The facts.
| Brand | K-Tech |
|---|---|
| Part Number | FSS-003 |
| Inner Diameter | 37.00 mm |
| Outer Diameter | 50.00 mm |
| Height | 11.00 mm |
| Quantity | 2x oil seals |
| Manufacturer | NOK (developed with SHOWA) |
| Fitment | Kawasaki ZX-4RR (2023–2026) |
DescriptionThe whole story▼
Engineered to keep your Kawasaki ZX-4RR's forks smooth, leak-free and performing at their best, the K-Tech FSS-003 oil seal kit pairs OEM-equivalent fitment with the renowned precision of NOK manufacturing — developed in direct collaboration with SHOWA. Whether you ride the ZX-4RR daily or push it hard on track days, these seals deliver the consistent, long-lasting protection your suspension deserves.
Key Features
- Manufactured by NOK in collaboration with SHOWA — the same engineers behind the original fork specification on the ZX-4RR.
- Direct OEM replacement with exact dimensions (37.00 mm inner diameter, 50.00 mm outer diameter, 11.00 mm height) for a precise, gap-free fit.
- Prevents oil loss and contamination that would otherwise compromise fork damping and suspension response.
- Kit includes two oil seals — everything you need to service both fork legs in a single purchase.
- Keeps suspension internals protected against dirt, moisture and premature wear for extended service life.
SHOWA/NOK Quality You Can Rely On
K-Tech has built its reputation on sourcing and developing suspension components that match or exceed factory standards. The FSS-003 seals are produced by NOK — one of the world's leading seal manufacturers — under a specification refined alongside SHOWA to suit the precise fork geometry of the ZX-4RR. The result is a seal that seats cleanly, resists blow-by under hard braking and compression loads, and maintains its integrity across a wide temperature range.
Suspension Performance, Maintained
A weeping fork seal does more than leave an oil smear on your stanchion — it progressively ruins damper feel, deposits oil on the brake disc, and allows abrasive contamination to enter the fork internals. Replacing worn seals with the K-Tech FSS-003 kit restores the fork to the precise action the ZX-4RR was designed to deliver. The 37 mm bore dimension fits the SHOWA fork fitted as standard to the 2023–2026 ZX-4RR, and the 50 mm outer diameter ensures a reliable housing fit with no movement or fretting.
Fitment & Compatibility
This kit is specifically designed for the following application:
- Kawasaki ZX-4RR — model years 2023, 2024, 2025 and 2026
Installation requires specialist tools and technical knowledge of suspension servicing. K-Tech recommends fitting by an authorised K-Tech Service Centre to ensure correct installation and optimum performance.
Specifications
| Part Number | FSS-003 |
|---|---|
| Inner Diameter | 37.00 mm |
| Outer Diameter | 50.00 mm |
| Height | 11.00 mm |
| Quantity in Kit | 2x oil seals |
| Manufacturer | NOK (developed with SHOWA) |
| Fitment | Kawasaki ZX-4RR (2023–2026) |
What's includedEverything in the box▼
- 2x oil seals
FitmentWhich bikes this fits▼
- Kawasaki ZX-4RR (2023–2026)
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