[jellish]

I recently had my friend (Engineered Mechanic Mike) do a M3 LSD swap into my 335i. I am a single turbo N54 with 6MT, and put around 700hp to the ground. I wanted to do a LSD swap because even with 265 R888R's out back, most of second and all of first gear were useless. I do most of my work myself when time permits, but since this involved shortening the driveshaft and changing bushings I asked Mike to take it on (he is a mechanical engineer by trade, and knows his BMWs!)

I decided to do the M3 LSD swap instead of a Wavetrac/Quaife for a few reasons:

• Way cheaper
• Reliability & tech of a M3 diff, plus added cooling with the M3 diff heatsink. The new pumpkin is a beast compared to the 335i one.
• M3 half shafts and driveshaft are way beefier than 335i. No need for DSS axles (save $1000).
• No deductibles or cores to send in when done. I can resell all my old parts!

This wouldn't have happened without the excellent threads by Theconnman2 (http://www.e90post.com/forums/showthread.php?t=1341843) and GeorgeSmooth (http://www.e90post.com/forums/showthread.php?t=321625). These guys rock, and hopefully this thread adds to their already awesome work.

I started by researching all the parts they listed, and then by buying off eBay and craigslist. I also found some parts at online scrap yards, but was able to find cheaper stuff on the other two sites. Any of them should work though, so do whatever you find easiest.

Final parts list (for me). Your list will be different!:

• M3 half shafts from 2011 (right/left). - $359 shipped - Found some that came with the proper bolts and retainers, which saved me $150. If you're getting these pulled for your build, GET THE BOLTS. Your 335i ones WON'T FIT. These are much more beefy than 335i half shafts, so you get a free upgrade here and no need for DSS axles.
• M3 DCT driveshaft. - $200 shipped - Came with guibo and center bearing.
• M3 DCT differential from 2008. - $580 shipped - Must be DCT for 6MT cars, as it maintains a (close) to stock 3.15 ratio. Note that these may require special balancing bolts or washers, depending on the paint mark on the differential. I was lucky and mine had a white paint mark, meaning no balancing hardware was necessary.
• Hardware
  • Driveshaft gasket - 26117507842 - $8.85
  • Bolts - 26117526322 - $23.64
  • Bolts - 26117527475 - $33.96
  • Nuts - 26127536563 - $9.00
  • Retainers - 33212283013 - $16.68
• New differential bushings (not necessary, but a good idea) - Rear PowerFlex PFR5-1226 - $48.99, front PowerFlex PFR5-426 - $50.99.
• Labor - $600
• Driveshaft rework - $100

So my total for parts was $1231, labor was $600, and driveshaft rework was $100.

To put one of the other LSD options in comparison, we will just stick to parts/rework cost without bushings. Labor will be really variable. On N54Tuning, the Wavetrac for my car (2009) would be $2694.00. Then you send back the core, and total is $1499+$35 shipping + $85 core shipping return = $1619. So I only saved about $288 to start with, but in the process I got upgraded and beefier half shafts, an upgraded and beefier axle, and a much beefier LSD/pumpkin with heat spreader than the LSD replacements for the 335i pumpkin. Seems like a no-brainer to me. OH, and I get to sell all my old parts and probably get a lot of money back!

So now that the costing/parts are done, here are the install pics. We will be doing a writeup soon as well, but this install is a bit more difficult due to needing bushing removal tools and a good way to remove axles (air hammer in our case).

Pics:
On the "lift" and ready for swapping.


Giant nuts on the 335i driveshaft to diff connection. These require a really big wrench. Make sure you measure your driveshaft lengths BEFORE removing anything, as you will need those lengths to have the new driveshaft reworked.


Center support bearing unbolted


M3 diff/driveshaft on the left, 335i on the right. Notice how much bigger the M3 differential is, and how much more beefy the heatsinks are?


Here you can (kinda) see that the front half of the M3 shaft is longer than the 335i one. This is why it needs to be reworked by a professional driveshaft shop.


This is after the driveshaft was reworked. The front flange from the 335i is different than the M3, so the M3 front shaft needs to be cut down and shortened, and then have the 335i flange welded on.


Here are my lengths, but yours will be different. Do not use these measurements before checking yours personally.


Hard to tell here, but the flanges are slightly different sizes. Need to make sure you 335i one is used for the finished driveshaft.


These are the two center support bearings. M3 on the left, 335i on right. You will need to put your 335i one on the driveshaft you are having reworked/balanced. The M3 one sits lower, so can't be used or your angles won't be right!


M3 axle (bottom) vs 335i axle (top). The M3 half shaft is MUCH beefier.


Old bushings coming out...


New (stiffer) bushings going in...


M3 diff in place. Notice the giant heatsink on this guy. Much nicer than the 335i pumpkin, which you won't get if you just do a Wavetrac/Quaife swap...


That's it! The car now gets some traction in 1st, and hooks pretty well in 2nd. Way better than it was before. Also feels substantially better in corners than it did before the swap. I know a lot of people argue that a LSD isn't needed since we have the BMW braking assist to "simulate" a LSD, but to be honest it feels totally different. Well worth the money.

Hope this thread helps!

Josh

[Theconnman2]

Great work and write up!

[zero2sixtyZ]

Great writeup! Just to ask, you said the diff is from a DCT but the driveshaft is from an SMG? Is that a typo or are we pulling between E46 and E9X parts?

[jellish]

Originally Posted by zero2sixtyZ

Great writeup! Just to ask, you said the diff is from a DCT but the driveshaft is from an SMG? Is that a typo or are we pulling between E46 and E9X parts?

Good question. The driveshaft was sold as from an "e90 auto SMG" on eBay. I do not know exactly what he was referring to, but I believe he just misnamed it and it was from a DCT car as well. It looks like any of the e90/92 driveshafts from a M3 should work for a 6MT build, as they need to be shortened either way. I changed my post up top to stop anyone else from being confused.

[Chris@VargasTurboTech]

Excellent write up. We agree this is a very good value, plus you get the upgraded shafts. The other thing is that the input shaft on the 335i differential is no where near as strong as the M3 version; we broke ours at the track. The M3 is stronger all around. I'll be doing this on my personal car. Thanks for posting!

Chris

[FEDE/E92]

Great write up! Im gojng tacke this project myself thanks to you

[LMB335IS]

Great info and write up. I wonder how this would work out on a DCT 335is since the ratio is 2.56? The TCU wouldn't be happy.

[AlexN]

Great write up. I am going to do this in a few weeks on my car, so this is great help.

[Theconnman2]

Originally Posted by LMB335IS

Great info and write up. I wonder how this would work out on a DCT 335is since the ratio is 2.56? The TCU wouldn't be happy.

People have put the manual lsd in that has a ratio of 3.85 in the manual 335i. It works but expect low gears to be pointless and rpms to be higher on the express way (and everywhere).

[terryd5150]

neuroclast

Excellent write-up.

Thanks for posting.

[Ozzie335i]

neuroclast, do you have the ediff coded out? If not, get it done, as the job is incomplete until the ediff is coded out. Topgear does a fine job for a reasonable fee.

[Unknown_Car]

So won't work with 335i auto?

[Theconnman2]

Originally Posted by Roma_335i

So won't work with 335i auto?

It's should be cheaper and easier for your to just do a lsd in your stock pumpkin!

Originally Posted by Ozzie335i

neuroclast, do you have the ediff coded out? If not, get it done, as the job is incomplete until the ediff is coded out. Topgear does a fine job for a reasonable fee.

From my experience and from what I have read, this is not needed. If the LSD is doing its job the e dif should never come on.. it never has come on in the year I've been driving it. If I am missing somthing please let me know! This is just from personal experience but I will be the first to tell you that I don't know everything and am always willing to learn.

[Ozzie335i]

What kind of power are you putting down connman? Asking since I have but 530 at the wheels and unless I click the button the traction light flashes. At 700 whp neuroclast's will likely kick in constantly.

[jellish]

It does come on in first if I get on it, but to be honest that's okay with me. If I didn't have R888R's and warm tires, pretty much anything is going to go up in smoke at these power levels. I just turn on DCT when I plan on getting on it, or turn off traction control entirely when planning on doing something stupid. Other than that, I haven't found a need to code it out. But I haven't had the LSD in long either.

[Theconnman2]

Originally Posted by Ozzie335i

What kind of power are you putting down connman? Asking since I have but 530 at the wheels and unless I click the button the traction light flashes. At 700 whp neuroclast's will likely kick in constantly.

Currently at mid 4s looking for 5s this summer. I guess I will see if it is a problem for me then. Do you have new bmw fluid in it when you installed?

[Ozzie335i]

Originally Posted by Theconnman2

Currently at mid 4s looking for 5s this summer. I guess I will see if it is a problem for me then. Do you have new bmw fluid in it when you installed?

That extra 60 to 80 will make your car fly, and will likely be enough. If you mean differential fluid I went with Redline when I had the LSD installed. And again at 300 miles.

The coding is under 100 bucks, and we'll worth not needing to constantly turn the DSC off.

[N54POWR]

Originally Posted by Theconnman2

People have put the manual lsd in that has a ratio of 3.85 in the manual 335i. It works but expect low gears to be pointless and rpms to be higher on the express way (and everywhere).

Who has done this big a change without problems? I have heard from many people that putting even just a 3.08 into the dct triggered major codes and problems.
I myself have the dct with the final drive changed to 2.81 it does not cause codes or major problems that I have noticed. but the tach does get a little confused when shifting gears. Always moving from where it thinks the engine should be to where it actually is.

[DR-JEKL]

Did you have any vibrations at all? Unfortunately I had a massive saga with my M3 driveline install the shop who performed the dirveshaft swap checked balanicing twice but it still vibrated. I had it sent to another workshop who found it to be out slightly and this made a huge improvement but still not 100% vibration free...

How do you find the diff bushings, lots of guys state that these cause lots of extra NVH.

This was on the N5X enthusiasts FB page a few days ago

https://www.facebook.com/INEVERL0SE/...0796188438694/

[titium]

Originally Posted by Ozzie335i

That extra 60 to 80 will make your car fly, and will likely be enough. If you mean differential fluid I went with Redline when I had the LSD installed. And again at 300 miles.

The coding is under 100 bucks, and we'll worth not needing to constantly turn the DSC off.

ediff stays on even with traction control completely off. The only way to turn it off is to code it.

[AlexN]

Originally Posted by DR-JEKL

Did you have any vibrations at all? Unfortunately I had a massive saga with my M3 driveline install the shop who performed the dirveshaft swap checked balanicing twice but it still vibrated. I had it sent to another workshop who found it to be out slightly and this made a huge improvement but still not 100% vibration free...

How do you find the diff bushings, lots of guys state that these cause lots of extra NVH.

This was on the N5X enthusiasts FB page a few days ago

https://www.facebook.com/INEVERL0SE/...0796188438694/

The NVH that guy is having is most likely due to the fact that he used solid aluminium DIFF bushings.
The OP has the purple powerflex which are much more forgiving and based on reviews I've seen for these bushings in the E9X M3 forums, the added NVH with these should be minimal

As for the driveshaft vibrations, keep in mind that you could always have a custom carbon fiber driveshaft made by The DriveShaft Shop.
It's pricey, but its a lighter, stronger, 1 piece DS...

http://www.e90post.com/forums/showpo...&postcount=322

[jellish]

Originally Posted by DR-JEKL

Did you have any vibrations at all? Unfortunately I had a massive saga with my M3 driveline install the shop who performed the dirveshaft swap checked balanicing twice but it still vibrated. I had it sent to another workshop who found it to be out slightly and this made a huge improvement but still not 100% vibration free...

How do you find the diff bushings, lots of guys state that these cause lots of extra NVH.

This was on the N5X enthusiasts FB page a few days ago

https://www.facebook.com/INEVERL0SE/...0796188438694/

No NVH so far, and no vibrations. What color paint mark was on your M3 diff? Did you use the proper hardware to balance it based on the paint mark color?