FJ40 Frame

After we found the crack on the passenger side, I figured it would be a good idea to inspect the rest of it.  So I ground down every single (and there are tons) rivet and seperated each piece of the frame. Turns out, the inner channel on the passenger side was completely rusted, and the rear leaf brackes, were riveted to flakey rust. 

Initially I wanted to just sandblast it and coat in in POR 15 after carefully patching each of the rusty sections.  Unfortunately when sitting the frame rails side by side, the front and rear of the passenger rail was one inch lower than the drivers rail.  I don't know if the heat from welding the crack bent it, or the inner channel held them both in the same plane, but this was not gonna be an easy fix.

In the end I decided to scrap the old frame and start from scratch.  The new frame will be 5 inches wider in the front and narrower in the rear so that the rails will be completely parallel.   This gives me plenty of room up front for the new 5.3 Vortec and also gives me enough room in the rear to run coilovers.


The factory frame needed a little TLC.  When I brought the FJ40 into the shop, the frame was cracked.  The problems didn't stop there.  After wasting several weekends working on the original frame, I decided to scrap it and start from scratch.

 Once I had separated the factory frame rails I chose the straightest one and traced it onto our assembly table (a 5'X12'X1" plate on legs). After tracing it in chalk, I lined the top edge with 3/4" angle iron.  At that point it was relatively easy to measure the angles and miter  the new steel tubes.  For the center section I used 2"X6" 1/8" wall and for the front and rear went with 2"X4". 

After cutting all the pieces they were clamped to the table to keep them straight. 

From this angle it is easier to see the transition from the large tube in the center to the smaller tubes.

 Clamping the rails side by side made it difficult to assure each was identical.  To remedy this, the second rail was built on top of the first rail.

 First we made the front and rear sections, and then connected them to the mid section.

 Each of the welded seams was then gusseted for additional strength.

Where the smaller ends meet the larger center, a triangular section was cut in order to gradually taper them together.

 Here is a close up of that joint after welding and grinding.  It to will receive a diamond shaped gusset.

 After building each rail I set them up on the table and here's what I had.  Next I'll add Cross Members and Body Mounts