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- 1989 RX-7 GXL Blaze Red
No recent progress what so ever. All of the guys are out on a job so, nothing new.
Drag Truck Build Thread
- Thread starter Cleverfrog
- Start date
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- 1989 RX-7 GXL Blaze Red
I'm starting to lay out plastic windows for this bad boy. I'm also in charge of designing the dash for it. All aluminum with minimal gauge ports.
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- aggressive auto culture
That rear back half scares me.
Otherwise pretty beast
Otherwise pretty beast
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- 1989 RX-7 GXL Blaze Red
Right? The roll cage should relieve any uneasy feelings. It will brace the entire chassis.
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- 1989 RX-7 GXL Blaze Red
Some roll cage pics. I can tell you that there is no way I'm getting in that truck now. I'm pretty sure the bends will not clear inspection.
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- 1989 RX-7 GXL Blaze Red
Not finished yet.
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- 1989 RX-7 GXL Blaze Red
Honestly I've given up on trying to advise/ help them with this project. More stubborn than a mule. I know there are creases in some of the "mandrel" bends and that it will not pass any inspection with those. I'm just documenting now.
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- 1989 RX-7 GXL Blaze Red
I mean I have faith that my boss will tell the guy that bent them to redo it but still. I can tell you that that chromoly tubing isn't cheap that's for sure. (yes I used two thats)
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- aggressive auto culture
Sounds like they used a pipe bender, not a tube bender. Also, mandrel bent is typically done with pipe, not tube. Pipe caries fluid or gas and is not structural, tube is.
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- 1989 RX-7 GXL Blaze Red
Not sure what you're on about here
For some tube bending processing, a mandrel is placed inside the tube to prevent collapsing
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- aggressive auto culture
the equipment & tooling required to mandrel bend tubing is very expensive. if they told you it was mandrel bent, there more than.likely blowing smoke up your ass. You don't see a mandrel bent cage, you'll see a mandrel bent exhaust.
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- 1989 RX-7 GXL Blaze Red
My bad. (facepalm)
I've made some pretty nice bends in 4130 tubing with regular die bender (no mandrel) for FSAE space-frames. It is silly to use CroMoly for a regular cage because of the expense and fabrication difficulties (bending, cutting, and welding) where the strength and small weight savings is not needed.
Le sigh.
Le sigh.
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- 1989 RX-7 GXL Blaze Red
You realize it's 4130 Chromoly tubing right?
Yup, thus my comment on non-mandrel bends being just fine and disapproval of its use in a roll cage. I have written a WPS (welding procedure specification) for, and been AWS and ASME certified in, 4130 space-frame TIG welding and I wouldn't use it in a cage.
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- 1989 RX-7 GXL Blaze Red
It's in their rule book to use specific OD's of 4130 chromoly tubing for the cage.
Yep. And there's a mild steel specification too I'd bet. Mild steel can be MIG welded effectively, 4130 should be TIG'd. Mild steel has a lower carbon content, making it far less prone to cracking. In terms of crash safety the added strength doesn't buy you anything. In terms of chassis stiffness they will be the same; or better if the rules spec a thicker mild steel sidewall.
