Most high-performance RC vehicles are equipped with oil-filled shocks that require periodic maintenance to insure consistent performance. Dirt and grime build-up on the shock shafts can work its way into the O-ring seals, and eventually inside the shock bodies if left unchecked. Dirt and grime will contaminate the oil, causing inconsistent performance and possibly damaging the seals. This can lead to leaks. If you want your RC vehicle to handle at its best, you'll need to rebuild your shocks often.
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Things you need
- Silicone shock fluid
- Electric motor spray or denatured alcohol
- Replacement O-ring seals and bladders (shock rebuild kit)
- Needle-nose pliers
- Small flat-blade screwdriver
- Philips screwdriver
- 2 millimetre hex wrench
Remove the threaded shock caps and empty the oil out of each shock absorber. An old jar or empty coffee can makes a great storage vessel for used shock fluid.
Remove the rubber bladder inside each shock cap. Wedging the tip of a screwdriver between the edge of the bladder and the inside wall of the shock cap. Wipe the oil off the bladders with a rag and set them aside along with the caps.
Unthread the rod ends from the shock shafts. Use needle-nose pliers to grip the shaft and remove the rod end with your fingers if you can. If the rod ends are tight, slide a 2 millimetre hex wrench through the ball inside the rod end for more leverage.
Push the shock shafts up into the shock bodies and out though the top of the shocks. Apply a couple of drops of shock fluid on the threaded portion of the shafts and remove them slowly to prevent damaging the O-ring seals. Leave the shock pistons installed on the shock shafts.
Remove the O-ring seals from the shock bodies. Most RC shocks have threaded end caps that house the seals. Others have compartments inside the bottom of shock bodies and the seals are secured with Teflon washers and C-clips. If your shocks have C-clips, use the blade of a thin screwdriver to wedge them out.
Use electric motor cleaner or denatured alcohol to clean all of the shock components except the O-rings and bladders. Allow the parts to dry for 30 minutes.
Inspect the O-ring seals and bladders for small cracks, tears or other imperfections. Replace the damaged components as needed. Most RC manufacturers sell rebuild kits that include new O-rings, bladders, Teflon washers and other consumable shock components.
Lubricate the O-rings, bladders (and Teflon washers if applicable) by placing them in a pile and dousing them with fresh silicone shock fluid.
Reinstall the lubricated O-rings inside the shock bodies. Depending on the shock's particular design, this may require threading the end caps on the shock bodies, or using Teflon washers and C-clips to secure the seals to the shock body.
Apply a couple of drops of shock fluid on the threaded portion of the shock shafts, and then push the shock shafts into the shock bodies and out through the seals.
Screw the rod ends back on the shock shafts. You may need to use needle-nose pliers to grip the shafts while you thread the rod ends into place.
Refill the shock bodies with fresh silicone shock fluid. Push the shock shafts in and out of the shock bodies to work out the air bubbles. Set the shocks aside for a few minutes to allow any air bubbles to rise to the surface.
Place the bladders on the top of the shock bodies and then push in the shock shafts half way up and then back out. This should seal the bladders to the shock bodies. Have a rag handy to wipe off excess oil.
Screw the caps back on the shocks and then test the operation. You should be able to push the shafts all the way up into the shock bodies, and then the pressure inside the shocks will push the shafts back out partially.
Bleed the shocks if necessary.Not being able to push the shafts all the way into the shock bodies is a sign that the shocks have too much oil (hydro locked). Unscrew the caps partially and push the shafts up and out of the shock bodies a couple of times to let out excess oil.