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Fabrication 101 Everyone has to start somewhere and for some, theOFN might be that somewhere.

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Old 10-23-2015, 08:59 PM
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88YJ 88YJ is offline
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Rock Crawler Tubing

I'm starting to build a rock crawler from the ground up. I want to go 4 link front and rear but can't decide what size or type of tubing I should use. I've also thought about building a tube frame using the factory frame for a jig. Any ideas, suggestions or comments are welcome! Thanks.
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Old 10-24-2015, 03:21 AM
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johny5 johny5 is offline
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We need way more info , what running gear? How many seats , what diffs ?

I would go and look at other built buggys and take lots of measurements of the style you like .
There will be no advantage to building off a truck frame. It will be too wide and won't kick up enough over the axels.
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Old 10-24-2015, 12:43 PM
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Right now I have a Sterling 10.25 rear axle and am planning on running 5:28 gears with 41 inch tires. I have a 400 csb with a TH 400 tranny. Transfer case is still in the air. The only thing I was using the Jeep frame for is the body mount location for the tub. This is still way early in the build so changes are no problem at this point.
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Old 10-26-2015, 01:49 PM
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2 x 4 x 0.187 Rect-tube in mild steel for the main frame rails maybe 2 x 3 x 0.12 Rect-tube over the kick ups... But a ton more information could easily change those.

E

Edit:
The rect-tube for the frame rails only with the typical round tube for the remainder, I would build with 2" for the main hoops and overhead (A to B) and various smaller for the straight tubes.
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Last edited by entropy; 10-27-2015 at 01:53 PM.
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Old 11-19-2015, 11:23 AM
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RogueFab RogueFab is offline
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I can't actually tell what you are asking about material for. A cage on the stock frame? The suspension links? I see you may be replacing the frame as well.

People usually go stronger than stock. Try to get a measurement on the stock frame in several places. Understand that adding height to the frame will add strength faster than adding width (like taking 2x2 tube and considering going to 2 wide x 3 high or 3 wide by 2 high, the taller profile is stronger). Entropy is right on the money with a good starting point for frame material. I agree.

For links, 2x.250 lowers and 1.75x.250 uppers is a good moderate place to start. If you are going to slam the thing into rocks, go bigger. But it depends on your link length, double the length, double the bending stress with the same load. How long do you think your links might be? 2" OD anything is flimsy on a 60" link. But it is way overkill on a 20" link.

Cage material is nearly always 1.75x.120 DOM. 2.00x.120 is a big step up in strength. Your stock cage (at least on a late TJ) is about 2.125x.120. I think the engineers did that because the stock cage has so little material and triangulation they had to use a crazy beefy material.

Here is a tube strength calculator my company developed: https://www.roguefab.com/calculator.php

It is great for running numbers to find out which materials are stronger and things like that.
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Old 12-14-2016, 11:25 AM
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Quote:
Originally Posted by RogueFab View Post
I can't actually tell what you are asking about material for. A cage on the stock frame? The suspension links? I see you may be replacing the frame as well.

People usually go stronger than stock. Try to get a measurement on the stock frame in several places. Understand that adding height to the frame will add strength faster than adding width (like taking 2x2 tube and considering going to 2 wide x 3 high or 3 wide by 2 high, the taller profile is stronger). Entropy is right on the money with a good starting point for frame material. I agree.

For links, 2x.250 lowers and 1.75x.250 uppers is a good moderate place to start. If you are going to slam the thing into rocks, go bigger. But it depends on your link length, double the length, double the bending stress with the same load. How long do you think your links might be? 2" OD anything is flimsy on a 60" link. But it is way overkill on a 20" link.

Cage material is nearly always 1.75x.120 DOM. 2.00x.120 is a big step up in strength. Your stock cage (at least on a late TJ) is about 2.125x.120. I think the engineers did that because the stock cage has so little material and triangulation they had to use a crazy beefy material.

Here is a tube strength calculator my company developed: https://www.roguefab.com/calculator.php

It is great for running numbers to find out which materials are stronger and things like that.
that's an awesome page.. link changed from the one above though. https://www.roguefab.com/tube-calculator/
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Old 12-16-2016, 03:02 PM
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CarterKraft CarterKraft is offline
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No doubt, bravo for creating that. Not only the calculator but the primer as well.
Very good info.
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