318is VS 89 325i rear subframe

[bloodshot-e30]

just making sure B4 i decide to swap all my stuff out, these are the same right?

[SkiFree]

Yes, they are the same part number.

EDIT: part #33311135456

[bloodshot-e30]

thanx!! yea i finally got my comp to load realoem and found out!! lol

[84driver]

Only the early model (84-85) 318s have a different rear subframe (aka rear axle carrier), slightly smaller which matches the smaller diff on that model. Oddly, even RealOEM shows the same part (#33311135456) but I can guarantee you they are not the same part. Many places advertise the later/larger subframe as fitting the early 318s -- I have been sold one and had to return it since it didn't fit my diff.

[bloodshot-e30]

im not talking about a early 318 im talking about a 318is (only 1991 in us)

[84driver]

I know, I was confirming SkiFree's response. Also since they are both listed under the same part number there is a slight chance you could get sold the wrong one as I did. Just an FYI.

Not to mention I need more posts to get rid of this Noobie tag :-P

[mikeedler]

Only the early model (84-85) 318s have a different rear subframe (aka rear axle carrier), slightly smaller which matches the smaller diff on that model. Oddly, even RealOEM shows the same part (#33311135456) but I can guarantee you they are not the same part. Many places advertise the later/larger subframe as fitting the early 318s -- I have been sold one and had to return it since it didn't fit my diff.

B.S.

the M3 is the only one that has a different subframe, and that is only because of the different placement of the exhaust carrier bracket.
the small, and medium case diffs all mount the same.

[bloodshot-e30]

I know, I was confirming SkiFree's response. Also since they are both listed under the same part number there is a slight chance you could get sold the wrong one as I did. Just an FYI.

Not to mention I need more posts to get rid of this Noobie tag :-P

lol i pulled it from my 318is

[84driver]

B.S.

the M3 is the only one that has a different subframe, and that is only because of the different placement of the exhaust carrier bracket.
the small, and medium case diffs all mount the same.

Double BS.

I know they are not the same, I saw it with my own two eyes. It is rare and mostly undocumented though, so it's OK if you haven't come across it.

Here's someone else with the same experience:

Yeah this doesn't make any sense...

I searched on realoem.com and it says the rear subframe part numbers for the 1985 318i (small case diff), 1991 318is (small case diff), 1985 325e (medium case diff), etc. basically the e30s all have the same subframe... Therefore, the bolt patterns (where they mount to the subframe) on the diffs should be identical and can be interchanged with this respect.

Also, people on this forum have not reported any issue with swapping the medium case e30 diff into the ti or have any problems with aligning the bolts of the diff with the subframe.

Therefore, the small case diff from a 1985 318i should theoretically have no problems with mounting onto the subframe.

Yet there's around a 8mm spacing difference between the carrier bolt pattern of the diff and the subframe holes.

wtf? Is this some kind of mutant diff or something?

And here:

The [early 318i] chassis is similar to the the E30 6-cylinder cars, however there are a few differences. The battery is located in the engine bay as opposed to the trunk, the car has less sound deadening, a different rear sub-frame and smaller differential.