Seatbelts in a Gullwing are a must
What’s the best method to install?
Photos from Hahn and Woodward Auto Restoration
Safety considerations when mounting 300SL Gullwing or Roadster seat belts
As we’ve mentioned in previous articles, the 300SL Gullwings and Roadsters were born out of a racing heritage. Their tubular frames and alloy components make for a nimble, light weight machine. We’ve already discussed ways to mitigate the heat transferred by the aluminum floorpan, but there is another important consideration that must be made related to the floorpans…..the Seat belt Mountings.
We have seen several cars come into the shop with the seatbelts mounted through the aluminum floorpan and secured with a flat washer and a nut. This arrangement is dangerous as it is unlikely to hold together in an accident. There is a significant chance the bolt will tear through the floorpan…and the result will not be pleasant for the individual in that seat.
This floor-pan photo illustrates how thin the aluminum is. Considering it is over 50 years old and has been subjected to the stress of regular road use, seat belts mounted to the pan alone could easily fail in a moderate accident.
In a 30 mph crash, a 160 Lb. driver will strain the seatbelt mounting with a force of 2.4 tons. It is easy to see why the floorpan may not be up to task. Obviously, higher speeds or greater occupant weight will increase the amount of force.
During our restorations, we always take the extra step to address the seat belt mounting points. There are several options for doing this. These include welding a steel mounting plate to the tubular frame or adding an aluminum plate to the bottom of the floorpan to increase the mounting surface area then securing a piece of aircraft cable to the bolt. The aircraft cable is then anchored to the frame. In the event the floorpan gives way, the cable will anchor the seat belt.
Here is a typical anchor cable that can be used to secure the seat belt mounting hardware to the tubular frame of your 300SL Gullwing or Roadster.
In all cases we utilize grade 8 hardware for strength and durability. We also strongly recommend nyloc nuts for added security. Another important consideration is having the seat belts themselves re-webbed. There are several companies that specialize in seat belt restoration and the end result is well worth the price. Your car will look great and you will enjoy piece of mind knowing you’ve taken steps to make the vehicle as safe as possible should the worst happen.
Talk with your restoration shop about these options as well as other ways you can make the ride of your dreams safe for you and your loved ones. If you have any questions about the enhancements we’ve suggested, please feel free to contact us at info@hahnandwoodward.com
Paul Vorbach
Hahn and Woodward Auto Restoration
404 Yellow Creek Rd.
Harmony, PA 16037
724-865-9684
Comment on this Article