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Post by Self Absorbed Turnip on Oct 25, 2021 19:26:47 GMT -5
I haven't completely talked myself into building this yet but this might as well act as a build log, I guess.
Mrs Turnip has expressed concern about safely driving such a small vehicle in a world filled with distracted SUV drivers. I dug out the SCCA rule book at looked at Section 9.4. ROLL CAGES FOR GT AND PRODUCTION BASED CARS. I'm moderately certain my design meets those standards.
Quick overview:
I'm not fond of purchasing a tube bender for one project so I'll need to find a local fabricator to at least bend the tubes. Not surprising, the guy who fabricated my Spec Miata cage has retired.
The rest of the chassis would be standard square tube 1" x 1" x 16ga like a Locost.
Below are a couple renders of my Thorazine influenced design that I hope you find pleasant to look at. As always, ideas and suggestions are welcome!
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Post by liteway on Oct 26, 2021 14:56:12 GMT -5
So how does that work to connect the front end? Is the front supporting structure then bolted onto this? Not saying this is how it should be done and maybe the way it shouldn't, but here are some images of my frame when I was getting started back in in 2006. i.pinimg.com/originals/d6/97/b4/d697b4fcd8ffb4ea11f1f82bd8578270.jpgi.pinimg.com/originals/a6/37/d5/a637d5039850be93d57210d8158bee12.jpg Mostly .065 x1 1/8. chrome moly. I would not have tried to do such a complex frame without a tubing bender as I initially planed to have much of frame exposed and curves, in my opinion, make for a neater appearance. It wound up around 80 lbs, a little heavy but there are tubes it probably could have done without. Out of ignorance, I mig welded the moly as my first welding project ever. I still use the same technique and material for mods, just because I have had no failures to make me do it the right way. The frame has taken a pretty good beating due to the potholed roads around here and trike's stiff springs. No fractures in 13k miles, but then it only takes one to put the hurt on you. As you have rightfully deduced, mild steel is only smart way to go for us with limited skills and resources. |
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Post by Self Absorbed Turnip on Oct 26, 2021 19:18:36 GMT -5
So how does that work to connect the front end? Is the front supporting structure then bolted onto this? Mostly .065 x1 1/8. chrome moly. I would not have tried to do such a complex frame without a tubing bender as I initially planed to have much of frame exposed and curves, in my opinion, make for a neater appearance. It wound up around 80 lbs, a little heavy but there are tubes it probably could have done without. Out of ignorance, I mig welded the moly as my first welding project ever. I still use the same technique and material for mods, just because I have had no failures to make me do it the right way. The frame has taken a pretty good beating due to the potholed roads around here and trike's stiff springs. No fractures in 13k miles, but then it only takes one to put the hurt on you. As you have rightfully deduced, mild steel is only smart way to go for us with limited skills and resources.
I was planning on welding the 1x1 directly to the roll structure. I've always been told drilling holes in your roll bar is not a good idea.
An exo-skeleton would be really neat but it's beyond my reach. They look real nice in my opinion.
My latest idea is 103 pounds an a few ounces. Hmmm... I suspect there's some tubes that can go away but the roll bar's pretty much a no touch item so I'll have to remove some other tubes. I'm also using this project to learn CAD and so there's a good chance I've told Fusion360 I was working with a different material.
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Post by davej98002 on Oct 27, 2021 0:24:39 GMT -5
Over kill to a certain level is a good thing. But on your seat harness you have to think of what if you do crash, are passed out upside down and on fire. When someone tries to get you free but can not figure out the release, what happens? Everyone knows how to release a seat belt buckle/latch.
Just my opinion here. I'd use a standard inertia seat belt.
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Post by liteway on Oct 27, 2021 8:30:43 GMT -5
I have to disagree Dave, but as you said it is only my opinion. "But on your seat harness you have to think of what if you do crash, are passed out upside down and on fire." A horrifying picture, but fortunately a set of circumstances not near so likely to occur as crashes in general. The possibility of being unconscious post crash can be greatly diminished if you are wearing a good helmet, a huge extra layer of safety in other ways as well.
I sometimes wish I had used an inertia belt strictly as a matter of convenience.
But once under way I appreciate the more secure feeling of a four point which will restrict movement much better in a crash, particularly a rollover. An inertia belt without an auto tensioner may or may not be snug at the instant of a crash. And these home builts have no airbags to supplement the limited effectiveness of a 3 pt in a forward collision.
It's not for nothing many racing sanctioning bodies require 4 or 5 point belts and do not care about bags. I have no data to support it, but IMO You are safer in a four point with no air bags than in a 3 point with bags, let alone a 3 point without bags.
I can agree with you that a little over kill on chassis construction of a home built is not a bad thing.
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