[isenc2]

Hi all, after seeing Farkle's review of the wavetrac diff unit, I was really tempted to get mine in as well. Unlike his wagon, mine is a 340i xDrive. I always thought the LSD with my B58 would make the handling even better. I have already put in a B12 coilover, Dinan sway bar, and VAC monoballs front control arms(upper+lower). However, the car's behavior in the snow/ice conditions has always been a bit iffy and very unnatural.Makes driving on low friction surfaces very unpredictable, just one second it’s oversteering, the next second the car understeers and bogs down completely(with dsc full off). Also, taking corners aggressively felt a little more to be desired. I really miss the feeling of being pushed around a corner by an LSD.

One thing to note and to compare wavetrac to M performance LSD. Wavetrac is an ATB(automatic torque biasing) differential, it only has lock up during acceleration, during decel it is basically an open diff. The bias ratio, as reported by wavetrac(I called them), is 2.5:1 normally, which translates to lockup percentage is about 42.86%; the patented wave hub can vary the lockup ratio all the way to 5:1, which is 66.67% in lockup percentage. All wavetrac units have the same exact bias ratios, as they told me. M performance is a 1.5 way clutch based LSD, providing decel lockup as well, at 9%. Wavetrac does have the benefit of handling high torque figures extremely well and engages very smoothly. As a side note, MFactory claims the Wavetrac only has a bias ratio of 2.1:1 normally, which translates to 35.5% lockup. I will not be diving into the wavehub vs lift wheel scenario, just hit your brakes lightly and that’s enough for the diff to work.

Unlike Farkle’s review, my experience with my wavetrac diff is a bit different from his. First of all, my b58 is running on 93 oct stage 1(dinan flash), quite a lot of torque in 1st and 2nd gear, unlike Farkle’s 330i wagon. It is very easy for me to slightly break traction in the winter of northern Arizona. (I run 255 square conti dws 06+) When traction light kicks in, xdrive automatically sends more power to the front, making the car more neutral. However, where the diff shines is when I apply 5-10% throttle during turn, the car rotates beautifully. With my old open diff, the car would ever so slightly understeer, I really wanted the extra rotation during turning. This is best illustrated by exiting a roundabout, slight throttle and exiting the turn, the car hugs the inside line extremely easily. Essentially, the car’s dynamics just make more sense to me. Also, I’ve had this car for 5 years now, I’ve gotten completely used to how it handles, and I really noticed the added torque vectoring effect provided by this Wavetrac.(not a real torque vectoring but it certainly feels like it) Best way to describe the difference is, before, it felt like the car was being pulled by the front wheels during cornering, now the car feels pushed by the rear wheels.

It must be noted that the effect of wavetrac is very subtle, I bet if my friends drove my car, they would never notice the difference. But for me, this was the last missing piece for my 340ix. Next up will be the rear chassis brace. I now understand why bmw does not add the oem brace to 340ix, the open diff really does not need the brace. But now that I have the LSD(ATB), I can really feel the rear end wiggle when the outside tire is struggling for grip. The chassis rigidity will definitely stiffene the rear end a bit. Such is modding I guess, never an end to it.

In conclusion, the wavetrac differential has been amazing. The car’s dynamic around a corner just makes it a more enjoyable machine. And you can pretty much feel it in every corner with light throttle input, b58 is a bit of a torque monster at 2000 rpm. Honestly, it kinda reminds of the 991.2 C2S I drove this summer. The way the car would just propel out of a corner beautifully and be planted like that, makes my 340i xDrive just that much better. Definitely cherry on top.


As for cost, I paid $4,000 for the part from diffsonline. They were slow but did a phenomenal job at building the diff. I opted to go for the REM polishing, it helps with break in a bit and I’m an engineer, I geek after mechanical perfection(REM doesn’t matter much, you probably don’t need it). I do not recommend everyone go ahead and do this mod, it is hella nice, but the price makes it very difficult to justify. I long for that RWD feeling in my BMW, and I could justify it. I personally would do suspension parts and everything else before doing this.

Got my swapped out open diff for sale if anyone’s interested to do this mod, it will make a great donor unit. Still in great condition, was service once at 60k, now the diff is at 80k.

[isenc2]

Installed Rolls Chassis brace. Damn that was a noticeable improvement. No wonder the new G8X have so much chassis rigidity braces. The difference is where you do a quick turn in into a corner and existing a corner when my LSD kicks in. The rear end is solid and matches the front end a lot better. Not gonna lie, I love my BMW now, it handles perfectly.

[iamsammtheman]

I'm fucking stoked to get mine as well. Please keep us updated on your findings as you continue to drive. Have fun!

[B58]

Very nice. Been eye balling the M Performance LSD. I might pull the trigger on it tomorrow or within the next few days.

[isenc2]

Originally Posted by B58

Very nice. Been eye balling the M Performance LSD. I might pull the trigger on it tomorrow or within the next few days.

The M Performance LSD is a perfect purchase for b58. Ready to be installed out of the box. You won’t regret it!

[isenc2]

Originally Posted by iamsammtheman

I'm fucking stoked to get mine as well. Please keep us updated on your findings as you continue to drive. Have fun!

Of course, so far I have passed the 1200 miles mark, it has been an awesome driving experience. Will be doing the first service soon enough.

[iamsammtheman]

Originally Posted by isenc2

The M Performance LSD is a perfect purchase for b58. Ready to be installed out of the box. You won’t regret it!

I don’t think this is the case for manual 340 drives… correct?

[isenc2]

Originally Posted by iamsammtheman

I don’t think this is the case for manual 340 drives… correct?

I believe for RWD 340i with 6MT, BMW made a M Perf LSD with the correct final drive ratio. But not for the AWD 6MT 340i. However, I never really looked into it, only saw forum members talking about it.

[isenc2]

Update!

I have just finished my 1200 mile break in, changed the fluid with Motul Gear 300, as recommended by Wavetrac. I decided to not go with Diffsonline's recommendation of Redline fluid since Wavetrac themselves highly recommend against it. The magnetic drain plug picked up quite a bit of tiny metal flakes, indicating that break in is still very much necessary even with the REM polishing.
The diff has behaved wonderfully during the 1200 miles, and it must be pointed out that the rear chassis brace is a must if you want to do this mod properly. You can go with the OEM option and order the BMW OEM rear chassis brace that fits onto existing subframe attachment points or you can do what I did, which is the Rolls Performance's aluminum brace. This mod truly makes this BMW handles like it should!

Edit:
Just went out for a drive this morning since it snowed here in Northern Arizona, did a bit of drift and donuts around the neighborhood. The diff behaved amazingly, even with BMW’s brake based “eLSD” in DSC off mode, the diff performed as it should. The rear end loves to come out and that felt super predictable.

[Lada-1]

Originally Posted by isenc2

The diff behaved amazingly, even with BMW’s brake based “eLSD” in DSC off mode, the diff performed as it should. The rear end loves to come out and that felt super predictable.

Can you describe the feeling of the eLSD vs Wavetrac+eLSD driving experience?
I think the eLSD can actually help to mimic some flaw of the gear type LSD.

[isenc2]

Originally Posted by Lada-1

Can you describe the feeling of the eLSD vs Wavetrac+eLSD driving experience?
I think the eLSD can actually help to mimic some flaw of the gear type LSD.

The problem is, eLSD is only active in DSC full off mode. It mimics what you expect LSD would do but it's not even close. It kicks in way too late, kicks in not hard enough and just unnatural feeling.(I'm taking about eLSD by itself)

I've tried drifting in snow now, in DSC full off, and the eLSD works just fine with my new LSD, kicks the rear end out so freaking fast I couldn't believe it, it was pretty awesome.

The traction control is what will help with the gear type LSDs. Since the only instance they don't work, is wheel lift off or on ice, traction control will apply brakes and give you the resistance needed for a gear type to function. All of the feelings described above only applies to my xDrive car. Never driven a RWD 340i, can't exactly comment on that.

[Lada-1]

I believe you are on 8AT with 2.81 final drive ratio and 188size diff, right? What was the PN for the Wavetrac LSD?

Im debating myself if the stage 3 car(340ix 8AT) with 560whp and 680Nm can still have the 188size rear LSD or would need to upgrade to a 215size. Any thought someone? Would pretty appreciate it

[isenc2]

Originally Posted by Lada-1

I believe you are on 8AT with 2.81 final drive ratio and 188size diff, right? What was the PN for the Wavetrac LSD?

Im debating myself if the stage 3 car(340ix 8AT) with 560whp and 680Nm can still have the 188size rear LSD or would need to upgrade to a 215size. Any thought someone? Would pretty appreciate it

Coorect, AT with 2.81. Also You should be fine, remember it's 40/60 split on xdrive, it's really not that much load to the rear. As long as your ZF8 and transfer case can handle it, the 188 rear is adequate.

As for P/N, 33108485723 and 33108485724 both work.

I have my original open diff for sale in the member classified section. It'd be an excellent donor diff. If you decide to go for it, let me know!

[Lada-1]

THanks, I have meant the Wavetrac PN. On their site it is not clear to me
http://www.wavetrac.net/application.htm or https://wavetrac.eu/

[isenc2]

Originally Posted by Lada-1

THanks, I have meant the Wavetrac PN. On their site it is not clear to me
http://www.wavetrac.net/application.htm or https://wavetrac.eu/

I see, here in the US we have a company that takes care of that for us. Well in your case you might want to look into Quaife in the UK, might be easier for you to get a hold of. Very similar products and pricing.

I believe for Wavetrac it is this:

Install Kit, F3X 340i/440i auto r=2.81

30.309.193WK

Double check with someone tho.