e30 diff cover won't fit e28 lsd!

[Doughnut]

Went to put the e30 rear diff cover on the e28 lsd today only to find that the too bottom bolt holes don't line up, the e28 diff is much bigger...

e30(3.46) and e28(S 3.45) diff covers:

e28 diff:

e30 diff cover does not fit...

So are all the people that say "swap the diff cover, and output flanges" talking crap? What is going on here - lol.

[Doughnut]

Also, is it possible to remove the lsd center from the larger diff and put it in my smaller e30 diff?

[asubimmer]

I can't see the pics at work but you may have a small case e30 diff.

[Erick]

Doesn't look like a small case. I've definately never seen that shape of a diff cover from the e28.

I've heard in the past that there is such a thing as large case differentials, although I have never seen it (most e30s and all e28s I've seen have the medium case). Quite possibly this might be that large case diff.

- Erick

[Doughnut]

This is the diff in my 318i, that I was hoping to swap the e28 lsd (with e30 rear cover) into for my m30 swap:



It only has 6 bolts for the rear cover so would that make it the small case?
You guys mean to tell me that I have a small, med and large case diffs... Just fucking great!

Do any of you guys know if the medium and large case centers are interchangeable? ie: putting the large case e28 lsd unit into the medium e30 case?

also, I personally pulled this diff from an e28 so i know it's from the e28. thanks guys

[Rigmaster]

your 318 has a small case diff, you need a medium case E30 rear cover and it will work fine.


Medium case E30's are all 6 cyl's plus E30M3, at least for the US market.


As for swapping the internals- it won't work unless you're swapping the same size internals- i.e. Medium case to medium case or small case to small case only.

[craz azn]

Went to put the e30 rear diff cover on the e28 lsd today only to find that the too bottom bolt holes don't line up, the e28 diff is much bigger...

e30(3.46) and e28(S 3.45) diff covers:

e28 diff:

e30 diff cover does not fit...

So are all the people that say "swap the diff cover, and output flanges" talking crap? What is going on here - lol.

You have an 'early' e28 diff. Sometime in '84 they changed the castings of the housing so all the bolt patterns would be the same. You will have to switch you internals from your e28 diff into your existing housing. I know, because I ran into this problem not too long ago.

[Doughnut]

You have an 'early' e28 diff. Sometime in '84 they changed the castings of the housing so all the bolt patterns would be the same. You will have to switch you internals from your e28 diff into your existing housing. I know, because I ran into this problem not too long ago.

Well that makes sense - as the e28 was an early model 1980 528i.

As for swapping the internals- it won't work unless you're swapping the same size internals- i.e. Medium case to medium case or small case to small case only.

So can I swap internals from my early model "large case" diff into the e30's "medium case" diff?

[xwill112x]

just buy a medium cased lsd, its not like there hard to find. lol

[Doughnut]

just buy a medium cased lsd, its not like there hard to find. lol

In Aussie they are rare to find in the ratio that I want let alone any ratio. Also they sell for around $700-$800 on ebay and wreckers generally want about that too.

If it was that easy I would have done it by now lol!

[e30cbe]

You have an 'early' e28 diff. Sometime in '84 they changed the castings of the housing so all the bolt patterns would be the same. You will have to switch you internals from your e28 diff into your existing housing. I know, because I ran into this problem not too long ago.

Also, to the best of my knowledge, including the 4cyl e28 518/i upto the 525i maybe the 528i also used the medium 188 size diff 535i/is used the 7 series (210) large diff - euro spec info. 188 med size is supposed to be transferable between e30,e36,e34 and e28 models - basically ring gear and pinion of the same size can be used in another series with the same size ring gear and pinion. The e30s used 168 small and 188 medium diffs only and as regards what torque and horsepower loads each ratio in each diff size can handle Metric Mechanic has some comprehensive info on their site.

And I think you need to use the diff casing that belongs to the car e30 for e30 and e28 for the e28etc cos it takes care of the halfshaft flange and spacing requirement. Also the mounts needed for each casing, their placement and design are different.

Hope this helps