4R70W Rebuild Diary - Part 2 - Output shaft, Ring gear and Hub

[Glacier991]

This is PART 2 of a series. Part 1 is here:

http://www.explorerforum.com/forums/showthread.php?t=128800

OUTPUT SHAFTS

Plural? Well you have two choices... and they are not vanilla and chocolate but 2WD and 4WD. Often people ask if they can swap a 2WD tranny into a 4WD application, or vica versa. The answer is no. Why ? Output shafts are different. Look at them side by side:

Quite a difference. The 2 WD has a sealed extension housing, the 4WD model is intended to bolt up to a transfer case so it the extension housing is a short casting that is open on both ends. Also since the output shaft is the FIRST thing into a case, it is the also LAST thing out.... meaning a full teardown to replace JUST an output shaft. Nuff said? Anyway here are the two end-case housings....

Some things to note.... on the later 4R70W's they did not use a gear driven speedometer, so the hole in the 2WD extension housing got closed off...

Also due to the length, there is a support bushing in the tail end of the 2WD housing... it is a big one, and needs to be checked or replaced... here is my attempt to show you this:

The 4WD extension is bigger and shorter:

[img]http://www.explorerforum.com/data/503/DSCN6599.JPG

and open on both ends

Anyway back to the shafts themselves. (I apologize for the "blown out" photos. My monitor was failing and I did not recognize it so over "brightened" these a little, sorry. I will try and fix these)

Note that the longer 2WD shaft has a speedo gear on it for the earlier trannies that needed it... but I am getting ahead of myself. The "top" end is the same as you can see from these prctures....

In this pic the top one is a "used" 2WD and the bottom is a 4WD I bought off Ebay used and sandblasted clean. (Note: I do not sandblast a machined surface or gearing or splines as a rule.. in this case I did sandblast the 4WD splines since they do not slide).

Here is the bottom part of both... NOW, notice the speedo gearing?

What strikes me about these output shafts is that they are massive strong things. I have a "brand new" 4R70W 2WD shaft and it is indistinguishable from it's used brother. I doubt these ever need to be replaced in normal use..... still.... always check the splines for any adverse kinks, twists or busted splines...

(that baby blue paint is a factory process for acceptance) Notice the splines look good....

Then sight down them...

Perfect. Someone will ask why the 2WD splines are so long. There is a slip yoke that can ride up and down them... the 4WD goes right into the TC.

So my advice is.... REUSE your output shaft. Clean the fluid passages in it (yeah it has those) but unless you are running 600+ HP, it should be FINE !

[Edit] I will add that Jerry W in his article on the TTCOA site notes that in 98 FORD started using a stronger material for this shaft. ..So if you are doing something exotic (nitrous, blower, etc) you may wish to locate a 98 or later shaft. I'll see if i can find some part No's for this and post them [here].

Oh the ring seals on the top end of the output shaft.... the original factory build and most rebuild kits use a beveled (scarf) cut seal. There are apparently aftermarket new design solid seals. It is recommended elsewhere that you use the new solid ones as a precaution against leakage where these seals seal in the direct drum. The "upgraded seals" are teflon, one piece, and apparently not fun to get on and need to be sized. Currently I am discovering that in spite of my assumption that the Sonnax upgrade kit contained them they do not - they include a teflon scarf cut seal. I am now looking for a source for these one piece seals... so this may hold me up a little.

[Edit] I have found a source, and the special tool needed to install them. I'll be upgrading this when I get the tool and seals.

The lower seals are metal and easy to put on. Here is a pic of the new ones as I finsihed putting them on... takes a few minutes tops.

The purpose is to make sure that the delivered fluid flow here travels up the shaft to get used in the direct dum and clutch. In that clutch drum there are also some shaft seals to further insure the fluid goes where it is supposed to... these are the ones I referenced above.... Here are the teflon scarf ones.... installed. A scarf cut seal has a proper and improper way to install it... kinda intuitive.... here is how it SHOULD be...

I also sandpaper areas that are supposed to carry oil as the lubricant.. the sandpaper scratches helps them do it.... here is the tip of the output shaft that goes into a bushing...

That little red arrow shows the places that the teflon sealing rings go... make sure you check these for any burrs. They should not be there and likely wont. but check check check! (Also I suggest you consider the 1 piece seals described above - the direct drum is a failure point in this transmission and this is in the pathway where the hydraulic power comes from to apply it).

Auto trannies are all about attention to detail.

So when the shaft is all done, it next goes into a hub... an attaching piece to the rear ring gear. Since I have NEW. I will try where possible to compare new to old and show you where to look for possible re-use or replacement. The hub is not a likely replacer unless you had a catastrophic failure with shards of metal througout the tranny (In which case you might want to punt and start afresh with another transmission....) I Digress. Here are the two hubs side by side, old on the left new on the right...

The hub is where the transmission drive "line" is supported as it leaves the case.... in the rear bushing I talked about replacing. This COULD be a "wear" point. BUT... the bushing is bronze and these things are hardened steel. So let's compare NEW to "used".

Here is new:

and here is used (no catasprophic failure at work)

Difference? A machinist would say five tens.... or translated.... one HALF of a THOUSANDTH of an inch. In lay terms.... NADA. Unless something really bad happened, REUSE the hub.

I always scuff up any oil carrying surface with sandpaper 220 grit minimum.... I did it on the NEW one..... here is a comparison.... just for grins...

(not a great pic) Here is the used one...

It had some shiny parts and some scuffs. After I took the pic I scuffed it and it looked good as new. REUSE your hub unless you have had a bad failure.

REAR RING GEAR

This is an important piece...and also built like a brick shjthouse. Once again unless you were grinding metal shards in the tranny... re-use should be fine. Here is a new one next to a used one....from above...

and from the side view

There are two important things to check.... one is where the parking pawl engages... are these sharp and square?

The other is the gear splines.... are these looking ok, no pits.. missing spots or obvious bad wear? (Should not be)

Once again, barring a catastrophe....this should be reuseable.

To finish this thread... let's look at a finished unit..... output shaft installed in hub... hub and output shaft installed in the the ring...

Here is the shaft in the hub....

Here is the shaft showing where the snap ring goes to retain it in the hub (red arrow shows the retaining groove)

Here is the installation of the retaining snap ring

Here is the finished hub and out put shaft assembly

And here is a view inside where the direct drum will go...

This assembly rests on a torrington bearing and goes into the rear case bushing. Here is a look at the assembly, the bearing and the package the torrington came in

And as the package says:

The bearing has a ring that wraps around the case output shaft area... but it rides on the rear ring/output shaft assembly like so (a shameless attempt to get yet another hand picture on the internet by me!)

....

 

[Glacier991]

Geeze I had forgotten how 20 minutes of work translated to several hours of WORK to photogragh and create the post.

 

[toy720]

maybe you can show both sides of the torrington bearing and the proper way to put in they look different on each side? i know when i did the 4r that confused me but that could have just been the beer?

 

[Glacier991]

Good point. Some torringtons DO have a proper orientation. Most do not. In this case, the torrington has a raised edge on one side that goes DOWN onto the "snout" in the rear case enclosing the rear case bushing. The other side is plain. This is one where you'd not likely put it in upside down. (g) I will however keep your excellent comment in mind where there may be a difference on one side or the other.

 

[Glacier991]

As I put the above thread together I was aware that you can install a teflon one piece seal (a pair actually) in place of the scarf cut orange seals that i show you above. At the time I did this thread I did not have the knowledge or tools to do that, so showed you the way it is done 99% of the time. HOWEVER.... that scarf cut seal tends to leak as I understand it, and since the pair more or less serve as seals to help preserve the feed to the direct clutch, which is a problem child in this transmission, it seemed to me to be a good idea to figure out how to install the solid seals.

Well, I did that. Here is the thread on how to install them.

SOLID TEFLON SEALS ON THE OUTPUT SHAFT

These seals are not out of some 4R70W parts kit. In fact they come from an entirely different transmission... the GM 325-4L. Relax guys, this changeover is done all the time. This seal is not only one piece, which eliminates the scarf cut, it is also .010 wider. Wider is better (apologies to Pontiac). The problem was, how to get the D#*n things on.

At the risk of editorializing, tranmission guys are incredible inventors. Many of the aftermarket tools are literally inventions from the workplace. Someone came up with a neat little kit to install these seals. It sells for $60 but is worth every penny.

Here it is:

I know looks like a trip to the Home Depot plumbing section. The bottom row are the seal installation tools, and the top row, including the big thing on the right are seal sizers. SIZERS... you will understand why soon enough.

These are the solid rings. orange teflon.

Here is one of these solid rings on my finger next to the scarf cut (arrow)... notice the difference in thickness? (.010 - yet apparent)

and here is a view again of the scarf cut installed. I am not being critical but the solids make SO much more sense....

Oh, that big hole in between is the oil feed to the direct clutch!!

All right, enough. Lets see how this kit works. We start by filling the space between the seal lands with something to allow us to slide a seal over it.... here it is...

It spreads open and allows us to install it in the space between where the seals go...

All that is left open to snare a seal is the front seal groove.... so we next fill that

Sort of a pseudo seal. Here they are installed....both the middle filler are the pseudo seal front

We next add the seal expander/installer...

Here is a closeup.... you can see the idea here, allow a smoth place for the seal to be pushed over into position...the front arrow points to the pseudo seal filler, the rear arrows point to where the rear seal will rest:

Next we lubricate the apparatus with our old transmission rebuilder's friend:

vaseline... I recommend if you plan to build transmission you buy a BIG container of it.. and walk out of the store with a superior smile on your face. Anyway, we add this to the tool to aid in installation...

Next we add the first (rear) ring to the expander at the tapered end....

Using the "pusher" we carefully and smoothly move it back into the rear most ring groove

When we remove the center piece it looks like this.... rear seal in the groove!
(Notice how big and sloppy it is!)

When we remove the "pseudo seal" here is what we have, but wait.... what does the arrow see?

A snarfed piece of teflon seal. Now this is probably not critical, but I repeated the process and made sure my seal was intact. Sooo...one seal down. (Attention to detail is critical in transmission building.) So while I did not show the repeat, I did repeat this step....but anyway now it is time for the front seal... We reinstall the expander/installer and lubricate it.... add the front seal to it...

and carefully push IT into place

pulling the pusher away

Here are the solid seals, installed... but VERY loose (unsized):

So now what? We SIZE them (compress them to fit into the direct drum)..

Stay tuned. Sizing is up NEXT.

 

[Glacier991]

SIZING THE SEALS

Sizing is the process of adjusting the seal size so as to allow it to be inserted into a mating place (usually some related bore). We saw this process in the A4LD Diary, and in fact anytime you have a one piece seal, it is necessary, as in the forward cluth input shaft in this transmission (more later).

For these seals, the Installation tool we just showed you also comes with a Sizer. It consists of two clamshell halves, and a tube (with TWO different Inside diameters) that you use to slowly compress the seals.

Here are the clamshell halves

You put them on over the seals... here are a couple different views of that - you start by squeezing them with your fingers as you go...

Then with it's big end well lubricated (can you say VASELINE!) slide the sizing sleeve over it... this is just the first step....

And push it all the way on. This will rest for a while (hours is best)

After this step the sloppy seals start to be "less" sloppy...

You next repeat this process with the smaller end of the sizing tube.... and at the end of the sizing process you SHOULD be able to insert the shaft into the well lubed direct drum bore.... Store it there until you are ready to install it.

On final build, that will mean pulling the output shaft and direct drum apart, adding the ring gear and snap ring to the putput shaft, inserting the output shaft and ring gear into the prepped case, and soon after adding the direct drum. We'll show you all that.

For now... GM meets FORD. FORD wins on this one... why? It gets solid seals on a weak link!

[Edit: Well... recently on a hunch I picked up some FORD tools on E-Bay.. one of which seemed to be their answer to this problem and response to it. I had really hoped to get a set of instructions with it (not usual but not unheard of with late tool additions) but did not.

It took me a few minutes to figure out how this tool was designed to work, but once I did... well... it was, exactly what I thought it might be... a FORD tool to do what this tool above does... only better and easier. I was awed by the design and function. I will post the same thing I posted above only using the new FORD tool.... and forever give up buying them on E-bay for $9.99 plus shipping.end edit]


Part 3 of this Diary continues here:

http://www.explorerforum.com/forums/showthread.php?t=157376

Stay tuned it gets better!

 

[Glacier991]

If you have questions, comments, ideas or just feel an overwhelming need to post about this thread, please go here ...

http://www.explorerforum.com/forums//showthread.php?t=161450

I am trying to make it easy for folks just wanting basic information. The questions etc can have their own thread. Thanks for understanding.