T-case housings - 3 different types?

[D.Martijn]

Hey guys,

So I just started with the teardown of my whole suspension this afternoon and also got the transfercase out from under my car.

When putting it on the bench and comparing it with two other transfercases I have I noticed the following.
The section at the outputshaft is totally different between mine and the two others. There are a few small differences between the two others but noting mayor.

Than there it the corner, where the part of the output shaft - where the actuall VC lives meets the flat section.
On the two others there is some extra reinforment triangle, on mines it's more straight.


(The one from under my Touring is the on at the back)
I'm thinking this is an earlier case? On the two others, there are a few reinforcment ribs added, does any one know that there was a problem with these transfer cases? Or any other explination?



Close up pictures

Mine - back one;


Middle one


front one



I'm planning on swapping my VC into the case on the front, this one is the old TC from my uncles iX Touring as the threads of the drainplug were stripped by he previous owner.

Just wanted to share this with you guys :)

[The Dark Side of Will]

The big square thing at the back unbolts.

The clocking of the vent is different, the ribs also, as you noted. Doesn't look like there's anything that would give and problem with form, fit or function.

[nando]

the big rubber thing at the end is a harmonic damper.

no idea what that cast 'slit' is for. Probably just a difference in casting over the years. they're all functionally identical, in any case.

[D.Martijn]

Yeah, I know that rubber part is a vibraion demper.
Was talking about the section after this part.

Yeah, I know there shouldn't be a problem with fitment between the three. Just wanted to know if there was a reason for the changes between the castings.

[The Dark Side of Will]

Do you know if there are year-by-year differences?
The iX was built for a few years before it came to the US. Maybe those changes pre-date the trip across the pond.

[D.Martijn]

Do you know if there are year-by-year differences?
The iX was built for a few years before it came to the US. Maybe those changes pre-date the trip across the pond.

I haven't checked the little tag or casting for a year stamp. Not sure if there is any

[MattPro]

On the last iX I manual swapped, that slit lined up perfectly with the shift carrier bracket. Maybe they added it for more clearance or to keep the bracket supported on the bottom?

Maybe some auto castings didn't have it? (I know that doesn't make sense on paper). I'm curious now.

[D.Martijn]

So just to add some more info about the differences in the housings

Turns out there is an early and late type of housing / VC.


As you can see, the output axle is the same lenght however the positions where the bigger bearing sits is different. So the the internal seat of this bearing in the housings is also different.


the small VC is 2700122648
the bigger/'normal' is 2724122640

[nando]

Now that's interesting! is the small one from an 'early' 325ix? like the 1985-1987? we never had those here of course.

I guess they made it bigger at some point. Reliability or just better response? It looks like the number of plates must have doubled between the old/new design.

Obviously, you couldn't swap the VC from each housing, which up until now I don't think anyone even realized there were two versions. thanks for posting. :)

[D.Martijn]

Now that's interesting! is the small one from an 'early' 325ix? like the 1985-1987? we never had those here of course.

I guess they made it bigger at some point. Reliability or just better response? It looks like the number of plates must have doubled between the old/new design.

Obviously, you couldn't swap the VC from each housing, which up until now I don't think anyone even realized there were two versions. thanks for posting. :)

Well I'm actuall not sure, Realoem calls the 27001226481 part no a 'retrofit' and lists this also for the US models? I think it was used up to 02/1987

http://www.realoem.com/bmw/enUS/showparts?id=1201-EUR-12_1986_E30_BMW_325ix&diagId=27_0003#27001226481

I just checked the BMW factory workshop manual and it looks like they used the smaller version as well for taking their pictures.
Yeah I'm wondering why + if you could feel the difference. However, when I tested it on the car it's still nice and tight. So I'll be using this small one as the other one is completely shot anyway.

I mean... it's smaller, so it weighs less = faster ;) ;)

[nando]

the TC in my car now is from a 10/87 production 1988 ix - and I swapped in the VC from my late 1991 build, so who knows.

Yeah, if it works, it works!

[D.Martijn]

the TC in my car now is from a 10/87 production 1988 ix - and I swapped in the VC from my late 1991 build, so who knows.

Yeah, if it works, it works!

I mean, the shape of the housing gives it away. If there's a step it's probably an early/small VC, if it's more conical towards the output shaft it's the later type. :)