DIY: How To Swap a Differential (plenty of pics)

[skuyler]

Not to revive the dead/old, but how hard is it (and can someone post clear instructions) on how to change the driveshaft flanges? My 328is has a 4 bolt 2.93 Open diff, and the one i was is from a 95 M3, and is a 6 bolt 3.15 LSD. how hard will this be?

[Tommy R]

Reviving an existing thread should be ENcouraged, not DIScouraged. People create too many new threads as it is....but I digress.

I've swapped an input flange. It's a matter of removing the nut, using a puller to remove the flange, inserting the new flange, and torqueing the nut down to the proper specs and with the proper thread locker. It may require a new nut to be safe. I would measure the preload on the pinion flange before removing it. When you install the new one, torque the nut until the same preload is reached.

I would verify this with the Bentley.....or a good manual if you have one.

Good luck,
Tommy

[old skool]

Not to revive the dead/old, but how hard is it (and can someone post clear instructions) on how to change the driveshaft flanges? My 328is has a 4 bolt 2.93 Open diff, and the one i was is from a 95 M3, and is a 6 bolt 3.15 LSD. how hard will this be?

It isn't terribly hard. you need to take your 328 output shafts out of your 328 diff. Pretty straight forward.

Then you need to inspect the seals and bearings in the output shafts of the M3 diff. The best bet is to replace these. Then just press the 328 shafts in.

When it is on the car I would drain and refill the fluid as well.

[BraveUlysses]

Not to revive the dead/old, but how hard is it (and can someone post clear instructions) on how to change the driveshaft flanges? My 328is has a 4 bolt 2.93 Open diff, and the one i was is from a 95 M3, and is a 6 bolt 3.15 LSD. how hard will this be?

You should also inspect the innards of that 3.15 diff--check the link in tommy's sig. The factory omitted threadlocker on a few of the bolts and they have a tendency to back out, bounce around and get stuck in the gears. You should verify that everything is as it should be.

[EdirtySicks]

thanks! Im needing this right now.

[patrickofcash]

Great great writeup. If I get my 3:15 replacement this weekend, I'm ready to do this thanks to the quality of the pics and narrative. Thansk! *Crosses fingers*

[patrickofcash]

Speaking of, can anyone confirm that the E12 TORX is available for $3.99 from Autozone, and if so, perhaps show a link? I'd rather not waste the money on the extra Sears set if I don't have to. Thanks!

[BraveUlysses]

I can confirm it was 4 or 5 bucks. Just call whichever store you're planning on going to.

[Hathaway]

Not sure whether this has been mentioned already in this thread or not, but the exhaust and sway bar do not have to be removed from the car inorder to swap the diff.

I just swapped mine this past weekend, and I left the exhaust completely bolted in place (a few extensions are required to get at the drivers side halfshaft to diff bolts). I also only unbolted the swaybar from the frame, not the suspension. This allows you to push the swaybar up enough the get at the rear diff mount bolts, and lower the diff out of place.

[carbon monoxide]

Reviving an existing thread should be ENcouraged, not DIScouraged. People create too many new threads as it is....but I digress.

I've swapped an input flange. It's a matter of removing the nut, using a puller to remove the flange, inserting the new flange, and torqueing the nut down to the proper specs and with the proper thread locker. It may require a new nut to be safe. I would measure the preload on the pinion flange before removing it. When you install the new one, torque the nut until the same preload is reached.

I would verify this with the Bentley.....or a good manual if you have one.

Good luck,
Tommy

so how do you measure preload?

[HiTheNameIsBj]

I was told that there was quite a bit of "timing" when it came to installing the new diff as far as spinning it a few times until input and output shafts were synchronized. This isn't the case?

Great write up by the way

[Tommy R]

Not sure whether this has been mentioned already in this thread or not, but the exhaust and sway bar do not have to be removed from the car inorder to swap the diff.

I just swapped mine this past weekend, and I left the exhaust completely bolted in place (a few extensions are required to get at the drivers side halfshaft to diff bolts). I also only unbolted the swaybar from the frame, not the suspension. This allows you to push the swaybar up enough the get at the rear diff mount bolts, and lower the diff out of place.

Yep, it was mentioned in the first or second page, if I recall.

Tommy

[Tommy R]

so how do you measure preload?

There are several ways. You could get a torque wrench that measures in in-lbs. and simply use a socket that fits the input flange nut. Increase the torque setting on the wrench until the flange rotates. That's youre preload.

Or you could use a fish scale in a hole on the input flange. Measure the amount of "weight" required to get the flange to turn. Then use some math to determine how that force (applied "x" distance from the centerline of the flange) correlates to the amount of torque in in-lbs.

Tommy

[Tommy R]

I was told that there was quite a bit of "timing" when it came to installing the new diff as far as spinning it a few times until input and output shafts were synchronized. This isn't the case?

Great write up by the way

Nah, 'cause the input and output flanges will all change relative to one another as the differential does its job.

And thanks.

Tommy

[mmpete0131]

This is a GREAT write up, thank you! It is a job I look forward to doing sometime this year!!

[Tommy R]

My pleasure....

[JUS2K]

Thanks for the write-up and pictures. As mentioned, pics do a world of justice when us DIY'ers want the challenge/satisfaction of doing something ourselves....now if I can only find an LSD that'll balance my auto trans(ugh) with better low-end take-off power....anyway, the search continues. Peace. PG

[gcalvey]

great job, i'm considering swapping but it looks like a lot of work

[patrickofcash]

If you have doubts about the DIY nature of this for a relatively new DIY mechanic - let me say from experience - DO IT!!! It took my dad and I approximately 2.5 hours with air tools and no prior experience with BMWs. There were a couple of times when we got stumped, and of course the natural profanity when one of the half-shafts smacked him in the face (I always manage to escape injury), but other than that it's well worth it and fairly straightforward.

[1fast325]

is it normal to go 65 mph at 3500rpm I did a manual swap on my 93 325is dont know if I also had to swap the differencial

[Tommy R]

is it normal to go 65 mph at 3500rpm I did a manual swap on my 93 325is dont know if I also had to swap the differencial

Nope. If you had an automatic, you had a 3.91 gearset so you would likely be better off with a 3.15 from a 5 speed car.....or a diff from an M3, but those carry a premium for only a marginal improvement in gearing. At least all M3 diffs have a limited slip whereas not all 5 speed diffs do.

Tommy

[1fast325]

thanx did I have to change my wiring to get my check engine light of and the ecu or is there a way to get around that

[1fast325]

also do i have to change my wiring and my ecu to get my check engine light off and my back up lights to work because I don't have anything plugs connected to the trans

[kgvickers]

What the heck, bring back a really old thread . . .

I'm about to go through this and I am concerned about how much torque to put on the input flange nut. I found this info, see post #32:

http://forum.e46fanatics.com/showthr...6&pp=20&page=2

According to this post, the necessary torque is all about "spinning torque". Interesting.

Tom stated that the nut on his diff was not torqued . . . I suspect it was originally. Once the "crush sleeve" has done its job, the nut will likely back off very easily.

[cabrio1998]

hi people!!!
did anyone put m3 dif on 320i cabrio 1998?
datails,pics,info plz