empowerment Part 3 - frame Mount Point - Photo 41970756

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One challenge to welding on factory frames is that many times they’re painted inside and out. You can clean the paint off of the outside, but there’s still paint on the inside that can get pulled into a weld. When paint gets pulled (by heat) into a weld it creates porosity in the weld. No good! To avoid that problem, rings were made that allowed the tube to be welded to the radiator crossmember without getting paint pulled into the weld. This tube pierces through the radiator crossmember and will eventually tie into the main bumper structure.

Our 2004 Toyota 4Runner has a really wimpy crossmember running under the radiator and AC condenser. We’re going to replace the thin, stamped mild steel with 1-1/2-inch-by-0.120-inch-wall 4130 chromoly tubing. The AC condenser was left in place, but removing the radiator opened up some critical working room. Putting the front of the ‘Runner on jack stands and pulling the front wheels created even more working room. An orange Home Depot multipurpose bucket stored the not-so-old coolant for post-fabrication reuse. Yeah, a little got spilled.

To keep things in place while the crossmember was being replaced, angle iron was temporarily welded onto the factory tie-down rings.

The factory crossmember was cut out in two steps. After marking the final cut location with tape, the middle of the crossmember was sliced free.

After that, sawing and sanding brought the metal up to the tape line.

The open ends of the remaining factory brackets were capped off with 1/8-inch-thick 4130 chromoly plate and then the 4130 round tube was welded between the plates.

Using 4130 chromoly isn’t an attempt to gain style points; the stuff is very strong and material quality is consistently high. Cold-rolled plate and DOM tubing are good alternatives for those who want something stronger and higher quality than hot-rolled plate and welded-seam tubing, but don’t want to pay the premium price for 4130 material.

The factory crossmember included mounts for the transmission cooler line, so new mounts were created using pre-stamped steel tabs. The factory weld nuts were transferred to the new tabs. The factory tie-down rings won’t be used for winching, so they were cut off.

To further strengthen the radiator crossmember, it was tied to the forward-most A-arm crossmember. These brackets were built mostly on the bench before they were welded into place on the vehicle.

One challenge to welding on factory frames is that many times they’re painted inside and out. You can clean the paint off of the outside, but there’s still paint on the inside that can get pulled into a weld. When paint gets pulled (by heat) into a weld it creates porosity in the weld. No good! To avoid that problem, rings were made that allowed the tube to be welded to the radiator crossmember without getting paint pulled into the weld. This tube pierces through the radiator crossmember and will eventually tie into the main bumper structure.

The factory bumper bolts to a pair of 1/8-inch plates on the front of the frame. That’s fine for holding a factory bumper in place, but a factory bumper wasn’t designed to hold a winch or withstand the pulling forces that a winch will put into a frame. Since the factory mounts inspired zero confidence, they had to go.

There’s an AC condenser line that was going to crowd the new bumper, so a pair of spacers was made to cheat the bumper a half-inch forward. Two 1/4-inch cold rolled plates were welded together to create the spacers.

Two spacers ready to go. The welder’s ground clamp (AKA “work clamp”) didn’t open far enough to fit around the frame, so it was attached to a bar clamp that did. As always, the battery was disconnected before the welding commenced.

The next step was to put the new crossmember in place. The winch mount and the rest of the bumper’s tubing will bolt to this crossmember. To level the crossmember, I used a jack stand on one side and a factory bottle jack to fine-tune the other side. Since the vehicle wasn’t on perfectly level ground, it didn’t make sense to use a level on the crossmember. Instead, measurements were taken to ensure the crossmember was centered horizontally on the frame and was centered vertically on the front spacers.

Test-fitting the Warn 9.5 XP-S winch was fun. It looked like progress! The approach angle looks good, and the winch tucks nicely under the grille.

The solenoid barely kisses the bottom of the grille. The solenoid will either be lowered slightly or relocated.

The factory plates on the front of the frame aren’t welded all the way around. The outside vertical face features stitch welds. Merely welding the gaps shut was likely to produce porous welds because the paint on the inside of the frame was sure to get pulled into the weld.

The solution was to circumvent the problem by plating over the stitch-welded section. This plate was cut out by hand on a band saw. No band saw? Try the versatile Sawzall.

Here’s the AC line discussed earlier. In addition to spacing the new crossmember forward, clearance was created by carefully tweaking the line rearward. This factory bracket needed to be modified to match.

To modify the bracket, it was cut in half and then the two halves were overlapped. The overlapped section was welded along the outside edges. Rattle-can paint gives a finished look.