Limped Kletus home tonight.

[Bill Pedersen]

I agree with Mr. Fixit, 4130 Chromoly wouldn’t be a bad choice for radius rods if done correctly. For our applications (hot rod/racecar), the best filler rod to use would be ER70S-2 or ER80S-D2. The ER70S-2 rod would be better for welds requiring more flexibility or ductility, like here with the radius rods, while the ER80S-D2 has a higher tensile strength. 4130 filler rod typically is only used where the weld will be heat-treated. Because of the increased hardness and reduced elongation, it is not recommended for applications such as radius rods, racecar frames, roll cages, etc.

If your welding 4130 tubing that is less than 1/8” thick you usually don’t need to do anything else to the weld. If the tubing is thicker than 1/8” thick it is usually recommended to stress-relieve the weld area at approximately 1,100ºF. I use a 900ºF temp stick and put a mark about 1” away from the weld and an Oxy/Acetylene torch with neutral flame to heat with.

For most all of our applications (hot rod/racecar), you could also use mild steel plate for support gussets with the 4130 tubing without any problems.

I’ve found that DOM tubing is not that much cheaper than 4130 Chromoly. You can buy 1”x .188 wall 4130 Chromoly at Wicks Aircraft supply for $7.84 a foot in small quantities.

Bill

 

[Northstar T]

Here is a pic of a local guys T Bucket front axle that tangled with a tree at about 30 mph. Bent the axle bent the bat wings, broke both clevis. It did not bend our radius rods.

It's hard to see from that photo, but I find it interesting that both clevis broke without (apparantly) bending the ears of the bat wings. do you know it the clevis were SS or not? I'd also commend the guy that welded the bat wings onto the axle. who made the axle?. whoever made it I'd want one just like it, as I've seen too many just break off rather than bend like that.

Russ

 

[Mike]

If the tubing is thicker than 1/8” thick it is usually recommended to stress-relieve the weld area at approximately 1,100ºF.

When I was still at the race car shop, the welders used vibratory stress relief, during the welding process. Once the car was tacked up in the jig, they would start shaking it before they started the finish welds. And it can't be age, but I simply cannot recall what filler rod they used.

 

[Ironhead]

Dave, that was Toolman's ride. The slight bump into the barrier did a little bit of damage to the front end, and those wimpy little Speedway Stainless bars have been replaced with some of RPM's stout products.

Yeah, I don't think I'll be ordering any of those Speedway Stainless bars any time soon.

For such heavy walled tubing it's a shame it was welded with such a small undercut fillet. Some people are fooled by that pretty "stack of dimes" look. How many chinamen do you think are educated on the heat affected zone? Mig welding is ugly in some cases but regular DOM tubing with a good mig weld is a better choice in this application.(opinion)

 

[Ted Brown]

As one can see here, this tube was not ground back (chamfer) at all, to allow for a full weld and complete penetration of the weld to both tubes...

 

[Youngster]

While I haven't had much to do with chrome-moly, I have done some SS. It looks pretty on a trailer queen but I have seen more failures with it than with good old steel. I agree with Ted. There obviously wasn't the joint prep that that type of weld requires. Using helium for shielding gas while TIG welding will give you the best penitration IMO. The problem is because it's lighter than the air it trying to shield, it takes 2 to 3 times as much as agron. For this reason most shops use argon. If you are using argon for a joint like this, you need to chamfer the joint and purge it with an argon backup. It would also require a multi-pass weld. Trying to fill a chamfer in one pass introduces too much heat in SS causing brittleness.

Northstar T ... That axle is a '32 to '36 stocker. Ol' Henry made lots of 'em.

Ron