4 AD Axles Heat Treated

[Stephen]

Hi,. After finally finding an engineering firm that will make new axles for the 4 AD Roadster in a stronger material than the original, and preparing to pay out the amount of $800. The owner of the Engineering firm advised to not get them made up, but to have the existing axle tested for hardness and maybe get them heat treated .

Firstly I am no Engineer and know nothing of hardness etc !!
He cut a section of my 4AD scrap axle up, had it tested for hardness and it came back at 20 on the Rockwell Scale ???, so he has cut a few more samples up and sent them to the Heat Treatment place to see what hardness they can bring them up to ..

The engineer advises that the axles will be a lot stronger .. he has been in business for 40 years working on Hot Rods, Dragsters and racing cars, etc

My question is ... has anyone been down this track before, and if so what were the results ? it is a lot cheaper. ( $300 for both axles, which included testing etc)

Regards Stephen

[mikeyr]

The harder you get the more brittle you get. $800 is cheap for a set of axles made, I paid more than that when I had them made for my 4AD and that was about 30 years ago.

[Stephen]

Hi Mike ..As I said before I am not an engineer and my knowledge on heat treating metal is very limited ..but I do understand that they become brittle if hardened too much, which is why the Heat Treatment place is experimenting with Singer axle samples to find some happy medium, also they were talking about "stress relieving the axles" ??

This will not happen until they get back from the Xmas break, sometime mid January... so I will keep you posted

[Stephen]

Ok after the Xmas break and numerous axle samples heat treated & tested, the engineer has come up with a formula that he is satisfied with .. He would not tell me the procedure ,but he did say the axle material was very soft to start with but is good quality metal.
The axles are now Rockwell C Hardness 41, and have been machined, & straightened, as one was bent....
This process is a fraction of the price of getting new axles made up, and for the Singer's massive horsepower going thru the massive 525 x 16" tyres should be adequate for the rest of it's life .( only time will tell).
These axles are not brittle, as he gave me an example by putting one in the press and bending it, and I panicked, and had to tell him to stop when it went to about 1 1/2 inches, then it sprung back to it's original shape !!
As stated this chap is old school, has been in the Engineering business, specializing in performance cars for over 40 years , and knows his business,.. for anyone wanting to know more about the process his name is Jim Howard, of Slider Machine Service, 10/93 Research Road, Pooraka, South Australia 5095, phone ( Australia ) (08) 83494060..
Stephen

[Mark Thompson]

Axles are typically 45-55 on the Rockwell Hardness C scale. Your axle has been greatly improved from 20 to 41 and you are approaching the normal range for modern axles.

Best regards,
Mark Thompson

[Stephen]

Hi Mark ..
Thank you for your comments ..
Stephen