Fight Shock Fade With New FOX ECS2 Cooler

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Born out of the FOX R.A.D. program, the ECS2 Cooler upgrade puts UTV race-dominating technology into a package that can benefit anyone who has a  FOX-equipped sport UTV and a need for speed! Racing or riding at high speed for sustained durations heats the shocks significantly. As oil temperature climbs, viscosity decreases. Decreased viscosity means less damping force and less control.

Extreme heat can push shocks past their ideal operating zone, resulting in shock fade. The ECS2 Cooler functions as a heat exchanger, reducing shock oil temperature so damping force stays more consistent.

During development, test engineers observed more than a 70°F drop in shock operating temperature in both dyno and field tests.

The cooling system can be added to most 2.5- or 3.0-inch diameter FOX UTV shocks and relies on a check valve to produce unidirectional oil flow. As the shock compresses, oil flows through the ECS2 Cooler and dumps into the reservoir. On the rebound, cooled oil flows back into the shock, maintaining optimal damping function.

Factory Polaris RZR racer Branden Sims churning up the Arizona dust.

Branden Sims interview: Racing the ECS2 Cooler

Arizona-based motorsports athlete Branden Sims pushes his #913 Polaris RZR Turbo R hard, looking for every competitive advantage to cross the finish line first. Sims is a key FOX Racing Applications Development (RAD) wheelman, and his racing resume includes 2X Baja 1000 and 2X Baja 500 champion, 2X Mint 400 champion, Best in the Desert Pro Turbo UTV champion and UTV World champion. We asked him a few questions about his experience racing the new ECS2 Cooler.

Branden, how long have you been using the FOX ESC2 Cooler on your vehicle, and what were your initial thoughts?

I’ve been running the FOX ECS2 coolers on my race RZR since March when FOX gave me the opportunity to run them at this year’s Mint 400. I’m a huge fan of technology and I love pushing the envelope in off-road desert racing, so I was ecstatic to see what the ECS2 coolers could do. My initial thoughts after installation was that they instantly added a “cool” factor to my race RZR, and I was excited to get some time on them to see the performance advantages they offered.  

How many races have you done with the ESC2 Cooler? Feedback?

I now have five races and over 2,000 race miles on the FOX ECS2 coolers, including the rough terrain of The Mint 400, the relentless heat and whoops of the Baja 500, and the unforgiving Vegas to Reno desert race. No issues or failures with the FOX ECS2 coolers and they have given me the confidence to push harder and faster in the rough terrain, knowing that I’ll have more control due to better shock cooling and less inherent shock fade.  

In your opinion, what are the competitive benefits of upgrading your FOX shocks with the ESC2 Cooler?

Many, actually! Heat is the biggest killer off-road; these ECS2 coolers help control extreme shock temps, providing more consistent shock performance by reducing or eliminating shock fade, while keeping the shock fluid in better condition to extend the service life of your shocks. The coolers also help reduce or eliminate the excessive heat that can destroy or melt the seals inside the shock, which could lead to premature shock failure. 


  • Unidirectional oil flow
  • Impact extruded 6063-T5 aluminum alloy
  • Internal and external fins for maximum cooling surface area and heat dissipation


  • Maintain consistent damping force
  • Longer service intervals in extreme heat conditions
  • Better performance for racing and riding at high speed for extended durations


  • Existing FOX UTV shocks only
  • Most FOX 2.5” and 3.0” rear shocks

Professional installation required by Shock Therapy in Phoenix, Arizona or the FOX Midwest Service Center in Baxter, Minnesota. Fitment options and pricing are based on your existing FOX shocks.


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