Len Performance Front Track (Center) Shock, Polaris Switchback / Rush / SKS 146 / Switchback Assault 2012–2026 (54-50000F)
Len Performance Front Track (Center) Shock, Polaris Switchback / Rush / SKS 146 / Switchback Assault 2012–2026 (54-50000F)
Len Performance
FREE ANCHORAGE PICKUP
Most orders are ready within 24 hours. Supplier-order exceptions are confirmed by email; freight to A2D is included in the product price. Need same-day pickup? Call 907-306-3062.
Shipping options and charges are shown at checkout. Shipping information.
CHECK YOUR FITMENT
Confirm your machine’s year, model, submodel, and the selected size or option before ordering. Need help? Contact the A2D team.
Product details
Len Performance LS4-50000F rebuildable front track shock, also called the center shock, for the rear suspension on the 2012–2014 Pro-Ride Switchback 600 / 800, 2015–2021 AXYS Switchback Pro-S / Pro-X / Adventure / Assault 144 / XCR, Rush Pro-S / Pro-X and SKS 146, and the 2021–2026 Matryx Switchback Assault 146 (650, 850, Patriot 9R and Patriot Boost). It replaces the factory front track shock with a coil-over reservoir shock. At $479.95 each, it is A2D's value pick for a rebuildable, adjustable reservoir front track shock: clicker adjustment, a reservoir and a serviceable design without the cost of a race-level shock.
The front track shock controls how the skid loads under acceleration, how the sled transfers weight and how much ski pressure you keep when you get on the throttle. Being able to adjust it, rather than living with fixed factory valving, is the single biggest change most riders feel in the rear suspension. 5-click compression adjustment and threaded preload rings let it be set for rider weight and trail conditions.
Fitment. Sold each. Pairs with the Len Performance 54-50001R rear track shock on the Switchback Pro-S / Adventure / ES and Rush (Len kit LS4-50001K), or with the 54-50000R rear track shock on the Switchback Assault 144 / 146, Switchback XCR and SKS 146 (Len kit LS4-50000K). Matching ski shock: 54-50000 (Switchback, Rush) or 54-50002 (SKS). Chassis: Polaris Pro-Ride (2012–2014), AXYS (2015–2021) and Matryx (2021–2026).
Fitment list (Len Performance year/model lookup)
- Switchback: 2012-2013 600 Switchback ES; 2012-2014 800 Switchback; 2012-2013 800 Switchback ES; 2013-2014 600 Switchback; 2015-2019 600 Switchback Adventure; 2015-2021 600 Switchback Pro-S; 2015-2020 800 Switchback Pro-S; 2015-2018 800 Switchback Pro-X; 2016-2019 800 Switchback Adventure; 2017-2021 600 Switchback Assault AXYS 144; 2017 600 Switchback Pro-X; 2017-2020 800 Switchback Assault AXYS 144; 2019-2021 850 Switchback Assault AXYS 144; 2019-2021 850 Switchback Pro-S; 2019-2021 850 Switchback XCR; 2021-2026 650 Switchback Assault 146 Matryx; 2021-2026 850 Switchback Assault 146 Matryx; 2023-2026 Patriot Boost Switchback Assault 146 Matryx; 2025 Patriot 9R Switchback Assault 146 Matryx
- Rush: 2017-2018 800 Rush Pro-X; 2019-2020 600 Rush Pro-S; 2019-2020 800 Rush Pro-S; 2019-2020 850 Rush Pro-S
- SKS: 2018-2020 800 SKS AXYS 146; 2019-2021 850 SKS AXYS 146
Features
- 5-click compression adjustment, tool-free.
- Aluminum reservoir shock: the remote-style reservoir keeps oil temperature down and damping consistent on long pulls.
- Fully rebuildable, serviceable shock. Len Performance rebuild kits and replacement parts are available.
- Hardened chromoly shaft for strength and seal life.
- Forged aluminum eyelet heads with premium steel and NBR bushings.
- Powder-coated spring resists corrosion and holds rate in cold, wet conditions.
- Threaded shock body with anodized dual-ring locking preload adjusters: set sag once and it stays set.
- Sold each.
Specifications
| Part number | 54-50000F (Len Performance LS4-50000F) |
| OEM part number replaced | 7044575 (per distributor listings) |
| Shock location | Front track shock / center shock (rear suspension) |
| Chassis / platform | Polaris Pro-Ride / AXYS / Matryx |
| Adjustments | Compression (5), plus threaded spring preload |
| Length, extended | 332 mm / 13.1 in |
| Length, compressed | 247 mm / 9.7 in |
| Stroke | 85 mm / 3.3 in |
| Spring | Powder-coated coil spring included, 71 mm / 2.8 in diameter |
| Top eyelet | 17.7 mm ID x 29.7 mm wide (0.7 in x 1.2 in) |
| Bottom eyelet | 17.7 mm ID x 22.2 mm wide (0.7 in x 0.9 in) |
| Weight | 4.35 lb (7 lb shipping) |
| Includes | One shock |
| Rebuild kit | 54-00002 (Len LSR-00002), per Dennis Kirk |
| Sold | Each |
Ordering and installation. Sold each. Ships from stock at our Anchorage shop, or from our distributor's Boise, Idaho warehouse when not on the shelf. In-store pickup is available at checkout. Installation and shock setup are available at A2D Motorsports; call (907) 306-3062 to schedule. Len Performance rebuild kits are available, so the shock can be serviced or re-valved rather than replaced.