Nothing beats the small-bump compliance and traction of coil-sprung suspension. While many companies may try to sell you on “coil-like performance” from an air spring, there is no substitute for the real thing. Therefore, Push Industries is offering its new ACS3 fork conversion kit, which is a drop-in kit that takes an ordinary Fox 36 (and more models to come) from a standard air spring to coil-sprung sweetness. The $390 system comes with everything you need to dial in your suspension with tons of different coil-stiffness options, as well as end-stroke and bottom-out performance. The guys at Push are suspension nerds, no doubt about it. Now, you can reap the benefits of their work on your bike.
1. This is the Push ACS3 kit. It comes with a plunger assembly, spring, preload cap, spacers and an adjustable Air Bump Stop that allows the rider to control the end stroke’s bottom- out feel. This kit is available for Fox 36 air forks, but may soon be available for other fork models as well.
2. To begin the installation, remove the air top cap and release all the pressure from the air-spring chamber.
3. Then, use a 32-millimeter socket to remove the air top cap. This is best done with a chamfer-less socket to prevent stripping of the edges. If you don’t have one of these, you can make one by grinding down a standard socket to make it flat on the bottom. If you happen to not have a 32-millimeter socket, this step can also be done with an adjustable wrench, although doing so increases the risk of scratching the crown or stripping the top cap.
4. Remove the upper-air shaft assembly from the fork. It’s normal to hear a slight “pop” when doing this step.
5. Using a 2-millimeter Allen wrench, loosen the setscrew on the red rebound knob. Then, remove it and set it aside.
6. Using a 15-millimeter socket, loosen and remove the foot nut on the damper side.
7. Next, use a 10-millimeter socket to remove the foot nut on the air spring side.
8. Now, we must break the air and damper 78 assembly free from the lower legs. This must be done with a tap from a hammer or mallet. On the air spring side, simply tapping on the threaded bit usually works fine. On the damper side, it’s critical that you cover the end with the 15-millimeter socket before hitting it. This prevents damage to the rebound adjustment rod.
9. Once you’ve tapped and broken free the air spring and damper rods, the lower legs should slide off easily. There will be some oil dripping out when you remove them, so be sure to have an oil pan ready.
10. Use a lint-free paper towel and some isopropyl alcohol to clean the entire upper chassis.
11. Now, use a scriber (dental pick) to pry up the retaining ring from the bottom of the inside of the air spring (left) side.
12. Once the retaining ring is removed, then remove the lower air-shaft assembly completely.
13. Using another paper towel, clean the old oil from the inside of the air tube.
14. Slide the travel indicator ring onto the left-side stanchion.
15. Get ready to install the new Push lower coil-spring assembly.
16. Start by applying a thin layer of suspension grease to the O-rings and red spring seat.
17. Then, slide the assembly into the bottom of the left stanchion tube. The assembly will seat and stop when fully inserted.
18. Reinstall the original Fox retaining ring. Be sure it’s fully inserted and sitting flat and fully seated. It should “snap” into place.
19. Now, install the spring by sliding it in through the top of the left stanchion tube.
20. Install the preload cap housing onto the spring you just installed. If everything is done correctly, the top of this part should be sitting about 3 millimeters below the top of the left stanchion.
21. Apply a thin coat of suspension grease to the top cap and O-ring on the upper assembly.
22. Insert the upper assembly and Bump Stop and begin to thread it into the top of the stanchion. It’s best to start the threading by hand to avoid stripping the threads if it gets cross-threaded.
23. Use a socket to torque the top cap to 200 inch-pounds (22.6 Newton meters).
24. At this point we would typically replace the dust wipers and foam rings, but this is a relatively new fork. If your fork is more than a year old, those seals should be replaced. Once ready, gently slide the lowers back onto the uppers, being careful to keep the seals and foam rings aligned.
25. Once you’ve wiggled the lowers onto the uppers, turn the fork so that it’s pointed up with the lowers halfway installed.
26. Use a large syringe to measure 20cc of fork oil. Push recommends Maxima Plush fluid, although Fox recommends their own fluid. Either will work well.
27. Inject the 20cc of suspension fluid into the bottom of the fork leg, and then repeat the same process on the other side. Both bottom legs should have 20cc of oil in them.
28. Now, fully slide the lowers onto the fork. The threaded ends of the rods should come out on both sides. If they don’t, you can use a pick to guide them into place like so.
29. Install the new foot nut and plastic crush washers on both sides.
30. Then torque the foot nuts down to 50 inch-pounds (5.7 Newton meters)
31. Spray the whole fork down with isopropyl alcohol and clean with a paper towel.
32. Use the 2-millimeter Allen wrench to reinstall the red rebound knob to the bottom of the fork leg. Be sure that the set screw aligns with the slot on the rebound rod when tightening it.
33.Be sure to install some of the included Push decals to the fork to let everyone know you’re rocking the good stuff, and then go hit the trails.
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