Anyone taken apart rear differential on X5 2003 3.0?

[Bmwe5320023.0]

Long story short, I need to transplant the ring gear assembly from another diff.
I sandblasted and painted my diff, and the roller bearings got some sand on them.
So the ring gear assembly has 2 bearings already. They're insanely expensive, so I just purchased another diff from marketplace to use the ring gear assembly from it.

My E53 is 3.0 2002. The diff I purchased on ebay seemed to be E53 2003
As I started taking it apart, I realized the marketplace differential had a different spacer/snap ring.

The original rings were 3.68 and 3.82. I expected the marketplace diff to be the same, it looked the same from outside. However I noticed it's snaprings were 3.82 and 3.74

The ring gear assemblies also have different part numbers, so I'm kinda confused by all this.
I decided to take a chance and transplant the ring gear assembly along with the snap rings to my painted case, but I wonder if there are going to be issues.

[aureliusmax]

not sure exactly what your question is but there's some important theory like pinion bearing pre-load which is a special assembly procedure coupled with pinion and crown gear backlash and gear transfer pattern...
just can't throw things together and expect it to be quiet or last. looks like those clips are part of the spacing used to adjust preload or gear pattern.

[Bmwe5320023.0]

I'm trying to understand what's different between these two differentials.
And since the cases look to be identical, can I swap internals from one differential to another.

[Henn28]

The snap rings will differ in thickness by individual differential assembly. Each diff case, carrier and output bearing (s) are very slightly different simply due to manufacturing tolerances. The snap rings account for this, in very small increments, in order to get the proper preload on the output bearings, backlash, and pinion/crown gear mesh patterns.

Hopefully by mixing and matching your available rings, you can get the adjustments right, or close enough. I’d start with the OE rings that came with the new diff carrier. Left side first, then right. You may need a punch, or the old race to get them to seat. Then check backlash if good, check the gear tooth pattern. Try a different combo if not to slightly shift the diff crown towards or away from the pinion.

Not sure about the different casting numbers on the crown, but count teeth on your pinion and crown and divide to get the ratio. If it’s the same as your OE ratio then the numbers on the crown don’t matter. Maybe factory or some other identifying mark?

[Bmwe5320023.0]

I was able to get the rings from the "new" used differential from market place installed into my painted differential without any issues.

Now I've already sealed the differential, used my old housing case and pinion ring, but installed the ring gear, probably the same thing that you refer yo as crown gear, from the differential I purchased on market place.

Unfortunately I don't know how to measure backlash or gear tooth pattern, never took apart a differential before.

What I'm thinking about now is whether the old pinion gear and old ring gear will match together properly.
When I turn the end where the driveshaft bolts, seems to be turning ok on the sides

[Bmwe5320023.0]

Counted teeth on my old x5 2002 ring gear, 41 teeth. Counted teeth on the "new" pinion gear, X5 2003, 10 teeth.
So I'm pretty sure the teeth on both differentials are the same, since both differentials are the same as well, 4.10 ratio.
I understand your explanation why the snap rings are different sizes. So basically same differentials can have slight variations.
The only thing I don't understand why now, is why the numbers on the two ring gears are different. Both have 41 teeth looks like.
The differential I purchased from X5 2003 has these letters and numbers on the pinion gear. Not sure what they mean?

[Henn28]

Originally Posted by Bmwe5320023.0

Counted teeth on my old x5 2002 ring gear, 41 teeth. Counted teeth on the "new" pinion gear, X5 2003, 10 teeth.
So I'm pretty sure the teeth on both differentials are the same, since both differentials are the same as well, 4.10 ratio.
I understand your explanation why the snap rings are different sizes. So basically same differentials can have slight variations.
The only thing I don't understand why now, is why the numbers on the two ring gears are different. Both have 41 teeth looks like.
The differential I purchased from X5 2003 has these letters and numbers on the pinion gear. Not sure what they mean?

If the tooth counts/ratios are the same, and the new ring gear bolted up to your diff carrier then I think the numbers don’t matter. Im no expert, but I think the gears gears must be the same dimensionally. Perhaps the different numbers are different suppliers, or factories, etc.?

Testing backlash isn’t too difficult. You just need a dial gauge which are cheap on Amazon.

Edit...you need a dial guage and some time to watch youtube videos! RacingDiffs has some good ones on building diffs, and the guy who does "spank ranch garage" videos on youtube does good work too and super entertaining. He's got a thrasher 3Series drift car that he did a quick diff rebuild for that is entertaining, and is worth a watch from a learning standpoint.

My dial gage was cheap and worked well. The magnetic base can be attached to the diff case, or a metal workbench table.

[Bmwe5320023.0]

Thanks for the info! I didn't know it was magnetic, now it makes sense, I though I needed some intricate mounting system...
I'm just thinking if I pull the diff apart again, after the rtv cured, or just take a chance with what I put together.

I've also installed this racingdiff LSD plate in it. I was watching the video, and at 9:30 minutes he's using a lathe machine to shorten the flanges on the half shafts by 4mm.

https://youtu.be/bLESfhaCROE?si=zaXbuTNVQ6xaSVjc

Not sure if you know anything about it, but that's definitely complicating the project by having to look for someone with a lathe machine...

[EODguy]

Originally Posted by Bmwe5320023.0

Thanks for the info! I didn't know it was magnetic, now it makes sense, I though I needed some intricate mounting system...
I'm just thinking if I pull the diff apart again, after the rtv cured, or just take a chance with what I put together.

I've also installed this racingdiff LSD plate in it. I was watching the video, and at 9:30 minutes he's using a lathe machine to shorten the flanges on the half shafts by 4mm.

https://youtu.be/bLESfhaCROE?si=zaXbuTNVQ6xaSVjc

Not sure if you know anything about it, but that's definitely complicating the project by having to look for someone with a lathe machine...

Try your local Vo-Tech school, they'll usually do work for cheap or materials under the instruction of a master machinist.

Sent from Embassy network using Tapatalk

[Henn28]

Originally Posted by EODguy

Try your local Vo-Tech school, they'll usually do work for cheap or materials under the instruction of a master machinist.

Sent from Embassy network using Tapatalk

Excellent idea. Reminded me too that I need to reach out to the local community college here and see if their paint program needs a donor car. Definitely willing to pay, but won’t do it for the market cost of a good paint job that won’t make me sad every time I open a door.

I’m told it’s an excellent program, and would love to take a class myself. But I think learning to weld would be much more useful at this stage.