Classic Mustang 3-Point Seat Belt Installation Guide

Safety is an important consideration when restoring any classic car without modern safety features. For 1968-1973 Mustangs, one essential upgrade that helps fill in the safety gaps is a 3-point seat belt. Classic Mustangs only came with lap belts, so installing 3-point seat belts will help make your Mustang's interior look better while keeping you much safer in the event of a collision.

In this article, we'll walk you through the step-by-step process of installing a 3-point seat belt in your classic Mustang. Whether you're a seasoned DIY enthusiast or new to automotive projects, our step-by-step guide will help you bolster your Mustang's safety features with a few simple tools.

Classic Mustang 3-Point Seat Belt Installation Instructions

Tools Needed:

• Drill
• Drill Bit Set with 5/16-inch & 1/2-inch bits
• 1/2-inch Box Wrench
• 5/8-inch Box Wrench & Socket
• Socket Wrench & Extension
• Flat Head & Phillips Head Screwdriver
• Blade or Exacto Knife
• Duct Tape

Step 1: Remove Quarter Panel Vent Trim

Unscrew the Phillips-head screws holding the quarter panel vent trim in the interior of your Mustang and remove it from the car. These panels can be flimsy so be careful not to damage them during the removal.

Remove the Mustang windlace just enough to expose the headliner from around the quarter panel and pillar. You do not need to remove all of the windlace.

Step 2: Remove Coat Hooks

Remove the coat hooks attached to the Mustang headliner using a Phillips head screwdriver. Carefully pry the headliner loose with a flat head screwdriver. Once you have an edge of the headliner freed along the pillar, carefully pull it away from the metal.

Be very careful not to damage your headliner. You do not have to remove the headliner all the way around. Only remove it around the pillar area to get to the anchor bolt hole.

Step 3: Locate Factory Anchor Point

Pull up the headliner right above the rear of the door near the pillar and locate the three round holes. The larger, round hole on the right is the factory anchor point bolt hole.

The factory anchor point bolt hole doesn't have a nut on the opposite side, but the seat belt installation kit will provide the hardware to complete the installation.

Step 4: Cut Hole in Headliner

Using a blade, cut a hole through the headliner at the anchor bolt hole location. Make sure you're cutting the hole in the right spot by feeling for the anchor bolt hole through the headliner with your fingers.

Step 5: Remove Seat Belt Washers

Remove the plastic cover from the seat belt as shown below to gain access to the bolt head. Remove both washers from the bolt.

Step 6: Attach Seat Belt Shoulder Bolt to Anchor Point

Push the Mustang front seat belt shoulder bolt through the hole you made in the headliner and into the factory anchor point hole.

It's a really tight fit, so if you can't thread it into the hole by hand, use a 5/8 box wrench or socket to thread the bolt in as shown below.

Step 7: Prepare Seat Belt Locking Nut

Place the locking nut into the 5/8 box wrench and put a piece of duct tape around it to hold it in place.

Step 8: Install Locking Nut

Insert the box wrench into the larger hole in the quarter panel and turn the bolt either by hand or with a socket and extension to tighten. This will take some patience to finally get the nut threaded onto the bolt.

Step 9: Tighten Locking Nut

Leave the box wrench in place and install the plastic seat belt cap to check for fit. Tighten the bolt, but don't tighten it all the way yet. The mechanism will have to swivel a little bit, so don't over-tighten the nut to the point where the assembly doesn't move at all.

Step 10: Determine Retractor Unit Placement

Pull back the carpet and insulation to expose the floor. Measure an inch from the wall and mark the area to drill a mounting hole for the seat belt retractor. When mounted, the retractor will need some swivel room for the arm to move, so keep this in mind when you position the mounting hole.

Step 11: Drill Mounting Hole

Once you have the placement determined, drill a pilot hole with a 5/16-inch drill bit and test the retractor assembly for placement. If you're happy with the placement, use a 1/2-inch drill bit to drill into the pilot hole you previously made.

Step 12: Insert Seat Belt Retractor Into Mounting Hole

Insert the seat belt retractor through the Mustang's carpet and into the mounting hole.

Step 13: Secure the Retractor Unit

Place the supplied anchor washer onto the bolt beneath the floor, then place another washer over it and install a locking nut at the end of the bolt.

Step 14: Locate Buckle End Mounting Point

Locate a mounting point for the buckle end. It will likely be attached behind the seat tunnel if the seats are pushed forward on the track all the way. If your car has had a new rug installed, it may be covering up the holes.

Step 15: Attach Buckle End to Anchor Point

Install the buckle end into the existing factory anchor point with the bolts supplied. These factory anchor points in the tunnel should be threaded, so you can screw in the anchor bolt.

Step 16: Tighten and Cover Supplied Bolts

Place the included plastic cover over the bolt access hole of the buckle end and tighten the bolts.

Repeat all steps on the passenger's side, and your installation is finished.

Upgrade the Rest of Your Classic Mustang's Interior

Installing a 3-point seat belt on your classic Mustang is a simple way to stay safer on the road. A 3-point seat belt is much better at absorbing force than the factory lap belt, which can lessen the forces on your body in a crash.

If you're looking for more ways to upgrade your classic Mustang's interior, there are plenty of options available. From aftermarket seats, to trim, to hardware, check out the button below to shop our wide selection of Mustang interior parts.