Looking for metallurgist info.

[crazywelder72]

So after some thought and discussion about modifying the torsion bars, I think I need some advanced knowledge about metallurgy. I have been a welder for over 20 years working mostly in aerospace and medical equipment and have a lot of geeky knowledge but i don't know everything.

My existing dogbones are the round bar style and were cut in half, and spliced with a longer middle piece of pipe. I want to do similar the I-Beam style I have.

Anyhow, The I-beam style dogbones seem to be a type of cast iron.

I know when welding most cast iron a minimum of pre-heat and post heat is required. It also needs to be welded with Ni-Rod (welding rod high in Nickel). The slower the cooling process helps prevent thermal shock and crystallization of the metal causing cracks and brittleness. Usually when i weld cast iron I place the part in a bucket of sand and cover it with sand.

can anyone provide any more information about this?

 

[SuperJoe]

 

[Heavysteven]

You have an either gear oil or brake fluid leaking. Looks pretty bad I would definitely pull that hub for inspection.

I can't comment on the dogbones.

Edit: looked again both hubs in photo

 

[crazywelder72]

Its just the axle seals, they should dry up when I get more miles on it.

 

[Ridgerunner]

I thought the I-beam dogbones were steel, not cast iron. Did you try cutting one or a grind test to confirm?

 

[crazywelder72]

No i haven't. I was only going off looking at the molded look of the dogbone.

 

[Squirt-Truck]

They should be cast steel, cast iron has very little shock resistance and would not play well with the axle loads.
If you really want a metallurgist and or weld engineer of specification drop me a PM. My lab has the metallurgist, weld engineers, CWI's, chemist, and whatever to test, identify, or modify the parts. Stuff like this is what we do. (www.atslab.com, yes shameless plug)

 

[197thhhc]

I personally like the tube style better because they are easier to modify and the bushings are replaceable.

 

[SuperJoe]

i have cut one in half. i can provide pictures of it but i do not know how to test the variables. could someone explain what to do and i can get at it for the OP

 

[crazywelder72]

Squirt-Truck,
Your lab can with out a doubt flood me with so much information i would never be able to understand it all. I don't think I need to waste your time asking for a massive amount of info that isn't necessary.

If i was making them for production to sell to the military I would.

I guess just some guidance for a good way to reweld them. What type of rods? Any pre/post heat?

I'm not sure if its something that you and your colleges can shed some insight to over a coffee break.

 

[crazywelder72]

I personally like the tube style better because they are easier to modify and the bushings are replaceable.

Funny, mine need replacing.

You cant remove the bushings from the I-beam type?

 

[tm america]

It seems to me it would be way easier to buy some round tube that the dogbone end fits in and some nice thick walled round tube to go between the two pieces of round for the dogbones.And just remake them altogether..That way you could use weldable metal that will be structurally sound when finished.

 

[crazywelder72]

That dosnt sound like a bad idea. But all the stress would be at the ends where the shaft would be welded to the other parts where the bushings go thru.

 

[tm america]

The amount of load on the dogbones is probably a lot less than you would think.as the weight of the spring goes right to the axle.many aftermarket control arms are made with round tube welded to round ends.if you really wanted over kill you could get rectangle tube like 2x4 then drill it for the tube where the dogbone end will be pressed in that way if would be surrounded all the way around with the rectangle tube

 

[SuperJoe]

this was cut this afternoon with a chop saw. IDK what we will be looking for but this will save someone the effort of cutting one if there wrong

 

[BillIdaho]

I would reckon those are made out of the same type (and temper) of common car axles. A lot of people don't realize it, but car axles have a "grain" much like wood. They are designed to be strong in the right directions considering the force applied.
Probably a cast steel. When you hit it with the chop saw, what did the sparks look like? There is a noticeable difference in the appearance of the sparks. If they leave the piece you are grinding, flutter away and go out, then it is NOT a high carbon metal. If the sparks "flower" like a firework would, it is high carbon. The easiest way to explain it is just grab a piece of steel, one known not to be hardened- like a common grade 5 bolt. Grind on it and watch the sparks. THEN, grab a socket-head (or sometimes called an "Allen" head) and touch that to the grinder. Again, watch the sparks. You will see the sparks "flower" or "explode" as they reach their farthest point from the piece.
Personally I wouldn't weld on something involving tons of steel going down the road depending on what you think has been done properly. Most anything with a torsion application is not friendly to welding and alteration.

I designed, built, welded, and eventually raced a 450 horsepower "funny-bike", including every weld on the frame. I knew what particular metals I was dealing with.

 

[SuperJoe]

i will have to watch the sparks tomorrow. i usually clamp the piece tight and put the glasses on and turn my head away and cut by feel. i have been in the er more than once for eye injuries. not my favorite thing. is there anything else i could look for? also i know how to get pictures here but can i load short movies? i could record it so you could determine yourself opposed to take my novice opinion for what i thought i saw

 

[SuperJoe]

seems it uploads like a standard picture. just takes longer

 

[plym49]

I would suggest that the arms are steel forgings. The forging process correctly aligns the grain - bet you didn't know that.

By now you have probably seen my other post regarding the considerations when modifying or building new torque rods. In a nutshell, they have to be able to twist to permit the rear bogie to articulate.

Look at that cross section above. You can just visualize how that arm can twist.

Any hot rodders on here? Have you ever heard the discussion about how a stock Ford I-beam axle can handle split radius rods, because the i-Beam can twist, but that a tubular axle needs a different radius rod setup because the tube axle will not twist? Now, how much articulation does the front axle of a street rod see? Compare that to a Deuce. Perhaps this example will resonate.

I submit that coming up with a replacement with tubing would need to take into account the torsional characteristics. Most builders just think about 'strong enough, this baby ain't going nowhere'.

Perhaps a mechanical engineer can chime in. I might be mistaken about this, but I believe that my statements are correct.

 

[PROSTOCKTOM]

Those beams are forged steel and you should be able to weld them with no problem.

However rather modify them I would get some rod ends, bungs, and some tubing

and build a new set, but the price of cutting and welding is much cheaper.

Tom