Saturday, April 12, 2008

Studdly....

Remember Sesame Street?? "One of these things is not like the other...."

So last weekend running at Giants stadium I hear a knocking noise towards the end of my run. No biggie, it happens every so often. I pull to the side and wait for a rerun, check my tire pressures and get back in the car. I pull up to the line and Joe Austin finds this next to my car:
I immediately recognize it and without hesitation Joe points me out of line. I pack up and drive home, thinking about what I'm gonna replace all this stuff with. So I splurged and got these:

Studs are ARP's P/N: 100-7717 and you need 4 of them for the whole car. New lug nuts are steel, I've been running Aluminum for 2 yrs now with no problems but I figured it was time for some fresh ones anyway. They are from Pegasus, P/N 3548-005. Supposed to be high strength steel, def heavy, but they are open ended and 19mm w/no locks which make for easy changing.

So here is the failure point on the stud:
Looking at the cross section it is pretty clear the stud began to fail awhile ago. There is oxidation (rust) visible and there are also "rings" which point to a fatigue related failure. These studs have a minimum of about 80 tire changes so it's not hard to think they would fail sooner or later.

So here is a comparison of the ARP and the KYO-EI studs. It looks like ARP worked a little harder to reduce any stress raisers, especially at the failure point on the KYO-EI stud. I'll also have 5-10mm more of thread to use, which I'm happy about.

All better now.

- Jay

2 comments:

Anonymous said...

Jay, I've had some stud issue's in the past and replace them at least every other year. It's that repeated sheer and tension stress that kills them. Also I don't see a lot of antiseize on those. That will minimize some torsion forces when zipping them on and off with your impact gun.

dan said...

jay's impact gun a year ago was his right foot!

lemme add that you have to reduce your torque settings if using antiseize on the studs.