Rear shoulder belts in a 1970 Charger

[CoronetDarter]

Some shots of mine

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I've noticed on several of the member's photos that the package tray cover was left in its raw state. I had covered mine in some sort of fabric from Joann's. I like the look of the uncovered cover too. Another decision tree to climb.

 

[furious70]

Andover restraints

 

[Kern Dog]

Some people have precision instruments to measure and fabricate unique parts.
Others like me use tape measures, torpedo levels and caveman logic.
Inside the trunk of this car…

The retractors will mount to the back side of the upper rear seat mounting panel. Since it is sloped back for seat comfort and since the retractors Rich and I are working with prefer to be mounted “close to vertical/plumb/upright”, I’m looking at ways to make mounts to reverse the rearward angle of the seat back panel. The goal is to make a platform that is plumb to attach the retractors.
This bracket illustrates the concept…

When viewed at approximately the angle of the seat back panel…



Suddenly there is a vertical mounting point. Inside the trunk looking forward….

Look close, to the upper left you can see the horizontal slit where the belt passes through.

Note the diagonal brace and where it ends near the package tray. Now the right side.

To the upper right is the seat belt slot but look where the diagonal brace ends. THAT is Chrysler build quality in the 60s!

How much of this mis alignment is due to the drive shaft tunnel offset that our cars have? I never noticed this in these cars before.

 

[Kern Dog]

The strange placement of the upper ends of the diagonal bracing means that the left and right brackets will have to be different. Those braces are important, they provide torsional resistance to the roof moving sideways in relation to the lower section of the car. Up front, the windshield in a small way achieves a similar function. I'm wondering if I could trim back the left side a bit like so:

I could add more welds to the brace to equal the right side...I count 7 spot welds there. If I cut and removed what is above the line, I could add welds below it.
I took a torpedo level (approx 10" long) and held it plumb with the top of it resting on the back side of the trunk/seat back panel. The bottom of the level was approximately 1 1/4" from the panel so I made a quickie cardboard mock up test bracket...

This will be attached to the trunk divider panel back side, likely welded at the side flanges.

The side flanges could be drilled and bolts with nylocks could also be used. I wouldn't want this to rattle loose not only for the safety issue but for the rattles as well.

Knowing I'd need to cut it to fit around the diagonal bracing, I got back into the trunk armed with scissors.

Right side, I'll trim the cardboard back a bit and test fit....

It is very hard to lay in a trunk, hold a flimsy piece of cardboard and get a decent picture with one hand...!
Look at the white cardboard piece. Note the distance the top is from the horizontal slot in the package tray where the belt passes through...

The seat belt sits real close to the edge of the retractor frame so maybe the brackets I'm making need more of a standoff from the trunk divider panel to get the belt in better alignment with the horizontal slot.

 

[furious70]

I might try to crawl into my trunk but the subwoofer is in the way. I just used the flat bracket mine came with and welded several spots to the diagonal brace where it touched.

 

[Kern Dog]

The sloppy placement of the diagonal braces got me thinking. Were other cars as bad?
My red Charger, formally GREEN!

Those look pretty even. Next up, 67 Dart.

Okay, not bad. The Dart did not have slots for shoulder belts though. Now a 72 Duster.

The Duster had shoulder belt slots and the braces were pretty close to even. Finally, a 69 Dart:

The Dart had slots for shoulder belts.

The bracing looks even.
The Jigsaw Charger looks like the braces were installed by a first day apprentice.

 

[DeltaV]

Just weld in a full cage and install 4 sets of SCHROTH harnesses.

 

[Kern Dog]

The non matching angles for the diagonal braces still cracks me up. Was this a Friday car?
Moving on…
This means I can’t just make matching mounting bases for each side. Each will be similar in function but shaped slightly different.
It is obvious that I was not trained in fabrication but I do enjoy it. Starting with the right side, I bent some 16 gauge sheet metal in the vise.

I expected to have to cut the flanges to get them to rest against the flat sections and clear the diagonal brace.

This extension was needed since I want three points of contact for the base mount.

Three self tapping screws just for mock up purposes.

How does it fit?

It lays flat.

The standoff wil align the belt with the slot which is about an inch in from the edge of the package tray. Rich measured the retractor frames and they are 3 3/4” tall. This base mount is 4 3/4”.

 

[Kern Dog]

That right side mounting base was welded and holes were punched so I can plug weld it to the car.

I do need to get the retractors so I can establish the exact mounting position. Rich sent me the measurements so I knew the vertical height these brackets need to be. I'll drill holes and weld a nut on the back side to secure the retractors.

The left side was easy.
The upper corner....

Was cut here so the base would fit and clear.

It was shaped, welded, holes punched and welds ground down.

The lower right corner lays over the diagonal brace.

The left side will be interesting to weld, I'll be reaching around the mount here and between the wheel tub.

Like with the right side, this still needs the retaining nut welded to the back side. Think of it like the hidden nuts that you screw into to retain the steering box. Of course, I'll weld a thick washer to the back side to reinforce the nut.

 

[Kern Dog]

The mounting face of the retractor has a locating peg with the mounting hole below.

Rich tested how far the retractor can be out of plumb before the belt won't roll out.
Straight up and down like this, no problem.

About 10 degrees or so, it was starting to either spin freely or lock.

I put a torpedo level against the mount as I held it in place and found I was 1/8" out of plumb. That is well within the range of operation.
The plan now is to use the left one as a pattern...

I need to make 2 more for the red car. Rich is making a pair for his Coronet and maybe even the Dart.

 

[Kern Dog]

I had an idea about how to replicate these retractor mounting bases. I thought back to the welding class that Rich and I took earlier this year. Part of the in class instruction was a rudimentary summary of reading blueprints to then cut and shape the metal objects that we would weld together. My years in construction came in handy there so it was familiar.

My rudimentary math shows that the trunk divider panel sits at approximately 13 degrees from plumb. To get the retractors to sit vertical, the mounting bases have to be shaped to accommodate that 13 degrees.

I already test fitted the bases I made in a reverse engineering sort of manner. In short, I worked with the lay of the land and just figured it out. Having done that, I made this pattern (out of a grocery shopping bag) that can be laid over the top of a section of sheet metal to then trace the outline and then be bent to the proper shape.

I took the above pattern and traced it to another piece of paper.

It was folded on the lines and taped together.

The traced pattern was then compared to a LH mount.

It is almost identical dimensionally.

I made it with full length flanges that can be cut back for clearance as needed.

This ought to help speed up the process of making these mounts since it skips past the numerous times I had to climb into and out of the trunk.
The degree of the mount may vary slightly on the model of car, the forward rake of the car too. Still, since @CoronetDarter found that these retractors can still work if tilted a few degrees from vertical/plumb, this ought to work for most people.
One potential issue though….

Making all the bends.
Without a sheet metal brake, you’re limited to bending the metal in a vise or by hand with clamps and hand tools, then tuning up the edges on an anvil or vise.

I’m going to try this now… I suspect that making the multiple bends will be difficult without the versatility of a well engineered sheet metal brake with multiple dies. This would necessitate making the mounts in at least two pieces and then welding them together as I did on the prototypes.
More to come…

 

[Kern Dog]

I can only imagine the complexity of an OEM process to make even a simple mount like this. There is probably a stamping fixture that makes all the bends, right? I’m just some dude in my backyard shop trying to make a few of these for myself.

I have a cheap Harbor freight sheet metal brake, a 6 inch vise and an anvil.

I am no expert at this stuff, like other things that I’m unfamiliar with, I try things and if it doesn’t work, I try something else. It seemed like it made sense to make the innermost bends first.

Since the brake is longer than the bend I have to make in between the outer two….

…. I have to find a way to make the 90 degree bend here.

Again, you can see why the brake won’t help here as the section on the right lifts up to bend the metal.

The die hits as I tried to lever it over.

The mount is 4” wide. A 4” vise would work here but this vise is too wide.

 

[Kern Dog]

Just experimenting…

What if I took a stiff piece of metal like this…

Cut it down to fit inside the outer flanges of the mount…

Used it as a die to pry against…

Clamp the mount vertically…

This got me started but the outer flanges hits the body of the vise.

I finished the bend with the duck bill vise grips.

Then tuned it up on the anvil.

The side flanges are supposed to be 3/4” but what really matters is that the bottom section measures 2 1/16” and the top in 1 1/16”.

With such crude tools, I need to hammer the inside to get a cleaner 90 degree bend.

 

[Kern Dog]

Tuned up, welded, grinder work and it is ready for the final step.

Next to the “prototype”…

I can make several of these with full flanges on 3 sides and trim away what interferes with the bracing in the trunk. The flanges can get the holes punched after I know how much flange is retained.

My caveman fabrication skills actually resulted in the newest mount almost exactly the same size and shape.
This tool works as a flange maker and hole punch.

Air powered… it is a great tool.

Put it in place, pull the trigger for a Ka-chunk!

Now I have a hole to plug weld.

 

[CoronetDarter]

Great work. Greg doesn't even have retractors yet, he fabbed the mounting plate face using this photo that I texted him.