[Differentiall]

hey guys. i have an e90 330i 6mt and i happened to get a 328i auto differential from a buddy for free. would it be a direct p&p? tried looking it up here but couldn’t find an exact answer. thanks for your help!

[atmosphericM]

You must not have looked very hard, lol. Yes, it will work.. as long as they're both RWD models.

EDIT: Nope, looks like it is not a direct swap due to different input shaft bolt pattern.

[hassmaschine]

why would it matter if it was RWD? the rear diffs are the same.

[Differentiall]

Originally Posted by atmosphericM

You must not have looked very hard, lol. Yes, it will work.. as long as they're both RWD models.

apparently haha. I saw that it was direct for the 328i 6mt and 328i auto diff but wasn't sure about the 328i auto diff into the 330i. both are rwd

[atmosphericM]

Originally Posted by hassmaschine

why would it matter if it was RWD? the rear diffs are the same.

Is this true, you're sure? When I was browsing a while back I thought I noticed that the XI's input shaft had a different bolt pattern. I also could have sworn I read that the XI's weren't compatible...

If they are, that means we can get a 3.91 FD because that's what I'm seeing for the XI models (at least for the 328xi).

EDIT: I hate to disagree but I just re-checked eBay and I'm seeing a 3 bolt pattern for the 328 XI-AWD models whereas the 328i RWD models have an 8 (4) bolt pattern on the input shaft to the differential pumpkin. So I'm going to say again that I don't think the AWD carrier would work (sure you might be able to change the input shaft but why bother with all of the extra work?).

[atmosphericM]

Originally Posted by Differentiall

apparently haha. I saw that it was direct for the 328i 6mt and 328i auto diff but wasn't sure about the 328i auto diff into the 330i. both are rwd

AFAIK, the only difference between the 328i and 330i AT RWD Differential is the FD: 3.64 for the 330i AT and 3.73 for the 328i AT.

EDIT: This is actually incorrect! It appears that the 330i/330xi (and 328xi) uses the 3 bolt pattern input shaft whereas the 328i (rwd) unit uses the 4/8 bolt pattern input shaft.

[hassmaschine]

Originally Posted by atmosphericM

Is this true, you're sure? When I was browsing a while back I thought I noticed that the XI's input shaft had a different bolt pattern. I also could have sworn I read that the XI's weren't compatible...

If they are, that means we can get a 3.91 FD because that's what I'm seeing for the XI models.

EDIT: I hate to disagree but I just re-checked eBay and I'm seeing a 3 bolt pattern for the XI-AWD models whereas the RWD models have an 8 (4) bolt pattern on the input shaft to the differential pumpkin. So I'm going to say again that I don't think the AWD carrier would work (sure you might be able to change the input shaft but why bother with all of the extra work?).

I'm was going off part numbers - 330i and 330xi both have the exact same diff at least.

it's not easy to tell because the gear ratios are usually different between RWD and AWD models.

All the flex disks in the rear are the same:
http://www.realoem.com/bmw/enUS/part...&q=26117527392

I have to believe the input shaft isn't different or they couldn't share flex disks.

[Biginboca]

Some of the diffs have different pinion flanges. I noticed this when I was shopping for my diff.

You can swap the pinion flanges from one to another though.

[Differentiall]

Originally Posted by atmosphericM

AFAIK, the only difference between the 328i and 330i AT RWD Differential is the FD: 3.64 for the 330i AT and 3.73 for the 328i AT.

i was thinking the same exact thing. but i always want to double check to make sure on these types of things. i appreciate the feedback!

[atmosphericM]

Well I'm glad you brought this up, because actually I think I was totally wrong (I blame the other thread here ).

Originally Posted by hassmaschine

I'm was going off part numbers - 330i and 330xi both have the exact same diff at least.

it's not easy to tell because the gear ratios are usually different between RWD and AWD models.

All the flex disks in the rear are the same:
http://www.realoem.com/bmw/enUS/part...&q=26117527392

I have to believe the input shaft isn't different or they couldn't share flex disks.

Interesting. You are totally right. I'm really glad you brought this up. In the other thread going, the consensus seemed that one could use 330/325 units interchangeably with 328 units, but after digging through the link you just posted, it looks like the 330i flex disc is the same as that of the 330xi. And the more I looked around... it appears that the 330i, 330xi, 325xi all share the same 3 bolt input shaft (looks like the 325i RWD unit uses the 4/8 bolt pattern found on the 328i RWD.. just to make things more confusing). I didn't see anything about 328's for that part number (except for XI's and EURO models), so I would now say that the 328i diff would not be a direct swap into the 330 platform, as the 328i unit has the 4/8 bolt pattern input shaft vs. the 3 bolt pattern found on the XI's (all models?) and 330i. Thanks BMW... thanks. lol they really don't make it easy for us do they?

As biginboca said, you could probably swap the input shafts; however I've never done that personally so I don't know how involved it would be. Not super hard, I'm sure.. maybe someone here can chime in. I do know that swapping the shafts usually involves new seals.. all of which can be kind of a pain at times I've heard due to possibility of leaks, etc.

The good news here is that you 330i guys now seem to have an even more aggressive option for swapping final drives via changing the entire pumpkin - the 330i auto RWD diff (3.64), as well as the 328xi auto XI diff which is 3.91 (however I cannot commit to saying 100% for sure that the 328xi unit works, as perhaps there is another difference between the 325/330 and 328 platform.. hopefully someone with a 330i can chime in here)! That'd be a jump, heh. I'd also imagine the 330xi auto XI diff would be a direct swap; I'm not sure what the final drive on that unit is though.

I suppose this also means that one could rock the 3.91 328XI rear pumpkin in a 328i, however you would need to swap the input shaft.

I wonder if there are any other differences internally, regarding the actual differential itself. (Probably not, but the XI diff would not need to handle as much power as the RWD diff, so who knows?)

Disclaimer: This is all based upon internet reading though, just to be clear. What we really need is someone who has personally done a swap between the 330/325 platform and the 328 platform to confirm these findings.

[desertman123]

http://www.1addicts.com/forums/showthread.php?t=1418770

[hassmaschine]

Originally Posted by atmosphericM

Well I'm glad you brought this up, because actually I think I was totally wrong (I blame the other thread here ).



Interesting. You are totally right. I'm really glad you brought this up. In the other thread going, the consensus seemed that one could use 330/325 units interchangeably with 328 units, but after digging through the link you just posted, it looks like the 330i flex disc is the same as that of the 330xi. And the more I looked around... it appears that the 330i, 330xi, 325xi (looks like the 325i RWD unit uses the 4/8 bolt pattern found on the 328i RWD.. just to make things more confusing) all share the same 3 bolt input shaft. I didn't see anything about 328's for that part number (except for XI's and EURO models), so I would now say that the 328i diff would not be a direct swap into the 330 platform, as the 328i unit has the 4/8 bolt pattern input shaft vs. the 3 bolt pattern found on the XI's (all models?) and 330i. Thanks BMW... thanks. lol they really don't make it easy for us do they?

As biginboca said, you could probably swap the input shafts; however I've never done that personally so I don't know how involved it would be. Not super hard, I'm sure.. maybe someone here can chime in. I do know that swapping the shafts usually involves new seals.. all of which can be kind of a pain at times I've heard due to possibility of leaks, etc.

The good news here is that you 330i guys now seem to have an even more aggressive option for swapping final drives via changing the entire pumpkin - the 330i auto RWD diff (3.64), as well as the 328xi auto XI diff which is 3.91 (however I cannot commit to saying 100% for sure that the 328xi unit works, as perhaps there is another difference between the 325/330 and 328 platform.. hopefully someone with a 330i can chime in here)! That'd be a jump, heh. I'd also imagine the 330xi auto XI diff would be a direct swap; I'm not sure what the final drive on that unit is though.

I suppose this also means that one could rock the 3.91 328XI rear pumpkin in a 328i, however you would need to swap the input shaft.

I wonder if there are any other differences internally, regarding the actual differential itself. (Probably not, but the XI diff would not need to handle as much power as the RWD diff, so who knows?)

Disclaimer: This is all based upon internet reading though, just to be clear. What we really need is someone who has personally done a swap between the 330/325 platform and the 328 platform to confirm these findings.

Yeah it looks like only the RWD 328s have the different bolt pattern.

For swapping the input, you would need to mark the position of the nut, count the number of turns when you remove it, put in a new crush bearing, then tighten it back down to the exact same spot.. Otherwise the pinion bearing lash won't be right and it will fail. It's not impossible, but for many people they probably shouldn't try it themselves unless they know the consequences..

[Biginboca]

Originally Posted by hassmaschine

Yeah it looks like only the RWD 328s have the different bolt pattern.

For swapping the input, you would need to mark the position of the nut, count the number of turns when you remove it, put in a new crush bearing, then tighten it back down to the exact same spot.. Otherwise the pinion bearing lash won't be right and it will fail. It's not impossible, but for many people they probably shouldn't try it themselves unless they know the consequences..

In my experience when swapping pinions on diffs you need to use a new crush sleeve and check backlash as you torque the pinion nut. You continue torquing in small increments (5ft/lbs or so) until you get the right backlash. This is a science and the longevity and performance of your diff depends on accuracy. That is the best and correct way.

But...

I’ve also done it myself the shortcut way Hass described a few times and never had a problem. I agree with the way he described above but with a small exception...

For the shortcut way I was taught and have always done it like this. I marked the nut position and REUSED the same crush sleeve. If you use a new crush sleeve you need to do the other procedure I described above and torque to spec measuring the backlash. Using a new crushsleeve requires starting over with setting the backlash. That’s how I was taught anyway.

[juld0zer]

That's also the BMW method when you replace a pinion seal as they don't want anyone rebuilding diffs for that matter either.

A pinion flange swap won't work because a guibo pinion has the additional section for the centring bush of its matching propshaft.
You could build a frankenshaft, get it balanced and not have to muck around with the diff.
There could be a chance you can just swap the entire propshaft if the donor car is the same chassis and has the same transmission for example.

Unfortunately the best I'd be able to get here in Australia is a 3.73 as we never got Xi models here. Not much of a gain for my manual 130i's standard 3.46. 3.73's are rare here too as they were only in 330i's. Ideally I'd want to import a low mileage 328Xi and just slap it in but there isn't many good donors available

[markslc1]

This has been a helpful thread for my 128i diff upgrade. But I'm now considering a 325xi manual and wondered how a diff upgrade would work for that car. Assuming I get a 3.91 diff from an auto, would I need one or two diffs? (front and rear). Or would I really only need a rear one? I'm new to this 4WD stuff.

[E92William]

You would need both the front and rear diff. Front diff is a long job as you have to drop the subframe.

[jonwilli]

Originally Posted by juld0zer

That's also the BMW method when you replace a pinion seal as they don't want anyone rebuilding diffs for that matter either.

A pinion flange swap won't work because a guibo pinion has the additional section for the centring bush of its matching propshaft.
You could build a frankenshaft, get it balanced and not have to muck around with the diff.
There could be a chance you can just swap the entire propshaft if the donor car is the same chassis and has the same transmission for example.

Unfortunately the best I'd be able to get here in Australia is a 3.73 as we never got Xi models here. Not much of a gain for my manual 130i's standard 3.46. 3.73's are rare here too as they were only in 330i's. Ideally I'd want to import a low mileage 328Xi and just slap it in but there isn't many good donors available

I have a manual 130i in the UK. I managed to get a 328xi diff imported into the UK from the US for less than the price of a second hand diff from a scrap dealer in the UK! Cost me £175 for diff, shipping and import duties. Might be an option for you? Found it on eBay.

Makes a big difference to acceleration with my Quaife in it.

[200,000 club]

I'm guessing that the diff from a 335i wouldnt fit a 325/28/30i, anybody know?