bending/notching and other questions

zooper

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Hello all, I am currently building up a isuzu trooper with full size chevy suspension arms. Its very slow going but i think i will actually see it running some day. I plan on making front shock hoops to house coilovers, what type of tubing is needed for this? Also, lets say your faced with a option of either bending a tube or notching it and welding a another tube to it. Which one would theroetically be stronger to all differnt types of stresses, axial, torsional, bending, shear? One more question, what angle should I mount my new arms, I have heard straight up and down keeps the wheel base the same (which is good) but i was thinking bumps dont just effect suspension vertically, there is also a horizontal jolt that the suspension incures, having an the arms angle slightly back torwards the cab might reduse the stresses, what are your guys' thoughts on this? Thanks a ton
Brady

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JrSyko

Jerry Maguire
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Also, what is a "c-notch frame"?

See ya in the dirt!
 

partybarge_pilot

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"Also, what is a "c-notch frame"?"

Where you cut out the bottom of the frame rail over the rear axle for more up travel. When you renforce the area above the cut out it tends to look like a C faceing down.

"One more question, what angle should I mount my new arms,"
Everybody's probiblly got a different opinion on this one. I personally like a little angle to them, About 5DEG.
 

zooper

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I asked the question about bending vs. notching because I was taught that as the stress of a metal icreases, it goes through different stages of strain, first the elastic range, where the metal will not deform, and then yeilding were the limits of safety usually are, then the strain-hardening section where deformation occurs and finally the necking point which is right before metal ruptures. When one bends a tube the stress causes enough strain to bring the metal to the strain hardening section which is well past the .2% yield stress that I was told was not to exceded. Obviousely tube bending works well, I guess I dont understand how the metal withstands extreme stress when it has already been put though a lot of strain.

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Kritter

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Thats why you triangulate in space frames...because you cant heat treat to relieve the plastic deformation that occured due to bending it. Triangulation would not be as necessary if you could heat treat the whole thing.

Kris
"Buy American before it's too late..."
 

ACID_RAIN28

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I was taught(sp) that you anneal any bend in 4130 and when bending seamed tubing that the is to be at the top, so that it is not compressed and not streached. If building shock hoops for a coil over, I recomend 1.5" tubing with .120 wall 4130, just incase.

IF ALL ELSE FAILS.......DROP THE "HAMMER"!
 

Kritter

Krittro Campbell
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Who is to say that it is annelaed properly? Anealing is the correct thing to do with 4130 but most people do not have the abilty to do it right or dont do it at all!

Kris
"Buy American before it's too late..."
 

ACID_RAIN28

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here is the theroy that is thrown around that I know of.
Less than or equal to cherry red on the anneal, I know that that is not an exact temp but when you are making 5 to 6 sets of arms a day it does the trick.

Aneal the parts of the tube that are under stress, ie compress and stretched areas

If it gets past the cherry red it is too hot and created unwanted brittleness

Heat the whole area as a whole not section by section and do it slowly.

And last that I can think of when 4130 is to be welded it should be at about 450F, but I only use that if it is a piece of NICE and THICK.

Am I in the ball park?
there is more but i can't think of it right now

IF ALL ELSE FAILS.......DROP THE "HAMMER"!
 

AZmiik

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Just a thought here have any of you heard of a temple stick. You know the temperature-sensing crayon that is the industry standard for pre and post heating temperatures. That or an infrared temp sensor. I mean les get serious if you want to do the job right you need the tools and the information to get it done.

Mike
 

ntsqd

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Sounds like the question is "Do I bend the the ends of the shock hoops so that they dive into the side of the frame rail or do I weld on short stubs near perpendicular to the hoops and butt the hoops into them ?"
The goals are putting the load where it is best transmitted to the frame rail (no moments introduced) and getting enough bead length so that the stress in the weld is below yield. How you go about this is up to you.

Annealing is not what you want, Normalizing is what you want.

The only way to Normalize (sp ?) is to take it to a heat treater. Anything else is a compromise.
That being said, most dragster chassis are 'Normalized' by using a rosebud around the welded joint. The effectiveness of this is limited completely to the experience and control the person doing the work. Usual color is dull red, not cherry red. Using Tempilaque crayons to indicate the metal's temp is an excellent idea.



TS

I used swerve around my halucinations, now I drive right thru them.
 

ACID_RAIN28

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dull red is what I ment, i usually heat it till it starts to change color, or until color shows.


IF ALL ELSE FAILS.......DROP THE "HAMMER"!
 

zooper

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So to clarify a bit, when a tube is bent, heating it to the correct temp/color will relieve the stress in the tube, is this correct?

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ntsqd

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I'm talking about a welded joint in 4130. Most of the time you wouldn't try to Normalize or Anneal a bend in tubing.

Unless you know the loads and have the ability to properly engineer it or the experience to estimate it, and you have the need to make it absolutely as light as you can, I really don't see any advantage to spending the more money that 4130 will require. Young's Modulus is the same for all steels, so the only thing you're gaining in 4130 is greater tensile strength. Go with 1020 DOM and move past this point.

TS

I used swerve around my halucinations, now I drive right thru them.
 

ACID_RAIN28

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hell build it out of EMT seen that done before and it worked. Don't know how but it did. 4130 is about 2.69 a foot for 120 and 1020 by 095 is about 1.40 a foot, not that much price differance.

IF ALL ELSE FAILS.......DROP THE "HAMMER"!
 
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