Question about differentials. Small case vs Big case diffs.

[Erick]

Ok question:

Slushboxes 325iS have a small case or a large case 4.10LSD? I am guessing a small case, but I just want to make sure. If so, would it be worth it getting one of those instead of the M3's 4.10 large case? Sounds like a diff off a slushbox 325iS would be a lot cheaper than the M3s....

Just a thought.....

[M-technik-3]

Now all 325i's and iS's got large case diff's and Autos got them also. Mine had a 3.73lsd and will be a large case 3.26 soon.

A 3.91lsd from an iX or a euro 325i will be a better alternative to revy 4.10lsd. It's offers a good compromise and you don't loose to many mpg.

[Erick]

So basically the M3's diff and the slush 325iS's diff are the same?

Yeah a 3.91LSD would sound better, but they are a rare find. You see more slushbox iSs out there :P

[M-technik-3]

iS were predominately standards, late auto's sometimes had 4.10lsd's. The 3.91's are not that uncommon but you need to find a iX that has been wrecked there is a comment about it in this months Bimmer.

[Erick]

Alright sounds good, when I get home I'll drop by the local junkyard one day and look at some diffs.

[Saul325is]

Yeah, the 325 iS came with 3.73 large case diffs. While the later e30 318is came with a small case 4.10 LSD. Allthough the e30 M3 came with a large case 4.10 diff which is a common swap for a non ///M e30. If you are thinking about putting a small case 4.10 on an M20 motor, dont! It will most likely blow sooner or later.

-Saul

[nando]

the auto ix and 325is both came with big case 4.10lsd

not sure if you'd want an ix diff in a RWD car though..

[M-technik-3]

Yeah, the 325 iS came with 3.73 large case diffs. While the later e30 318is came with a small case 4.10 LSD. Allthough the e30 M3 came with a large case 4.10 diff which is a common swap for a non ///M e30. If you are thinking about putting a small case 4.10 on an M20 motor, dont! It will most likely blow sooner or later.

-Saul

Yes we realise that the small case will not handle the additional stress, that is why we are talking about large case alternatives.

[Erick]

Yeah, the 325 iS came with 3.73 large case diffs. While the later e30 318is came with a small case 4.10 LSD. Allthough the e30 M3 came with a large case 4.10 diff which is a common swap for a non ///M e30. If you are thinking about putting a small case 4.10 on an M20 motor, dont! It will most likely blow sooner or later.

-Saul

Yes we realise that the small case will not handle the additional stress, that is why we are talking about large case alternatives.

Yup.... and the 3.73s were on 5spd 325iSs..... we are talking about the auto 325iSs, which were the only ones that could come out of the factory with the 4.10s.

[M-technik-3]

the auto ix and 325is both came with big case 4.10lsd

not sure if you'd want an ix diff in a RWD car though..

iX rear suspensions use the same rear diff.

[Erick]

Yeah it's been done before.... I've seen some 325i's with 3.91LSDs off an iX

[nando]

the auto ix and 325is both came with big case 4.10lsd

not sure if you'd want an ix diff in a RWD car though..

iX rear suspensions use the same rear diff.

no they don't. the ix diff has a viscous-fluid clutch, all other E30s use a regular clutch pack.

[Saul325is]

Yeah, the 325 iS came with 3.73 large case diffs. While the later e30 318is came with a small case 4.10 LSD. Allthough the e30 M3 came with a large case 4.10 diff which is a common swap for a non ///M e30. If you are thinking about putting a small case 4.10 on an M20 motor, dont! It will most likely blow sooner or later.

-Saul

Yes we realise that the small case will not handle the additional stress, that is why we are talking about large case alternatives.

Yup.... and the 3.73s were on 5spd 325iSs..... we are talking about the auto 325iSs, which were the only ones that could come out of the factory with the 4.10s.

Oh, I see thats pretty interesting(sorry had my head up my ass earlier). So would an automatic have the advantage over the manual since it has a 4.10? very interesting.

-Saul

[M-technik-3]

the auto ix and 325is both came with big case 4.10lsd

not sure if you'd want an ix diff in a RWD car though..

iX rear suspensions use the same rear diff.

no they don't. the ix diff has a viscous-fluid clutch, all other E30s use a regular clutch pack.

I was told they that use the same type as any other e30 by a BMW shop here in Germany. I have watched them swap one into a customers car one day while I was stripping another car. So maybe they are and they were wrong, I know that mine had a 3.91 in it and I had put a 4.10lsd in it.

[nando]

you can use them on any E30, but they are different internally. that's all I meant

it's pretty easy to tell, the IX diff would say VC3.91 or VC4.10, any other E30 would have S3.73 or S4.10, etc.