Add Oil to Shocks

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Oil-Filled Shocks Perform Better

Shocks on an RC car.
Shocks (shock absorbers) help to give a smoother ride and better control over bumps and obstacles. Photo © M. James

Shocks and springs are part of the suspension in RC vehicles. Oil-filled shocks give RC vehicles more stability over rough terrain. Without the oil the shocks compress and rebound too quickly and fail to absorb or dampen the bumps in the road. When you feel that your shock absorbers aren't performing properly you can check the fluid level and add more oil to the shocks.

Shock oil comes in different weights such as 40, 70, or 100. Ask your hobby shop sales associate for recommendations based on your car/truck and the conditions under which you run it. Changing the weight of the oil changes the damping rate -- the compression of the shock -- so that you can finetune it for different road or track conditions.

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Remove Shocks, Gather Supplies

Things you need to change the shock oil.
In addition to your shocks, all you need are shock oil, paper towels, and pliers. Photo © M. James

To add oil you will need to remove the shocks from your RC.

Things you need:

  • Silicone Shock Oil: Sold in small 1-2 oz bottles in hobby shops as Shock Oil or Shock Damper Oil there are many brands such as Trinity and AE (Associated Electrics).
  • Paper Towels/Shop Towels: Use towels to absorb any oil leaks.
  • Needlenose Pliers: Use pliers, if needed, to aid in disassembly of the shocks.
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Remove Lower Spring Retainer

Compress the spring to remove the spring retainer.
Compress the spring to remove the spring retainer. Photo © M. James

Press the spring away from the shaft-side of the shock and remove lower spring retainer.

Note: Photos show shocks held upside down so the bottom or lower spring retainer is at the top of photo.
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Remove Spring and Upper Spring Retainer

Remove spring and upper retainer.
Remove the spring and the other spring retainer ring. Photo © M. James

Remove spring from shock and set aside then remove upper spring retainer ring.

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Unscrew Cap on Shock

Remove the cap on shock.
If necessary, use pliers to loosen the cap on the shock. Photo © M. James

Unscrew the cap end of the shock. It can usually be done by hand but if too tight, use pliers.

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Fully-extend Shaft

Extend the shaft.
Extend the shaft on the shock. Photo © M. James

Pull out shock shaft until fully extended.

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Pour in Shock Oil

Fill shock with oil
Carefully pour shock oil into the shock. Photo © M. James

Slowly pour shock oil down into the shock until it's almost (but not at) the top.

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Work Out Air Bubbles

Remove air bubbles
Pump the shaft a few times to remove air bubbles. Animation © M. James

Work the shock shaft up and down to remove air bubbles from inside the shock.

Too much air in the shocks -- either from not filling the shock enough or leaving pockets of air -- can cause the plunger to drop suddenly or stick which could cause your vehicle to lose control and become damaged.

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Put Cap Back on Shock

Replace cap.
Replace the end cap on the shock. Photo © M. James

After all air bubbles are removed, place cap back on shock and tighten by hand. Avoid overtightening the cap because it can strip the threads, resulting in oil leakage and you'll get air in the shocks.

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Reassemble Shock and Spring

Reassemble shock and spring.
After filling with oil, reassemble the shock and spring. Photo © M. James

Reverse the order of disassembly to put the shock and spring back together then put them back into your vehicle.

  1. Place upper spring retainer on shaft.
  2. Place spring on shaft and compress it.
  3. Place slit in lower spring retainer onto shaft.
  4. Release spring.