JustMtb44 wrote:
Akpilot wrote:
Well I finished up the nerfs, hopefully with it being aluminum it will bend in before the frame. The lower rear arm that will take most of the hit is at a pretty good angle, the plan is some of the force the nerf takes will bend it backwards and not be transmitted to the frame. I plan to brace across these two mounting points (between seat and gas tank) and also this brace will pickup the skid plate.
Justmtb44, mine is kind of like yours without the cross brace going from the front bend to the back mounting point. Maybe make the brace with a slight bend in it to help it collapse or even thinner material.
Those turned out nice, I like them. The aluminum will definitely bend before the frame, hopefully not too easily.
I got mine almost done this past weekend. I made the cross brace you are talking about out of 0.75" x .049" wall steel tube so it should give fairly easily. Although now that they are built they seem pretty beefy, but I think they will work well. I still need to add one more tube from the front outer corner to the upper outer corner.
Thing is you want the mounts to bend first then if their is still enough energy from the impact you want the nerf tubing to bend next, if its a really bad impact even with the best design you can bend the frame.
Having the tubing straight into the frame removes one or the first absorbing area its like removing the collapsible canister from your autos bumpers and replacing them with a solid pipe.
I guess I need to dig my nerfs out of the attic and take some pictures.
Also look at the OEM Hondaline bumpers they are designed the same way, the first to bend is mounting points or tabs where they attach to the frame then if that does not absorb enough energy then the cheap ass paper thin tubing they use for the actual bumper crushes, when the stock front bumper has a complete failure it tucks under the tub and ends up against the frame usually protecting the plastic from damage.