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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
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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!