# Diff Swap: you are invited



## JonM (Jan 28, 2002)

If anyone wants to come to my house on Sunday, Andy and I are swapping my 3.15 differential for a Z3 3.0i Auto 3.46 diff. I've never swapped a diff before, so this should be fun.

FYI: 
1999-2000 S52 M Coupe diff = 3.23
2001-2002 S54 M Coupe diff = 3.15, no gas guzzler
2001+ S54 M3 diff = 3.64, gas guzzler even with 6th gear

Worst case everyone can stand around a Seattle suburbian neighborhood and talk about their cars. My neighbors already think I am a tad bit eccentric, so this should be icing on the cake. Heck, if we get the diff installed and the car running, we can go for a test run on Mountain Loop Highway.

Actually, I am skeptical we will get it done in a day considering I want to swap the M diff cover for the Z3 diff cover. But who knows.

Diff Swap Thread 1

Diff Swap Thread 2


----------



## scottn2retro (Mar 20, 2002)

*Dang!*

Too bad I'm not in the area - I'd definitely be there. 

Look forward to the updates


----------



## Nick325xiT 5spd (Dec 24, 2001)

Aren't you giving up an LSD?


----------



## JonM (Jan 28, 2002)

Nick325xiT 5spd said:


> *Aren't you giving up an LSD? *


No. Both are limited slip. 3.46 is a Torsen type.


----------



## Nick325xiT 5spd (Dec 24, 2001)

JonM said:


> *
> 
> No. Both are limited slip. 3.46 is a Torsen type. *


Grrr... That's irritating... So even some of the non-M Z cars got real diffs...


----------



## JonM (Jan 28, 2002)

Nick325xiT 5spd said:


> *Grrr... That's irritating... So even some of the non-M Z cars got real diffs... *


If you are really bored or are getting ready to go on Jeapardy... read this from the Torsen website on a T-2A type diff Torsens are torque-sensing, limited slips are speed sensing.


----------



## The HACK (Dec 19, 2001)

Anyone here (JonM, Styger...etc) know if the Z3 diffs will fit an E46?


----------



## JonM (Jan 28, 2002)

The HACK said:


> *Anyone here (JonM, Styger...etc) know if the Z3 diffs will fit an E46? *


No idea. I think it is worth noting:

E46 325 manual = 3.15 diff (mysteriously matches S54 M Coupe)
E46 325 auto = 3.46 diff (mysteriously matches Z3 auto)
E46 330 manual = 2.93 diff
E46 330 auto = 3.38 diff

I have *not* done any E46 research on this. I just grabbed the final drive ratios from BMW USA. It may just be a coincidence the 325 and M coupe/roadster both have 3.15s. On the other hand, it may not be a coincidence.

I _suspect_ 330 owners would benefit from an upgrade to a 325 diff. No idea if this works... pure speculation on my part.


----------



## scottn2retro (Mar 20, 2002)

*Interesting . . .*

Kaz and I were contemplating my 3:15 (01 M Roady) for his 3:46 (e46 wagon) :dunno:


----------



## Kaz (Dec 21, 2001)

The 3.15 diffswap seems to be something that goes on pretty regularly with 330 owners. Guess what Dinan charges $1400 for???

Late 01 and later 325iT MT get the AT diff, and I will attest to the fact that the resulting 'granny gear' 1st is punchy. Also as a result, I can't make it to 60mph in 2nd.

A friend of mine with a E36 '330is' ran its original 318is diff in it till recently, and said before the swap, 1st gear was essentially useless. So it is possible to over-do it.


----------



## Kaz (Dec 21, 2001)

*Re: Interesting . . .*



scottn2retro said:


> *Kaz and I were contemplating my 3:15 (01 M Roady) for his 3:46 (e46 wagon) :dunno: *


Hmm, after what JonM just mentioned about the LSD, maybe you WOULDN'T want to do this...


----------



## JonM (Jan 28, 2002)

*Re: Re: Interesting . . .*



Kaz said:


> *
> 
> Hmm, after what JonM just mentioned about the LSD, maybe you WOULDN'T want to do this... *


Is the diff in *The T* not limited slip?? Appears it is not from bmwusa.


----------



## Kaz (Dec 21, 2001)

*Re: Re: Re: Interesting . . .*



JonM said:


> *
> 
> Is the diff in The T not limited slip?? Appears it is not from bmwusa. *


E46 diffs except for the clunky oddity in the M3 are all non-LSD and is a source of frustration for some, especially Nate.


----------



## scottn2retro (Mar 20, 2002)

*Re: Re: Interesting . . .*



Kaz said:


> *
> 
> Hmm, after what JonM just mentioned about the LSD, maybe you WOULDN'T want to do this... *


If yours is not LSD, then you're right.


----------



## Guest84 (Dec 21, 2001)

JonM, you south of Seattle or north? I'd come if the wife wasn't working, I don't feel much like dragging my 3 and 6 year old over there. I might even get motivated to do my own work on my cars!


----------



## The HACK (Dec 19, 2001)

JonM said:


> *
> 
> No idea. I think it is worth noting:
> 
> ...


Not only that, they would get a limited slip...

Time to hit the salvage yards and see if I can find some used Z3 diffs!


----------



## scottn2retro (Mar 20, 2002)

The HACK said:



> *
> 
> Not only that, they would get a limited slip...
> 
> Time to hit the salvage yards and see if I can find some used Z3 diffs! *


Another HACK project in the making 

Ssshhhhh!

Don't tell Nate


----------



## JonM (Jan 28, 2002)

Ripsnort said:


> *JonM, you south of Seattle or north? I'd come if the wife wasn't working, I don't feel much like dragging my 3 and 6 year old over there. I might even get motivated to do my own work on my cars!  *


North. Way North. City is called: "Damn That is Far North and Almost in Canada", Snohomish, North, WA.


----------



## Guest84 (Dec 21, 2001)

LOL< damn, that IS far north! I hear it snow up there in the summer time?


----------



## Raffi (May 18, 2002)

scottn2retro said:


> *
> 
> Another HACK project in the making
> 
> *


Dooooodddd, I am SO interested! HACK????


----------



## The HACK (Dec 19, 2001)

Raffi said:


> *
> 
> Dooooodddd, I am SO interested! HACK????  *


Bring me the parts and I'll do the research to make it fit...


----------



## Raffi (May 18, 2002)

The HACK said:


> *
> 
> Bring me the parts and I'll do the research to make it fit... *


Damn, you want ME to do the research??? :lmao: :lmao: :angel: Where do I start??? :dunno: :dunno:


----------



## nate (Dec 24, 2001)

Take a look at page 5

http://www.world-challenge.com/competitors/vts/02-bmw-2.5-01-02.pdf

Also, read the first entry http://staff.connect.com.au/lheather/318ti/1999-01/msg00280.html

So, BMW uses Zexel-Gleason Torsen LSDs in Z3s. Turner uses the 3.46 and 3.91 ZG diffs in thier world challenge E46 325i. Also, it says that the driveline components are E36. The Z3 is an E36/7, no?

BMW uses the 3.46 in the Z3 3.0i (2.8i probably too) autos and 2.5i manuals. The 3.91 in the 2.5i auto. A 3.07 is used in the 3.0 manual.

Coincedence? I doubt it. Seems like it might fit.

A 3.07 would work pretty well. The 330/328 share the same tranny ratios as the 3.0i Z3. I think 3.46 would be pretty short...


----------



## Kaz (Dec 21, 2001)

OK, I took a reqlly quick look at the ETK to see how 'easy' this might be.

What I can see is that a simple swap of the entire diff won't work. At the very least, the back half of the diff assy (i.e. the cover) is quite different between E36, E36/7 and E46. E36s have 2 mounting tabs, E36/7 have 1, and E46 have none.

This means any swaparoo of diff bits between them will involve some hacking around with the various bits of each model, e.g. using a E46 housing, outdrives, etc. with guts from a E36/E36/7 or something.

Anyone wanna find a junker E46 and E36 rear end and I'll be happy to help hack the bits together.


----------



## lip277 (Jan 7, 2002)

JonM-
I just sent you a note...
I'd be interested in seeing what you've gotten yourself into...  
(unlike those 'other' folks, I'm probably less than 10 miles from ya...!)
Just let me know when and where...


----------



## JawKnee (Dec 20, 2001)

Jon,

I'll see you Sunday. I'll be swapping out my 3.15 (from stock 2.93) for a 3.38 or 3.46 -- both of which are waiting for me to pick up as soon as I decide.


----------



## scottn2retro (Mar 20, 2002)

nate328Ci said:


> *
> A 3.07 would work pretty well. The 330/328 share the same tranny ratios as the 3.0i Z3. I think 3.46 would be pretty short... *


There is also a 3.23 for S52 M roadsters and a 3.38 for S52 M Coupes.

Randy Forbes (M Roadster AutoX guru) is running a 3.73!


----------



## scottn2retro (Mar 20, 2002)

Kaz said:


> *
> Anyone wanna find a junker E46 and E36 rear end and I'll be happy to help hack the bits together.  *


Shouldn't that be HACK the bits together?


----------



## RKT BMR (Sep 7, 2002)

JonM said:


> *If anyone wants to come to my house on Sunday, Andy and I are swapping my 3.15 differential for a Z3 3.0i Auto 3.46 diff. I've never swapped a diff before, so this should be fun.*


Jon (or anyone) -- any good advice on where to place a floor jack onder an E46 to safely jack the car up and get it on jackstands? I've really struggled with this, and have used a point that I am unwilling to use again -- the U-shaped reinforcement rails that run front to back along either side about 12-18" from cneterline. I ended up deforming the rails very slightly (indented, not bent), and while I don't think If done any serious damage, I don't want to jack from these points again.

BMW will only say that the four factory jack points (two on each side -- where the factory tire jack goes) are the ONLY safe places to lift the car. Problem is, *this* is where I have to put the jackstands!

So, anyone...help! FYI, I'm doing this work on a 330cic.

Dave


----------



## scottn2retro (Mar 20, 2002)

*I think . . .*

Dave got his question answered on another thread.


----------



## JonM (Jan 28, 2002)

*No Diff Swap this Weekend!!*

I forgot to order a pair of $0.38 lock rings. Ordered from Bellevue. Will be in on Monday.

We will do a detailed how-to with all of the part numbers as we go.


----------



## jbrandt (Apr 5, 2012)

*diff*

I just swapped a diff on a 97 z3 1.9 last night.Taking it out is the hard part.Stuck bolts. It took me 2 hours to put it back in, including the oil change. They have 5 bolts holding the case and 12 on the drive axles and 4 on the driveshaft. Get some PB blaster the night before and soak everything or you'll be bustin knuckles. LOL Take off the electronic speed sensor connection first or you will rip it apart when you lower the unit. I used blue loctite on the refit.


----------



## drrpm (Feb 9, 2010)

The original post is almost 10 years old. That's got be close to a zombie resurection record. I wonder how it all turned out.


----------



## SD ///M4 (Jan 24, 2011)

drrpm said:


> The original post is almost 10 years old. That's got be close to a zombie resurection record. I wonder how it all turned out.


Chances are, JonM probably doesn't even still own that car! He hasn't posted in almost 2 years.


----------

