Quote:
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..