[Boostedphil698]

Originally Posted by FaRKle!

Preface
Some of you may recall the thread where I tore one of my rear half shaft boots, and BMW in their ultimate wisdom don't have a replacement boot (or even procedure for changing it) for the rear half shaft, thus making complete unit replacement the only official option. It wasn't going to be a fun job, or even one that's really DIYable looking at how they press out and pull in the half-shafts with the rear hub. It was going to be a pricey job.

Well I decided to turn that expensive lemon, into an even more expensive lemonade. Since the half-shaft replacement work was a large chunk towards the work required to replace the differential all together, I said, "Why not?" and ordered a complete Wavetrac LSD/ATB unit built up by Diffsonline to be swapped with my OE open diff unit. I had been thinking about seeing what an LSD could do for my car, and the sway bar unfortunate event gave me just the excuse to jump on it.

Wavetrac xDrive Impressions
There's exceptionally little detailed experiences out there with LSDs on xDrive, so I didn't have a good basis on what to expect. Some comments out there said an LSD would be worthless with xDrive, and that xDrive wouldn't let an LSD shine. What I expected, was that I wouldn't really notice an LSD in daily driving, unless really pushed, and I'd probably notice it at the track. Boy, was I in for a very pleasant surprise!

Over the past week I've been daily driving with the Wavetrac and I'm very pleased to report that the improvement is quite noticeable across a wide range of daily driving scenarios! Anytime the car is taking off where you'd normally run into issues with wheel slip, such as taking off from a stop with the steering wheel set up for a turn, is vastly improved. Normally there's always a bit a hesitation, stuttering, and uncertainty as the car is struggling for traction, but no more! It just grabs and launches.

One of the most interesting things I found about adding an LSD was that it makes the xDrive vehicle feel more RWD. My hypothesis for this is that since the rear wheels are better locked together, the xDrive system/transfer case ECU doesn't detect enough wheel spin difference to shift more power to the front axle and instead maintains the default 40% front/60% rear power delivery. The effect is the same sensation you get from a RWD vehicle where you have a push and rotation from behind in a corner. The benefit of that is the car can hold a tighter inside line and feels like it has more corner grip.

Additionally I found the car has greater stability and less "vagueness" when entering corners at higher speeds. This increases driver confidence and has allowed me to increase my entry speed into corners. I'm very much looking forward to getting the car onto the track next and seeing if this holds true there and I can achieve greater corner speeds than before.

And of course, can I "hoon" the car out more? YES. Being an AWD car, it's been pretty difficult to get the rear end out under power alone with the open diff, but the LSD has made that much easier, and in a controllable manner.

So I'm a happy camper, and even though this was an expensive mod, it feels like it was well worth it to me!

Do you have to have the electronic differential coded out after install?

[FaRKle!]

Originally Posted by 435i_Phil

Do you have to have the electronic differential coded out after install?

Nope. There's no need to on this platform.

[FaRKle!]

Originally Posted by CntryClub007

Got it. So basically if I'm getting an LSD for an 340i XD, I'm just going your route, correct? That seems like the most amount of confidence for it to work on the first attempt. You've done some serious research here IK6SPEED and FaRKle!, thanks gents.

Oops, I missed this question.

Yes, you'd need to go the same route as I did. You can use the same diff I did too since my vehicle and yours use the same.

[CntryClub007]

Originally Posted by FaRKle!

Oops, I missed this question.

Yes, you'd need to go the same route as I did. You can use the same diff I did too since my vehicle and yours use the same.

Perfect - thanks for confirming!

[Boostedphil698]

Originally Posted by FaRKle!

Nope. There's no need to on this platform.

Is there a reason why not? I'm just curious.

[FaRKle!]

Originally Posted by 435i_Phil

Is there a reason why not? I'm just curious.

The physical LSD starts working well before the amount of wheel slip that the eLSD would. The physical LSD even works before xDrive thinks it should start pulling power from the rear and sending it to the front.

[J-Michael]

Originally Posted by FaRKle!

Except that there isn't evidence that the official BMW LSD for the xdrive M240/340 actually exists. If you look at the PN BMW provides, it's the same PN as the RWD M240/340i.

The M240/340i RWD use a 215mm ring gear diff, the xDrive M240/340i use a 188mm ring gear diff, same as my 328d. The axle shaft seals are different sizes. I couldn't find one example of the M-Perf LSD actually being installed on an M240/340i xDrive vehicle, but there is a post on these forums of an xDrive 340i owner who tried to have the M-Perf LSD installed and the dealership found out it wasn't compatible. So it was an easy choice to go with Diffsonline and a Wavetrac, which I KNEW would work, versus buying the M-Perf LSD from a dealer, and finding out in the middle of the install that it won't work...

So if you could please just confirm. If I go with the exact same setup as you for my 2017 240i xdrive it will work?

[FaRKle!]

Originally Posted by J-Michael

So if you could please just confirm. If I go with the exact same setup as you for my 2017 240i xdrive it will work?

I would double check the PNs on RealOEM between your car and mine (328d xDrive F31). If the diff PNs are the same, then you can do exactly what I did.

[J-Michael]

Originally Posted by FaRKle!

I would double check the PNs on RealOEM between your car and mine (328d xDrive F31). If the diff PNs are the same, then you can do exactly what I did.

It would appear so! I also spoke to Dan today to confirm as well. I am going to order one tomorrow! Thank you for the prompt reply, I appreciate it.

[Boostedphil698]

Sorry to revive this old thread but I finally got around to having Diffsonline build me a rear LSD for my 435i Xdrive. I wanted to ask, what was your break-in for your diff? I'm having the REM polishing done which I have been told negates the required break-in.

[thisismikeyb]

While I don't have a Wavetrac unit, I would have to agree that xDrive really shines with an LSD. I was able to source a new M-Performance LSD from a forum member back in August of 2020, it took a few months before I got it installed. The local BMW dealership in Maryland told the Indy Shop that it was missing the flange and was unhelpful about the install. Not surprised though as it's not "blessed" for the 328. A friend was able to locate the installation guide in the 2-series forums and it's been on the car since November 2020.

The before and after wasn't earth shattering, but it was at least noticeable in daily driving. The rear of the car definitely feels like it's putting down more of the power than before.

Additionally, I have finally started to participate in autocross and have been really impressed with the ability of the car with an LSD(and all the other mods). The local group up in Alaska held a Starting Line class with a SCCA instructor flying up here to teach the basics. As part of the class the instructor will drive your car. He commented that traction control was intervene under sport mode, I switched it to Sport+ and he indicated that it was significantly better. I do wish I had autocrossed before the installation to have a better understanding of the changes, but I don't feel I'd have nearly the capability of putting power down the way I can around the corners of the courses.

[Boostedphil698]

Hey everyone,

Sorry to revive an old thread. But, is there any instances where an LSD hurts Xdrive. Getting ready to have my LSD installed.

[FaRKle!]

Originally Posted by Boostedphil698

Hey everyone,

Sorry to revive an old thread. But, is there any instances where an LSD hurts Xdrive. Getting ready to have my LSD installed.

I'm not aware of any cases of an LSD negatively affecting xDrive. Mine is still going strong and xDrive still works well on dirt/gravel roads.

[Boostedphil698]

Originally Posted by FaRKle!

I'm not aware of any cases of an LSD negatively affecting xDrive. Mine is still going strong and xDrive still works well on dirt/gravel roads.

Good to know! My Quaife goes in Thursday.

[WrxToBeamerGuy]

Would there be any benefit in upgrading the front differential as well?

[Boostedphil698]

Originally Posted by WrxToBeamerGuy

Would there be any benefit in upgrading the front differential as well?

It's hard to say how the car would react to the torque biasing of a front LSD. The new M cars don't even use a front LSD. After almost 2 months of driving with XDrive with a rear LSD, I can say that it is an immense improvement in the fun factor and overall how that car handles. I feel like adding a front LSD would add issues and take away the fun that the car now has with being able to get the back end out and the crab-walking the car does in the rain.

[isenc2]

I am seriously considering doing this. I do have a question however, for 340i xdrive, there are two part numbers showing for the rear diff, are they the same? I'm thinking about buying a donor diff and send it in like you did, but I don't wanna buy the wrong diff. There are 33108485723 and 33108485724.

[Boostedphil698]

Originally Posted by isenc2

I am seriously considering doing this. I do have a question however, for 340i xdrive, there are two part numbers showing for the rear diff, are they the same? I'm thinking about buying a donor diff and send it in like you did, but I don't wanna buy the wrong diff. There are 33108485723 and 33108485724.

It might better to contact diffsonline and have then source a core for you so you don't make the mistake.

[isenc2]

I have put forward my order for the LSD from diffsonline. I have it fully spec'ed out with both REM polishing options. I must say that so far into the ordering process, it has not been pleasant. I sent in my donor diff and took them more than three weeks after it was delivered to send me an invoice so that I can finally pay them to start the process. They told me the lead time is about 3-4 weeks, with this ridiculous delay, it is 6-8 weeks. Also, I have called them more than 4 times to ask for an invoice so I can pay. I've never dealt business with a company that care this little about getting paid.

[Boostedphil698]

Originally Posted by isenc2

I have put forward my order for the LSD from diffsonline. I have it fully spec'ed out with both REM polishing options. I must say that so far into the ordering process, it has not been pleasant. I sent in my donor diff and took them more than three weeks after it was delivered to send me an invoice so that I can finally pay them to start the process. They told me the lead time is about 3-4 weeks, with this ridiculous delay, it is 6-8 weeks. Also, I have called them more than 4 times to ask for an invoice so I can pay. I've never dealt business with a company that care this little about getting paid.

They're very busy. It took me about 8 weeks from order to install.

[isenc2]

Originally Posted by Boostedphil698

They're very busy. It took me about 8 weeks from order to install.

Funny thing is, they told me they couldn’t send me the invoice because Dan was either at a friends wedding, or he’s off to somewhere else. First time I called, nope he’s not available today. Second time I called, nope, at friends wedding in another state. Third time, he’s off to vacation mode. I understand they can be busy, but all I was trying to do was paying the bill, and it was difficult.

[isenc2]

I have received the diff, it is going into my car next week. Ahh, 4 grand later. Will post a review on it soon. I haven’t seen anyone with a b58 and xDrive getting the Wavetrac. Will be a pretty uniquely awesome experience IMO.