i dont understand launching cars.

the concept seems to be SO bad for the transmission.

couple questions:

is there a way that it doesnt hurt the car? if so, how?

cars with the dual clutches like the gtr and 458, do their clutches get worn from high rpm drops? if not, why not.

thanks

 

I think the point is that they probably hurt the car less than if most drivers tried to launch the car themselves (high clutch wear or else drivetrain shock loading). Either way, any sort of shock loading on a vehicle is bad for it, even with launch control.

The "gentlest" way to launch a car is to lightly preload the drivetrain (gears, specifically) so the teeth in any geared parts don't slam against each other at launch. A slight incline with the parking brake holding the car in place will do that trick just fine. Otherwise, you're still going to get clutch wear if you don't get enough spin off the line and you're going to get tire wear if you have a strong clutch. If everything grabs and grips perfectly, the transmission and differential teeth take a pounding because there is no other part of the system releasing energy.

Yes, DCTs do get wear from high rpm launches if there is any slip (and there usually is). However, since there are two clutches, only one gets worn at launch (whichever one drives first gear).

Basically, a drivetrain can be set up to protect certain parts. In the S2000, the clutch delay valve (CDV) puts wear and tear on the clutch itself (by allowing slip) to save the transmission and rear differential from being damaged in a hard launch. The BMW Z4M has the same thing for the same reasons. DCTs often allow for clutch slip (and hence, clutch wear) since the transmissions themselves are ultra-expensive in comparison to replacing one of the clutches.

 

thanks for that info. exactly what i was asking.

seems pretty lame that car reviews do these types of launches in their tests since i cant imagine real people ever doing that to their own cars on a regular basis. but then maybe im wrong about that.

 

I for one hope to never own a car for performance driving that I wouldn't feel comfortable driving hard in every way.

That translates into either getting a bullet poroof car or being a very understanding owner, the latter of which is oftn a function of the cost associated with . My boosted Miata has an upgraded diff that will allegedly take a reasonable beating but it's something that I have ever only done a few times. The transmission will eventually grenade under hard launches and decent power. Again, I have rarely ever launched my car but I resigned myself to the fact that stuff will break and it's worth it to get the fun out of the car that I want to get out of it (on a track of course). But that's also why I bought a Miata and not another s2000. I am a firm believer in the adage that you shouldn't track any car that you wouldn't be willing to push off of a cliff. I can afford a Z06. I can afford to destroy a Miata, and there's a difference.

 

As my dad said, drag racing is all about going faster and faster until you break something.

 

IMO launch control couldn't much better or worse than just doing it yourself. If anything I'd expect it to be a little worse since the whole point is to minimize wheel spin, and increase acceleration. If you yourself were doing it, you'd probably break the tires loose more times than not, so there would be less drivetrain shock. I see LC as about as bad for your car as just reving the hell out of the engine, and dumping the clutch. Will it break the first time? Probably not, but do it enough times and something will break or wear out.

Johnboy did a good job of describing largely how any why things do what they do, so there's not point in echoing that.

I will echo EG in that you shouldn't be abusing something that you wouldn't be willing to see destroyed, and add that Launching a car hard is probably worse than just about anything else you could do to it.

 

I'm just coming home from doing Launch Control on my friends Panamera 4S. That shit feels like it's super abusive lol.

 

If I were a major manufacturer, I'd program launch control to kill the clutch (something that the car's owner would have to replace at their expense) vs. the transmission/diff (something the manufacturer would have to replace at their expense).

 

I know for a fact that VSA in our cars hurts the clutch.

 

Unless I am wrong, and I am always wrong (ha), doesn't the zr1 have launch control which, instead of slipping the clutch, it retards spark timing to reduce torque (which it can adjust like a bazillion times per second) to the point where you have optimal wheel spin and/or acceleration?