Symptoms
Flaking, swollen or holed frame rails, rear control-arm brackets and crossmembers, often hidden under fresh undercoating on salt-belt trucks.
The fix, step by step
- Probe the rear frame, the lower-link brackets, the crossmembers and the coil-spring buckets with a hammer and pick.
- Wire-brush and treat surface rust; anything rotted through has to be cut out and replaced.
- Rust Buster makes FJ-specific caps for the last 28.75 inches of the rails and for the center rail section, plus crossmembers, coil buckets and body mounts shared with the 4Runner.
- All of them need welding.
- One IH8MUD owner replaced his rear lower-link frame brackets with Rust Buster pieces and added weld-on reinforcement.
Tools & part numbers
- MIG welder
- grinder and cutoff wheels
- jack stands
- rust converter
- Rust Buster RB8432 (rear rail), RB8433 (center rail) and RB8427 (rear control-arm crossmember) as needed.
Where to buy the parts
Rear frame repair kit for 2007–2014 FJ Cruiser (RB8432)Rust Buster ↗Amazon ↗
Center frame repair kit for 2007–2014 FJ Cruiser (RB8433)Rust Buster ↗Amazon ↗
Rear control-arm crossmember, 4Runner/FJ/GX470 (RB8427)Rust Buster ↗Amazon ↗
Rust converter primer (RB9917)Rust Buster ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Toyota FJ Cruiser parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.