Auto driveshaft application for racing

[flowgrid]

Most common driveshafts today (other than exotic lightweight shafts) are 1020 carbon steel welded to 1035 forged steel yokes which are adequate for strength in our application but we experienced a fatigue failure in the tube adjacent to the weld. What post weld heat treatment and or shot peening would be recommended to improve the fatigue life. The original tube was .085 wall and we are going to .120 wall DOM tubing.

 

[stanweld]

Stress relieving PWHT can be done at 1100 F for 15 minutes minimum for 1020/1035 weldment. Shot peening with steel or glass bead shot will also provide added life.

Since it appears that failures are uncommon, was the fatigue failure simply due to a poor quality weld or added loads incurred in racing?

 

[flowgrid]

Thank you for the reply and the information. I think the failure was due to higher loads imposed by racing. The car is a 65 Corvette that we have been running in vintage racing and the part that failed is the rear halfshaft which on the Corvette also functions as the upper "A" arm. with modern tires, tires, and engines making 600 to 700HP and a 4:11 rear axle we can put loads exceeding 2200 ft-lbs of torque thru this halfshaft. The failed shaft had probably two seasons or roughly 60 hours of use at the time of failure. We are going to magniflux the part more regularly and change them out annually.

Do you think the tubing should be changed to chrome moly steel??? We are pretty much stuck with the 1035 yokes.

 

[stanweld]

While you may save some weight using a Cr-Mo shaft, the weak point remains the weld to the 1035 shaft.

 

[metman]

That's a pretty rummy deal to be stuck with 1035 beings it comprises your weak link. Makes one wonder why yer stuck with it!

Jesus is THE life,
Leonard

 

[Metalguy]

Looks like the "weak point" is NOT on the 1035 side-he said the failure was in the thin 1020 tube.

BTW, if the rules allow, I'd change the whole rear assembly to the alum. Dana. You get a slightly larger ring gear (8.5" vs. 8.2 in the orig. Eaton) AND larger dia. axles too.

I did this swap in my warmed 500+ HP L89 '69 Vette because I wanted a 2.72 gear for cruising, and a 5 speed Doug Nash trans. allows this with its very low 1st gear.