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Installing Late Shoulder Belts in Early (pre-'72 Cars)

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Written by Bob Hildebrand Wednesday, 07 September 2005 Installing Late Shoulder Belts in Early (pre-'72 Cars)

Parts Needed:

  • Set of late Inertial-Style '02 seatbelts (STRONGLY! recommend buying a new set, for say, a 1976 model)
  • Set of eight nuts and bolts (SAE 7/16" / 20tpi bolts and nuts will work just fine)
  • Four pieces of 3/4" x 1/8" flat steel stock about 3" long each
  • Access to a welder

The benefits of installing later-style inertial-reel three-point belts in early cars are obvious once you've lived with the early belts for a while! It is definitely a worthwhile upgrade, but there are a couple of things that may cause you to hesitate: 1) drilling, and 2) welding.

The first thing you need to do is get some late-style seatbelts from a '72 or later car. It is probably worthwhile to get a NEW set of belts, or at least ones that you have checked thoroughly for wear, fraying, signs of stretching. You also will need the metric nuts that will fit the anchor bolts that are stock to the 02. You will need eight of them total, as well as the bolts to go with them (in case the belts didn't come with hardware). [We will be getting exact specs on the hardware ASAP -Ed.] Also, you'll need some flat steel stock approx. 3/4" wide and 1/8" thick, about a foot worth of it which you will cut into four 3" pieces. You'll also need access to a welder. I prefer a 110v wire-feed MIG, which are available for rental or you might enlist a buddy who has one and knows how to use it. MIG welding really isn't that hard, it just takes a little practice and basic knowledge on how to use the machinery.[Watch for an upcoming feature on basic welding techniques! - Ed.]

To get down to it, remove the carpet, front seats, and rear bottom seats from the car. Also remove the black vinyl "fabric" that covers the "B" pillars where you will be mounting the shoulder belt anchors. Measure down from the headliner retaining strip about 6" and mark for drilling along the centerline of the pillar. You may want to individually adjust where you put these if you are an especially large or small person, or even put more than one hole so you can move the anchor from one to the other for some adjustability later on. (It's probably best to make these measurements, etc., before you remove the seats.)

Next, mark the inside rocker/frame rail near the floor, just behind the front seat. Use the new seatbelt retractor as your guide for marking this hole. Try to get it lined up on a vertical plane with the hole you're drilling above in the "B" pillar for the shoulder anchor. At the same time, try to mount it as low to the floor as possible so that it is out of the way of rear-seat passengers as they enter/exit the car.

You are going to have to drill four holes that will be big enough (5/8?) for the metric nuts to pass easily through but smaller than the 3/4 inch steel plates. I used a step bit and drilled progressively larger holes just until the nuts fit through.

Once you've got the holes laid out and drilled, you're going to practice weld. If you're already a decent welder, then you're just going to WELD, but for those who are just learning, this is a great way to get a little practice in before you melt any actual '02 metal. The idea is to weld the metric nuts to the 3/4" x 3" pieces of steel. These will in turn be welded to the various mounting points in the car. If you're wondering why I don't just use 1" stock instead of the 3/4" it's because the 1" would be too noticeable once installed. On my car, the 3/4" is barely detectable. Up until now, I'm the only one who knows it's there!

Before you begin, drill a hole in the center of one of the strips just big enough for the retaining bolts to pass through but leaving enough material to weld with on the flat stock. Secure the nut to the flat stock by tightening a bolt on. This will serve to both clamp and center the nut for the welding. Then, weld away! Make four of them.

Now all that's left to do is weld them to the car. This was the hardest part for me. Welding in an un-stripped car is Very Scary. BEWARE of the plastic FUEL (!) line running next to the pass-side rocker! You can either remove it or just make sure it is sufficiently shielded/covered/ or sent on a nice holiday to The Bench. Take the time to ensure that EVERYTHING is covered/protected. I mean EVERYTHING: windows, floor, any and all plastic, even the windshield! (I have some bizzare pits in mine that I can't account for so maybe it was the welding!)

Go overboard with covering and you'll never regret it. I used cardboard, which worked well for me. [spray with some water!?! - Ed.] The sparks cool pretty much immediately but not so fast that they won't melt the hell out of any uncovered carpet. Don't ask me how I know that.

Naturally you'll want to grind down to bare metal any area to be welded. A clean weld is a strong weld. I started with welding the "B" pillars because they were easier to get to and got me into a rhythm for the rest of the work in the car. Use the big C-clamps to place the anchor bars/plates (whatever you want to call them) with the nuts well centered and sticking into the inside of the pillar itself. This will come close to providing a "flush" appearance once everything is ground clean and covered up.

Welding two different-thickness pieces of metal together is probably one of the most tricky operations. But by playing with the recommended settings on your particular welder, you should be able to get decent results. Remember that at this stage the prettiness isn't as important as the ultimate strength of your anchors. You are going to grind/contour it to make it more flush-appearing anyway, so don't kill yourself trying to get a "perfect bead". Next, do the rockers. Carpet will be covering this area, so just go for the strongest result. CLEAN and rustproof both sets of welded areas with some good rust-killing primer and then paint it.

Now you're done with the scary part! The existing point of attachment down low on the rocker just in front of the rear seat for the original seatbelts works well to attach the fixed end of the new seatbelt assembly. The new point just ahead of that one is for the inertial-locked retractor assembly, and the new mount on the "B" pillar is for the shoulder loop. Be sure that when mounting the retractor that it is as level as possible and very tight so that it works smoothly. I had a 73 and this installation on my 72 appears identical other than the unused point of attachment along the side interior panel in back. Once I replace that with one from a 73 it will look totally stock.

On a final note, be aware that this type of surgery on a perfect original car will probably affect its collector value. Just something to think about if you have a particularly nice original car. That said, I plan on keeping mine and am very happy with the far superior/more convenient seatbelts! If you have any questions, please just post them to the Message Board!

COPYRIGHT 2002, BMW 2002 FAQ, Rob Shisler and Steve Kupper. All Rights Reserved.

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I was wondering the same thing. Actually welding a bolt to the pillar and rocker and use a nut/washer to lock the retractable box at the rocker and the holder for the strap at the pillar...


Wouldn't this work?




David matthew

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