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Modern mountain bike forks are packed with all the greatest tech. Believe it or not there are internal upgrades out there for these already advanced suspension forks. Our valued customer shares their experience with the Push industries ACS3 Spring Assembly for Fox 36 forks. Check it out!
The Push industries ACS3 Spring Assembly for Fox 36 forks was installed on a Fox Performance 36 160mm fork, fit grip damper (single damper knob and 3-position compression), that came with my Ibis Ripmo V1 build. I’m about 195lbs geared up and opted for a green spring since my weight falls right in the middle of the spring chart recommendation. Sag settings should be between 15-20% or 24-32mm, where mine came out to 27mm with no tokens installed. This is also where I ran my fork prior to installing the coil. Installation was fairly straight forward, especially with Push’s service videos and if you’ve had prior experience servicing suspension. I needed to order a 32mm socket, which actually was not chamfered and worked fine. The spring-clip that holds the air spring in place was reused. I also stuck with Fox's recommended fluid for 5wt Teflon Infused oil on the damper side and 20wt gold on the spring side. Slick Honey was used to grease the spring and pushrod.
The air bump stop was pressurized to 20psi by default, where I’ve since lowered it to about 10-15psi after a few rides. Due to the small air volume of the bump stop and using a high-pressure shock pump, I needed to determine how much pressure was lost from removing the pump. So multiple iterations are required to set a different pressure, intentionally setting a higher pressure on the gauge to target a lower pressure after leakage is factored in from pump removal.
I put about 1,000 miles on my fork at the time of Push ACS3 spring assembly installation and the fork was 1yr old, so the warranty expired (there’s no converting back to air). During that time, I’ve serviced the lowers with fresh fluid and changed the dust wipers. I also have a damper and air spring service kit but chose to convert to the coil and wait on the damper rebuild till offseason. The air spring did suffer from more stiction as time passed, which is why I was prepared to rebuild the air spring. Stiction was definitely noticeable during riding, affecting small bump compliance. I always ran 5-10psi less than recommended in this fork, to get the right sag. The damper setting was 7 clicks from closed, where I’ve set it to 6 clicks with the ACS3. I almost always run compression fully open.
On the trail, I immediately noticed how sensitive the fork was for small rocks and roots. It felt so much more active than the air spring, even when it was brand new. Much of my riding is in the northeast forest setting, which has tons of rocks, roots, and rough terrain. There is a very noticeable difference charging into these technical, unforgiving sections, comparing the air spring to the coil. The coil’s linear nature smoothly soaks up chatter and hard knocks, where the air bump stop prevents any harsh bottom outs on 3-5 foot drops. If you listen, you’ll hear the bump stop engage, but most of the time I don’t notice it when focused on a fast line. I find myself carrying more speed through these rough sections, which is a lot of fun. I’ve also been on some flowy pump track rhythm trails, where the Push ACS3 is very predictable and responsive on take-off/landing or pulling G’s. Also, even though the coil is slightly heavier, I don’t notice any extra weight.
I did have one issue with internal spring chatter after the second ride. I removed the spring and found the shrink wrap had moved up. After repositioning, regreasing, and reinstalling, the chatter went away for a few more rides. However, it came back again and would only chatter at 1/3 travel. I removed the spring again and found the shrink wrap slide down this time, regreased and installed. Since then, I’ve ridden about 200 miles with no noise. Push sent me new shrink wrap in case I need to reapply, requiring a heat gun.
I’d definitely recommend Push’s ACS3 to anyone wanting to smooth out their fork! Great product!