E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > E46 BMW > General E46 Forum

General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 07-28-2008, 12:08 PM   #1
kpeng
Banned User
 
Join Date: Jan 2004
Location: Gainesville, FL
Posts: 25,710
My Ride: E46 330 and E30 325
**Everything you need to know about differentials**

In light of recent noob activity, and as a follow up to the popular eBay headers thread...I shall now discuss differentials.

I can't take credit for most of this information because it was posted on sycE46's extremely handy website (one that I've reference many times). He has created a great site, and I give him a ton of props for it. However, I will attempt to create a more concise version for this site so it's easily accessible via searches. So no more excuses.

Ready? Here we go.

What is a differential? Do I gain horsepower by swapping it?
A differential is what distributes power to your drive-wheels from the engine/tranny, via a driveshaft. You don't gain any horsepower from swapping to a higher ratio, but you do change when the power is put down. Through torque multiplication, it feels like you have more power, when in reality, you're just changing when you put it down. So it feels like you gained torque, but you're just getting the power more towards the low end. Read this if you want a good description.

Well sweet gee willickers Ken! I have an E46, but I is too fail to find what diff ratio I have. Can I findz outs?
Yes, you can findz out.

330 Non-ZHP
Steptronic: 3.38
Manual: 2.93 (3.07 convertible)

330 ZHP
Steptronic: 3.64
Manual: 3.07

325
Steptronic: 3.46
Manual: 3.15 (3.46 convertible/touring)

328
Steptronic: 3.46
Manual: 2.93

323
Steptronic: 3.46
Manual: 3.07 (3.46 convertible/touring)

M3
Manual: 3.62 LSD


Cool beans Kenneth! Now...are all differentials between E46s interchangable? What other BMWs can I pull a diff out of and plop into my car?
Why, excellent question young man! All E46 diffs are interchangable except for the M3 diff, which will require that you swap the rear subframe to even bolt up. You can also pull a differential out of a Z4 or an X3.


Yay! Knowledge! Now, where can I find a differential? I looked it up at the dealer, and gosh! They are expensive! What can I do?
Do not buy it new. You have two real options, A) look on eBay and hope for the best, or B) go onto www.car-part.com and do a search of junkyards in the U.S. You will have to call them and order it (most junkyards have very...unfriendly employees, but it's worth it). You can usually find a diff anywhere from $200-$450. Any more and you're wasting your money/time.


Ken, I have a manual transmission, I want more peppyness, what are most people swapping into their cars?

3.38's and 3.46's are very popular to swap into manuals because it yields a difference, and doesn't destroy your gas mileage too badly. You can pull a 3.38 out of a steptronic 330, whereas the more widely available 3.46 (therefore more popular) can come out of a steptronic 325, steptronic 323, steptronic 328, steptronic 3.0 Z4, or manual 2.5 Z4.


Well poopsticks, what if I have a steptronic? What can I swap in that will make a difference since I already come with a 3.38 or 3.46?
You have two real options to feel any sort of gain on an auto, and it is definitely one of the best things you can do to get some more pep out of your slushbox. One would be to pull the 3.64 out of the steptronic ZHP, steptronic Z4, or steptronic 3.0 X3. Another would be to use the 3.91 out of the 2.5 X3. I did the 3.91 swap, and while it does take some work, it is worth it. Here is another thread covering that.


Oh noes, I want both my rear tires to do the spinny dance. What if I want an LSD on my non-M? What can I do?
Either you spend a ton of money to get the M3 rear subframe and fit the 3.62 out of the M into your car, or you spend a ton of money on a custom built diff from Quiafe or Diffsonline. Either way, you're going to spend a ton of money.


This is all fine and dandy, but what about installation?
A typical shop will charge you anywhere from $150-$300 to install it. You can do it yourself with a buddy if you feel mechanically inclined. Here is a DIY.


What kind of stinky poo smell fluid do I need to use?
Synthetic 75w-90 gear oil. I recommend Redline, you can get it from Turner Motorsport. You will need 2 bottles, and new seal rings (BMW part# 07119963355). You can find a DIY here.


I think that covers the basics, if I missed anything, please feel free to add to this thread.

Last edited by kpeng; 07-28-2008 at 01:06 PM.
kpeng is offline   Reply With Quote
Ads by Google

Guests, get your FREE E46Fanatics.com membership to remove this ad.
Old 07-28-2008, 12:11 PM   #2
JesLet
Registered User
 
Join Date: Apr 2007
Location: Chandler AZ
Posts: 283
My Ride: not an ///M
This is cool
JesLet is offline   Reply With Quote
Old 07-28-2008, 12:16 PM   #3
tblue3cibm
Registered User
 
Join Date: Dec 2004
Location: Brooklyn, N.Y.C.
Posts: 6,387
My Ride: allroad / Hayabusa
kpeng for mod
__________________
tblue3cibm is offline   Reply With Quote
Old 07-28-2008, 12:18 PM   #4
tblue3cibm
Registered User
 
Join Date: Dec 2004
Location: Brooklyn, N.Y.C.
Posts: 6,387
My Ride: allroad / Hayabusa
Oh and congrats on joining EP
__________________
tblue3cibm is offline   Reply With Quote
Old 07-28-2008, 12:19 PM   #5
kpeng
Banned User
 
Join Date: Jan 2004
Location: Gainesville, FL
Posts: 25,710
My Ride: E46 330 and E30 325
Quote:
Originally Posted by tblue3cibm View Post
Oh and congrats on joining EP
Thank you good sir.
kpeng is offline   Reply With Quote
Old 07-28-2008, 12:20 PM   #6
Len013091
Registered User
 
Join Date: Jan 2008
Location: Tuscaloosa, AL
Posts: 3,956
My Ride: S52 E30, 330i
Send a message via AIM to Len013091
Thank you, this was a long-overdue thread.
Len013091 is offline   Reply With Quote
Old 07-28-2008, 12:21 PM   #7
Custom3
Registered User
 
Join Date: Sep 2005
Location: Dirty Jersey
Posts: 5,379
My Ride: HellRot 330CI
cool...thanks for posting
Custom3 is offline   Reply With Quote
Old 07-28-2008, 12:30 PM   #8
skang330
Registered User
 
Join Date: Jun 2008
Location: Bradley Univeristy / Dallas, Texas
Posts: 2,477
My Ride: 2005 E46 330ci
Send a message via AIM to skang330
nice write up like always!
skang330 is offline   Reply With Quote
Old 07-28-2008, 12:38 PM   #9
MJRMatt330
Registered User
 
Join Date: Oct 2007
Location: OC/SD, SoCal
Posts: 1,561
My Ride: 2002 330Ci
Send a message via AIM to MJRMatt330
hip hip hooray!
__________________
Mods
Exterior- M-tech II front, M3 Lip, Predator Chromiums 6000K, 6000K xenon, matching fogs, 30% tint, Eagle Eye LED's, Staggered 19" CSL's w/ Falken 452's
Performance- CF Dinan CAI, 3.38 Diff, Ebay Headers
Interior/Sound- Tri-M3 wheel, Leather ///M shiftknob, DICE iPod integration, JL Audio 10" Whoofers, Custom Box, JL Audio 250/1 Amp

MJRMatt330 is offline   Reply With Quote
Old 07-28-2008, 12:39 PM   #10
Genghis74
Registered User
 
Join Date: Jun 2008
Location: Washington, D.C.
Posts: 187
My Ride: 2000 323Ci 5SPD Vert
Actually my 5spd 323 rear diff is a 3.46 as it is a convertible and most likely some of the other cic models differ from their coupe/sedan brethren.
__________________
Genghis74 is offline   Reply With Quote
Old 07-28-2008, 12:41 PM   #11
kpeng
Banned User
 
Join Date: Jan 2004
Location: Gainesville, FL
Posts: 25,710
My Ride: E46 330 and E30 325
Shoot, I forgot to cover the convertible differences! Thanks Genghis! Fixed now.
kpeng is offline   Reply With Quote
Old 07-28-2008, 12:42 PM   #12
Genghis74
Registered User
 
Join Date: Jun 2008
Location: Washington, D.C.
Posts: 187
My Ride: 2000 323Ci 5SPD Vert
Thank you for sparing us from further rear differential threads!!!
__________________
Genghis74 is offline   Reply With Quote
Old 07-28-2008, 01:01 PM   #13
MachRc
E46Fanatic
 
MachRc's Avatar
 
Join Date: Sep 2002
Location: City of Angels
Posts: 6,414
My Ride: 2003 Technik S1 M3
gee willikers! cool beans!, poopsticks!

do the spinny dance..

when you ask yourself these questions you make it sound like

big ghey al..

and 5speeds please stay away from a "super duper" short ratio.

as much as bmw wants u to save gas and give out performance.. it affects your daily drivability down to the way u you switch cogs during traffic and easier wheel spin on lower gears that can potentially kill you. since your not spreading the power over the gears but dumping onto the diffs.

last thing i want is kids/noobs with super duper short ratios barrel roll-ing off the roads due to traction issues.
__________________

"I never met a girl that make me feel like you do,..you're alright...Whenever I'm asked who makes my dreams real, I say that you do, you're alright..
Baby, baby, baby.. I'm bringing you a love that's true..Baby, baby, baby.. I'm bringing you a love that's true.."


Bimmerfest BBQ 2014
MachRc is offline   Reply With Quote
Old 07-28-2008, 01:03 PM   #14
kpeng
Banned User
 
Join Date: Jan 2004
Location: Gainesville, FL
Posts: 25,710
My Ride: E46 330 and E30 325
MachRc, just keeping with the theme of the other thread.

I think a 5 speed would be fine with the 3.46 or 3.38, I didn't recommend they go 3.64 or 3.91
kpeng is offline   Reply With Quote
Old 07-28-2008, 01:04 PM   #15
Arsevader
Registered User
 
Join Date: May 2006
Location: Ontario, Canada
Posts: 1,813
My Ride: '90 325i, '02 325it
Gag me with a spoon..you forgot that the Tourings use the 3.46 straight from the factory..
__________________

- James

'85 E30 325e
'90 E30 325i
'02 E46 325it
'03 E46 320i

'96 Volvo 850R


Arsevader is offline   Reply With Quote
Old 07-28-2008, 01:07 PM   #16
kpeng
Banned User
 
Join Date: Jan 2004
Location: Gainesville, FL
Posts: 25,710
My Ride: E46 330 and E30 325
Quote:
Originally Posted by Arsevader View Post
Gag me with a spoon..you forgot that the Tourings use the 3.46 straight from the factory..
Doh again. Fixed.

Sorry, I was still blinded by rage while writing that. Thanks to you and Genghis for catching the misses.
kpeng is offline   Reply With Quote
Old 07-28-2008, 01:15 PM   #17
Arsevader
Registered User
 
Join Date: May 2006
Location: Ontario, Canada
Posts: 1,813
My Ride: '90 325i, '02 325it
Quote:
Originally Posted by kpeng View Post
Doh again. Fixed.

Sorry, I was still blinded by rage while writing that. Thanks to you and Genghis for catching the misses.
No problemo. You should call the thread, 'What's the Diff?"
__________________

- James

'85 E30 325e
'90 E30 325i
'02 E46 325it
'03 E46 320i

'96 Volvo 850R


Arsevader is offline   Reply With Quote
Old 07-28-2008, 01:28 PM   #18
Jason5driver
Registered User
 
Join Date: Sep 2007
Location: Honolulu
Posts: 113
My Ride: 2001 E39 525i sport
Can I use the 3.91 out of the 2.5 X3 for my 2001 E39 auto 525i?
Jason5driver is offline   Reply With Quote
Old 07-28-2008, 01:30 PM   #19
kpeng
Banned User
 
Join Date: Jan 2004
Location: Gainesville, FL
Posts: 25,710
My Ride: E46 330 and E30 325
Quote:
Originally Posted by Jason5driver View Post
Can I use the 3.91 out of the 2.5 X3 for my 2001 E39 auto 525i?
No, the E39's use a different differential/subframe. The reason you can use the X3 diff on an E46 is because they share the same subframe.
kpeng is offline   Reply With Quote
Old 07-28-2008, 01:32 PM   #20
2000_328CI
DK Jack Sparrow
 
2000_328CI's Avatar
 
Join Date: May 2004
Location: Isla de Muerta | DC/VA
Posts: 29,018
My Ride: 328Ci | Range Rover
Send a message via AIM to 2000_328CI Send a message via MSN to 2000_328CI
ken, you used to bug me... now the only thing that bugs me is when i read through a funny thread that you haven't posted in

kpeng for mod
__________________

Everything you need to know on muffler deletes : http://forum.e46fanatics.com/showthread.php?t=745244
Back Up Camera for E46 : http://www.youtube.com/watch?feature...&v=ckrDiAClGgM
Muffler Delete on E46 : https://www.youtube.com/watch?v=ofYhRq0T3eI
2000_328CI is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON





All times are GMT -5. The time now is 07:52 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
(c) 1999 - 2011 performanceIX Inc - privacy policy - terms of use