Having correctly filled shock absorbers is very important for the behavior of your car.
1st step: Preparing the shock absorbers
Previously, the shock absorbers will have been opened and emptied of the old oil if necessary.
2nd step: Positioning the rod in the middle of the stroke
Once the rod is positioned, I start filling with the selected oil, I generally fill up to 2mm from the edge. I pull on the rod, an air bubble rises and I have thus removed the air under the piston. I press the piston to check that there is no longer any trapped air.
Ideally, I position each shock absorber on a support that keeps them straight (a rim, a homemade support or even the vacuum box that contains this support).
3rd stage: Disappearance of air bubbles
The fastest method is our vacuum box where we put our shock absorbers and we remove the air in the box via the pump. The classic method is to check the shock absorbers that all the bubbles have disappeared.
4th step: Reassembly of the membrane & top cap.
Depending on the type of shock absorber you have, the method differs. For "classic" membrane shock absorbers, the membrane is replaced and the excess oil is wiped off with a paper towel or cloth, and the top cap is reassembled. For the double-piston, we position the piston with its purge pipe, we put the piston to the desired position. The excess is returned to the vial of used oil. We replace the screw, the spring and we finish the assembly by locking the top cap.
Here is your shock mounted. You can group the filling by trains or the complete car.
If the track conditions or the temperature change, just empty them and change the oil by repeating the steps in our tutorial.