Maximum Motorsports Sub Frame Connectors Full Length Set Mustang 1979-2004

Maximum Motorsports:
99% of 100


  • Tap To View 3D Model
  • Full Length Weld On Connectors
  • 95% Stiffer Than Bolt Ons
  • Made Of 1.5"X2" .083" Tubing

Set of Maximum Motorsports Full Length Subframe Connectors for 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 and 2004 Mustangs.

If you own a 1979-2004 Mustang then you need to consider strengthening the unibody with a set of Maximum Motorsports Full Length Subframe Connectors (MMFL-5B-FULL) from CJ Pony Parts! The Maximum Motorsports (MM) weld-on subframe connectors improve handling and ride quality by reducing chassis flex. 

This helps to keep the forces caused by road irregularities in the suspension, rather than being absorbed by the flexing of the unibody. This results in a Mustang that will be much more dampened and controlled over rough roads, eliminating the shaking and shuddering that is characteristic of stock Mustangs.

Maximum Motorsports subframe connectors include seat braces that attach to two of the four front seat mounting bolts. This prevents the chronic tearing of the Mustang's sheet metal floor pan at the rearward seat mounts. The subframe connectors do not hang any lower than the lowest part of the car, which is the exhaust system. 

Features and Benefits:
- 95% Stiffer than Standard Subframe Connectors 
- High Strength 
- More Weld Area than Other Connectors 
- Made of 1.5" x 2" x .083" Wall Thickness Rectangular Tubing
- Original Full-Length Design

Don't let claims of easy installation entice you into buying bolt-on subframe connectors! The Mustang's unibody lacks the structure needed to allow the bolts to be tightened properly. The ideal way to distribute loads across the unibody and prevent chassis flex is to weld subframe connectors to the bottom of the car's front and rear subframes, connecting them together. These subframe connectors extend from the rear lower control arm attachment point on the rear subframe all the way up to the firewall, providing substantially more weld area than other connectors.

MM subframe connectors are strong enough that you can lift the car by placing a jack anywhere along the length of the connector tube! Maximum Motorsports created the first full-length subframe connectors; beware of imitators who attempt to copy the original innovative design!

Please Note: 1996-1998 Cobras must notch the transmission crossmember at the frame rails so that the subframe connectors can sit flush on the frame rails.

California Residents: Proposition 65 Warning

Installation Difficulty


Advanced skill is required for this installation.

Installation Videos

Video Transcript

We all know that 1979 through 2004 Mustangs, like this Notchback behind me, make excellent drag cars, but if you're serious about racing your car, you definitely have to worry about stiffening up the chassis. From the factory, the Mustang is a unibody chassis, meaning you have a front subframe and a rear subframe that are tied together by the floors and rockers which isn't particularly stiff from the factory. The first step in stiffening up the chassis is to install a set of subframe connectors that will tie the front subframe and rear subframe together, and make it almost like a solid frame vehicle.

Today we're going to show you how to install Maximum Motorsports subframe connectors using this 1987 Mustang Notchback.

There's several different options when it comes to subframe connectors. First of all, you've got two styles. You've got a weld-on subframe connector and a bolt-on subframe connector. The bolt-on ones will work and will help. In my opinion, the only one that's really going to make a huge difference in the chassis is to go with the weld-on one, which is what these Maximum Motorsports ones are.

There's also two different versions of weld-on. There's a shorty style and there's the full length one. These again are the full length, which again in my opinion is going to be your best choice for your Mustang. These are going to go from the front frame rail all the way back to your rear torque box and are going to weld in, and they include braces for your seats. I've installed these in several cars over the years, and they definitely make a difference in the overall chassis feel and make the car feel a lot stiffer.

A couple of words of caution before you begin this installation. It does require welding. If you're not comfortable welding or not a decent welder, leave this one to a professional because if the welds are not done properly, you're going to have a problem with the subframe connectors. The other part is going to be set-up. A drive-on lift is going to be ideal for this installation. Not everybody has one. We obviously don't have one in our shop. If not, make sure the car is supported by the suspension. You don't want to have it on the body. You want it on the suspension itself, and load the suspension like the car would be on the ground. That's going to give you the best installation. When the car is up, make sure the doors open and close smoothly like they're supposed to, and you know you have it supported properly, and you can begin your installation.

For this installation, get a lift and pole jack or a jack and jack stands, 3/8” ratchet, 15 mm socket, 17 mm socket, 17 mm wrench, marker, grinder, welder, and safety glasses.

Once you get the car up in the air, before you begin the installation, you want to make sure you have room and clearance for everything for the subframe connector. It's going to go from the torque box here on the rear frame rail all the way to the front of this floor support to the front frame rail, so make sure there's nothing in the way. In the case of our car, it does have a fuel system on it. We were able to move the fuel lines so they can go underneath the subframe connector and will be okay for clearance. The other thing you want to check is this front floor support here. Make sure it's not overly damaged. A lot of cars get jacked up over the years on this, and it can get bent. As long as it's reasonably straight, you'll be able to weld it and install your subframe connectors.

At the beginning of the installation, you'll want to put the subframe connector up into place and get an idea of where we want to grind before we can weld it. The subframe connector looking down on it with the stud sticking up like this and the flanges up, the flange on the front here goes on the outside of the frame rail. That's how you determine the driver's side versus the passenger side.

To install these, you want to make sure you test fit both sides before you cut, weld, or grind to make sure they're going to work. Once you have it fitted, I'm going to be able to mark off the areas here to remind myself where I'm going to grind so we can weld. We'll make some marks in the general area so we remember.

Now we're just about ready to start installing the subframe connectors. Before you do so though, you want to coat the top with either a zinc spray or some sort of a weld-through primer. Once they're on the car, you won't be able to paint this part, and you don't want it rusting in the future.

Okay, with them painted and ground down, now we're going to put it back up into place. Once the subframe is fitted, before you weld it, make sure you install the seat braces first. You can install them after, but it's easier to do it now. What you're going to do is put it over the subframe and put it over the studs to the back of the seat bolts and just leave that there. It will be the last thing we actually weld once we weld the subframe connector on.

Now we're going to start the welding process. You don't have to weld the entire thing. You want to focus on these tabs. Weld the edges of this, the edge of this tab here, and then also this front lip right here on both sides.

We'll do the inside here as well. The inside's not as important. There is no tab here, but you're going to have a little bit of a gap, so you want to kind of fill it up and just put some seams in here as well. Next we're going to move on to the rear part. The rear has no tabs, so here we're just going to put some seams up against the frame rail.

Now that we're done welding the subframe connector, we're ready to weld the seat brace. Before we do that, we're going to remove the factory hardware and replace it with the hardware provided by Maximum Motorsports. We'll install the new hardware, which will thread in just like the original. Now we're going to install the nuts underneath through the brace. Now that everything's bolted in, we're ready to weld the seat brace. We're going to weld the edge here and the edge on the inside as well.

The last step of the welding process is this little plate here. Where this is going to go, if you look at the subframe, it has a little indentation right here. This is going to go right over the indentation, and just basically makes it smooth. This part, if you're not using them by now, you definitely want to have a glove of some sort to hold it, and then you'll put a couple of tacks to hold it in place and weld it on.

Once everything's welded into place, you're going to want to go back through and prime it and then paint it, the reason being that the subframe connectors themselves were bare steel. We also ground down the bare steel to weld, so we want to make sure the surfaces are primed and painted, or they're going to rust. I'm going to repeat the process on the other side, and your installation's finished.

Even if your Mustang is just a daily driver, these Maximum Motorsports full length subframe connectors are an excellent idea, and if you have a race car, they're going to be a must-have. They're going to stiffen up the chassis and make the suspension overall work a lot of better. As far as installation, figure between three to five hours depending on skill ability. You'll be back on the road in no time.

Vehicle Fitment

This product will fit the following Mustang years:

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