08-24-2011, 07:29 AM
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#1 |
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Join Date: Jul 2008
Location: piqua, ohio
Posts: 76
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Suspension tubing question
I've noticed that on xtreme Ian always uses two piece tubing setups. He always uses two .120 wall pieces together to make .250. Why would he do this instead of one piece .250 wall tubing? I've seen him do this for both suspension arms and steering arms.
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08-24-2011, 07:57 AM
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#2 |
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I'm not sure why he would do that when he has the choice. Theoretically, it is not as strong because the 2 pieces can flex separately. Think about it like lumber, if you can afford the 4x4, get it rather than sandwiching a couple of 2x4s instead.
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1988 Suzuki Samurai on propane FJ 40 axles (4.10) 5.14 tcase 36" TSL SX |
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08-24-2011, 10:21 AM
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#3 | |
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Join Date: Sep 2008
Posts: 573
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S10 with a few air shocks.. 
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08-24-2011, 12:29 PM
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#4 |
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Join Date: Jul 2008
Location: piqua, ohio
Posts: 76
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Thank you. I was thinking it would be weaker but wasn't sure as I'm new to fabrication.
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08-24-2011, 04:47 PM
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#5 | |
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Join Date: Nov 2010
Location: NE Scott County, KY
Posts: 39
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Well, with wood it is likely different to some extent. For a given type of wood, two 2x4s screwed/nailed together are stronger than one 4x4 alone and will warp, twist, and bend less. I'm not a metalurgy kinda guy and not a chassis builder by a long shot, but the use of twin frame rails, double rail cage hoops, etc is widely practiced. They could have just used larger or thicker tubing, but the effort needed to work that into shape, the cost, and the weight are probably big factors. It's likely why we don't see monster truck frames built with 4" OD .750 tubing. Once upon a time I tried to understand the physics and mathmatics involved with building a TF Dragster chassis so I could grasp why they build them like they do and why some work better than others. It got deep in a hurry so i gave up and said 'it just does and I'm glad for it'. A non-solid frame that can handle that kind of power, flex as a chassis, AND break apart in an accident to save the pilot is an engineering wonder. Definitely one group of engineers that will be allowed to live under my clemency program. |
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08-24-2011, 09:04 PM
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#6 |
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Actually, the mechanics of materials applies no matter what it is. The moment of inertia and section modulus are dependent on the distribution of the material from the centroid.
The exact example that was originally asked about was using 2 pieces of steel and sliding 1 into the other and passing it as equivalent strength as a single piece of steel that has the same OD and wall thickness. With my example, you brought another dynamic into it. When you screw/nail the 2x4's together, you are beginning to create a composite section; much like glu-lam lumber. Screws or nails that connect the sections experience a shear force that is generated along the interface and thereby connect the two pieces into a single composite section. For that situation to apply to the sleeved tubing, it would have to be plug welded in many different spots along the circumference and length so that the 2 pieces act as 1.
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1988 Suzuki Samurai on propane FJ 40 axles (4.10) 5.14 tcase 36" TSL SX |
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08-24-2011, 09:41 PM
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#7 | |
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White ranger guy
Join Date: Nov 2007
Location: Red river gorge,ky
Posts: 274
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91 Ranger ext cab, 60, 14 bolt, 4:88's, 39.5's, doubler, lot's of character
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08-24-2011, 10:23 PM
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#8 |
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Tiny Member
Join Date: Jan 2007
Location: Colerain
Posts: 798
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I have no knowledge whatsoever on this subject ... but I do have access to a couple different engineering software packages.
We have a simple little Excel MOI worksheet that generated a .537 MOI with 2.0x.25 DOM .. It generated .325 MOI on 2.0x.125 and .264 on 1.875x.125... for a total MOI of .589... in theory doubled tube is stronger correct? check this thread out... http://www.pirate4x4.com/forum/showt...+tube+strength |
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08-24-2011, 11:12 PM
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#9 | |
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Join Date: May 2007
Location: cincinnati
Posts: 18
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08-24-2011, 11:14 PM
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#10 | |
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The idea is technically correct, however 1.875 is too big to fit in 2.0x.125. When it is reduced to the 1.75x.125, he combined MOI is equal. This is assuming that the nominal vs actual diameters and wall thickness are exact. Mind you, I am not advocating that sleeving is never worthwhile; I am only saying that it is not a worthwhile effort to go and purchase the tube to make your own when you can buy the product ready-made.
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1988 Suzuki Samurai on propane FJ 40 axles (4.10) 5.14 tcase 36" TSL SX |
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08-24-2011, 11:52 PM
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#11 |
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Join Date: Sep 2008
Posts: 573
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Lot if good info in that thread... Crazy to think 1.75x.12 is stronger than 1.5x.25. That means this 1.75x.12 cage I just finished up is stronger than what I used to use for link bars (1.5x.12).... Learn somethin new everyday... Thanks cw and the pirate crew for doin your homework
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S10 with a few air shocks..
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08-25-2011, 12:27 AM
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#12 |
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Cleaning off the rust...
Join Date: Jan 2007
Location: Cincinnati, OH
Posts: 1,009
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I'm glad that we're keeping this theoretical.... It's a great discussion topic... MOI is a great indicator for bending resistance...
nshefbuch, I'm not sure of when or which projects these were on ("budget builds" vs "unobtanium"), but I'm guessing that Ian (a former teacher) chose to use the materials that represented what the largest cross-section of the Extreme 4x4 audience might have available... Do I believe that Ian's personal buggy has sleeved tube, umm... NEGATIVE.
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brad  5.0L | 435 | 203 | 300 | 4.10 | 39.5 Buildup BACK underway... 
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08-25-2011, 03:54 PM
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#13 | |
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Join Date: Nov 2010
Location: NE Scott County, KY
Posts: 39
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I'd have to go see my neighbor (crane engineer) to give me numbers and such. |
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08-25-2011, 10:36 PM
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#14 |
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pimpin' IS easy
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wow... that's a 5 year old pirate thread, funny.
this is a much argued topic... and people will swear on their lives that their answer is right. use what works for you and what you have on hand or available to you. myself, no sleeving for me. I will only use a solid wall tube. it's stronger. the air gap, no matter how slight, opens the door for failure of the tubing. If you could get a tube to slide into another with ZERO tolerance and gap, then it might be close, but still not as strong. you'd have to have an insane press to get it that tube in there, and the one yer sliding it into would have to have been bored to an exact dimension. Any discrepency would allow for a failure point. Don't buy 2 pieces of tube, just buy one in the size you want and never look back. Then again, I'm no engineer, I just have some real world experience. There's reasons I run .500 wall lowers on my rigs...
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08-25-2011, 11:09 PM
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#15 |
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Join Date: Jul 2008
Location: piqua, ohio
Posts: 76
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wow, i didn't think this thread would be this detailed. i watch xtreme all the time and i actually have learned some things from ian. he just did this on his supension arms for the current buggy he is building on that search and restore project. i've seen him use this method on steering links as well on his own show.
on his blazer solid axle rig he was working i noticed another part i didn't think was safe. on his drag link bar he has it bolting on top of the tie rod bar on the same knuckle(passenger side) using the same long ass bolt. to me it looked like the sheer point on the bolt would be moved to the distal end and from looks looked like it would snap pretty easy. |
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09-02-2011, 08:43 AM
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#16 |
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Join Date: Nov 2008
Location: Pleasant Run Farms (near Fairfield)
Posts: 378
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I think it all has to do with the angle of the dangle............
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Romans 7-8 |
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09-02-2011, 02:22 PM
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#17 |
Join Date: Mar 2008
Posts: 188
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as redriverranger can testify to.... i am lost. tooo many big words for my little brain. now on the other hand, if their were some naked girls in there i might understand a little more..lol
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95 yj, fresh fuel injected 302, c-6, twin sticked 205, 3 linked high pinion d60 front, double trianulated 4 linked 14 bolt rear (all aluminum links) locked both ends, 4:56 gears, full hydro steering, high steer, 4 wheel discs, 16" 2.5 fox air shocks, 39.5" irok's. just finishing a full frame-up redo thanks to a great friend and one knowledgable(sp?) s.o.b casey cravens for without him this could not have been done in such a short time and done right! LOOK OUT "WHITEY" HERE I COME!!! |
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09-05-2011, 05:12 PM
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#18 |
Join Date: Aug 2010
Location: winchester, ky.
Posts: 4
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If Im mounting shocks to rearend i use 2.250 dia. 7075 solid alu. on lowers and if mounting shocks to arms I use 2.250 dia. with .375 wall chromoly tubing and have heat treated for strength. In my opinion in time the steel arms no mater how thick will bend.
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09-05-2011, 06:29 PM
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#19 |
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barely breathing
Join Date: Mar 2008
Location: alexandria, ky
Posts: 889
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Better to bend over time, then have heims pull threads out suddenly.... Imo.
Sent from my LS670 using Tapatalk
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my next rig will be on the trail before zuk 2.0 will 
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