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Quaife ATB Differential - Focus ST 2013-2018
Quaife Focus ST Helical ATB Differential 2013-2018 QDF41Z


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Quaife ATB Differential - Focus ST 2013-2018

Maximize traction and performance with the Quaife ATB helical limited slip differential for the Focus ST / MMT6 gearbox. A direct replacement for the standard Ford open differential, the Quaife ATB differential transforms your car's performance and improves cornering. Unlike a conventional plate-style limited slip differential, the Quaife differential relies on gears rather than clutch plates for its operation. That means it is much smoother in operation and never locks harshly with a set pre-load of wheel slip across the driven axle. Instead, the Quaife differential automatically biases the torque away from the spinning wheel, across the axle to a constantly varying degree.

Quaife PN QDF41Z

Benefits over a standard open differential:
  • Maximize traction
  • Minimize wheel spin
  • Reduced torque steer and snatching in front wheel drive cars
  • Maintenance-free design which retains the standard oil lubrication
  • Quaife differentials are proven in circuit and drag racing, rallying and road use
  • All Quaife differentials are produced from Corus steel billets, and are CAD-designed and CNC machined before being inspected to ISO 9001 standards
  • Quaife Automatic Torque Biasing Differential - Track Tested and Proven

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Average Rating: Average Rating: 5 of 5 5 of 5 Total Reviews: 6 Write a review »

  0 of 0 people found the following review helpful:
5 of 5 Straight as an arrow August 15, 2019
Reviewer: Timothy Robinson from Whitby, ON Canada  
Best Buy to date takes all the torque from one wheel and puts it to both exactly where it should be

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  2 of 2 people found the following review helpful:
5 of 5 Best upgrade ever January 18, 2018
Reviewer: Mario Noronha from SAN DIEGO, CA United States  
The ST really needs this as a factory option. It isn't. Luckily Quaife and Mountune are around to handle it. I had Mountune install this part and wow talk about a professional installation. They completed the work quickly and there wasn't so much as a plastic tab out of place when they were done.

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  2 of 2 people found the following review helpful:
5 of 5 Best upgrade I've made September 4, 2017
Reviewer: Christopher Maskey from Fairfax , VA United States  
This is magic!  I have a basic bolt ons and tune and could spin the inside tire on slow 3rd gear corners occasionally, autocross was brutal before the Quaife.  Now it pulls out of corners like a train an is much easier to put down the power.  Best modification I've made.   Mountune's customer service is great, they went the extra mile to try and get me my diff in time for GridLife.

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  3 of 3 people found the following review helpful:
5 of 5 Best performance upgrade for the Focus ST December 24, 2016
Reviewer: David Miller from Gibsonia, PA United States  
This product is absolutely like getting a new car!  The Focus ST has plenty of power but unfortunately a good deal of it can be wasted through torque steer and wheel spin.  Installing the Quaife ATB differential is like adding a large horsepower modification to the car because it takes the power of the Ecoboost and applies it directly to the road. Your car will definitely accelerate and handle better.  It's as if it is no longer a FWD car.  Do not make any additional power modifications until you install this. Otherwise you are just increasing your torque and wheel spin problem.

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  3 of 4 people found the following review helpful:
5 of 5 Maybe the single most important upgrade November 14, 2016
Reviewer: Ken from WA United States  
From the beginning I'd intended to significantly upgrade my 2015 ST3, but was aghast at the performance of the stock differential and traction management.  Incredible nervousness, the car is all over the place just trying to get the basic power it has to the ground.  I realized that before power made sense, I had to do what Ford should have already done.

For anyone wanting the best out of their ST, this should be first on your list.  Do this and the rear motor mount at the same time.  It really will transform the handling of the car and not just on the track. I have better traction and acceleration on wet, rainy surfaces with this differential and all-season tires (pirelli pzero) than I did on dry with the stock Eagle F1s and the basic tune I had before.

Finally. even when the tires can be overloaded with power (easy with the MRX turbo), it still pulls more or less straight unlike stock.

If you're on the fence, do yourself a favor.  Just get it.

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