[SuperMacGuy]

I was at Summit Point yesterday for FATT. During my 2nd heat I had my left front hub fail. It let loose in turn 5-6 or so, and if you know Summit, that's about the slowest part of the track. Which is right after the part of the track with the highest pucker factor IMO (downhill at 80-100 depending, about a 30 degree turn a little off camber and max braking soon as you're through it). So I am OK and there is no body damage.
The hub flange sheared right off, and the wheel getting pushed back it must have bent up either the brake caliper or the slide pins, the caliper doesn't float any more. A guy with a TA next to me thankfully had a spare hub, so I got that on and drove carefully home. This was a Mike Minear hub so I'm contacting him to see if he wants to inspect it. I'll probably get a new one from him over the winter.
I'm thankful that was all relatively low drama. If that happened almost anywhere else on track, well all the other places are pretty high speed, and it would've been a real wreck, literally.

Chris

[00 SS]

The part was "supposed" to be a forging. Either the individual part that failed was a very bad forging or a casting passed off as a forging. My supplier, mark Williams Enterprises, believed them to be forgings. They buy generic blank axle shafts from another supplier, they do not forge their own parts. So they are at the mercy of their supply as well.

A cast part with the exact right amount and type of heat treatment might work, but I think in this case the part is better off starting with the stronger forging.

Carburizing is an interesting idea, but I don't know if the blanks can be obtained in 8620 or not. It's my understanding that 4340 is not particularly well suited to carburizing. Yes, no? 4340 is what the blanks are supposed to be made of. But it is something I can discuss with Mark Williams.

Originally, through hardening was selected because it is the easiest process to control and the only process Mark Williams offered me. I know they now have induction capabilities, but I don't know if they had it when we first started making this part. It's worth revisiting with them as is carburizing. If we can get the heat treating profile right with either of these process, it would likely result in a stronger and more durable part.

I think the first hurdle is making sure the blanks are properly forged in the first place.

I really appreciate all the help and knowlege I'm getting from all of you. It's invaluable. Please keep it coming.

Thanks,

This post has been edited by 00 SS: Jan 17 2011, 06:03 PM