Cool info!
By that logic a 31 spline is 21% stronger than a 30 spline simply from size. Moser/strange claims the 1541H axles are something like 20% stronger than stock. I havnt seen claims for 4340 over stock. So basically good aftermarket 30 spline=stock 31 spline
Stock axles are 1050
Low grade aftermarket are 1541H
High grade aftermarket are 4340
The shear modulus for all steels is the same (80gigapascals or 120ish thousand PSI, also called KSI)
What you gain is that 1541 is more hardenable than 1050 and 4340 moreso than 1541.
Hmm, they claim 1541H is equal to 4340 in torsion, just that 1541 is induction hardened (uses an electric coil that moves over the part, think hard surface soft core) which is fast and cheap, done in an open air environment, vs 4340 which is likely carburized which is done in an oxygen depleted furnace that has "cracked" natural gas in the air so that the high amount of carbon from the gas diffuses into the outer surface
https://dutchmanaxles.com/axle-rearend-tech.html
That dutchman link claims 4340 has a higher yield strength with 4340 vs. 1541H (which is true), thus making it stronger, but my engineering degree says that doesnt matter and torsion is calculated with shear modulus (which is the same). I'd have to dust off my textbooks, it's been 4 years since i took that class. It seems like their link info is a bit inaccurate in that earlier it says 4340 is better in torsion (which formulas say no, I guess depending the effect of heat treat, but then 2 sentences later says they are the same if you do it right.
What I see is that even if I went with a 9", I better go with 35 splines since if I blew up a 30 spline, and stock 31 spines are only 20% better than stock 30, and good 31's are only 20% better than stock 31', Id be dumping 2 grand on shafts and a 9" axle that is at best 40% stronger than what I had which blew up without too much effort (assuming I didn't just have an axle that had poor material and was weaker than it should be)
By that logic a 31 spline is 21% stronger than a 30 spline simply from size. Moser/strange claims the 1541H axles are something like 20% stronger than stock. I havnt seen claims for 4340 over stock. So basically good aftermarket 30 spline=stock 31 spline
Stock axles are 1050
Low grade aftermarket are 1541H
High grade aftermarket are 4340
The shear modulus for all steels is the same (80gigapascals or 120ish thousand PSI, also called KSI)
What you gain is that 1541 is more hardenable than 1050 and 4340 moreso than 1541.
Hmm, they claim 1541H is equal to 4340 in torsion, just that 1541 is induction hardened (uses an electric coil that moves over the part, think hard surface soft core) which is fast and cheap, done in an open air environment, vs 4340 which is likely carburized which is done in an oxygen depleted furnace that has "cracked" natural gas in the air so that the high amount of carbon from the gas diffuses into the outer surface
https://dutchmanaxles.com/axle-rearend-tech.html
That dutchman link claims 4340 has a higher yield strength with 4340 vs. 1541H (which is true), thus making it stronger, but my engineering degree says that doesnt matter and torsion is calculated with shear modulus (which is the same). I'd have to dust off my textbooks, it's been 4 years since i took that class. It seems like their link info is a bit inaccurate in that earlier it says 4340 is better in torsion (which formulas say no, I guess depending the effect of heat treat, but then 2 sentences later says they are the same if you do it right.
What I see is that even if I went with a 9", I better go with 35 splines since if I blew up a 30 spline, and stock 31 spines are only 20% better than stock 30, and good 31's are only 20% better than stock 31', Id be dumping 2 grand on shafts and a 9" axle that is at best 40% stronger than what I had which blew up without too much effort (assuming I didn't just have an axle that had poor material and was weaker than it should be)
