While seat upholstery gets cleaned, vinyl dashes and door panels get scrubbed, and carpets get shampooed, most folks forget about (or ignore) the lowly seat belt and shoulder harness. With a small amount of elbow grease and a few common cleaners, you can make the seat belt and shoulder harness assemblies gleam like new.
This photo shows the buckle "before." Compare this to the clean buckle above. In order to get there, the buckles have to be removed from the belts.
Strip The Parts First, the belts and harnesses have to be stripped. To remove the buckles, turn them upside-down on a soft surface such as a rolled up terry towel. Next, a couple of thin gasket or paint scrapers must be inserted into each side of the buckle. This photo shows how two gasket (paint) scrapers are inserted in the sides of the buckle cover to release the mount tabs. By carefully sliding the scrapers in place, you'll release the side attachment clips for the cover.
Then insert a large flat blade screwdriver into the latch slot in the face of the buckle.
With the pair of scrapers wedged along each side, slowly (with the screwdriver positioned steel-on-steel; don't allow it to touch the plastic), rotate the screwdriver in the latch slot (maintaining steel on steel, rolling the latch off). The plastic buckle cover will release, and the buttons will simply pop off. Repeat with the entire selection of buckle assembles, and remove anything else such as plastic covers. Set all the hardware (fasteners, buckles, covers and so on) aside.
At this point, the webbing can be removed from the buckle. These two photos show the orientation. Note the way the webbing is positioned. The belts have to be reassembled in the same way.
Wash and Wear Next up, clean the bare belts and harnesses (keeping in mind you cannot remove anything sewn in place). Prepare a 5-gallon wash bucket with hot water and a splash of common biodegradable automotive degreaser. Use a mix of approximately 25:1 (12 fluid ounces of degreaser to 2.5 gallons of water). For belts that are heavily soiled, you might have to use a bit stronger mix. With the belts completely submerged in the water/degreaser mix, simply stir occasionally and allow the cleaner to work. Continue this for a couple of hours. Rinse the belts with cold tap water then "recharge" the bucket with another mix of hot water and degreaser. Continue rinsing the belts until the water in the bucket comes out clean. String the belts out on a section of steel doweling and drape them out in front of a simple house fan to dry.
Here's a look at three belts ready to go into our cleaning solution mix. It's impossible to remove the latches. We tossed them into the cleaner assembled and they too came out spotless (keeping in mind we soaked them for several hours in the solution).
Polishing and Detailing
While the seat belts are drying, you can turn your attention to the buckles and covers. The basic buckles (the steel parts) can be detailed with good quality chrome cleaner. If there is any corrosion, a bit of polishing with fine (0000) steel wool will cure it. Buff and you're done.
The plastic buckle covers are just as easy to detail. Simply wet-sand the scratches with 2,000-grit sandpaper mounted on a rubber-sanding block. Just like automotive paint, use a mix of household liquid dish soap and water as a lubricant. Be sure to flood the cover with the soapy water mix, as you're wet sanding. (If you soak the sandpaper overnight in a tray of soap and water, it works better.) Next, hand-polish the covers with a good plastic polish. Finally, apply a light coat of automotive paint swirl remover on the buckle bodies and buff with a (damp) soft synthetic pad mounted on a variable speed buffer (turned to low). The buffer can be clamped upside-down in a shop vice using a couple pieces of plywood on each side of the buffer to keep the vise jaws from destroying the buffer.
The buckle covers were wet sanded first (2,000 grit) then hand-polished and finally machine buffed.
This photo shows how the variable speed polisher was clamped in our bench vise. We used a soft synthetic pad (damp) for the final swirl remover polish job.
Finally, once the belts are completely dry, reassemble the works in the reverse order of the way they were taken apart. The seat belt material wraps around the buckle (see the photo), and the covers and actuator button simply snap into place. Clean the associated mount hardware and plastic trim separately.
Figure a couple of days to complete the job (taking drying time into consideration). You might be surprised at how good the belts turn out!