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BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > xDrive All-Wheel Drive Discussions > Wavetrac LSD/ATB + xDrive, WORTH IT!
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      05-08-2020, 12:22 PM   #23
Boostedphil698
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Originally Posted by FaRKle! View Post

Quote:
Index:
0:00 Intro, why Wavetrac, and Wavetrac benefits
1:25 What's delivered from Diffsonline/unboxing
2:04 A look inside the differential, and F2x/F3x variants
3:52 What Diffsonline modifies/renews
4:24 Installation at VT Motorworks
5:04 Daily driving benefits and impressions
6:41 Test road features and impressions
8:52 Conclusion
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?
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      05-08-2020, 12:44 PM   #24
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Originally Posted by 435i_Phil View Post
Do you have to have the electronic differential coded out after install?
Nope. There's no need to on this platform.
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      05-08-2020, 12:45 PM   #25
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Originally Posted by CntryClub007 View Post
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.
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      05-08-2020, 01:08 PM   #26
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Quote:
Originally Posted by FaRKle! View Post
Quote:
Originally Posted by CntryClub007 View Post
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.
Perfect - thanks for confirming!
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      05-08-2020, 01:20 PM   #27
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Originally Posted by FaRKle! View Post
Nope. There's no need to on this platform.
Is there a reason why not? I'm just curious.
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      05-08-2020, 04:18 PM   #28
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Quote:
Originally Posted by 435i_Phil View Post
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.
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      04-10-2021, 01:32 AM   #29
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Quote:
Originally Posted by FaRKle! View Post
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?
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      04-11-2021, 11:15 PM   #30
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Originally Posted by J-Michael View Post
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.
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      04-12-2021, 10:20 PM   #31
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Quote:
Originally Posted by FaRKle! View Post
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.
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