How to fix lower arm slop on MJX 10303

Excessive slop on the lower swing arms of the MJX Hyper Go 10303 is mostly caused by worn hinge pin holes and loose clearance of ball cups. You can diagnose the issue with these checks:

1. Slop between the steel pin and the arm inner hole: the hole turns oval and worn out. Shims will not fix this; it is permanent part wear.
2. Side-to-side play of the lower arm sliding along the pin: gaps exist between the swing arm, chassis arm mount and steering knuckle. You can add thin shims for fine adjustment. After shimming, compress the shock absorber manually to confirm smooth up-down travel, proper rebound and no binding.
3. Slop from the ball joint: loose ball cup or worn ball socket. You need to service the ball joint separately.

If the arm hole is heavily worn, replacing the lower swing arm or installing brass bushings is a long-lasting solution to keep your buggy tracking straight and maintain consistent steering feel.