Aftermarket seat belts for '58 Speedster.

[Steve Raucher]

356[/img]egistry Magazine Jan./Feb.2011 page 29 near the top.
Where can I find and buy a set of these seatbelts?What should I expect to pay?
They use a hook to clamp shut and have a tan leather piece included.
When you guys put in belts like these,do you do driver only or a pair of like belts?[img]
Thanks,
Steve

[Jim Karaba]

Don't have my issue near by to check but here is what I just did on the speedster I am restoring. Modern safety is taking priority over originality. Bought them from seatbeltpro.com. Made a custom stepped boss to mount both top and seatbelt together. The boss is welded to a stiffener plate to transfer load at the attachment point. Used pre threaded mounting plates welded to the body and inner tunnel along with extra bracing metal to tie into the body structure for the bottom mount points.

[Christopher Wettstein]

Hi Steve, I just ran into the very same issue with a 57' Speedster! I got a set of tan colored belts and they look great! They ran around $250 for lap belts for both seats. I purchased them from Professionally Engineered Products in Los Osos, California. The website is http://www.peparts.com, contact Jesse he is a good guy! You can ask him for a swatch of material to see how it matches up with your interior before ordering a set. They also have "Y" belts and retractables, just talk to Jesse he will steer you in the right direction! Good Luck, Chris W.

[Barry Brisco]

There is a potential issue of spinal compression occurring in an impact if the shoulder belt mounting point is too far below the level of the occupants shoulder. Placing that mounting point near the floor is, in my opinion, very risky.

The problem is that in a stock 356 there is no good location to attach the shoulder belt mount point so that it is at the same level or higher than your shoulder, which is the ideal location. The B pillar in the 356 was not designed for that purpose and in my opinion is too weak to use as a mounting point .

However, placing the shoulder belt mount point just below the back of the rear quarter window so that the mounting bolt is located through the rear inner fender well is a reasonably satisfactory solution, and works in coupes or convertibles. The resulting angle of the shoulder belt is close to horizontal.


See Gordon Maltby's excellent article on installing seat belts in a 356, at http://porsche356registry.org/resources ... r-356.html

Another approach is placing mounts in the engine firewall, like Greg Scallon did in his Speedster. See http://porsche356registry.org/resources ... dster.html

[Chuck House]

Barry,

You are absolutely correct about the risk of spinal compression when anchoring a shoulder strap on the rear floor. I'm not sure if you were referring to Jim's arrangement or not but from his photo you can see that the shoulder strap goes through an anchored guide at shoulder height and therefore is perfectly fine and will not have the spinal compression issue even though the reel is on the floor (the caveat is that all the anchor points are securely fastened).

[Barry Brisco]

Chuck, thanks, and my apologies if my post gave the wrong impression. I would still be concerned about the anchored guide shown in Jim's photo tearing out in the case of a severe accident, which would then cause the shoulder belt to be forced downwards very rapidly.

In contrast, if the shoulder belt mounting point is a far to the rear and as high as possible, even if it comes out during an accident there would be no downward pressure on the spinal column. The shoulder belt would be useless, but it would not potentially cause additional injuries.

Of course there is only so much we can do to make our cars "safe". They have their limitations, and we accept them.

Best regards,

[Chuck House]

Agreed that there is only so much we can do to make a 356 safer and it will never approach a modern car. However, the arrangement of the shoulder restraint on Jim's speedster is similar to most modern cars, i.e. the reel is mounted down low (and usually hidden) and the anchored guide is at or above shoulder height.

[Jon Warshawsky]

The vital questions (literally...) are probably:

1. How much force can that upper attachment point take?

2. How far above the seat do the driver and passenger's shoulders come? I've read that the safe range is 5 degrees below or up to 30 degrees above shoulder height with regard to shoulder strap positioning.

[Barry Brisco]

However, the arrangement of the shoulder restraint on Jim's speedster is similar to most modern cars, i.e. the reel is mounted down low (and usually hidden) and the anchored guide is at or above shoulder height.

Agreed that is the way modern cars are designed, but modern car bodies are engineered so that those attachment points are structurally integrated and far more secure. In a 356, seat belt attachment points are usually just a hole in one layer of sheet metal, and the bolt will probably rip right out in a severe accident (I am not counting on the 3-point belts I installed in my A coupe to protect me in a serious collision: it's unlikely). Even welding in an additional small piece of metal to make two layers for the mounting bolt to go through is nothing like the way modern seat belt attachment points are designed.

So if a shoulder-level anchor guide placed in a 356 just behind the top of the seat detaches in a hard impact the belt will then exert a great deal of force downward on one shoulder of the occupant because it may still be attached at the floor. The chance of serious injury is significant.

A shoulder belt mounting point in the rear seat area and nearly level to the shoulder will produce minimal downward compression if it holds, and no compression if it fails. That is the point I was trying to make.

Best regards,

[Jim Karaba]

However, the arrangement of the shoulder restraint on Jim's speedster is similar to most modern cars, i.e. the reel is mounted down low (and usually hidden) and the anchored guide is at or above shoulder height.

Agreed that is the way modern cars are designed, but modern car bodies are engineered so that those attachment points are structurally integrated and far more secure. In a 356, seat belt attachment points are usually just a hole in one layer of sheet metal, and the bolt will probably rip right out in a severe accident (I am not counting on the 3-point belts I installed in my A coupe to protect me in a serious collision: it's unlikely). Even welding in an additional small piece of metal to make two layers for the mounting bolt to go through is nothing like the way modern seat belt attachment points are designed.

So if a shoulder-level anchor guide placed in a 356 just behind the top of the seat detaches in a hard impact the belt will then exert a great deal of force downward on one shoulder of the occupant because it may still be attached at the floor. The chance of serious injury is significant.

A shoulder belt mounting point in the rear seat area and nearly level to the shoulder will produce minimal downward compression if it holds, and no compression if it fails. That is the point I was trying to make.

Best regards,

In reguards to the B pillar I had stated I made a stiffener plate at that point. It is more than just another layer of sheetmetal. And if that point would fail there is no possible way you would experience rapid downward force on your shoulder because of it. In fact it would be just the opposite. It would be a rapid loosening of the shoulder belt. The only way you would get tightening is if the retracter could immediately retract the belt with enough force to compress your spine. I have thought this setup through and I feel it is just as safe as the rear mounts but look much better, not to mention more convenient. It is also much better than the alternative, NO SEAT BELTS.
JIM

[Jack Staggs]

Barry, that's totally cool that the driver sports a really nice goatee in the coupe diagram. Where did you find that wonderful vintage artwork?

[Barry Brisco]

Jack, it's from the Registry magazine article by Gordon Maltby at http://porsche356registry.org/resources ... r-356.html

Best regards,

[Jim Alton]

Is there something close enough at Aircraft Spruce & Specialty?

Simpson's Latch & Link restrants look very similar. As do Crow Safety Gear's Latch & Link belts.