I returned home last night after three days of racing my #16 Simoniz Special at the Phoenix Int'l Raceway. PIR is only 2+ hours north of my home in Sonoita, Arizona. This event was a vintage-only weekend -- no IRL, CART, NASCAR activity to get in the way. Pam Shatraw and the Vintage Oval Racing magazine crowd were invited to share some track time with 100+ sports/racing guys. Lots of activity and a very crowded paddock--but it all worked well. We ran the one-mile oval--the teabaggers ran the road course, which includes about half of the oval.
The weekend started with a bang as my external starter motor cratered on our first start-up attempt. The motor housing cracked adjacent to the clutch housing and completely separated like it had been cut with a can opener. Bob Neilson had extra equipment and was kind enough to keep me going the rest of the weekend.
Once started, Friday's session went fine. Car ran great. However, later in the day, back in the pits, it was obvious my left rear tire was soft. I had picked up a nail on the track and had a flat tire. The Goodyear guys at the track took care of me. All set to go racin' on Saturday.
I followed the normal routine Saturday morning, including another walk-around with the K/O hammer and rear hub bolt socket, etc. Ran hard for 20-25 minutes before the white flag. One lap to go. Want to look good as we take the checker. Hard on it down the back straight, through the dogleg, wheel-to-wheel with Bob in his Travel-On Trailer Offy champ car, and just entering turn 3. I'm near the middle of the track -- maybe a little high. Left rear wheel leaves the car and the rear end loops to the right as I see the wheel in the air out of the corner of my eye. No jolt, no bang no bump -- all very smooth. I'm turning into the spin but no way can I hold it -- and over my shoulder the turn 3 wall is getting bigger. Car keeps coming around 'till I'm sliding backwards toward the wall, watching my pals approach and enter the turn. Trying to steer the car (backwards) away from the wall, but losing the battle. A miracle occurs and I get it stopped parallel to, and within a foot of the wall.
The guys behind me saw the K/O nut come off and knew something bad was going to happen in turn 3. Bill Barringer hit the bouncing nut, blew a tire, and almost lost it. And he couldn't find another tire in town so was through for the weekend. Sorry, Bill -- my fault. The tire/wheel continued around turns 3 and 4, rubbing blue paint off the wall and eventually crossed the S/F line at the center of the front straight.
The crash crew retrieved the tire and nut, lifted the car with a strap at the roll bar, mounted the wheel and nut and flat-towed me to the pits. The ONLY damage to the car is a relatively small area of scrapped paint, fiberglass and aluminum at the bottom left side of the tail section, and that can't be seen unless you've got your nose under the car. No damage at all to the left rear brake/suspension assembly -- it never touched the track. We checked everything carefully, including all the tires, hammered the nuts home (see below), and enjoyed a great track session again on Sunday.
So why did the nut come off? I talked to several guys who have been in the game a long time, including Parnelli and JR who saw the spin from the grandstand. Johnny said K/O nuts come off for two reasons (assuming they were tight when the car left the pits). 1) The taper at the nut/wheel interface is damaged or isn't a good match, and 2) There is foreign material (paint, dirt, etc.) between the wheel and hat that either crushes or works it's way out. Both conditions can result in "play" between the wheel and hat as the wheel is side-loaded in the turns. The nut eventually loosens and backs off. I have some remnants of paint on both the inside wheel hub and the hat which could have been a factor. But I think I know the real reason the nut came off -- it wasn't tight when I left the pits. For 12 years I've been banging those K/Os on and off with a large, heavy "dead blow" (lead shot in head) rubber-faced mallet. I hit 'em real hard. I've always known the hit wasn't as "positive" as that provided by a lead or brass hammer, but I thought it was good enough -- and I didn't want to mark up my pretty chrome K/O nuts. Prior to Sunday's session, and after going through my normal K/O hammer drill, I borrowed Bob's lead hammer and whacked them all again. In every case I got another 20 degrees or so of movement without beating them to death.
All this is to say that I really knew better, but 12 years of "success" convinced me I was OK. Problem is, it taught me the wrong lesson. From now on, I'll be lock-wiring the K/O nuts to the wheel. And I don't care much any more about how pretty the chrome is on my K/O nuts -- I'll be trading that big, heavy rubber mallet for a bigger, heavier lead hammer.