[68 TT]

Originally Posted by ryanroo

oh i agree. i am a professional welder though so i feel like its my responsibility to inform the public that improper technique could possibly cause issues. chances are slim, but in an area such as brakes, its not good to invite trouble. really CM is not hard to weld, nor does it weld different. in this application i would temper the part just to be sure i wasnt inviting cracks.

Ryan

I agree. As a certified TIG welder I welded plenty of 4130 in the air force and it is no big deal as long as you watch your heat and use the correct filler material.

The biggest misconception with chome-moly is people thinking it is going to make a part deflect less vs. a mild steel part of the same dimensions which it will not. They both have the same modulus of elasticity so they both bend the same amount under load. The chrome-moly just has a higher ultimate strength so it will fail at a higher load than mild steel giving you more safety margin. Same goes for titanium. It flexes a lot but fails at a very high load. You have to design with the flexibility in mind.

That is why sanctioning bodies allow thinner wall chrome-moly tubing in place of mild steel. They will both end up failing at the same load but the mild steel tubing being thicker is just heavier. It is the primary reason race teams use it. They can lose weight with it.

Dragsters have found they can actually use the extra flex of their thinner wall chrome-moly tube chassis to absorb some of the shock off the line allowing them to put more power to the ground off the line.