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I have a pretty complete gear train I have acquired piecemeal... (still working on accomodating Section525 to pick up that donor.. he has been WAY patient with me.)
As I put the stack together the one thing that struck me was how big and heavy everything was. Clearly a beefier trannie than the A4/4R/5R!
The top of the stack would be the pump - last thing in, first thing out. I like to always use new FORD pumps in rebuilds, and I have one, here it is:
and back.. the back also serves as the clutch piston for the intermediate cutch, wierd to my mind. More on assembly....
The front clutch has the input shaft which stabs thru the the hole in the pump and into the TC. Here is the asssembled stack
When installed this space is used to build up the intermediate clutch, it's kind of an odd setup, like I said, as you'll see on assembly.
There are some sealing rings that need special care... this is a new drum so these are factory and primo
The top of the stack is the "mechanical diode" an upgrade that is a critical upgrade.
I get a kick out of that name. For those not electronically inclined a diode is a device which permits current to flow in only one direction.... a valuable trick. But to name a one way clutch as a "mechanical diode"... who'da thunk it?
Under this is the reverse clutch drum. I have tried to highlight the "dog ears" that fit into the input shell. This is a critical wear point.
I'll post a few more pictures to illustrate this
can you make out the wear? Here is a dog ear close up... this is not "terrible" wear, but evident.
and here is a look at the input (drive) shell where the dog ear engages
With the reverse drum and clutch off, the forward clutch and input shaft can be removed
Not important per se, but sometimes when people wonder why they might suffer low line pressure, it is because a check ball might be stuck open... here is such a check ball in the forward clutch shell..
Next we come to a stub shaft, the "intermediate input shaft" commonly just known as just the "stub shaft". In super high horsepower apps this can snap in half...(yeah!) and there is an aftermarket super hardened one.... pricey. Probably only necessary if you are running 600 HP.
and here it out
Next up.. or down as the case may be, input (drive) shell and sun gear
Under this is kind of the equivalent of a "center support" in the A4/5R series.. it is the "planetary carrier" under it is a ring that engages a roller sprag in the end of the planetary gear assembly
The backside with the ring for the sprag
Here is looking into the back end of the planetary and the roller clutch (sprag)...
Then we can remove the forward clutch sun gear
Might want to pay special attention to these little splines....
and then the planetary, a HUGE beefy thing. Heavy.
this splined end fits into the hub for the direct clutch, making the direct clutch able to hold the planetary carrier stationary (you know what THAT does? right?)
Note the scoring in the bushing. It will get replaced with a new one. (as will everything else used that gets reused)
Now we are down near the bottom. We have the ring gear and inside it sits the direct clutch... this one is stamped steel. The direct clutch started in the AOD as cast iron, then went stamped steel then in somewhere along the line into the 4rR70W production went back to cast iron... so we know this one is "probably" not 4R70W..... but for illustration purposes it will do. (Trannies require a lot of research! Even then my info may not be right)
either way, it pulls right out
and then you remove the hub from inside it...
and then you are left with a pretty normal looking cluch assembly... can you count the plates?
(There are 6, upgrade kits can increase this up to 8)
lastly you have the ring gear
Now I don't have the output shaft so there are a few things you didn't see, and I didn't show the torrington bearings used throughout or some snap rings used in the case, but as a first glimpse, now you know what we will be working with.
No, actually, in the 4R70W is is pretty similar to the A4/4R and 5R. They lock on the output shaft. The 4r70W locks on the ring gear which is splined to the output shaft. Here is the ring gear cog for the parking pawl to engage
and here is the pawl, in an orchestrated "engagement" (cueing up soft music)
finally, looking into the bowels of the case (can I say that on EF?) you can see the pawl sticking in, as it would in park. ( do not even GO there!!)
Anyway, that's parking 4r70W style, 101. Hope that answers the Q for ya!
ps. thanks for the pan. Now I just need to figure oout where to put the drain plug in it. Suggestions?
Hello Chris, now you are working in my neighborhood. I haven't seen a sun shell/dog ears worn that bad, to need replacing. Nor hve any AOD's etc. needed any bushings, and that parking pawl looks rounded too much to me. Those parts have come from a hard usage AOD, etal.
The direct clutches are the old weakest link. Six clutches is probably the most factory available. Five was most common, until late in the 90's, likely the 4R70W's. I believe that the 97 Crown Vic 4R70W which I rebuilt had a steel direct clutch. The aftermarket kits which produce more clutches in there, do it by using much thinner steels/frictions. I have one of those kits in one of my previous Crown Vic AOD's. I think I'd prefer a better direct drum, if an aftermarket piece was available. I like the blue frictions, and Kolene steels, but they are high dollar, and really best for high stress applications.
Check on which planetary you have, for that dtermines whether you end up with a close ratio, or the wide ratio gearing. That determines first and second gear. For drag racing, the older planetary is best, as the closer ratios are better. The "W" in the 4R70W signifies that the first and second gears are higher ratios, and the 2nd to 3rd gear shift is a bigger change(rpm drop).
Thanks Don. Looking for any information I can glean. Fortunately this trannie has a lot of builders and users so there is a lot of info..... at least as compared to the A4LD where i was on my own. I am on a steep learning curve here, all comments and advice solicited.
Here is a Q. I picked up (supposedly) an "A" OD servo off E-bay. It won't even come close to fitting the hole in the case for the OD servo. (It is Way bigger than the bore). Were there cases made for larger OD servos or did I get a servo for some other trannie? Told ya this was a steep curve.
Chris, the overdrive servo in an AOD... includes three parts, the piston, the cover, and a matched spring. The "A" servo only fits inside of the "A" cover. I might be able to post a picture of those three tomorrow. Regards,
It is possible, I didn't look hard at the 97 4R70W which I went through. It only had 13,700 miles on it, and I just swapped the frictions and steels. Let me know if the 4R70W OD servo is different than the AOD's. I would definately change to an "A" OD servo set if I could. Regards,
The Case for the Case - (apologies to Perry Mason)
A transmission is much like an insect... it has an exterior skeleton (exoskeleton) or case. Cases vary, but they all contain the passageways for fluid (blood) to flow, and the strength to hold it together. Various parts are replaceable (bushings for example)... and some can be repaired if they wear out (like hip replacement surgery). Interesting comparison, no ? ok ok I'll stop, maybe.
When I build a tranny the first thing I do is to make sure my soon to be built transmission case is clean, the passages blown out and any bushings that need it, replaced. If there is an case upgrade that is applicable I will add it. I degrease, sandblast (!) pressure wash and then paint them (vanity thy name is trannie)...pick your color.... most of mine are black or silver. In the case of this 4R70W.... here is the finished case result:
This is a good time to examine the 4R70W transmission case. I was impressed that there are so many pressure taps..... I like that idea. On the passenger side there are 3 mid ships
each labelled. (I added the black magic marker for the pix) a closer view shows:
TV is synonymous with EPC.... at the back of the case on the passenger side is one more
I didn't have my glasses (getting old is a bitc*, ya know) so kinda mooshed up the application of the black on this lettering, but this is the direct clutch tap on the '98 case (more on that later).... here it is closer up.... (stop laughing I have 20/20 vision.... after 4 feet. Wait til YOU turn 50!)
On the drivers side there is a line tap (canya tell I had my glasses for this one?)
I like the idea of being to check pressures at a number of points in the system. I rag on FORD engineers at times, but this one is a definite thumbs up!
Ok... how to explain this.... (DEEP BREATH) IF you are taking apart a 4R70W.... MAKE SURE you remove the OUTPUT SHAFT SPEED SENSOR before you remove the guts. If you do not, you will destroy it.
"Case" in point. Here is the sensor in the case... was it removed and replaced by the disassemblers (I did not disassemble this one) or left in place?
(ok ok I knew because I removed it to sandblast and paint, but YOU do not know! Neener neener. Ok ... enough suspense and drama....here it is out...
Yep, BUSTED. Like lighting fire to a $20 bill. (DOH!) No reason for this. So if you are disassembling your 4R70W, REMOVE THIS FIRST BEFORE TAKING ANYTHING OUT OF THE CASE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Another pic of this unnecessary damage
Oh and the reference to '98? How do I know? Well on the spine of the trannie (don't you just love how I anthropomorphize transmissions?) there is a casting number...
I am gonna take a wild guess that is the year (not the max speed). If there is any doubt, go look up the FORD part number:
Our project case, is READY!!! I'm buyin the beer this time.
Next up... sub assemblies..... one at a time. Guts ball.
Picked up some new parts... interesting comparisons. Remember the sun gear (input) shell? Well compare it to a new one...
And the lug that was worn (I have one much worse than the one I showed before).... well here is a reman'd one...
I have been told that they repair these by mig welding hard steel onto them and grinding them, that they are even better once done that way as the wearing surfaces are harder... here is evidence of the truth of the method, anyway...
Then they put a new interior in the drum. These vertical slots are where the steels ride... over time they can make indents in the smooth columns and not ride up and down as they should during application and release.... like I said, this is a new one in a reman'd drum....the drum was $65. It is FORD part No. _______________.
The proof is in the pudding, as they say, and once I fit the new sun shell onto the reverse drum lugs... the fit is ***PERFECT***... no slack whatsoever!
I suppose that the sun shell could be fixed by welding too, but I do not have a MIG welder. Anyway the new sun gear shell was $80. And it IS new. The FORD Part No. is _____________________.
The 4R70W uses a planetary support/sprag ring as the case "center support". I read that it used an aluminum bushing that got sometimes got mashed as it did it's job...I am told it was later replaced with a Bronze bushing....anyway, so I checked mine.... first in one place..
and then in another spot....
sure enough. Mashed and mooshed. I'll see about replacing the bushing after I price out a replacement of the entire piece... bushings are NOT always easy to replace.... I'd say more often than not (not always) you will be better off replacing the part with one with a new bushing... try it, you'll see.
[Edit - I thought about rewriting this part, but instead I'll show you how this discovery process works. I got a brand new one, two in fact. BOTH exhibit the same thing... so I guess you can't assume the "moosh" is wear!]
Finally... I read that the stub shaft came in 2 flavors. One has a grove at the end of the splines and one had a taper. (and of course the super hardened one aftermarket for $150.) I have read that the groove acted as a stress riser and it often broke there, the one with the taper is the one you want. What one did I luck out to get?
The GOOD ONE! (finally I win at something!) Here is a sophisticated pointing device showing the taper I am referring to
[Edit: Well I found out that in addition to the two I mention above, NOW they make one where the splines are cut into the shaft with no groove OR taper at the inner end. I picked up one of those by luck, and so have the "latest" version now - the rebuild will use that one. I'll eventually post a pic of it here, but the FORD part Number is F8AZ-7F351-AA.]
I am continuing to learn... finding out conflicting info many times... I'll keep sharing what I find....
Chris, you see that the part number is F7, a 1997, meaning that 1997 is the earliest that the part was used. It can be a 97 or newer part. If nothing is changed year to year, the part number stays the same. You knew that, but before others chime in, I'll inform them.
Nice case work, I like that you are more thorough than I am. That is a rare trait. Keep your camera warm. Night,
Now we have arrived at a difficult spot - the time we try and decide exactly HOW we want to build this transmission. By that I mean how many clutches in clutch packs, upgrades to affect shifting, whether to use Kevlar in the bands, etc.
At first blush the task might seem to be easy - build it as strong as you can. Certainly in the case of the A4LD Diary that was the goal. But with this transmission we can REALLY go from mild to wild.... and frankly overbuilding a transmission may not be the best idea. Why? Well, just by way of example, a trannie built with unneeded extra friction plates will have thinner plates (less heat sink) and more of them (greater drag and more heat). Kevlar bands I am still researching but I have minor reservations about using them without higher line pressure than normal (at least). The stub shaft can be upgraded to something harder and stronger, at a cost of about $150 additional - is THAT necessary or worth it for stock/street? Probably not. You get the idea. Choices.
So in essence, I can build about 5 versions of this transmission, each one a little more expensive. I can rebuild it pretty much as FORD built it for the Explorer.... or; I can build it a little stronger for better towing capacity or offroad use, or; I can build it for someone with a heavy foot or who wants to race it; or, I can build it for a blown (supercharged) engine and 600 HP usage.
I wish someone wanted this transmission when I was done and could identify the use they wanted it built to. In the absence of that I will have to make some tough choices. I will probably do SOME upgrades to it, for towing etc.
Other things that make this tough is the range of parts choices...many of which are interchangeable, and some that aren't. Example, the direct clutch... stamped steel or cast iron? The list goes on.
So if someone is going to be replacing their 4R70W and wants a custom built one, let me know. Soon.
Next... the direct clutch.... stay tuned. We will use this chance to talk about frictions, friction plate thicknesses, patterns in the frictions vs. flat, fluid hydroplaning, plain versus kolene steels, to go kevlar or no kevlar.... and much more related to clutches and bands. Oh and... LINKS.. lots of links.
I want to reserve another spot..... so you get another tease. Operahouse.... a great trannie tech kind guy.... came up (first time I ever saw it anyway) with the idea of using an engine stand to rebuild trannies.... I have used it ever since. You bolt into the trannie pan bolt holes.... so... our tease is the 4R70 case on the stand... ready and waiting.... (ok it has the ring gear and output shaft installed)
here is a closer view.... this works really well.... and is a $40 solution to an age old problem. The 4R70W needs 3 inch 8.8 metric bolts..... 4 of em. I also use cardboard washers to protect the pan sealing surface.
This has been one of the more difficult research projects I have done to date. Some knowledgeable articles (admittedly a few years old) have suggested that Kevlar is not a good choice for friction material in bands, some not stating a reason, some stating it has a lower coefficient of friction, and still others claiming that it can stop rotation ok but may have difficultly with holding against rotation (often as not more a function of fluid than material). Still other information seems to suggest that all the high performance builders are using it, and that it has a slightly "stickier" friction that the standard organic, etc..... who to believe? Is it the just the "trendy" thing? Is it better? Or is it all hype? Or has it gotten better lately?
Maybe it might help to first describe what makes up the usual band friction material. Paper. Yep. Mind you it's not ordinary paper, but it is a close cousin. Paper. Paper with lotsa stuff added in to be sure... a major supplier is the Mead company. Ever buy lined college ruled paper? Bet it was a Mead product. (and no that's not the paper friction material is made of). Once the friction material gets heat burnished it becomes more carbon'ish and amazingly holds up well. So well in fact that most bands on a rebuild could probably be reused. So, you ask, why not stay with the stock bands?
An excellent Q, but as tinkerers we are always looking for better materials, things that grab better, resist heat better and help reduce a failure rate. Alto is a major producer of friction material and clutch frictions and bands. They make a special phenolic paper based band called Alto red... everyone swears by its properties.
And then there is Kevlar. Miracle of Dupont - better living through chemistry. It is a fibre spun in Sulphuric acid.... 5 to 20 times stronger than steel.... excellent insulating properties... good heat resistance.....in short, sort of a synthetic asbestos. Bulletproof vests are made of it.
How does it compare? Well to be honest I am having trouble finding good data. I think it is safe to say that in a long term application in a dry clutch, it may not be as good as organic material, ceramic or sintered iron.... But in a wet clutch application.. trying to find data is not easy.
The fact Raybestos is offering it, gives me some sense of relief. They are a quality company and I am sure have engineering data to back it up.... meanwhile.... My search continues. If anyone has any info they can offer, please feel free.
As it stands... I am on the fence. Kevlar versus stock? Hmmmmm. (By the way, they improved the stock lining in 1998. I'll get you part numbers.)
Coefficient of friction dry: Organic .25, ceramic .36, sintered iron .40
(Real Q is what is the wet coefficient of Organic vs. Kevlar - one website claims their Kevlar is 10% higher than paper)
Burnish time for Kevlar is apparently 3 - 5 times that of paper. Ok so how long is that?
Torque handling capacity T= P x F x N x R
where T = Torque, P = clamping force in lbs, F = coefficient of friction, N = Number of surfaces and R = radius of gyration. (size of plate)
(proof that greater plates equal greater torque handling capacity)
I promised you some links. I will take this opportunity to say that I think the internet is better than the Alexandria library of yore. If you need to know something it is here. Maybe. Somewhere. Here are some links that have formed the basis of my 4R70W "knowledge base" online. If you find other good ones please post them! ( I added one that wasn't 4R70W but it was soo good I had to post it.) Some of these I found by searching, some I found because other board members posted them, and for those I may have forgotten who and I apologize or I'd publicly thank you. To those of you who shared your finds I say thanks.... so here are some links... link listed first, then an explanation:
This site is home to the authoritative article on rebuilding the 4R70w, written by a FORD engineer (Jerry Wroblowski - of the fame of the so called "J" Mod to the valve body of the 4R70W). A Must read, it is my bible.
I was doing a little more inspection of the case.... EPC bore etc... and it occurred to me that in spite of the rear case bushing being nice and smooth, the ring gear which sits in it seemed looser than "was right". So, while I rather had expected to reuse it... I decided to mic it. Clearance? .030... that's right THIRTY THOUSANDTHS! So I picked up a new bushing and mic'd it.... clearance, PRIOR to any crush from case installation? .010. I'll bet from my prior experience in case crush it will be more like .008 by the time I get the old one out and the new one in. Moral? For a good trannie, even in easy to rebuild ones, leave nothing to chance!
Now my dilemma is getting the old one out. It requires a slide hammer puller attachment...Mine isn't exactly like the FORD version. SO... I'll give it my best shot and when (ok and if) I get too frustrated take it to an auto machine shop. The new one I have the installation tool for. (It's part of the 1980 Rotunda AOD tool kit... which shows the heritage) I'll show both parts of this removal/installation if I can accomplish them, otherwise just the installation of the new one.