1. How do you verify that a roll bar is chromoly versus mild steel?

2. You can't mix and match Chromoly and mild steel (e.g. adding steel bars to chromoly bar), right?

Just wargaming a little on the Street "Ruster" Duster ChumpCar idea...

_________________
Rob

I’m Mater
The Kentucky Poser

If it is Mig welded it will almost definitely be mild steel. CM pretty much has to be Tig welded, and CM that is Mig welded won't pass tech. (Well, not a any track that actually does tech anyway)

Some places Tig mild steel too, so that is not a sure tell.

CM will be thinner wall, but if you can't see an end on any pipe you won't be able to tell.

_________________
Official Cookie and Mater Tormentor.

Thank you so much for your help...

Ben SAID it was chromoly...

So, how do tech inspectors tell the difference then? Do they have some whiz bang thickness checker er sumthin'..?

I'll git my weldin' buddy over thar ta give it a look see...

_________________
Rob

I’m Mater
The Kentucky Poser

If it hasn't been painted you should be able to see the printed the full length of tube, both O.D. and wall thickness. At least it is on my CM tubing.

Richard

_________________
Part of Tyrde-Browne Racing

It's been painted.

I looked at the welds and to my uninformed eye it looks like TIG...

_________________
Rob

I’m Mater
The Kentucky Poser

Mig will look a lot like stick weld, Tig will have a lower bead and be a lot smoother.

Yes, if you have a car fast enough to need certed, the NHRA/IHRA will have a sonic checker for wall thickness.

_________________
Official Cookie and Mater Tormentor.

Most people are misinformed about the correct terminology of things in general, and hear the term "Chrome Moly" when guys talk about race cars and either intentionally or unintentionally call all race car roll bars and chassis Chrome Moly not knowing there is a difference between that and mild steel. Its also done a lot with aluminum when people call even the cheapest grades of it "aircraft grade", when only just a few really are. They also make thin wall mild steel, so make sure that someone wasn't trying to get by with lighter weight tubing in an attempt to save weight or money, but failing to realize they sacrificed strength and safety.

_________________
There's no such thing as too much cam....only not enough engine!

There must be some way they determine if a tube is 4130 or not. My old friend Dean Schoers told me it make different color sparks when you hit it with a grinder. It might sound different if you ring it also but I don't know if that works in the car. If all else fails Lou has the spectrometer.

_________________
If you didn't drive it there, it's not a street car.

Um, uh, yeah. You could do some sort of elemental analysis to see how much Cr and Mo are in there. The different color sparks might tell you this too. IIRC, Mo should make a more reddish color? I'll have to review this...

Lou

_________________
Home of Slant6-powered fun machines since 1988

Rob,

You could make friends with someone who works for a Natural gas pipeline company. They all have ultrasonic thickness equipment. Ask me how I know. If you bring your car to Mason Dixon I will have a tester there to check it for you!

Rick

_________________
2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

I a pershee-ate that offer Rick, but this here car prolly ain't gonna be movin' fer a little while. I dun yanked all the suspension off it fer yet another hairbrained idea I got goin'...

Once I got the K member out of the way I could really tell how bad the front framerail was. I think one of those Auto Rust Technicians "Safe T Caps" will work fine.

I can tell the frame is nice & solid, 'cuz when I put it up on blocks it would "three point" real good.

I'll post some pictures of the carnage here shortly...

I'll do a little here & a little there as time and resources allow and eventually we'll have ourselves a "Ruster Duster ChumpCar"!

Anybody that wants to play, just let me know.

_________________
Rob

I’m Mater
The Kentucky Poser