Welding 4130 chromoley tubing ??

[Highbanked Hauler]

 Can you weld it with a mig or does it need to be tig welded ? Up coming idea so I ask..

[Dans 68]

It is possible, but why? You really do need post weld heat treating to make it safe. Lots of information out there on doing this. http://www.netwelding.com/Heat_Treated_4130.htm

Dan

[Highbanked Hauler]

It is possible, but why? You really do need post weld heat treating to make it safe. Lots of information out there on doing this. http://www.netwelding.com/Heat_Treated_4130.htm

Dan

Thanks,will explain further shortly.

[Mike DC]

        
The bicycle frame industry TIG welds everything.          

The NHRA says TIG is the only safe way and MIG or oxy/acet is unsafe.  

The NASCAR world isn't supposed to use 4130 but they seem to use MIG welds when they do anyway.

The aircraft world cares a lot about structural failures and they allow oxy/acet welding only.  

The desert/4x4 world, and many industrial companies (like Boeing, Lockheed, NASA, etc), are known to do all 3 methods at various times.  

Some sources say post-weld heat treating is mandatory.  Others say it ruins things.  

Some say do the heat-treating with a torch.  Others say the whole item must be oven-baked or you'll do more harm than good.

Some say any kind of heat-treating will neuter the metal's original stiffening and renders it basically mild steel again.  Other say that's true but the weld isn't safe if you don't do it anyway.  

Some point out that that oxy/acet welding leaves the welded area in the same state as post-weld heat treatments.




The world is packed full of strong opinions about 4130.  But there is no agreement.


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My worthless uninformed BS opinion:  It probably depends on the circumstances.  


A bicycle frame is thin-walled tubing and it easily wicks away the welding heat.  Welding thicker steel would produce narrower (read: more brittle/fragile) heat-affected-zones.  

An airframe is triangulated as heck and it wouldn't hurt if the welds came out 'softer' than the tubing started off.  The softening effect of oxy/acet could be a bigger problem for something without that kind of triangulation.  

It's been suggested that the NHRA demanded TIG welding on rollcages (decades ago) mainly to force people to get thin-walled cages welded by professionals.  TIG machines were rarer & more expensive back then.  

Etc.

[Highbanked Hauler]

 Hey thanks it sounds like a matter of opinion..    WHAT I am considering doing is lengthening a set of tubular upper control arms by at least 1.5 in. to get back to a 0 camber situation. I have drop spindles but can't take advantage of them.  The best we could get is a  - 1.75 camber and  it is starting to chafe  the inside tread on both side tires as it is dragging the inside wheel in a turn plus I can hear and feel it in the wheel.  I lengthened a set of stock uppers and never had a problem in 18 years but bent the right side doing laps at Charlotte on track day. It laid the weight of the car on the right front So I figured I would upgrade to tubular arms but they are to short..

[Mike DC]

 
Adding 1.5 inches?  Are you sure they need that much?  That sounds enormous.  I guess the drop spindles can take the geometry pretty far away from stock stuff.


The job sounds do-able to me.  But this is the wrong situation to try to save weight.  I would vote to load it up with reinforcement.  I would MIG weld it (just my amateur opinion).  

Get a pair of arms with curved "legs" that go parallel near the chassis end, to provide a decent area to splice things.  Splice on some longer tube sections.  Sleeve them with another piece of tubing around the whole welded area.  Have some holes drilled in the sleeve before it goes on, for adding a few plug-welds.  Etc.  

Does that make sense?  

[Mike DC]

 
BTW - if the drop spindles are taking the geometry that far out of whack, maybe drop spindles aren't the answer here.  Maybe you should be modifying a set of LOWER control arms to allow more up-travel with the stock spindles & upper arms. 

It could be done if you cut the outer end of the LCA off, and re-attached it a little farther up above the mid-section (bump stop area) of the arm.  It would be some fabricating work.  But I don't think it would be any more dangerous than you are already risking and the results might be better.  I've heard of people doing this mod in the old circle-track days but I haven't seen it with my own eyes. 

The early NASCAR guys would just notch the subframe rail out bigger above the LCA.  But of course I understand why you might not like that option now.  Modified arms are more reversible than modified subframes.   

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For any of these mods I would be worried about bottoming-out the car and scraping the ground.  The factory set the bumpstop height so the car could flatten both front tires, bottom out, and still just barely keep the chassis off the pavement.  Any lower and you are risking a scrape. 

The factory figured on 14" wheels which means you've got another 1/2" to spare if you run 15s.  But that isn't a big difference. 

[Highbanked Hauler]

Adding 1.5 inches?  Are you sure they need that much?  That sounds enormous.  I guess the drop spindles can take the geometry pretty far away from stock stuff.


The job sounds do-able to me.  But this is the wrong situation to try to save weight.  I would vote to load it up with reinforcement.  I would MIG weld it (just my amateur opinion). 

Get a pair of arms with curved "legs" that go parallel near the chassis end, to provide a decent area to splice things.  Splice on some longer tube sections.  Sleeve them with another piece of tubing around the whole welded area.  Have some holes drilled in the sleeve before it goes on, for adding a few plug-welds.  Etc. 

Does that make sense?   

      YES we are EXACTLY on the same page here. Not after weight savings just drivability.  Yes it is 1.5  minimum as it is at max outward adjustment now and needs to come that much further. I have stood a short level up against the tire and it is that far negative. If you sight by the front tire to the rear tire its very obvious. With the old F 70 -14 tires this wouldn't be an issue that you would even notice at "correct" ride height. I have 10 in rims with 10 in. tires so it is very obvious and lowered its worse.  The stock arms I added 1.25 in. to and they drove fine till the first turn at Charlotte and I knew something happened as it got squirrely  instantly.  I don't fault the spindles at all its just the uppers.   I myself WOULD NOT cut the lowers to shorten them as there is tons of stress fluctuating there every time you stop or turn. The uppers keep the spindle in alignment and stop it from laying over. 

[Mike DC]

          
I never did think you were seriously trying to save weight, that was just an exaggeration on my part.  


I plugged that UCA length change into the front end using the calculator at vsusp.com.  (I've already got the stock B-body specs in there so it was an easy change).  I did come up with some viable improvements from adding 1.0" if the tires were huge, the car was running a 2" drop spindle, and the T-bar height adjustment was way down (basically on the bumpstops).  Adding 1.5" to the UCAs seemed like too much no matter how I monkeyed with it.    

But no two 50yo cars are exactly alike.  You know your own car better than I do.  If it needed 1.5 inches last time then maybe your car needs 1.5 inches.  

[Highbanked Hauler]

   I just went out and checked the adjustment slot in a piece of rail that I have and it is 1.25 long. So I am figuring the bolt is 7/16 dia. there is about 7/8 in. adjustment left in the slot and the adjustment With 28 in. bias ply tires is all the way out as far as it can go.   I stood a carpenters level with the bottom against the tire and at 0 vertical there is 1.5 in to touch the tire on the top so YOU ARE RIGHT 1.5 would be overkill because the  adjustment on the rail is what, 6-8 in. below the top of the tire So the tire top will move out more with less adjustment on the rail if that makes sense..
   If I was just going to track run the right side would have plenty of  negative adjustment and the left side would need maybe 2.0  positive or more added to it but this car is 99.9% street driven ..
     The trick is going to be getting the same size tubing and wall thickness to do the job to begin with.

Thanks, this is why I ask questions..