CVF Racing only uses 6061-T6 Billet Aluminum in our Pulleys and Brackets
Think everyone uses 6061-T6 billet aluminum in their pulleys and brackets? Think again!
Several manufactures of billet aluminum pulleys cut corners and use a lower strength aluminum or they conveniently forget the T6 temper. This makes a big difference! You definately want your billet pulleys made from 6061-T6 aluminum!
Here is the skinny on the strength properties of various billet aluminum grades (according to Wikipedia.)
6061-T6 Billet Aluminum
T6 temper 6061 has an ultimate tensile strength of at least 42,000 psi (290 MPa) and yield strength of at least 35,000 psi (241 MPa). In thicknesses of 0.250 inch (6.35 mm) or less, it has elongation of 8% or more; in thicker sections, it has elongation of 10%. This is a true billet aluminum which means it comes in extruded bars instead of poured into a casting.
6061-T4 Billet Aluminum
T4 temper 6061 has an ultimate tensile strength of at least 30,000 psi (207 MPa) and yield strength of at least 16,000 psi (110 MPa). It has elongation of 16%. This can technically be called billet aluminum, but it's not nearly as strong as 6061-T6.
6061-O Billet Aluminum
6061 Aluminum (6061-O temper) has ultimate tensile strength no more than 18,000 psi (125 MPa), and yield strength no more than 8,000 psi (55 MPa). 6061 Aluminum has elongation (stretch before ultimate failure) of 25-30 %. This is billet aluminum, but some manufacturers of billet accessories use this soft and weak material to save money.
A356-T6 Cast Aluminum
A356-T6 Aluminum has ultimate tensile strength of 33,900 psi (234 MPa), and yield strength of 23,900 psi (165 MPa). The material has elongation (stretch before ultimate failure) of 3.5%. This is NOT billet aluminum and many of our competitors use this on their pulleys. They use it because they can cast a pulley close to the final dimensions and then do a finish machining cut. That way the don't make as much scrap aluminum. Besides the fact that the material is weak, it is also less uniform and subject to porosity (sand from the mold and air get imbeded into the aluminum) This really cheap stuff!! If someone advertizes -T6 aluminum, run don't walk! You can assume that it is this cheap stuff...otherwise they would advertize 6061-T6 aluminum.
Insist on 6061-T6 Billet aluminum for your custom billet pulleys and brackets!