Halfshafts?

[Paddockrat]

Shouldn’t a halfshaft be strong enough to spin a tire? I really don’t remember halfshafts being a big problem with anyone else but Marco. Is the halfshaft a spec part, or could AGR beef them up for Marco?

[fla-agr]

Shouldn’t a halfshaft be strong enough to spin a tire? I really don’t remember halfshafts being a big problem with anyone else but Marco. Is the halfshaft a spec part, or could AGR beef them up for Marco?

Haftshaft is the kid's new name... it's what we will be chanting this May everytime we see him.

We had another kid who got sick to his stomach before his first half dozen races his rookie season, he's retired from racing now but when we see him to this day we still hollar "What's Up Chuck?"

[Lucky161]

Shouldn’t a halfshaft be strong enough to spin a tire? I really don’t remember halfshafts being a big problem with anyone else but Marco. Is the halfshaft a spec part, or could AGR beef them up for Marco?

There's more than one variable at work here. It's not just the strength of the part. I broke an axle on my dad's 53 Chevy, 108 hp once. Not that the part was that strong, but normally that amount of power wouldn't be put in a situation where it could break it. But if you come out of a slick (water in this case) suddenly into dry, as they say "stuff happens." So figure in conditions and driving style too.

[cleanupcrew]

halfshafts are rotating mass - thus they are "rubbed on" to make them as light as possible - they actually do not have that much stress on the the vast majority of the time, when car is rolling - EXCEPT when you are leaving pit box where they are under extreme stress

that said the halfshaft connects to gearbox and wheel thru "tripods" - like a fancy u-joint - which allows the half shaft to rotate thru range of angles as the suspension travels - failures is not actually always the halfshaft but the tripods

[mac miller]

The andrettis have a well developed technique for busting driveshafts that has been passed down from dadda to wawwa to babba. In their brilliance to make a fast pit exit, they engage first gear while still up on the jacks. When the, already spinning, wheels hit the ground..... blammo!!.... busted axle!

I saw mario and mike do it within a couple of laps of each other at Indy some years back. They both whined about bad luck and they were the only two guys that got a bad batch of axles. This new kid has taken this great family tradition to a whole new level.

A simple problem to isolate and explain but, apparently, beyond marco's ability to comprehend and solve.

The down side to this sideshow is that I know several crew guys who have taken finger and hand injuries because of the andrettis.

[ZOOOM]

During the race, the video seemed to show the shaft was broken itself. I understand Mac's point but this time I couldn't see ant part of the "U-Joint" still on the shaft.

Still, he seems to be the only one who is twisting them off.
Zooom

[fla-agr]

During the race, the video seemed to show the shaft was broken itself. I understand Mac's point but this time I couldn't see ant part of the "U-Joint" still on the shaft.

Still, he seems to be the only one who is twisting them off.
Zooom

There you go again introducing actual facts into the conversation... sure looked like the shaft was broken in half at it's midpoint and no where near the u-joints.

If one of the U-joints had failed then the shaft would have been disconnected at the tranny or the Wheel but that was what the two halves were hanging off of.

[flatlander_48]

Was there a concrete/asphalt transition in the pavement?

[CamKing]

If your name's Andretti, you can break an anvel in a sandbox with a rubber mallet.

[Indy-hp]

I hope someone with a Physics degree will chime in here. I've come to understand from the TV guys that letting the clutch out and getting the rear tires spinning before dropping the car off the jacks puts too much strain on the halfshafts, causing them to break when the spinning tires hit the ground. While I do not have the knowledge to challenge this information, what I don't comprehend is why that puts more strain on those parts than popping the clutch with the wheels already on the ground, which seems to be the way it is "properly" done. Anybody know the answer?

[LorenzoBandini]

Anybody know the answer?

Momentum.

http://en.wikipedia.org/wiki/Momentum

[cleanupcrew]

The andrettis have a well developed technique for busting driveshafts that has been passed down from dadda to wawwa to babba. In their brilliance to make a fast pit exit, they engage first gear while still up on the jacks. When the, already spinning, wheels hit the ground..... blammo!!.... busted axle!

I saw mario and mike do it within a couple of laps of each other at Indy some years back. They both whined about bad luck and they were the only two guys that got a bad batch of axles. This new kid has taken this great family tradition to a whole new level.

A simple problem to isolate and explain but, apparently, beyond marco's ability to comprehend and solve.

The down side to this sideshow is that I know several crew guys who have taken finger and hand injuries because of the andrettis.

or had their heads run over ....

halfshafts are very highly unlikely to fail in the "middle" - no stress point for a failure

[Coyote]

The andrettis have a well developed technique for busting driveshafts that has been passed down from dadda to wawwa to babba. In their brilliance to make a fast pit exit, they engage first gear while still up on the jacks. When the, already spinning, wheels hit the ground..... blammo!!.... busted axle!

Heh. I chuckle because in Clint Brawner's (with Scalzo) book he raves about how Mario was so savvy even early in his career. He talks about stressing to Mario to take it easy on his car at Indy, and because of that Mario left the pits "like a little old lady" which was exactly what Brawner wanted.

I guess as Mario gained experience he learned on his own that Brawner's advice wasn't so important...