[06AspenWhiteSTi]

depends on what you mean by dumping, do you mean side stepping, or just getting off it quickly

[06AspenWhiteSTi]

the first time i launched my car it was about 3000-3500 and i had my head turned a little and i almost snapped my neck, haha, i wasnt used to it

[Neanderthal Racing]

if youre going to be stoopit you better be tough. if you are going to get anxious every time you contemplate repairing it - just say no.

[panda.sti07]

Originally Posted by 06AspenWhiteSTi

depends on what you mean by dumping, do you mean side stepping, or just getting off it quickly

getting off it quickly but yeah, I wouldnt be doing that again.

[flatbox]

That guys axel broke because of the stock tires being super grippy also. I think 6k launches are softer on the car than 4k. At least at 6k you can spin the tires, rather than 4k all the torque will be instantly transfered to the axels.

[luSTI]

Before I got my 2-step I would launch my car from 5000-5500 with a quick slip of the clutch. I have over 300 launches on my car and not a thing broke. Its all in how you launch the car whether you will break an axel or not. Dumping the clutch from any rpm is not going to be either good for the car or the best way to launch.

[PowerLabs]

Panda STI; you should check out the "chirping 1-2 shift" thread on this same forum; it adresses a very similar question to yours.

And,

Originally Posted by flatbox

That guys axel broke because of the stock tires being super grippy also. I think 6k launches are softer on the car than 4k. At least at 6k you can spin the tires, rather than 4k all the torque will be instantly transfered to the axels.

This is absolutely NOT true. How is it that at 4000RPMs the torque is instantly transfered to the axles (that's how its spelled, btw), but at 6000rpms it somehow magicaly bypasses them and yet the tires still move?
The only reason you might not spin tires at 4000RPMs is because you aren't producing a large enough torque at your tires (RIGHT THROUGH THE AXLES) at that RPM. If your tires aren't spinning at 4K but they are at 6K that means you have that much more torque being instantly transfered through the axles and it is so much more that the tires break lose. The moment before the tires break lose you are producing VASTLY drivetrain stress than you would at 4K.
And don't ever think that just because you can spin your tires its OK to do clutch dumps. Palladin Rally snapped a half shaft on *ICE* this past sno*drift rally. There was no traction, but the tires and wheels have mass, and getting that mass to move requires force, and if you apply that force in the form of a very large impulse (I.E. high RPM) clutch drop you are going to break stuff.

Search on proper launching techniques. Essentially you want to make sure all drivetrain components are fully engaged and loaded by slipping the clutch a little bit before you finally release it all the way. Dumping it in any car -even a 100K dollar rally car- is always a risky proposition.

[t3h f4stAr]

When i was on nasioc they posted that vid and someone said that that guy had launch like that many times before he even made the vid so that car took quite a beating before it gave in

[WRX4ME LE 482]

I dont see how anybody could break anything with 0 traction, unless there stuff is already hanging by a thread. Yes the tires and wheels have weight, but that puts nowhere near the amount of stress on the drivetrain as having to move the entire weight of the car, and we all know *most* of the time our cars can take a few huge clutch dumps before teeth start breaking off.

That said, I agree. There's no since in risking a full clutch dump unless your clutch is already slipping like hell, negating the need for a slip on your part.

If the car runs fine after its done, however, theres likely no damage.

[PowerLabs]

Originally Posted by WRX4ME LE 482

I dont see how anybody could break anything with 0 traction, unless there stuff is already hanging by a thread. Yes the tires and wheels have weight, but that puts nowhere near the amount of stress on the drivetrain as having to move the entire weight of the car, and we all know *most* of the time our cars can take a few huge clutch dumps before teeth start breaking off.

That said, I agree. There's no since in risking a full clutch dump unless your clutch is already slipping like hell, negating the need for a slip on your part.

The guys at Palladin Rally were equally surprized when the half shaft came back broken, but it is not *that* surprizing when you think of it: your clutch drop is accelerating gears, gear hubs, differentials, driveshaft, halfshafts, hubs, brake rotors, wheels and tires; well over 150lbs of mass. Let me make a really simple, overly simplified example to illustrate the impact:
Say that the effective rotational mass is 100lbs and it sits at an average radius of 1 foot. It would take 100 foot pounds to accelerate that mass at 1 meter per second ^2.
Now say your clutch drop engages in 1/100th of a second.
Now it will take 10,000 foot pounds to instantaneously accelerate that mass. If your half shafts can't take 10thousand foot pounds, they will snap.
Obviously this is a very "dumbed down" example and the clutch disk springs, bushings, flex in the shafts, etc all lower that effective value, but you get the idea.
I do concurr: It is definitely easier to break stuff when you have traction though.

Originally Posted by WRX4ME LE 482

If the car runs fine after its done, however, theres likely no damage.

Not necessarily All drivetrain components are made of steel. There are 2 ways steel can fail:
1- Yield; I.E. You exceed its yield strength and it fractures of deforms permanently. This is obvious.
2- Fatigue. Fatigue works like this; above a certain stress level you enter the fatigue region where failure is the function of a probability relating stress * duration * number of stress cycles. Every clutch drop is a stress cycle and enough of them will fatigue the metal to failure. That is why many cars will take a couple of clutch drops to go. That is why (in part) you can bend a spoon a couple of times before it snaps. OK, on the spoon you get cold work hardening too, but you get the idea.