This is the strongest ball joint Keller makes for the RZR RS1, and it will not fit a stock A-arm. The Mega uses a substantially larger housing and stud than the standard Keller joint — so much larger that the A-arm has to be machined to accept it. On a single-seat car that gets jumped as hard as an RS1 does, that extra material goes exactly where the failures happen.
Read this before ordering: Mega ball joints require modification of your A-arms. If your arms are stock and you do not intend to have them machined, the standard Keller RS1 joint threads straight in and is the correct part for you.
Key Features
- Oversized housing and stud — significantly more material than the standard Keller joint
- Two-piece threaded design, no OEM snap ring
- 4340 hardened chromoly steel housings and studs
- Adjustable, greaseable and rebuildable
- One joint serves both upper and lower positions on this platform
- Requires machined A-arms — not a bolt-in upgrade
- Limited lifetime warranty against manufacturing defects
- Made in USA
Built To Solve: Repeat Ball Joint Failure On A Hard-Jumped RS1
- Standard-size joints that keep failing on a light car landed front-first
- Snap ring shearing and letting the joint separate from the A-arm
- Clunking or knocking from the front end over rough ground and whoops
- Play in the wheel when rocked top-to-bottom on a jack
- Long-travel builds that outgrow a stock-size joint
- Riders who have already fitted heavy-duty joints and broken those too
Best For: Built RS1 Cars With Modified A-Arms
- RS1 owners already running aftermarket or machined arms
- Riders who jump the car and land it front-first as a matter of course
- Long-travel builds loading the front end beyond stock-joint capacity
- Racers and hard chargers who treat joints as a consumable
- Anyone having A-arms machined anyway and wanting the strongest joint available while it is apart
If your A-arms are stock, order the standard Keller RS1 ball joints instead — same design principle, no machining required.
Specifications
- Material: 4340 hardened chromoly steel, stud and housing
- Design: two-piece threaded housing, no snap ring
- Housing: oversized Mega, larger than the standard Keller joint
- Serviceability: adjustable, greaseable and rebuildable
- A-arm modification: REQUIRED
- Positions: one joint serves both upper and lower on this platform
- Warranty: limited lifetime against manufacturing defects, original purchaser
- Manufacturer Part Number: BJKM-P-MTSPR#RS (one joint), BJKM-P-MTSPR-K-2#RS (two joints), BJKM-P-MTSPR-K-4#RS (four joints)
Fitment
- Polaris RZR RS1: 2018-2022
NOTE: Mega ball joints require modification of your A-arms. This listing covers the RS1 only. Fitment is not guaranteed on applications not listed above.
FAQ
What actually has to be modified on the A-arm?
The Mega housing is larger than the bore a factory arm provides, so the arm has to be machined to accept it. This is permanent — an arm cut for a Mega will not go back to a standard joint. Have it done by a shop that has cut arms for these before.
Should I buy the Mega or the standard Keller joint?
If your A-arms are stock and staying stock, buy the standard — it threads in as supplied and solves the snap-ring failure just as completely. The Mega is for cars already running machined or aftermarket arms, or builds where the standard joint has failed under load.
Do I need different joints for the upper and lower positions?
No. On the RS1 the same Mega joint serves both positions, so choose one, two, or a set of four for a complete front end.
Is the Mega overkill on a single-seat car?
Not if you jump it. The RS1 is light, but light cars land hard and the front end takes the hit. If you have already broken standard joints, weight is not the variable that matters.
Can these be rebuilt?
Yes. They grease and adjust, and the Keller ball joint rebuild kit for Polaris carries a Mega-specific option — make sure you order the Mega service parts, not the standard ones.
Is this the same Mega joint as the Turbo S and Pro XP?
It is the same Mega family, distinguished by part suffix. You are buying the correct part for the RS1 here.
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 Mega is what happens when that design is taken as far as the geometry allows: the same threaded housing and chromoly stud, scaled up past the point a factory A-arm can accept.
Before You Order
Confirm your A-arms are machined for Mega housings, or that you are having that done. If they are stock, the standard Keller RS1 joint is the right part. If the boots are torn but the joints are sound, the Keller boot replacement kit covers the Mega. If the joints are worn but the housings are good, the Mega option in the Keller rebuild kit for Polaris services them.
Installation Video
Official SuperATV installation walkthrough with Todd Keller: How To Install Keller Ball Joints
