Installation Precautions (Extremely Crucial!) Most of the oil leakage is caused by improper installation

1.Preparatory work: "Thorough cleaning: This is the most important step!" After completely disassembling the shock absorber, thoroughly clean the oil seal installation groove (inner wall of the cylinder), the surface of the inner tube (piston rod), new oil seals, retaining rings (retaining rings), dust-proof seals and their installation grooves with a lint-free cloth and special shock absorber oil or isopropyl alcohol. Make sure it is absolutely dust-free, oil-free, free of metal debris and free of residues of old sealing rings. Any tiny particles can scratch the sealing lip or the mating surface, causing leakage.

Inspect relevant components: Carefully check the surface of the inner tube (piston rod) for any scratches, pits, rust or peeling of the coating. Even the slightest damage can cut through a new oil seal. Severely damaged inner tubes must be replaced or professionally repaired. Check whether the inner wall of the oil cylinder (installation groove) is smooth without burrs or damage.

Lubrication: Before installation, apply a thin layer of the specified shock-absorbing oil on the sealing lip of the new oil seal, the outer diameter surface of the oil seal, and the stroke area where the inner tube (piston rod) contacts the oil seal. This provides initial lubrication and prevents dry friction from damaging the lips. Do not use butter, grease or non-specified lubricants! 

2. Installation process
 direction confirmation:

confirm the direction of the oil seal again! The dust-proof lip (secondary lip, usually thinner and softer) must face outward (towards the external environment of the shock absorber). The main sealing lip (with spring) is facing inward (towards the oil chamber). Installing it in reverse will result in immediate failure.

Use the correct tools:strongly recommend
use the dedicated oil seal installation tool/sleeve. These tools are of matching size and can evenly apply pressure to the outer ring of the oil seal metal skeleton, ensuring that the oil seal is pressed in place vertically and without distortion.
Avoid using improper tools: Absolutely do not use sharp metal tools such as screwdrivers or chisels to directly pry open the rubber part of the oil seal (especially the sealing lip), as this will almost certainly cause invisible damage and lead to oil leakage. If alternative tools (such as a PVC pipe or sleeve of appropriate size) must be used, it is also necessary to ensure that the pressure is only applied to the sturdy outer metal frame of the oil seal, and the operation is smooth and vertical.
Smooth and vertical pressure application: When installing, ensure that the tool or sleeve is parallel to the end face of the cylinder and apply a smooth and vertical pressure. Avoid any Angle of tilting, otherwise the oil seal will be skewed, deformed or even damaged.
Installation depth: Press the oil seal into the bottom of the installation groove and ensure it is completely level and not tilted. Usually, it is necessary to feel it touching the hard stop point at the bottom of the groove.
Install the retaining ring: Install the retaining ring (retaining ring) carefully to ensure it is completely and firmly inserted into the groove.

3. Install dust-proof seals: The dust-proof seal is installed in its slot, usually right next to the outside of the oil seal. Also, confirm the direction (usually with the opening facing outward), and use the appropriate tool or by hand (if the design permits) to press it in place smoothly. The contact surfaces also need to be cleaned and lubricated before installation.

4. Install the inner tube/piston rod: 
When inserting the inner tube into the cylinder and passing through the oil seal, be extremely careful! Make sure that the end of the inner tube (especially the thread or any sharp edge) does not scratch or hook the main sealing lip of the oil seal.
Protect the sealing lip: You can completely wrap and cover the threads and sharp edges at the end of the inner tube with a dedicated plastic protective sleeve (usually provided with the new oil seal), cling film or tape coated with a large amount of shock-absorbing oil (be careful not to leave any residue). When passing through the oil seal, move slowly and straight.
Alignment: Ensure that the inner tube is concentric with the cylinder to avoid forced insertion at an Angle.

5. Follow-up Work: Re-cleaning: After installation is completed, clean the exterior of the shock absorber again, especially the oil seal and dust-proof seal areas.
Correct oiling and venting: Strictly follow the requirements of the maintenance manual, use the specified type and capacity shock absorber oil, and carry out the correct oiling and venting procedures. Air mixture will affect the shock absorption performance and the service life of the oil seal.
Preliminary test: Before reinstalling the shock absorber on the motorcycle, manually compress and release the shock absorber several times and slowly to observe if there are any immediate signs of leakage in the oil seal area. This is a good opportunity to check if the installation has caused any obvious damage.
Post-loading test: After loading, conduct a medium and low-speed riding test under safe conditions to check if the shock absorbers are working properly. After parking, carefully inspect the oil seal for any oil stains.