There is a common belief that a synthetic rope eye termination should possess a diameter D/d ratio in the 6-8 range. Most synthetic winch ropes come with metal thimbles providing this ratio when new. The trouble is that the metal thimbles eventually yield and collapse onto the retaining pin, thus reducing the D/d ratio considerably. Is this so bad? What happens to synthetic rope strength when the D/d ratio is reduced? Luckily for us off roaders, many technical papers have been written on this by rope manufacturers and cordage experts and corresponding tests have been completed. Even when a single leg rope eye is pulled against a D/d of 1 (3/8 rope eye pulled against a 3/8 pin), the rope still retains almost all of its original strength. Why is this? Its because you have the load of the pin being carried by two legs of the rope, similar to basket loading a synthetic sling. In fact, the testing standard for pull testing synthetic rope single legs is to use a shear pin. So what's the bottom line, and what does this mean to us off roaders? It means that if your rope retaining pin is smooth, and at least as big as the rope diameter or greater, you can run a soft thimble-less eye on the end of your rope and lose little to no breaking strength. We just released a rope spools with a D/d ratio of 2.6 for those who would like to run soft eyes on the Factor 55 products.
Boise, Idaho-based Factor 55 is an engineering design firm focused on mechanical design and analysis, which translates to parts and accessories like winch shackle mounts, fairleads, locks and receiver hitch D-ring mounts for off-roaders. Some of their more popular products lines for Jeeps include ProLink, FlatLink and HitchLink and they manufacture soft and Crosby shackles. Destructive tests are performed on every design produced to ensure they pass muster and will be capable of excelling out on the trail or on the highway. The Prolink shackle mount for winch cables and synthetic ropes can be a vital component to keeping your Jeep's winch operating smoothly and efficiently. Shop Factor 55 Now