rear axle shafts material

[firstboaz]

hi,
I'm from BGRacing, a team from Israel. in the last 4 years we used titanium for the rear axle shafts.
This year we're thinking on changing the material because of availability and budget issues.
I wanted to know which materials are recommended? and which you have experience with?

thanks

[jd74914]

Titanium-interesting. Why did you use that?

Typical axle materials are 300M or 4340.

[scotty young Taylor Race]

firstboaz

Over the last 18 years we have made our axles out of 4340 , And have switched in the last 4 years years to 4130 with an HRC 42-47

Scotty
Taylor Race Engineering

[Z]

This is the really interesting one.

firstboaz

Over the last 18 years we have made our axles out of 4340 , And have switched in the last 4 years years to 4130 with an HRC 42-47

Scotty
Taylor Race Engineering

Scotty,

I am guessing the switch was a "cost-effectiveness" vs "outright-performance" decision?

But how do the two compare just on performance? And is it mostly about the heat-treatment (or shot-peening++) rather than just the raw material?

Z

[jd74914]

I agree with Z there. Switching to 4130 is a bit curious-it would seem like a cost/availability-driven switch but I'm curious to hear from Scotty/TRE.

[Z]

To be clear, I think the switch from 4340 to 4130 is an example of very GOOD engineering. A valuable lesson that students can learn from. Especially since it took TRE some decade-and-a-half of real world testing to discover this lesson.

My technical understanding is that it is the 0.30 - 0.40% Carbon in the above steels that adds most of the strength to the raw Iron. The extra pinches and dashes of Cr/Mo/Ni/Va++ in the 41xx and 43xx "alloy steels" are there mostly to help get the heat-treatment effects deeper into thick sections of the workpiece.

But since an FS-sized axle shaft, especially if it is a hollow tube, has a smallish section thickness, I guess some plain old 1030 or 1040 "medium carbon steel" might be enough to get the required performance. Assuming, of course, that it gets the right processing in terms of heat-treatment/shot-peening/cold-rolled-splines, etc., which seems to be the real "secret ingredient" in all this.

Still interested to hear what Scotty can add?

Z

[StefStam]

Why dont you use carbon half shafts????????????????????

[mech5496]

Depends; no single right answer here as well. We have played with 4130, CK60, Aluminum and CF over the years. What are the performance indicators you are interested in? Weight, inertia, stiffness, cost, recyclability, bling factor?

[BillCobb]

Whatever you do, make the left and right side drive shafts different torsional stiffness, especially if your LSD is tight.

[MCoach]

Why dont you use carbon half shafts????????????????????

Do you? That would personally cause me too much concern to consider such a high risk, low pay off option...

Whatever you do, make the left and right side drive shafts different torsional stiffness, especially if your LSD is tight.

Really, I'd just prefer a spool and call it a day...