I was disappointed with the original o-rings that came with the gear... they broke down within a few months just sitting on the build table... I came home from work one day and noticed the cub was slumped to one side... the o-rings had cracked and broken right at the radius where the o-rings bend around the pegs... not sure if its due to ozone in the air, or possibly fuel / oil residue or a combination of the elements.
I didn't like the gear action the o-rings provided anyways, so I went looking for an alternative... tried fuel tubing, but it didn't have enough elasticity... rubber bands worked better, but they suffered with the same problem as the o-rings... one of our flying buddies at our field has a cub with the robart landing gear, and I asked him if he had any issues with the o-rings... he showed me what he uses, which was some 3/16" black woven nylon covered bungee cord he got from the hardware store... he made one bungee per side; made loops at the ends and tied them off with some bail wire... he rapped the bungees around the four pegs starting at one of the lower pegs and then over the peg above; then crossed over to the next lower peg and then up over the top peg ; crossed back over and then terminated the bungee back at the starting peg... it really provides a nice cushion effect with very little tendency to rebound or bounce... because each bungee is one continuous length, as the gear moves and the bungees stretch, they roll around the pegs like pulleys, which provides a fair amount of travel... the woven black nylon helps to keep the elements away from the elastic, and helps eliminate any chaffing as the bungees move around the pegs... its a bit of a fiddle getting the length of the chord right; just have to keep adjusting the length until you get the correct pre-load to support the weight of the aircraft... when its set correctly, it reminds me of the suspension action of some of these RC cars, where you drop them on the ground, and they kinda stick to the ground without bouncing... I like it better than the o-rings... once we got the length of the chord right, we made several sets... my inlaw is still on the first set, which has to be a couple of seasons... and since we have the fishing wire as a strain relief, if the bungees were to break it couldn't drop down on its belly... and as I stated earlier, if you land hard enough to break the 200lb test fishing wire, its really not a normal or even a hard landing; its a controlled crash landing,
John M,