0 Members and 1 Guest are viewing this topic.
Is weight not a factor here...a lighter car will be quicker, more fuel efficient, etc ,etc but that doesn't seem to enter the equation.
Nice post Dre.Someone needs to start arguing Trojans side though, as there is to much common sense prevailing here.Like you Dre, I am working on a design, and I am trying to be very weight conscious on it. It disappoints me that the shock makers give no info for guidance. If we have a two seater (1,200 lbs) with two people in it (1500 lbs total). And it comes down front first, and all of the weight hits on the front. First off all of the load will not be absorbed by the shocks on this landing but quite a bit will go into the suspension mounts. But gestimating that the load went into the shocks it would be 750 per side. Now if we land from 10 ft high and soak up the hit in 20" of travel how may G's are we seeing in decelerating the fall? 4? What does it spike to if the bottom of the shock is hit? 6? 8? If we have 750lbs and design for 5 G's then you have 3750lbs, and if the shock has a 2:1 ratio then it is 7,500 lbs at the shock eye.All of that is no more than guesses, and I am not sure how you would figure it for the real off-road world. As Dre pointed out, strain gauges on an existing known design would be the best option.Should probably start a new thread, but on sheetmetal arms, I was planning to go .062" on the top and .074-.120 on the bottom, possibly jumping size from around the shock mount to the end of the arm.If someone would volunteer the weight of their lower front arm, it would make it much easier to decide how much steel to throw at it.
Someone needs to start arguing Trojans side though, as there is to much common sense prevailing here.
Now...what happens if you don't jump level and it comes down one wheel first? Might try to lay out some calculations on all this, a lot of assumptions will have to be made either way. Is coming down off a jump the worst case, or is it hitting a steep whoop at speed? Or something else?
Thanks Ozpilot! I think you put this one to rest.To your question Dre, I think the worst case senario would be if the shock bottoms. Woop or jump, when it goes solid, the force has to spike IMO. That is the downward force on the shock. I don't know how you would design for something else to fail in that scenario. Now a Witch's eye or a square edge impacting straight on, is going to be altogether different, with its loads going more into rod ends and frame mounts.Another thought, if it comes down one wheel first, then the loads will also be going into frame mounts, not straight down on the shock. There was a video of a car on the front page that landed right on the nose. Also jet's pictures. I don't think that the shocks did much in either case.Wag + safety factor ............ Build then TestWAG=Wild ass guess
I felt like shit :-[