Review of Wavetrac LSD for Fiesta ST

Advantages of Wavetrac over other Limited Slip Differentials on the Market:

The unique feature of the Wavetrac is that it is designed to continue applying power to the wheel with the most grip even if the other wheel lifts off the ground.

Patented Wavetrac design automatically improves grip in low traction conditions such as snow/ice/rain/gravel. This feature is truly innovative and unlike any other torque biasing diff design.

FYI: All current market Limited Slip Differentials offer limited Lifetime Warranties that cover racing usage.... but Wavetrac warranty is transferable to a different owner, you just need to provide the new owner with differential and install shop purchase information.

Technical Explaination from Wavetrac - http://www.wavetrac.net/different/


Buying Information on Product:

I bought the Wavetrac Limited Slip Differential from FSWerks.com for $995.00 (SKU: 56.309.145WK)
https://www.fswerks.com/products/wavetrac-limited-slip-differential-ford-fiesta-st-2014

It was bought 7/21 (Friday) and took 6 days to be delivered to the shop that had my car.

I also bought the ATB Differential Installation Kit from Mountune USA for $124.00 (2364-ATB-HW)
https://www.mountuneusa.com/ATB-Differential-Installation-Kit-Fiesta-ST-p/2364-atb-hw.htm

Installation Information on Product:

I was having the transmission pulled out to have a bunch of parts swapped for OEM or replaced (Clutch was going to OEM from a Spec Stage 3+, new Dual Mass Flywheel, new Throw-out Bearing and Slave Assembly, new Master Clutch Cylinder) so.... the price of installation was significantly lower than it would normally have been. I paid $500 labor for the differential swap/bearing kit install but would have paid $1200 in labor alone according to the shop if I did it at a later time.

Another shop a few months back quoted me $1600 labor, they were also a shop recommended by a friend who builds racecars, and reputable.

Another shop that me and my friend had work done at before that was a performance tuning shop in Spring Lake Park, MN quoted me a ballparked $700 for the labor...but I feel that this shop cuts corners a bit and doesnt have as much expertise than the other two more expensive shops listed above.

I hope this helps outline the installation labor expectations to have.

The process of actually installing the diff in the gearbox, and everything back in with fluids was what I would estimate to be 2-3 days of not having the car. It's not a process that you want to have rushed. I believe it could take 2 days if the shop started early, was a bigger shop, and had all the things they needed provided by you on the 1st day.

Driving Impressions/Performance Improvement:

If you've already read everything above, then you already know this is something you may want in your car... and my honest opinion is that it is seriously worth it. In every situation that my car felt slightly unstable before... fast lane changing, rapid deceleration with fast downshifts, fast high and low speed corners, straight line acceleration in rain... the differential completely balances the car out.

Test Setup:
Tires/Wheels used were Federal 595RS-RR 215/40R-17 on OEM rims (available grip)
Brake pads - Front 2014-2015 Ford Fiesta ST OEM Track Pads, Rear 2016 Fiesta ST A/S non-track pad OEM (left foot braking, brake Torque Vectoring Control)
Cobb Rear Motor Mount
Stratified tuned on E30 220bhp 295tq (196.2whp 300wtq)
Castrol Edge w/ Dexos 5w20
Car weighs 2880 with driver
Electronic Stability Control OFF

Straightline Acceleration (worst case scenario, tested in rain)
[Open] One wheel slips and other wheel rolls along providing zero pull until spinning tire heat generates enough grip or let off to regain grip to get power transferred back to the non-spinning wheel. One tire mark.
[Wavetrac] Both wheels slip for a bit then grip. Time spent slipping or having to let off is MUCH less. Two tire marks.

Corners (accelerating quickly around a 45 degree bend or a cloverleaf on highway)
[Open] The car has a significant amount of push, since 50% of the torque is distributed to both wheels including inside wheel
[Wavetrac] The available grip and stability is a significantly improved, going far past the point the car would have started to understeer and staying tight to the line you chose. As long as you stay on power, 50-100% throttle you feel the car pulling in smoothly and staying stable. The differential makes the car much more stable in a turn, since the outside wheel torque is actually higher than the inside wheel torque, since the outside wheel is rotating the car and pulling it around the turn more than the inside wheel is pushing you out of the turn. It is very controllable and you can be in the throttle much more, even in the rain around a tight corner without worrying much about under-steer.

Torque Vectoring Control Interaction:
[Open] The inside wheel (50% torque, lower speed) pushes the outside wheel (50% torque, higher speed) past the limit of traction, inducing the Brake Torque Vectoring Control. bTVC brakes the inside wheel to reduce/eliminate understeer.
[Wavetrac] The inside wheel (down to 34% torque, lower speed) slightly pushes the outside wheel (up to 66% torque, higher speed) around the turn. bTVC works the same way, braking the inside wheel to reduce/eliminate oversteer.

I drive my car hard in all weather conditions and daily drive it also. This made a massive difference in both performance and driving enjoyment for me in the Fiesta ST. I will also add a winter driving impressions info later this year, and more 0-60mph data on this current set up now with the Wavetrac installed.

Thanks for reading!

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