A Quick Trip Thru The Guts Of The 4r70w
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.