair comparison

[410Fortune]

hahaha this is EXACTLY why I went 5.0l

It has never been a secret that the "light duty" driveytrain never should have been asked to motivate a 4 door explorer.


they started it all when tey put the 2.9L in a 4x4 BII = WAY too heavy of a truck for thay setup!

 

[CDW6212R]

This is a funny topic. The AOD was considered to be the worst transmission shortly after it came out in 1980. The direct clutch was weak, the overdrive band slipped, second gear would start to slip, and that was just the beginning. All of those problems have been improved on, and the 4R70W is the well developed decendant of that 1980 AOD.

The 5R55E is unfortunately still just a decendant of the A4LD which started life in four cylinder Thunderbirds in the 80's. The guts are too small. Regards,

 

[Brian_B]

It gets worse. The A4LD is a direct descendent of the C3 (pinto) 3 speed automatic transmission from the 70s.

Why they didn't build on the C4/C5/C6 line is beyond me. Glacier...comments?

 

[410Fortune]

the c4/c5 is also derived fromt he c3 as I understand it
the a4ld is nothing more then a c3 with a aluminum od added on, then later computer controls.

the 4r70w is basically an AOD, or AOD-E just with full computer controls and wide ratio gearing.

the 4r70w still has some weak spots, but they can be easily fixed with a light rebuild (upgrades) and then they can take 500+ HP. Very popular amongst the Mustang drag crowd

 

[Glacier991]

I will take a stab at the genesis of the A4LD. First one needs to understand that designing and tooling an entirely new automatic tranmission into a production line is incredibly expensive... WAY WAY WAY up in the millions. You have to make a lot of em to recover that cost.

Production on the C-3 lines had more or less stopped, the tooling was there. With some inventiveness they could re-use an existing production line, and what the heck, it might just work!

C-4 and C-5 each had shortcomings, either in terms of size, availability, gearing or fuel efficiency due to lack of OD, or something else I haven't yet thought of.

C-3 into A4LD was the result.

Mind you, this is JUST conjecture.

I might add, in defense of the lowly A4LD... that many of the mechanical problems got taken care of in the 5R (lots of it by adding beefier planetaries and torrington bearings). The A4LD is still alive in a way today... it's heart is in the 5R55N - powering the Jaguar and Thunderbirds!

[Edit: Vehicle weights in line with the capabilities of this trannie!!]

 

[Christobal65]

We towed a 22' Ski Centurion with our 92 Explorer, and the only reason the trans went out at 70k was because we improperly installed the flywheel when it cracked. Once rebuilt we got another 100k on it before the torque converter went out on it. According to our Trany shop there were some other pieces that were well on their way out though. Sure the A4 should have been bigger and stronger, but it still works pretty damned good and in reality is the only weak point in other wise extreamly reliable suv.

Glacier,

I wish i would have known you were in Sacramento and rebuilt transmissions, cause mine failed when i was at home in auburn last Christmas.

 

[Glacier991]

Not sure I'd have wanted to build one at Christmas ! <g>

 

[Brian_B]

Hmm...interesting hypothesis (probably right)

The C4 and C5 are almost the same transmission. The bell housing, valve body, tail shaft. and tailhousing are changed with the C5 (you can swap parts between the two ).

The C5 already fit our V6 engines (C3 did not as far as I know) and was used in the 83-84 Bronco IIs. I still think they should have added OD to the C5 and kept going. What do I know though. I can wish all I want and it doesn't change what ford did.

The C3 was too tiny to build off of. It was a 4 banger transmission. The BII, ranger, and aerostars they were to go in are a lot heavier than any pinto.

I am no engineers, but..........I think ford messed up bad and have spent many years trying to fix a bad design. I know its hurt their reputation with the public.

 

[Glacier991]

Remember also, that "piecemealing" is a dangerous thing. (meaning starting with smallish increments each based on the last success). Let's try this one: Hmmm... 2.9L and a C-3 with the added OD.... sounds good... into a Bronco... smallish back then in the 80's, so it is "probably ok" (speaking like I was the engineer with the accountant looking over my shoulder). Jump ahead. Now we come to the Explorer.... kinda a wild chance for FORD in 91. We sure as hell ain't gonna build a new trannie for it.... Hmmmm... looks kinda like a BIGGER Bronco.... HEY we used the A4LD in the Bronco! Why not here? And by then I think FORD was facing FED pressure on mileage in it's lineup... so we def. needed an OD.....

I'm just thinking out loud, but ya know what? I can see it happening just like that.

ps. I think I heard it costs into the HUNDREDS of millions for a new trannie production line. I also hear that the big automakers have discussed making a generic - use by all- CVT transmission, because the research, design, tooling and production could be nearer a billion! (probably BS but fun to share that shjt.)

 

[Brian_B]

Sounds about right to me. People who think (normal average people like all of us)....and engineers who deal with accountants are not the same thing.

I heard that rumor as well. Its always something going on. LOL

BTW: This thread is fun.

 

[Glacier991]

This stuff is 'spozed to be fun!

 

[Brian_B]

Its funny how it all turned out. The A4LD was not built strong enough to take the 2.9 (IMHO). I at least, kept blowing it apart. I am very hard on transmissions for some reason. I wonder why.......

I have seen 20 year old C5s that worked still. One guy swapped one in behind a 4.0 OHV and just changed the fluids (no rebuild) and drove it.

When I swapped in a C5 (89 ranger), I went through it, but it was just wear. Nothing was busted up or anything. I didn't have to rebuild it, but........it was there. That was not true for the 3 builds to the A4LD it used to have.

When I said this thread was fun, I was refering to your "diary" threads where I typically don't have anything to contibute. You know much more than I do about whatever it may be.

Someday, when I get my dream truck , I will hit you up for info on building a bullet proof AOD (some version of it anyway).

 

[Jefe]

Remember also, that "piecemealing" is a dangerous thing. (meaning starting with smallish increments each based on the last success). Let's try this one: Hmmm... 2.9L and a C-3 with the added OD.... sounds good... into a Bronco... smallish back then in the 80's, so it is "probably ok" (speaking like I was the engineer with the accountant looking over my shoulder). Jump ahead. Now we come to the Explorer.... kinda a wild chance for FORD in 91. We sure as hell ain't gonna build a new trannie for it.... Hmmmm... looks kinda like a BIGGER Bronco.... HEY we used the A4LD in the Bronco! Why not here? And by then I think FORD was facing FED pressure on mileage in it's lineup... so we def. needed an OD.....

If only they had known how many explorers they would sell. . . eh, nevermind, they still would have put the A4LD in.

 

[Brian_B]

That started long before anyone thought of the explorer. AFAIK the first A4LD was in the 85 ranger and BII with the 2.9. They should have dumped it when they went to the 4.0 OHV in 90 or 91 (whenever it was). There is no way they should have stuck it in the 91 explorer behind the 4.0 OHV.

I have a spare C5 sitting here. I won't get rid of it or part it out. I may need it someday when all this computer garbage goes bad.

 

[410Fortune]

The A4LD is a good transmission, especially from the factory when it was built "properly"
If you look at the tollerences inside the A4LD and compare them to oh lets say a Chevy trans, the rebuilder must be a ton more aware of the measurments and details when rebuilding/re-assembly. This is why the A4LD fails after rebuilds. From the factory, when maintained, and not OVERHEATED they typically last a good good long time.

Though still too light duty for the heavy Explorer IMO, heck anything with a 4.0L has too much power for the poor little trans. The newer versions are far superior, but we still get lemons

 

[Brian_B]

Hmmm...mine from the factory lasted less than 36K. That particular year they had tons of them come back in fried. Mine was not a random "lemon". Ford rebuilt it and it lasted less than that the next time.

I am certainly no kind of expert, but I rebuilt that time it and it lasted longer than either ford build.

It then cracked the flex plate (replaced that and front seal). Then it snapped something serious inside.

This time I was through with it and swapped in a C5. Thats been in it ever since and has seen some serious duty. The truck has approximately 187K on it now (same 2.9---nothing done to it). My vote is still that the A4LD is way too weak for any V6 4X4.

I know (from Glaciers posts) that the 5R55E is greatly improved, but I don't trust it at all. I know its roots. If the 4.0 SOHC lasts like the 2.9 (which I doubt), I have a C5 to swap in. Thats just my opinion of the A4LD and its grandchildren.

 

[410Fortune]

you = lemon Its always a controversy when I post that I think the A4LD is/was a good unit.

I had my share of issues with them as well.

 

[Brian_B]

Lets just hope the 5R is a better unit (whichever opinion we all have).

I have 77K on it and its stock. Nice clean new looking fluid as well.

 

[gregr]

There's some great 4R70W info at the TCCoA website:
http://www.tccoa.com/articles/tranny/transmission/page1.shtml
It's 17 pages that take you from "what it is" to "how to modify it".

Greg

 

[Glacier991]

Greg.... when I did the "My A4LD rebuild Diary I felt like a stranger in a strange land... there was precious little good solid info out there.... I hope in my own little way I helped change that. Now the 4R70W... WOW, tons of GREAT info abounds, and the TCCOA website is killer! Jerry W, a Ford Engineer has posted some really helpful stuff too on that site.

So ...the "My 4R70W Rebuild Diary" is more a Walter Mitty place..... yet I hope when I am through I will have added something to the knowledge base out there people can draw on.