Premium KONI Frequency Selective Damping (FSD) rear shock for Spartan Mountain Master / K2 / K3, Tiffin Powerglide, Roadmaster, and Freightliner diesel pusher Class A chassis. Direct OEM replacement. Eyelet upper and lower mounts. Made in the USA.
The Koni 8805-1009 FSD (Frequency Selective Damping) Rear Shock is the definitive suspension upgrade for Class A diesel pusher motorhomes on Spartan, Tiffin Powerglide, Roadmaster, and Freightliner chassis. Unlike conventional replacement shocks, KONI's FSD technology is specifically engineered for the unique and demanding dynamics of full-size motorhomes — heavy weight, tall bodies, varying road conditions, and the need for both stability and comfort on long highway trips.
KONI FSD technology automatically adjusts damping based on road conditions: firm when you need it most — during cornering, lane changes, and heavy suspension movement — and softer over expansion joints, bridges, and rough pavement. A specialized internal valve filters out annoying vibrations and road noise before they enter the coach, dramatically reducing driver fatigue and improving ride quality without sacrificing the rear suspension control that keeps these heavy coaches stable and safe.
KONI's patented FSD technology automatically adjusts between firm control and soft comfort based on road conditions — no driver input required
Specifically engineered for Spartan, Tiffin Powerglide, Roadmaster, and Freightliner Class A diesel pusher chassis
Specialized internal valve filters road vibrations and noise before they enter the coach — dramatically reduces driver fatigue on long trips
Premium KONI quality, designed, engineered, and manufactured in the USA. Distributed by SuperSteer Parts
Some Spartan and Powerglide chassis use a 5/8" lower shock bolt instead of the standard 3/4" bolt that this shock's eyelets are sized for. How to check before ordering: Try a 1-1/8" wrench on the head of your lower shock bolt. • If the 1-1/8" wrench fits snug → you have the standard 3/4" bolt and no bushing adapter is needed. • If the 1-1/8" wrench fits loose → you have the 5/8" bolt and will need a 3/4" to 5/8" steel bushing adapter kit. Check your lower mount bolt size before ordering to determine whether you need a bushing adapter set.
Sold Individually: One shock absorber per package. Order qty 2 for a complete rear axle replacement. Verify Your Specific Chassis: This shock fits a wide range of Spartan, Powerglide, Roadmaster, and Freightliner configurations. Always verify your specific chassis model and year against the fitment table and manufacturer documentation before ordering. Tag Axle Note: For tag axle positions, a different shock is required — see KONI 8805-1013. This shock is for the main rear drive axle position only. Front Shocks: For Spartan chassis front shocks, see KONI 99B-3234 (front). For Tiffin Powerglide front shocks, consult SuperSteer Parts for your specific Powerglide configuration.
In The Box (Qty: 1 Shock Absorber): • KONI 8805-1009 FSD Rear Shock Absorber Optional — May Be Needed: • 3/4" to 5/8" steel bushing adapter kit (if your lower shock bolt measures 5/8" — see danger box above for how to check) NOT Included: • Mounting Hardware • Second shock (sold individually — order qty 2 for a complete rear pair)
KONI 99B-3234 — FSD Front shock for Spartan chassis (pairs with this rear for a complete Spartan upgrade) KONI 8805-1013 — FSD Tag Axle shock for Spartan Mountain Master with Hendrickson axle and TAG axle K2/K3 KONI 8805-1022 — FSD Rear shock for Freightliner XC, Roadmaster RR4R, and Alpine chassis For a complete suspension upgrade on your Spartan chassis, use the full set: 99B-3234 (front) + 8805-1009 (rear) + 8805-1013 (tag axle if equipped).
SuperSteer Parts Technical Support: Website: supersteerparts.com KONI Warranty: KONI warrants new shock absorbers to the original retail purchaser for 2 years from the date of installation. Covers defects in materials and workmanship under normal operating conditions. Does not cover mounting hardware or bushings.
⚠️ Before Installation — Critical Stroke Check: With the vehicle at proper ride height, measure the distance between the shock mounting points. Then collapse and extend the new shock fully and measure both extremes. The shock should be near the center of its stroke when installed, with at least 3" of stroke available in either direction. If this clearance is not met, do not install — the shock could break and the warranty will be voided.
FSD Shocks Are Self-Adjusting: Gold-colored KONI FSD shocks (like this 8805-1009) automatically adjust their damping — no manual adjustment is needed or possible. Non-FSD KONI shocks can be manually adjusted by holding the shock upright, compressing it fully, then turning the lower half clockwise to increase damping or counter-clockwise to decrease it.
Full installation instructions PDF: supersteerparts.com/content/koni-shock-install-instructions.pdf Technical support: SuperSteer · 888-898-3281
The 8805-1009 fits the following Class A diesel pusher chassis configurations at the rear drive axle position. Always verify your specific chassis model and year before ordering. Sold individually — order two for a complete rear replacement.
⚠️ Fitment cross-referenced across SuperSteer Parts, Ultra RV Products, ShockWarehouse, and Amazon. Specific Tiffin model year spans sourced from SuperSteer's application guide. Always verify your exact chassis model, year, front suspension type,