# 3.15 or 2.82 differential



## bmw540i (Mar 30, 2003)

Does the 2001 540i 6speed come with 3.15 differential or 2.82 just wondering. Thanks.


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## Dustin540/6 (Nov 22, 2002)

2.82


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## PropellerHead (Jan 3, 2002)

and it's 2.81-- not 2.82.


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## bmw540i (Mar 30, 2003)

if i switch 2.81 to 3.15 how much TRQ am i gaining.


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## Greco (Feb 16, 2003)

You'll be putting more torque down to the wheels, but the torque within the engine stays the same. I heard estimates put it around 20% but I find that a bit too much.

Anyone know what the ratio on the E39 M5 diff is?


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## bmw540i (Mar 30, 2003)

I think its 3.15 but its LSD.


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## bmw540i (Mar 30, 2003)

You put down 11.7% thats roughly 38 trq.


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## Steve D (Oct 10, 2002)

I switched my 2000 540/6sp to the 3.15 last year (see my installation instructions on BmwTips.com). I love the increased thrust especially in third gear and now 6th is very flexible at the highway speeds in NJ. I rarely have to downshift for passing at speeds over 60MPH.

My mileage went down about 1/2 MPG and I have been running about 18MPG in mixed driving and I drive enthusiastically. One downside is that redline in 2nd is 58 and in 3rd is 88. I will be getting a "chip" upgrade soon to raise the redline so I can once again reach 60 in 2nd and 90 in 3rd.

This has made the biggest performance impact of all my mods. I paid $350 for the diff from Circle BMW ($450 - $100 core charge) but I understand that BMW has now raised the price to something around $1100. Perhaps you can find a used one.

Steve D


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## Ågent99 (Jan 7, 2002)

You may wish to consider going for the LSD that the M5 comes with in addition to a higher gear ratio.

Dave Z did this on his car and loves it. Sounds very intriguing.

Chris


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## jzdinan540i (Nov 22, 2002)

Ågent99 said:


> *You may wish to consider going for the LSD that the M5 comes with in addition to a higher gear ratio.
> 
> Dave Z did this on his car and loves it. Sounds very intriguing.
> 
> Chris  *


Dinan charges 4k for the 3.63 LSD. If you want a M5 LSD with a higher gear ratio then you need to buy the M5 core and ship it to someone. With Dinan you still need to send them a core otherwise its another 1500 out of pocket.
The best bet is to buy a quiafe before production ends. There are a few guys who build diffs for a living, I wont reveal my sources LOL, but if you want a LSD then shoot me an email and I can give you my homies number :bigpimp:


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## supercharged (Feb 18, 2003)

I second the dif mod as one of the best..also go for lsd while your there..wtf BMW does run lsd on a sport package car is absurd to me, and if you have a manual also light weight flywheel while your down there ...
I put a 3.38 on my e36m3 sc and it really helped out acceleration. 
I'm now contemplating a 3.45with lsd for my 2003 540it sport wagon .I was quoted $3500 installed from a friend. Dinan quoted me ..well let's just say Dinan smokes crack....Quaife's diff does not work the same as the m5 lsd. Quaife is locked to the best o my knowledge and is no longer selling this part. they said it took 5 years to sell the 25 they made before. The only way they will produce more is with deposits for a min run of 30. Vacmotorsports.com may be trying to get a group buy together and also get quaife to change some of there specs at the same time


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## jzdinan540i (Nov 22, 2002)

supercharged said:


> *I second the dif mod as one of the best..also go for lsd while your there..wtf BMW does run lsd on a sport package car is absurd to me, and if you have a manual also light weight flywheel while your down there ...
> I put a 3.38 on my e36m3 sc and it really helped out acceleration.
> I'm now contemplating a 3.45with lsd for my 2003 540it sport wagon .I was quoted $3500 installed from a friend. Dinan quoted me ..well let's just say Dinan smokes crack....Quaife's diff does not work the same as the m5 lsd. Quaife is locked to the best o my knowledge and is no longer selling this part. they said it took 5 years to sell the 25 they made before. The only way they will produce more is with deposits for a min run of 30. Vacmotorsports.com may be trying to get a group buy together and also get quaife to change some of there specs at the same time *


You are right, you can't compare a gear driven diff to a clutch diff. Jimmy was the first to intall the quiafe and not many followed. He has had good perormance and it is warrantied for life. I wouldn't install one in my car, but I would do a true LSD. VACmotorsports pays Revhigh for referals, so save some money and buy it from the source. To the best of my knowledge group buys aren't allowed on RF, so where would this be happening?


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## supercharged (Feb 18, 2003)

do you mean revhigh pays VAC or the other way around..
VAC is 5mins from my house so its easy to deal withthem for me the only problem is they have been working on another project of mine for a year and I am growing impatient


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## jzdinan540i (Nov 22, 2002)

supercharged said:


> *do you mean revhigh pays VAC or the other way around..
> VAC is 5mins from my house so its easy to deal withthem for me the only problem is they have been working on another project of mine for a year and I am growing impatient *


I wouldn't use VAC for a LSD, I would contact Jim Blantwell. Everyone knows Revhigh gets paid by a certain group of companies.


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## supercharged (Feb 18, 2003)

ok how do I get a hold of Jim blantwell do you have his number or e mail


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## supercharged (Feb 18, 2003)

Ok new quote for a 95 7 seris rear diff with 3.45 gears about 2k installed can JIm beat that


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## DZeckhausen (Mar 11, 2003)

Ågent99 said:


> *You may wish to consider going for the LSD that the M5 comes with in addition to a higher gear ratio.
> 
> Dave Z did this on his car and loves it. Sounds very intriguing. *


 Yes, this is the best modification I've done to my car. Well, perhaps the 2nd best. 

But my wife and I really love the fact that the little yellow triangle on the dash hardly ever flashes anymore and the DSC doesn't choke back the engine during most launches. If I could have done JUST the limited slip without going to the 3.15 gears, I would have done that. There is a trade-off on the highway. I miss the low RPM loafing in 6th gear at 80mph. Hey! Perhaps I should change my handle to RevLow. :rofl:


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## PropellerHead (Jan 3, 2002)

2.81 Quaiffe, baby... having cake and eating it too... Sideways sometimes...

BTW funny post, Dave. You never fail to dissapoint.


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## supercharged (Feb 18, 2003)

Dave Z , who did the swap for you and was it a direct bolt on or did you need some addaptors. Also why did you deceide not to go more aggressieve on the gears say 3.46 instead. This would give you great ACCELERATION , and allow you to really rev high as you cruise the highway. One of my all time favorite things to do


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## DZeckhausen (Mar 11, 2003)

supercharged said:


> *Dave Z , who did the swap for you and was it a direct bolt on or did you need some addaptors. Also why did you deceide not to go more aggressieve on the gears say 3.46 instead. This would give you great ACCELERATION , and allow you to really rev high as you cruise the highway. One of my all time favorite things to do *


 I did the installation myself with the help of Ben Liaw at Rogue Engineering and a couple friends, Harold Chang and Chris Hsu.

The M5 LSD is a different length and width than the 540i differential. So I needed to swap the driveshaft and halfshafts for the M5 parts too. I think it would cost about $3200 to buy the parts new. I was in the right place at the right time and picked the stuff up, slightly used, for just $1500. Someone else had bought the stuff new, installed it on his 540i and then bought the rest of an M5 just 17,000 miles later! So he took the parts off before turning his car back in to the dealer.









*The purchase (That's me on the left)*









*Also needed some new hardware. The M5 fasteners are much heftier.*

First step was to yank out the entire exhaust system from the cats back. This meant, of course, unhooking the O2 sensors from their harness and removing scads of heat shields.









*It may look small in the photo but it sure weighed a ton!*









*Ben, removing more heat shields. *

Next, we supported the transmission, then removed the tranny mounts and brace and the driveshaft.









*Chris Hsu wondering if we are in over our heads yet.*

Next step was to remove the old differential. This required lowering the subframe and grinding a socket so it was thin enough to reach up into an impossible space.









*What's going to make this car go now? * :yikes:

The halfshafts had to come out now and that was much harder than it looked. They did not want to come out. There must be trick of the trade, but we never figured it out. All the while, I was wondering how the heck we were going to force the M5 halfshafts back into the bearing assemblies.









*Seemed like the splined end of the halfshaft is bigger than the I.D. of the hub/bearings!*

Finally, after much swearing and sweating and the obligitory tool run, we got all the major pieces bolted in.









*M5 driveshaft and halfshafts finally connected*









*Ben taking a break before we put the exhaust back on*

After we finished the installation, about 5 hours later, we all took a vow never to do another M5 differential swap again! This was the job from Hell. By the way, the M5 pumpkin weighs 105 pounds and it seemed like it took forever for one of us to get a couple support bolts installed while the rest of us held the darned thing in place. Usually, after a cool modification, we all go out and grab pizza and beer. This time, we all went straight home.


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## Greco (Feb 16, 2003)

Awesome write-up Dave, can't wait for you to do my M5 diff swap in your garage :rofl:

I hope the tranny mounts are easy compared to this job..

Later..


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## DZeckhausen (Mar 11, 2003)

Greco said:


> *Awesome write-up Dave, can't wait for you to do my M5 diff swap in your garage :rofl:
> 
> I hope the tranny mounts are easy compared to this job.. *


 I can do the performance tranny mounts with my eyes closed! 

As for the diff swap, I think you'll just need to keep on driving down the Parkway, past my exit!:str8pimpi


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## Jon Shafer (Dec 15, 2001)

Excellent post Herr Z!


:bow: 


Thank you!!!


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## paradyme540 (Mar 24, 2006)

Im looking to do this on my 540ia & need a little help regarding M5 parts........

Do i need the prop (drive) shaft from an M5? ive seen some mention using it and some dont.......
Also, it the diff carrier required from the M5? ive seen no mention of this at all

Im based in the UK & for some reason nobody over here does a great deal to their gearing for whatever reason.

Any help or informative links would be much appreciated, 

many thanks


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