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Discussion Starter #1 (Edited)
Over my years of wheeling and abusing my rigs I have come to learn that there are VAST differences between wheeling styles and chassis strength. I know we all say that we beat on our shit, but for some of us there is a certain plateau of component strength that occurs where you stop breaking mechanical components and start breaking chassis components instead. Many with rockwells know the plateau that I speak of, but there are probably people out there that beat on their hi-dollar 1-tons enough to know what I mean, too. It's that point where you stop talking about how hard you beat your shit and just laugh internally at others who think they are beating theirs.

I have seen many of these types of rigs and drivers over my years and when you reach that point your main concern becomes chassis rigidity and bracketry strength. Lots of people think they have tough chassis, and they probably do. But some you know would never hold up to the kind of abuse I speak of.

When building a chassis to withstand the abuse that I speak of there are generally 3 schools of thought:

1) Build what you are used to and hope it holds up. (Usually dosn't.)

2) Throw enough steel into the chassis to where flaws in design engineering matter less. Often this theory works but results in an excessively heavy chassis.

3) The final (and best, IMO) school of thought is to design a chassis with a lot of thought and engineering so that weight is minimized and strength and rigidity is maximized.

An example of #3 is rare and hard to find, although they do exist and are out there. Moreso than anything else though I think there are a lot of chassis who CLAIM they were built using #3 but I know would NEVER hold up to what I do to my poor chassis.

I will admit that my current chassis was designed using principal #1. Well, for the most part. It was designed with mog axles and it did outlast them. But once I got tired of replacing $750 portal boxes and knuckle assemblies I threw my rocks in there and have been bending/breaking the chassis ever since. In a way, I'm kind of glad because now I know my components hold up. But over time the chassis patch-jobs start adding up and I find myself beginning the planning stages for a new chassis. It would be easy to use #2 but I would like to use prinipal #3 this trip around. I already have learned alot about chassis design just from fixing my breaks and bends. But the goal of this thread is to get a collection of ideas together of little things that engineering can do to save weight and make things stronger.

So if you think you know a trick to make something stronger by adding minimal weight, or you know a better way than the "standard" way, I ask you to kindly post it here. While this thread could easily be a bling-pic-thread, I think there are probably some pretty ugly tricks out there that also work well. Hell, even if you don't HAVE pics, I'd appreciate posting a description anyway!

Thanks!

J. J.
 

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Great topic J.J.

what are you leaning towards box tube frame or round tube frame. the idea that a box tube frame is a good platform to build off but can be extremely heavy in the .25" thickness.

in regards to what you are talking about I would think the box tube frame would be a better candidate but I thought I'd just throw my opinion out there.

I don't beat on my crap hard enough for this realization to come around but it's a topic that I haven't seen discussed before.

-Tristan
 

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Discussion Starter #3
Box tube frame is something I'm in the air about actually. I'd be interested to hear some more opinions on it. I think thinner-than-.25-wall-tube can be designed to be as strong if not stronger than box. But if you lack the know-how to design that way I think box is a good use of principal #2. I've seen both be successful.

J. J.
 

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Discussion Starter #4 (Edited)
A good example of a little trick that I have come to learn is worth its weight in gold is using weld-in spacers for your link bracketry. This allows you to spread the load from say the 3/4" bolt going through it over the space of 1" or even more, thereby allowing you to use overall thinner plate for the bracket. A great real-world application of this is in my upper chassis-side link brackets. When I had my mogs I never had a problemw ith bending the 3/16"-thick brackets. But after I went to rocks they started bending and bowing regularly. I welded the spacers in and haven't had a problem since.

J. J.
 

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Awesome topic, don't have much imput but I will def be watching, I was driving a built wrangler but started to get to the point where I was breaking shit everytime I wheeled. I decided its time to bite the bullet and build a buggy and I am hoping to build it as you described in #3.

I happen to work with CAD and talked to one of the engineers I work with, he hasn't done anything like it before but said he would like to run some computer animated tests on my chassis design once I am done. It may be a while till I finish but I will post the results when done.

Subscribed..........
 

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drill holes, dimpled sheetmetal and like you said weld in spacers so you can use thinner link brackets. also on trusses and boxing in stuff instead of using plate use 1/8" or thinner sheetmetal and drill holes in it. use different diameters of tubing in different area's. 1" for braces or dash pieces. nothing that is going to see abuse. use .095 or thinner for interior stuff.
i've seen people take tubing and cut it in half for the sliders and lower section that will see lots of rock abuse instead of fully sleeving a piece of tubing over it.

im subscribing to this thread. very good topic
 

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I am in the process of building a new rig right now trying to save weight where I can. My plan is to continue to use .120 wall DOM for all load bearing tubes/pillars, .095 wall for the remainder of tubes that could see any chance rock impacts, and .083 wall for all the interior tubes that wont see any rocks or loads.I actually have an engineer comming to my shop this weekend, to help me design all the link mounts for my rockwells. Right now I have 1/4" bracketry and its has held up fine, so the plan is to design a large link mount out of 1/8" with a few dimples in it, than add a second plate that is the same shape but 10-15% smaller welded to it. This will give me a 1/4" bracket in essence, but be considerably lighter. The belly and boat sides on my old buggy were all 3/16" steel, the new one I am going to use either 1/4" alum., or 1/8" alum with a 1/2" layer of U.H.M.W.. I also have planned to switch to an LS-1 from the LT-1 I had, and switch to ouversons super 8 kit and some forged alum. wheels to further drop weight.
 

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It's that point where you stop talking about how hard you beat your shit and just laugh internally at others who think they are beating theirs.

One of the best lines of read on this board in years.


Personally, Bender used the half tube trick on my subrame.

I would never build a cage again without using Chromoly.

Smaller thin wall tube in the non contact areas. Build your rig to 'similar' strengths. My car is light... therefore I could get away with birfs and now 9" chunks. I would have absolutely no use for rockwells on my car and I'm certain that my car would perform worse for it. Same thing goes for using airshocks to save weight on 1 tons. If you're building a heavier car... you need bigger axles, which means more motor and more cage and so on.
 

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I would think drilling and taping for all external panels, floors, roof etc would save some weight over having tabs welded in everywhere but it does take more time. Having a subframe of box tube would make it much easier to mount UHMW to easily by drilling and tapping.

I actually think that using thicker wall tubing in certain areas allows for a longer unsupported span which can end up saving weight in the end. Most of my chassis is .120 wall but the outer rail by my head is .188. Some will call me crazy but it has held up to many rolls much better than .120 did and its a longer span than in my old jeep cage.

If you are able to get your link geometry right the first time then not building any adjustable brackets saves weight.

If you have a rear radiator, using frame tubing to plumb it will save weight over special tubing just for the radiator.

Again a small item but they add up, make it so your 5 point harnesses wrap around tubing rather than having double shear weld in tabs. You have the weight of the metal on the harness, the two tabs on the chassis and the nut and bolt. plus its stronger and safer because the harness strap is wrapped around something that is welded in and has smooth edges that can't tear at the harness material over time.

Finally the weight you do have keep it down low. mount your battery under the floor, have your orbital low and not up in the typical steering wheel area (Jesse Haines had some nice ideas on this for his latest buggy) keep your fuel down low etc etc. I know this isn't the weight of material in the chassis but the chassis design supports and allows for all the items above.
 

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Another thought on the 1/2 sleeve tube on the wear areas is to wait until you see what the wear areas are going to be. Wheel it a year, see the parts of the chassis that is getting ground in or dented and then go back and sleve it.

I see people sleeve large areas of their lower chassis when in hindsight, they could have done the first 4" and have been fine.
 

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Start designing with all the parts that you can not change or make. Once you know where these parts should be, even if you don't draw them, mount them into place, and then design the chassis around the parts.

Design from all viewpoints, how would you design it if it was upside down or on its side, or broken or bent. Do you want to bent it or break it.

Use more than one size of material, change the OD and ID. One size does not fit all.

Use rectangle or box tube and plate, or make your own box out of plate.

If you can weld well then take the time to weld an assembly that is stronger and lighter compared to cutting up some tube and throwing it on there with a couple short welds.

If you just came up with a part design and are ready to cut and weld it on, stop and do something else and then come back to it later, the more time you can give yourself to look at it, you might find a better way.
 

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I can't wait to see how that torchmate sheetmetal frame holds up.
I think that could be the ticket.
 

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Chrom-Moly tubing, TIG welding, heat treating, shot-peening, stress relieving, eliminating stress risers (even by REMOVING material), remember "materials don't have strength, shapes have strength", CAD / FEA, read every book Caroll Smith ever wrote, pay someone to explain how to execute what Mr. Smith wrote, trial & error, remember "materials don't have strength, shapes have strength", good luck!
 

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I can't wait to see how that torchmate sheetmetal frame holds up.
I think that could be the ticket.
It seems to be holding up well, but I don't know that its really much lighter than most sub frames.
 

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When I built my buggy I used a lot of advice from my spotter, Brian Howard. Brian builds top fual dragsters and funny cars. In that sport they do anything they can to save ounces. A lot of the stuff he suggested I second guessed. We used .063 and .049 for some of the tubing and mounts. Nothing on the buggy is thicker than 3/16", its just well gusseted. The only thing that I have had a problem with was the ram mount on the rear axle. The mount bent during a hard roll, and I realized that one more small gusset could have prevented it. Here is the link to that build -

http://www.pirate4x4.com/forum/showthread.php?t=576381&highlight=badlands+2007
 
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