Front Progressive Damping Piston Set for XRAY XB2 & XB4

Description

These deliver quicker damping on the rebound stroke for improved traction and stability, especially on rough or bumpy tracks. Each set is OEM length and ready to drop right into your RC10B7 or RC10B84 shocks.
The pistons come blank and must be drilled before use. (The two inner progressive damping holes are pre-drilled at 1.1 mm.)
The included shafts are crafted from high-quality Japanese steel and are left uncoated by design—allowing shock oil to adhere longer for more consistent damping over extended runs. This setup is preferred by experienced racers who want maximum feedback and tunability.
INSTRUCTIONS:
The following instructions have been translated to English. We make no guarantees the translation is accurate. Please use your best judgment when assembling this product.
This product is a piston kit that improves road-holding performance during cornering.
This piston features multiple small holes on the outside and openings on the inner side.When the damper operates, oil flows through both the inner and outer holes during compression, while during rebound the oil mainly flows through the inner holes.
As a result, the suspension compresses firmly to maintain good road contact, while rebound speed is increased. This improves cornering speed and overall driving stability.
1. Drilling the Blank Piston
Drill holes in the outer circumference of the blank piston. It is recommended to start drilling from the locations shown in the diagram.
Note: The example illustration shows two 1.1 mm holes, but you may drill additional holes as needed.
2. Assembly Method
Assemble the parts in the order shown below. After assembly, make sure the shim moves freely.
If the shim is pinched between the seat and the piston, it will not function properly.
Assembly order (top to bottom):
Set screw
Seat
Shim (0.2 mm thick)
Piston
0.5 mm mini washer
Damper shaft (sold separately)
3. Operation Illustration
During compression: Oil flows through the outer holes.
During rebound: Oil flows through the inner and outer holes.
4. Tuning Tips
If the shock bottoms out or has too little damping:
Try the following tuning adjustments:
Increase damper oil viscosity (about +0.5 to +1 mm equivalent)
Use thicker oil
Change the shim thickness from 0.2 mm to 0.3 mm (optional part)
If rebound feels too fast:
Reduce the size of the inner holes (default is 1.1 mm)
Reduce the number of inner holes(Recommended to keep hole size at 1.1 mm or larger)

Explore more from our collection.