Mustang Torque Box and Axle Tube Welding

    Torque boxes are probably one of the most overlooked problem area on the Ford Mustang. Once you start adding power, better suspension, better tires a lot of pressure is put on these points and eventually they tear and cause even more damage that leads to cost repairs and a sloppy handling vehicle. For those of you that don't know the torque box is the mounting location for the upper and lower rear control arms where they meet the body. From the factory they are spot welded and for a stock Mustang they are fine.

   A variety of manufacturers make torque box kits that add reinforcement to these areas but unless you plan on making over 500RWHP and spending a lot of time at the track you will be fine with having the torque boxes seam welded. The factory spot welds allow the boxes to flex and eventually pull away from the body or tear at the bolt hole mounting locations. When they are seam welded it prevents the box from twisting thus keeping it from tearing. The two pictures below show the locations of the torque boxes and where they should be welded.

    Another area to look at for reinforcement is the axle tubes of the 8.8 rear end. Not so much an issue if you are racing the car at the track but if you are then you should be looking at having this done. A stock 8.8 axle tube is held in by two plugs that locate the tube to the housing. With a lot of hard launches at the track these plugs can give allowing the tube to spin. The tube has the mount for the lower control arm attached to it so if it spins it can throw your tires into the fender well causing severe damage or even worse if it happens further down the line. A way to prevent this is to have your housing welded up.

    The plugs on each axle tube can be welded to the center housing as well as the point where the axle tube meets the axle housing. It's recommended this is done with the housing empty because of the heat created in the welding process. Also make sure that the tube is welded in steps all around the tube not just one big weld all the way around in one sweep. The proper way is to tack weld the top, then the bottom, then the right and finally left side. This will keep the axle tube straight, also some shops have jigs set up to hold the axle tubes straight. Once the tack welds are done the welder will do short beads making sure not to allow the tubes/housing to get too hot. If the welds get too hot it can cause warping, you can burn through the axle tube and it can keep the cast center housing from cracking. Here is a picture showing a welded up axle tube.

Tech article and pictures by Bill Putnam.