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#805262 - 06/25/10 04:37 AM Adapting 3-Point Shoulder Belts to the Rear Seat  
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TPI Monte SS Offline
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This is a worthwhile upgrade if you have young children that need carseats or booster seats, or just want to make your rear seat passengers safer. I found Beam's Industries (www.seatbeltplanet.com), a company that manufactures and sells aftermarket FMVSS-certified seatbelts to be adapted into older vehicles. I ordered two hardware kits, and two burgundy 3-point retractable seatbelts in their "Nostalgia" line, which look very close to the original GM design except they have a chrome buckle. The burgundy belt is an exact match for the OEM color, but the color on the plastic trim for the buckles and upper anchors are off and will need to be dyed.

All right, lets get down to business - how do we install these? The first step is to remove the rear seat. Push in on the lower cushion near the front to release it from the hooks, then lift it up and out. The upper cushion has two T47 Torx bits holding it in (they're through the outboard seatbelts), so once those are out just lift the upper cushion up to release it from the three hooks across the back, then slide it out. Also remove the buckles, since you need to swap in the new ones - the new latch will not mate with the OEM buckle, so you have to swap them as a pair. If your car has a 3rd brakelight, you'll need to remove it and the bracket as well (held in by two 10mm bolts), then carefully pull the rear package tray out. Once the package tray is removed, you should see two holes on each side -



At this point, you need to open the holes up with a 7/16" drill bit to fit your new hardware - it's just a tiny bit, so be careful.

Next step will be to drill a 7/16" hole in the floor and install the lower bracket for the other end of the belt. I used the depression in the floor as my guide, since it's right near the edge of the seat cushion and the retractor.



And here's how it looks from the bottom -



Here's a shot of the new latch, retractor, and outer mount all mocked up. The belt runs up from the retractor behind the upper seat cushion to the shoulder anchor, then out over the top of the seat and down to the outer floor mount. The retractor gets mounted last, since the bolt that holds it down also holds down the upper seat cushion. I took this shot with the flash off so you can see the color match.



You need a way to distribute the load across the rear deck, and since a washer wont fit, I decided to use a piece of plate steel sandwiched underneath. I had one made from 3/16" steel into a 3"x4" rectangle, and drilled two holes in it to line up with the two holes in the rear deck. I also had to pick up two extra bolts with locknuts and washers because I ran out of supplied hardware.

I ran the extra bolt down through the rear hole (closer to the window) and tightened it up. Now mark the holes in your package tray trim piece and drill the holes for the shoulder anchor bolts to go through it, then re-install the package tray. The shoulder anchor gets bolted in the forward hole, closer to the seat. It has to be this way, otherwise the retractor will not work properly. You can use the sleeve supplied with the hardware to make up space between the trim and the steel deck underneath, then bolt down the upper anchor. Here's a shot from inside the trunk of the steel plate and the two bolts -



Once the upper anchors are tightened, you can install the upper seat cushion and retractors, and then the lower cushion. At this point, you're pretty much done, except for some details. The trim caps I mentioned before have to be dyed, so here they are after 3 coats of Duplicolor Adhesion Promoter and 3 coats of Mike's Montes dye -



OK, we're done! Here's how the upper shoulder anchor looks with the trim piece installed - again, sorry for the flash, but you get the idea.



And here's a shot with the belt latched -



Now remember, this is a custom install, and it's a safety item, so use this as a guideline. Please make sure to read ALL supplied instructions, tighten ALL hardware and be careful. Hope this helps!!


SSeeya,
Steve Ragusa - North Jersey
'88 SS - BudgetTourer - ZZ4-cammed 355 TPI, serpentine belt conversion, World Class 5-speed, 17" wheels, 12" front discs, Eibachs/Bilsteins, 1LE lower A-arms, tall lower balljoints, 34mm front swaybar, 3/4" straight rear bar, Celebrity headlights, and more. Sold on 2/28/11.
#805318 - 06/25/10 12:13 PM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: TPI Monte SS]  
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Tony_SS Offline
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Awesome writeup.. I'll be doing this soon. Thanks Steve.

#907977 - 12/12/11 08:04 PM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: Tony_SS]  
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345HP87SSAC Offline
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That looks much easier than the way I did it. Do these retract or are they fixed?


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New BTR Stage 4 cam makes 449 HP and 380 TQ TQ at the wheels. 6.0 LY6 VVT and 4L85E!blackgoldaero http://www.cardomain.com/ride/671193
#908315 - 12/15/11 12:14 AM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: 345HP87SSAC]  
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TPI Monte SS Offline
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Originally Posted By: 345HP87SSAC
That looks much easier than the way I did it. Do these retract or are they fixed?


They retract - the belt reel is located on the floor in the factory spot, and runs up behind the seat cushion to the shoulder hook and over. They retract a little slow because they're behind the seat, but they worked great.


SSeeya,
Steve Ragusa - North Jersey
'88 SS - BudgetTourer - ZZ4-cammed 355 TPI, serpentine belt conversion, World Class 5-speed, 17" wheels, 12" front discs, Eibachs/Bilsteins, 1LE lower A-arms, tall lower balljoints, 34mm front swaybar, 3/4" straight rear bar, Celebrity headlights, and more. Sold on 2/28/11.
#908377 - 12/15/11 03:05 PM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: TPI Monte SS]  
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345HP87SSAC Offline
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After I posted I saw the box, but I could not erase my last post. Your way was much easier than mine. I put the bos in the package shelf. Huge PITA.


[Linked Image]
New BTR Stage 4 cam makes 449 HP and 380 TQ TQ at the wheels. 6.0 LY6 VVT and 4L85E!blackgoldaero http://www.cardomain.com/ride/671193
#908535 - 12/16/11 05:22 PM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: 345HP87SSAC]  
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tonys57chevy Offline
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did you use grade 8 bolts?


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#908562 - 12/16/11 09:14 PM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: tonys57chevy]  
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TPI Monte SS Offline
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Originally Posted By: tonys57chevy
did you use grade 8 bolts?


I used the supplied hardware, which I assume they used in their FMVSS testing. I believe it's Grade 5 - it had the three marks in the shape of a Y on top.


SSeeya,
Steve Ragusa - North Jersey
'88 SS - BudgetTourer - ZZ4-cammed 355 TPI, serpentine belt conversion, World Class 5-speed, 17" wheels, 12" front discs, Eibachs/Bilsteins, 1LE lower A-arms, tall lower balljoints, 34mm front swaybar, 3/4" straight rear bar, Celebrity headlights, and more. Sold on 2/28/11.
#991536 - 12/30/13 08:46 PM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: TPI Monte SS]  
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olsey Offline
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You used the 140" retractable web length, right?

Not the 110" length?

Thanks

#1005098 - 06/16/14 04:01 PM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: TPI Monte SS]  
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Wakeman Offline
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This is great. My girls are starting to come on cruises with me and the rear bench lap belts aren't cutting it for me from the safety point of view.

#1031832 - 11/09/15 02:04 AM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: TPI Monte SS]  
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Is is a great write up. I wish GM would have done this at the factory.

#1032370 - 11/23/15 08:36 PM Re: Adapting 3-Point Shoulder Belts to the Rear Seat [Re: olsey]  
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Originally Posted By: olsey
You used the 140" retractable web length, right?

Not the 110" length?

Thanks


Each length web then also has options for 8" black sleeve, 12" sleeve, or 20" fixed. What did you pick?


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