e23 733i with e32 735, LSD?

[SushieateR]

Hello guys,

I am planning to buy e23. Got possessed and can't think about anything else:P The one I am going to see is 733i US with euro e32 735i Engine and Auto transmission. I have been searching for some answers, but haven't found them all. I am sure someone knows if:

- e32 Motronic 3.5L (211hp) is not a downgrade from euro e23 L-jet 3.5L (218hp)
- same with 4 AT
- I am wondering if it has LSD, if so what ratio and whether it is big case diff or not. Owner does not know and I am wondering how to obtain this knowledge (except fast cornering or lifting the car and turning wheels)
- which LSD should i look for? from e23? e32? e34? e36? do they all match? I guess "bigger" ratio would be better for me as I will not use the car on highways. https://www.bimmerforums.com/forum/s...large-case-LSD helped but did not find all anwsers.

Thanks!

[timgal1234]

The big case from the e32 won't fit an e23 with some pretty serious mods I would guess. So if it's a big case it would be the same as you would find in an e23/28. Other than being "big" there aren't many obvious identifying things about them. They have the same 4 bolt holes up top and a similar mount off the back cover. One of the bolts on the back cover should have a tag on it that says something like 346 S. if it's a limited slip it will have an S if not just a ratio. Maybe some other numbers or letters I can't remember. But the ratio will be obvious if you can get the tag cleaned up enough to read numbers

[kojo96]

Easiest to plug in last 7 #'s of vin into realoem.com and find out what it came with- also, e28 diff are medium case, would fit into e23 with no problem but you'll have to change the rear cover.

[SushieateR]

Ok thanks a lot, will check the tag on diff.

[DesktopDave]

I don't think the Euro E32 engine is any different than the US model, they're all the same "world engine" 209HP M30B35. I've never owned an early L-Jet, but the M30/M90 L-block has a reputation for being revvy and fun but those wide-bore pistons are hard on head gaskets. The later B35 is a great motor too, just a little more torquey and laid-back.

If that's a normal US spec car, you'll probably end up with a 3.55. I'd check the VIN, but also jack up the rear end and spin a wheel. Count the input shaft revolutions for one single turn of the wheel, then you'll know the ratio more-or-less. They'll spin the same way with the clutch-pack LSD.

The medium case diffs are the same between the late-model E24, E28 and E23 except for the rear case. The E30, and a few E36 (318Ti and Z3) got those 188mm medium case diffs as well, but only in the six-cyl models. The E30 has a different rear case and also uses a different output stub axle, it's a smaller bolt circle than the 5- and 7- series.

Big case diffs are easy to spot. They have eight bolts securing each of the side covers, the medium-case only has six per side.

[Jay535is]

To be clear, when Dave says the 'rear case' he is talking about the rear 'cover'.

[XAlt]

E32 Six uses a medium case diff which should bolt up.

Something something something then 3.91 up to 1990 or so and then 4.27. I believe posi was standard here until the introduction of ASC, which is bundled with EML.

[Jay535is]

No, they do not just bolt up.
There are no holes in the casting for 2 of the 4 bolts necessary.
Also, the input flange can be different, and of course the rear cover is completely different.

[SushieateR]

I ditched the plan this e23, but I am going to Sweden for another one. '86 (late '85) 735iA. I checked it's VIN in real OEM, and it shows me (Type Code 6721) and matching LSD the part number 33141206745. According to realOEM it was used in e23 , e24 (635CSi), e28 (535i, M535i, M5), e34 (m5), e32 (735i, 740i, 750i)..
33141206745

LIMITED SLIP DIFF.UNIT

25%

From:06/01/1977To:07/17/2012 (ENDED)Weight:11.500 kgPrice:$2120.40Part 33141206745 was found on the following vehicles:

• 5' E28   (01/1981 — 08/1990)
• 5' E34   (04/1988 — 08/1995)
• 6' E24   (12/1977 — 04/1989)
• 7' E23   (10/1976 — 11/1989)
• 7' E32   (10/1985 — 04/1994)

Does it mean I may look for 210 big case from e32 735i (v8 one since 6cyl uses medium case), or 740i?

[kojo96]

Hate to be the bearer of bad news but you're looking at an internal part, not the outer case and no e32 differential (case) will bolt up in an e32- Completely different housing. Most if not all e23 came with the "big case" diff in various ratios in both lsd and non lsd. If you're after just LSD, find an e23 case with the ratio you're after- much easier, you could also run an e28 unit (med case) with your original rear cover, there are many e28 cars running 300+ WHP with no issues and they run a medium case, except for the e28/e24 M cars, those had the big case.

[motohunter4]

I did the medium case swap. https://www.bimmerforums.com/forum/s...or-auto-m30b34

[SushieateR]

Bad news would be if I buy the wrong one

Thank you again for help and l will definitely read your topic motohunter4!

I also hope to buy e23 tomorrow, for which I'm flying to Sweden

[SushieateR]

The medium case diffs are the same between the late-model E24, E28 and E23 except for the rear case. The E30, and a few E36 (318Ti and Z3) got those 188mm medium case diffs as well, but only in the six-cyl models. The E30 has a different rear case and also uses a different output stub axle, it's a smaller bolt circle than the 5- and 7- series.

Mounting diff from E30 seems to be not that straightforward then. Same with E36Ti or Z3? Also different sub axle and smaller bolt circle?

There are lots of cheap E36 diffs with LSD, but I can hardly find any E23 big case or E28/24 medium case with LSD.

[motohunter4]

If you look at my thread I have pictures answering anything about making an E30 diff work in our cars