9" diff regear--how many want to see a write-up?

Below, out of the Ford Shop Manual, for REAR axles, the location of the pinion gear is called out: we all knew in rear axle use, the pinion centerline is below that of the ring gear. That's what makes it a Hypoid Gearset.




Below, the similar description for FRONT driving axle, explaining the pinion is located ABOVE the ring gear centerline.


Below, the blown-up diagram of the front driving axle having the pinion above ring gear centerline. Look at items 4, the housing, and item 26, the axle seal, which clearly shows the axle's centerline which corresponds to the ring gear centerline, as the axles ENTER the center of the differential carrier to which the ring gear is mounted. Obviously the part of the housing where the pinion is mounted in it lies ABOVE the axle's centerline. The housing pretty clearly a standard old Dana casting is upside down.

Also illustrated is the way in which Ford secured the housing's back cover plate: the cover is actually one of the "Twin-I Beam" arms of their front suspension of that name! mo.

 

Thanks for the off topic copy/paste, but my comment still stands.

 

Traditionally, on a big scale it was for Jeeps in the War, they took a regular rear axle, turned it around so the driveshaft from a transfer case would go on in the front of the vehicle, and you had a 4X4. It works. But the gears inside think they're going back wards all the time the vehicle moves forward. No big thing under puny conditions, but putting power to the steep-slanted side of the gear teeth ain't a real good idea. So, the "fix" for that started showing up in 4X4 pickups with what they term "inverted pinion", which is basically everything turned upside down. IOW, on a rear axle assembly: when the driveshaft is turning clockwise as you look toward the back of the vehicle, same direction as engine rotation, the vehicle moves forward, picture direction of say the passenger side drum, turning clockwise as you view it. Take the whole shebang and turn it upside down, and that drum, now on driver's side, still turning clockwise, pulls the vehicle backwards, while the driveshaft and gears still think everything's going forward.

See? mo.

 

Not the case, Mo.
Yes, people have done what you describe, but it doesn't work well, for the reasons you describe. I know a guy that has modified a Dana 60 front axle to work on the rear so that he has 4 wheel steering. There was a LOT more to it than just unwelding the end caps and rotating the pumpkin 180 degrees.
Also, the ring and pinion gears are cut differently for the front than the rear That is why the front gears don't wear out in 2000 miles as would happen otherwise.
Regardless of pinion location (something you seem to be confused as to the reason for) There are a lot of reasons why the center section is not installed upside down on the front of a 4WD. If you ever get the chance to work on one the reasons will become obvious, starting with the location of the fill hole.
As is all too typical, you are focused on defending your error rather than looking into how things really are.

 

Food for thought: Gears. Below is a post from my Explorer forum. What do you guys think of it?

"Can someone look at this pattern and tell me what you think? My backlash is at .10. I think the pinion is still to shallow. I have a .30 shim on it now"

Drive Side.


Coast Side

How would you go about helping this guy out? mo.

 

I'd start off by telling him the two pics are the same. I looked between them several times and came to that conclusion.

Edit: It's fixed.

 

Not only are they the same picture, drive and coast, but he doesn't have it set up properly as otherwise there would not be skipping in the markings.

 

My mistake, Andy! Ya know, I looked twice, and thought the curve of the teeth looked wrong, but then got called away. I've removed the duplicate image and posted the correct one. Thanks for catching that! mo.

 

It's off two ways.
Do the guy a favor and have him come here rather than having you help him.
It is said that the Lord watches over drunks and fools, but that is no guarantee, and you will provide none either.

 

I'll clarify something else, for the record. When I spoke of the idea of upside down center section housings, I had hoped it would not be construed that I condoned some guy doing that very thing. I speak at the level of the designer, the reasons why they do things in some particular way, to promote thought, not ridiculous rebuttal. Rebuttal with proof I can readily accept, and admit errors I make. Like the above post. I suppose I could mealy-mouth around with it, to "save face", at someone else's expense.

Yeah, front ring & pinion gears are "made differently", in that sometimes they are "reverse-cut". That's different all right. Otherwise, they are not. And yeah, the vent holes would leak oil out, upside down. Goes without saying, I thought, the manufacturers would cover that by moving the vent provision on inverted pinion housings. Thought a child would think of it.

It happens that knowledge of Hypoid Gearing is one of the very few Automotive Engineering topics with which I have been very deeply involved most of my life. Spicer Gear Division of Dana Corporation is the very same Spicer that makes those U-Joints we have all used. Now, I will mess with some other kind of mind-boggle for awhile. mo.

 

Thanks for the clarification.
Changing the topic to a discussion of the housing, rather than the rear end alters things considerably.
However, as you mention, even that has to be altered, and IIRC, a third member cannot be bolted in upside down (that is observational, I have never tried doing it), and considering that the new right side up would have been upside down before the rear end was flipped, even more modification is required.
Add to that the fact that the cases are not symmetrical top to bottom, (especially on the Dana units, the 9" is more round) and the problems start piling up in a hurry.
Now, based on your previously, and currently, stated vast knowledge in this area I expected that rather than change the subject from the rear end to the case that you would realize that your error is rooted in saying that the rear end is turned upside down.
As anyone who has worked on them and 4WD setups will know..... The axle is turned around, not turned upside down.
You can quiver and quake and clutch at yourself forever, but facts are stubborn things. That is why I am stubborn about them.

Now go out and actually look at a 4WD truck.
5 seconds of observation will prove that the axle is turned around, not upside down.
There are some interesting details about front drives that are different than the rear ones, besides the reverse cut gears, if you ever get a chance, take one apart and check it out.

 

OK, so now that all of that has been hashed out, all the votes are indicating "YES" 5-0. So once I receive the package, I will know how I will proceed. I haven't located a digital camera yet, so I may have to use my phone camera.

 

Now we're cookin' Andy! If only my wife weren't so tight-fisted with our Digital Cam., I'd lend it to you. That act would likely kill me........mo.

 

Naw, we don't want you to die. I'll ask my nieces. One of 'em has to have one.

 

Well, it's come down to the time for the trade to be confirmed or denied, and I can't get the guy on PM. He always is on in the morning, but not yesterday, or today, and I don't have either his addy or phone number. I'm wondering if he left for his weekend yesterday, So I'll hopefully hear from him and we'll get this done. The only way this'll turn out better is if he's already sent the gears, because of his return addy. So keep your fingers crossed, kids, and wish me luck.

 

I just talked to him and got his addy! I'm in business again!

 

Well, I told him that he didn't need to send the pumpkin in order for him to save money on the shipping, and just popping in the whole pumpkin would be no big deal in a how-to thread. I saw the swap photos on the FSB thread, and the rig's PO used Royal Purple or some such other lube so I have high hopes the gears are in excellent shape.

 

True, but I'm limited by what I don't have...in this case no dial indicator, no real experience. I want to do this to get that relevant experience at my former employer's, who have a dial indicator, as well as an inch-pound torque wrench. So do you see where I'm going with this?