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Retrofitting Rear Lap/Shoulder Belts in Older Cars

Original Retractor Lap BeltThose of us who have cars pre-dating the 1990s may have rear seats with lap belts, with no shoulder harness. This is not only a general safety deficiency, but a real problem for those who wish to put an infant or child seat in the back.

Fixed length lap belts, used with a brass clip that comes with the baby seat, can safely secure an infant seat. However, they cannot be used for forward-facing or booster seats, which need a shoulder harness or LATCH system (mandated starting with model-year 2001). Worse, a retractable lap belt, such as the ones in my 1984 Dodge Daytona Turbo Z, cannot be made to fasten any kind of child seat. So for the five years that I've owned this car, my daughter has not been able to ride in it — until now.

In this article, I am using my 1993 Daytona (daily driver) as a reference; Daytonas, like many cars, had lap-shoulder belts added in 1990. For the rear belts, the retractor is mounted halfway up from the floor, behind the side interior panel. The belt is behind the panel, anchors to a bolt and fitting through the hatchback pillar, comes down to the buckle tongue, and the other end of the belt bolts to the floor between the seat and the side wall.

In 1984, there is no welded bracket behind the side panel, so the retractor cannot be mounted there. It has to be mounted either at the floor or at the upper bolt/pivot point. You are not supposed to anchor the retractor and the end of the lap portion of the belt under the same bolt for safety reasons; so you would need three mounting points for a new conventional belt.

I turned to Wesco, a company that makes SAE-rated aftermarket seat belts, for a solution. For the Daytona, they recommended a belt that is typically used in convertibles, which have only two anchor points. The retractor bolts to the hatchback pillar where the pivot anchor normally is, and the lap belt end bolts to the floor where the original lap retractor was. The tongue is different from the factory unit, so the buckle has to be changed out, too.

So I bought a complete belt system (for two seats) with all of the mounting hardware needed, including angle brackets, bolts and pillar mounts, for about $160 with shipping. The belts and buckles look just like factory units, with the same weave and matching color (black).

I began by creating the pivot anchor mounting at the top. Using my 1993 Daytona as a reference, I opened the hatch and measured where the bolt was located, and marked the spot on my 1984. (For reference, it was 5 and 3/4 inches up from the liftgate shocks and 15 and 1/2 inches down from the rubber grommets at the top corners of the hatch.) Then came the leap of faith: I began drilling with a carbide bit from the outside in. There are two layers of metal, and within a minute I had drilled through them and the inside trim. Always wear safety goggles anytime you use power tools, and in this case, a lot of metal particles flew everywhere, especially in the hatch tracks.

NOTE: Do NOT tape the anchor mount in place and drill down through the center of it as a guide - you will damage the bolt threads. Just mark the spot and drill through the pillar.

Having finished that and cleaned out the debris, I tried mounting the retractor. The bolt is a carriage bolt, which means that a portion of it just below the head is unthreaded, and in this case, larger diameter than the threaded portion. What I found was that that added diameter would not fit through the hole I drilled in the interior trim, so the bolt could not reach up enough to engage the threads of the anchor plate. So I hogged out the interior panel slightly with the drill bit. I then found that the bolt hole in the retractor mounting plate was only wide enough for the threads, but not the unthreaded shoulder of the anchor bolt. So I reluctantly hogged out the anchor plate by a couple of millimeters.

I then coated the entire bottom of the anchor plate with Permatex Ultra Black RTV as a weatherseal to the holes that I had drilled, placed the plate and bolted in the retractor. The hatch closed as expected without hitting the tips of the bolts, and looked identical to the 1993 Daytona.

Next step was to remove the old lap retractor and bolt down the end of my new seat belt. To do that, I had to remove, in order, the door sill plate, the latch plate for the rear seat back, and one screw in the panel under the speaker grille. I then pried the lower rear interior panel up and out of the way. It had enough flexibility so that I only had to move it as far back as the rear wheelwell, without having to remove any other panels.

Now the retractor was exposed. I had to pry the black plastic dust cover off it to get clearance for the 13/16 inch socket to reach the mounting bolt. The bolt loosened without any unusual effort, and the old retractor lifted right out.

To install the end of the new belt, I had to use an L bracket that came with the belts, to get the proper orientation of the belt (vertical rather than bolt the end horizontally to the floor). HOWEVER, before bolting it down, make sure to do two very important steps:

  1. Check the twist of the belt a few times to make sure it's facing the right way to deploy and wear with no twists, and
  2. You must feed the end of the belt through the slot in the interior trim panel PRIOR to bolting it down to the floor.

So, I bolted the belt end to the L bracket using the bolt, lockwasher and nut that came with the kit, then bolted the L bracket to the floor using the car's original anchor bolt. I snugged it down tightly. Then the interior panel goes back into place - be sure not to bend it too much and crack anything - and the sill plate goes back on.

Almost done. Now the buckles have to be swapped out, as the new tongue is slightly different. Again, use a 13/16 inch socket to remove the retaining bolt, which is screwed horizontally into part of the seat frame in the center of the car, bolt head under the plastic lip of the buckle case.

As I tried to install the new buckles, the final snag that I hit was that the buckle mount was placed too low against the rear edge of the seat, so that the new buckles and their mounting holes would not line up. The mounting plate on the buckles was larger than the original, and the seat would not compress to accomodate, as the metal frame was right under the cloth. So I had to slide the buckle strap out of the rigid plastic sleeve and discard the sleeve, and rotate the buckle mounting plate enough to get the bolt to feed through into the seat frame. The other option would have been to cut off some of the plate, but that would violate any warranty and possibly make it less safe, so I opted not to do that. The finished installation leaves the buckle strap exposed with no rigid sleeve around it, lying loose like it did in cars before the 1980s, so you will need two hands to engage the buckle. However, its safety should in no way be compromised. Thread the bolt in and snug it securely with the socket wrench, and you're done.

Always follow the belt manufacturer's instructions, and if in doubt, call them for advice, or seek a qualified professional to help with or finish the installation if you run into trouble. The entire job took me about 3 hours to do both sides; the second side was faster once I knew all of the steps.

My daughter had her first ride in the Turbo Z on Memorial Day weekend and loved it. Finally, I can transport the family in all of our vehicles!

The finished product

 

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