Primary Drive Clutch Spring (173-385) for Ski-Doo 850 E-TEC pDrive (Long Track / Mountain) // SKU: 05-173-385
⚙️ SPRING RATE SPECIFICATION: Calibrated with a 173 lb initial engagement load and a 385 lb finish load. Color-coded with a durable Black body and Purple stripe for rapid identification during bench tuning and field checks.
SKU: 05-173-385
Color Code: Black / Purple Stripe
Spring Rate: 173 lb Initial Load / 385 lb Finish Load
Clutch Compatibility: Ski-Doo pDrive Primary Drive Clutches
Primary Application: Ski-Doo REV Gen4 & Gen5 850 E-TEC mountain snowmobiles (Summit and Freeride models).
Maximize power transfer, sharpen throttle pickup, and lock in consistent shift-out RPM with the Bikeman Performance 173-385 Primary Drive Clutch Spring for Ski-Doo pDrive clutches. Designed specifically for the high-load demands of long-track mountain sleds operating at high elevations, this spring manages initial clutch engagement and provides the critical finish force required to hold the 850 E-TEC engine right in its 7,900–8,000 RPM peak horsepower band.
The aggressive 173 lb initial load raises engagement RPM slightly to deliver crisp, instant track spin that gets deep-lug tracks up on the snow immediately without bogging or hesitating. As the pDrive shifts out under heavy deep-snow loads, the stiff 385 lb finish load resists the outward force of the clutch weights, preventing the clutch from shifting prematurely into overdrive and maintaining peak climbing momentum on sustained mountain pulls.
Manufactured from premium shot-peened, high-tensile chrome-silicon alloy spring steel, this primary spring is engineered to withstand extreme heat cycles, rapid compression rates, and severe harmonic vibration without sagging, binding, or losing its rate profile across multiple seasons.
Key Performance Features
- High-Elevation Mountain Calibration: Engineered to complement high-altitude track load, steep incline drag, and reduced atmospheric engine horsepower on deep-snow Summit and Freeride sleds.
- 173-385 Spring Rate Dynamics: 173 lb initial rate delivers responsive off-idle track pop, while the 385 lb finish load controls upshift speed and prevents high-load RPM fade.
- Shot-Peened Chrome-Silicon Alloy: Premium spring steel resists fatigue, collapse, and heat sag, maintaining factory load ratings through long backcountry riding seasons.
- Black & Purple Stripe Identification: Easy-to-read color coding ensures quick verification in the shop or trailside gear bag.
- Essential Kit Component: This is the exact primary spring included in our Ski-Doo 850 E-TEC Long Track High Elevation Stage 2 Clutch Kit (paired with the factory OEM secondary spring).
Fitment & Installation Notes
- Compatible Sled Models: Fits all 2017+ Ski-Doo REV Gen4 and Gen5 850 E-TEC mountain snowmobiles equipped with the factory pDrive primary clutch (Summit, Summit Expert, Freeride).
- Secondary Spring Pairing: Our high-elevation long-track clutching configuration is specifically calibrated to run this 173-385 primary spring in combination with the stock factory Ski-Doo secondary spring and our XP4 progressive helix.
- Installation Tooling: Requires a standard pDrive clutch spring compressor for safe removal and installation of the primary spring cup retainer.