Polaris RZR 900 ball joints fail at the snap ring, not the joint itself. That thin clip is the only thing holding a factory joint in the A-arm, and it deforms or shears under landings and the extra leverage of bigger tires. Keller ball joints remove it entirely — the two-piece housing threads into the arm like a nut and bolt. Hardened 4340 chromoly, greaseable, adjustable and rebuildable.
Todd Keller's original threaded design, covering the whole 900-class trail and sport range including the four-seat cars. On these machines the same joint serves both positions, so you simply choose how many you need.
Key Features
- Two-piece threaded housing eliminates the OEM snap ring
- 4340 hardened chromoly steel housings and studs
- Adjustable and greaseable for correct stud articulation over years of service
- Rebuildable — a worn joint is serviced, not replaced
- One joint fits both upper and lower positions on this platform
- Covers the RZR 900, RZR S 900, RZR 4 900, RZR S4 900 and RZR XC 900
- Limited lifetime warranty against manufacturing defects
- Made in USA
Built To Solve: RZR 900 Ball Joint Pull-Out and Snap Ring Failure
- Snap ring shearing and letting the joint separate from the A-arm
- Clunking or knocking from the front end over rocks, ruts and whoops
- Play in the wheel when rocked top-to-bottom on a jack
- Repeat OEM joint failures on a 900 running larger tires or added lift
- Torn boots admitting water and grit so the joint wears from the inside
- Replacing the same joint often enough that it has become routine maintenance
Best For: Trail and Sport Polaris RZR 900 Builds
- RZR 900 and RZR S 900 owners riding rough trail and desert rather than groomed two-track
- RZR 4 900 and S4 900 owners carrying passengers and more weight through the front end
- Riders who have already replaced OEM joints more than once
- Machines running larger tires than they left the factory with
- Anyone refreshing a front end on a car that is now several seasons old
If the joints are sound but the boots are torn, the Keller boot replacement kit is the cheaper fix.
Specifications
- Material: 4340 hardened chromoly steel, stud and housing
- Design: two-piece threaded housing, no snap ring
- Serviceability: adjustable, greaseable and rebuildable
- A-arm modification: not required
- Positions: one joint serves both upper and lower on this platform
- Warranty: limited lifetime against manufacturing defects, original purchaser
- Manufacturer Part Number: BJK-P-RG#AO (one joint), BJK-P-RG-K-2#AO (two joints), BJK-P-RG-K-4#AO (four joints)
Fitment
- Polaris RZR 900: 2015-2020
- Polaris RZR 4 900: 2015-2018
- Polaris RZR S 900: 2015-2020
- Polaris RZR S4 900: 2018
- Polaris RZR XC 900: 2015-2017
Each body style enters and leaves the range in a different year, so check your exact model and year against the list above. Fitment is not guaranteed on applications not listed.
FAQ
Why do RZR 900 ball joints pull out of the A-arm?
The factory joint is retained by a snap ring seated in a groove. Landings and the extra leverage of bigger tires can deform or shear that ring, and once it goes the joint has nothing holding it. Keller joints thread into the A-arm instead, so there is no clip to fail.
Do these fit the RZR S 900 and the four-seat cars?
Yes. The RZR 900 and RZR S 900 are covered 2015-2020, the RZR 4 900 2015-2018, the RZR S4 900 in 2018 and the RZR XC 900 2015-2017. Match your own year to the list before ordering.
Do I need different joints for the upper and lower positions?
No. On the 900 the same Keller joint serves both positions, which is why this product is sold by quantity rather than by upper and lower. Choose one, two, or a set of four for a complete front end.
How many do I need for a full front end?
Four — two per side. The four-joint option covers a complete front end, which is what most owners order when they are rebuilding rather than chasing a single failure.
Do Keller ball joints require A-arm modification?
Standard Keller joints do not — they thread into the factory arm as supplied. The Mega version uses an oversized housing and does require machined A-arms, which is the main reason to pick one over the other.
Can these be rebuilt instead of replaced?
Yes. They grease and adjust, and the Keller ball joint rebuild kit for Polaris services them with a new cup, boot and pin when the internals eventually wear.
Why Keller
Todd Keller designed the two-piece threaded ball joint to fix the one part of a stock front end that keeps failing, and SuperATV now builds and backs the line. The design has barely changed because it does not need to: thread the housing in like a nut and bolt, use a chromoly stud, and make the whole assembly serviceable so a worn joint gets rebuilt rather than binned.
Complete Your RZR 900 Front End Rebuild
Before ordering, confirm your exact 900 variant and year, then decide whether you are replacing a single failure or refreshing all four corners — the set of four covers a complete front end. If the boots are torn but the joints are sound, the Keller boot replacement kit is the cheaper fix. If the joints are worn but the housings are good, the Keller rebuild kit for Polaris services them. Tie rods and A-arm bushings are worth inspecting while everything is apart.
Installation Video
Official SuperATV installation walkthrough with Todd Keller: How To Install Keller Ball Joints
