Honda Pioneer 520 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 a narrow machine that lives at full steering lock in rocks and ruts finds it quickly. 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.
Uppers and lowers are different parts on the Pioneer 520 and are ordered separately, one joint at a time.
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
- Upper and lower sold separately, one joint at a time
- Direct replacement for the Honda OEM joints listed in Specifications
- Limited lifetime warranty against manufacturing defects
- Made in USA
Built To Solve: Pioneer 520 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 roots, rock ledges and ruts
- Play in the wheel when rocked top-to-bottom on a jack
- Repeat failures on a machine that works hard at full steering lock
- 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: Narrow-Trail and Property-Work Honda Pioneer 520 Machines
- Pioneer 520 owners riding tight, rocky or rooted trail systems
- Hunters and property owners working the machine through mud and standing water
- Riders who spend most of the day turning rather than at speed
- Owners who have already replaced an OEM joint and do not want to do it again
- Anyone who wants a serviceable joint rather than another disposable one
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: upper and lower are different parts, each sold as a single joint
- Replaces Honda OEM upper: 51375-HP5-601, 51355-HN0-A01
- Replaces Honda OEM lower: 51220-HL1-A01
- Warranty: limited lifetime against manufacturing defects, original purchaser
- Manufacturer Part Number: BJK-H-P1000U#FT (upper), BJK-H-P700L#FT (lower)
Fitment
- Honda Pioneer 520: 2021 onward
The Pioneer 500, 700 and 1000 each take their own Keller listing, so confirm which machine you have before ordering. Fitment is not guaranteed on applications not listed above.
FAQ
Why do Pioneer 520 ball joints pull out of the A-arm?
The factory joint is retained by a snap ring seated in a groove. Side load at full steering lock, rock strikes and mud all push on that clip, and once it deforms or shears the joint has nothing holding it. Keller joints thread into the A-arm instead, so there is no clip to fail.
Which Honda part numbers do these replace?
The upper replaces Honda 51375-HP5-601 and 51355-HN0-A01. The lower replaces 51220-HL1-A01. If you have an OEM number off an old joint or a parts diagram, match it to the upper or lower before choosing.
Do I need uppers, lowers, or both?
They are different parts on the 520 and are sold separately, so you can replace only what has failed. A full front end is four joints — two uppers and two lowers — ordered individually.
Is this the same joint as the Pioneer 500?
The upper shares a base part with the smaller Pioneer, but SuperATV lists each machine separately and the 520 also has a lower that the 500 does not. Order from the page that matches your model.
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 Honda 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 Pioneer 520 Front End Rebuild
Before ordering, work out whether the upper, the lower or both have gone — they are separate part numbers here, and a full front end is four individual joints. 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 Honda 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
