FJ40 Frame Boxing Kit

FJ40 Rear Frame Boxing Kit

3/16" steel reinforcement plates with 36" DOM crossmember

This kit boxes the rear section of the Toyota FJ40 frame using .1875" (3/16") steel plates for added strength. It includes a 36" section of 2" × .120" DOM replacement crossmember with four predrilled positions: one at the stock location, plus one forward and two rearward at 3" on center. The kit is designed to fit within the frame rails, and the short angled plates are made 1/8" long to accommodate frames that have shifted over time.

Installation requires removing the factory rear crossmember and mounting plate, repositioning the rear brake line, and fully welding all components. Tub removal is not required since the plates fit inside the frame, but verify clearance and alignment before welding. If you are moving the wheelbase significantly rearward, use a second crossmember to maintain the rigidity gained from boxing.

Key Features

• Part Number: R1129
• Application: Toyota Land Cruiser FJ40 rear frame boxing
• Plate thickness: .1875" (3/16") steel
• Crossmember: 36" of 2" × .120" DOM with four predrilled positions (stock, +1 forward, +2 rear; 3" on center)
• Plates fit inside the frame; tub removal not required
• Short angled plates are 1/8" long to aid fit-up on shifted frames
• Welding required

Kit Includes

• (5) Frame boxing plates
• (1) 36" × 2" × .120" DOM crossmember (predrilled)

Note

Remove the factory rear crossmember and mounting plate, reposition the rear brake line, and fully weld the boxing plates and new crossmember. Confirm frame straightness and plate seating before final welds, and add a second crossmember if the wheelbase is moved far rearward. Recheck all hardware and welds after initial shakedown.