[VanishingPoint]

Seems to be alot of confusion on this subject, so I wanted to start a thread explaining how and why.
I am no expert just someone with alittle experience at red lights an expired ASE cetification, and alot of stick time.

From what I have been reading alot of people rev from 3-5000rpm and let the clutch out as fast as possible ( letting the clutch slip off your foot or letting it up instantly ) If you think about it something is going to break. It is hard on everything. Your engine is turning at 4000rpm and within a fraction of a second you have tried to slam it to ZERO. That instant stoppage will transfer to engine mounts trans mounts car frame pistons rods and crank. Trying to soak up all that inertia is the drive train. The damper springs in the clutch the trans gears the CV joints and so on. If theres any slack at all in the drive train its like taking a sledge hammer to it.
Many think this is easier on the clutch it doesnt slip as much. IMO slamming the clutch with a 5000rpm engine is harder on it then a proper launch.
Breaking the tire loose may take some of the energy off the drive train, but whats the point, once you break them loose all your traction is up in smoke.

To launch fast (not hard ) its basically alot like driving normally just faster. Say what?
I know about where my clutch engagaes on take off, so I rev to 3500-4000rpm and have my clutch let out about to the point of take off. on launch I feather the clutch in just fast enough to hear the tire slip alittle While slamming the throttle to WOT at the same time. This puts the load on the drive train smoothly, but quickly. The clutch slips alittle more to make the speed change more gradual, but only for a fraction of a second longer. This way of launching will be much faster, tires dont totally loose traction, and the engine doesnt bog to almost zero RPM allowing it to make power faster.

Bottom line is its better to lauch smoothly then to try and do it with a sledge hammer.

The only way to get good at it is to practice. I would start with slightly faster take offs once in a while during your daily driving. Not a 4 grand launch, but maybe a 2-2.5 grand launch with WOT. The low RPM launch will let you know if you have it down. Its much easier to bog at 2500rpm then 4000 and if you bog at 2500rpm you have dumped the clutch to fast. To slow and you will be bouncing off the rev limiter before the clutch is all the way out.
Just so you know, to slow with the clutch and you slip it to much you will shorten the life of it alot. If you are having trouble dont do alot of launches in a row, let the clutch cool down before you try it again. Done correctly your clutch will not be damaged and may actually last longer.

AWD FTW

Tony

[solovus]

I have to agree the AWD takes some getting used to coming from RWD or FWD. I lost a transmission in my 02 WRX from stupid RWD type launches (although these were known to be weak transmissions). I now have great launches and do them pretty much exactly like you say...you get a bit of clutch odor...but I'd rather lose my clutch every 30k miles than a tranny every 10k.

[sti_kris]

i had mine at the track last night. i was launch at about 5000 - 5500, i know right about when my clutch in engages. i had no problems with tires slipping it just squatted and launch. but yes launch an awd is much harder. found that out last night.

[shan mann]

Thank you for the clarification.
Now I need to find a large empty parking lot to practice!

[SirMattieP]

Sooooooooooooooooooooooo sickkk, i cant wait to try this out!! hahaha Nice post.

[VanishingPoint]

Originally Posted by shan mann

Thank you for the clarification.
Now I need to find a large empty parking lot to practice!

Great idea just take her for a cool down run after a few launches.

Tony

[ytsohptwhere]

Unfortunately in Washington state I could goto jail for messing around in a parking lot... Damn reckless driving laws...

[Mykl]

VanishingPoint, what 60' times do you get? A picture of an actual timeslip would be good.

[Hitman83]

This method might be easier on the drivetrain but there's no way it cuts the best 60' times. Rev it up to 5500 or so and slip, don't dump the clutch and you'll get a faster 60'

[Mykl]

Originally Posted by Hitman83

This method might be easier on the drivetrain but there's no way it cuts the best 60' times. Rev it up to 5500 or so and slip, don't dump the clutch and you'll get a faster 60'

Yeah, the key is to keep the RPM's high. I pull my foot off the clutch quite fast, but when it's done right you get just the right amount of wheelspin to keep the RPM's up.

What you *don't* want to do is sidestep it. That's what doesn't work.

[Hitman83]

Originally Posted by Mykl

Yeah, the key is to keep the RPM's high. I pull my foot off the clutch quite fast, but when it's done right you get just the right amount of wheelspin to keep the RPM's up.

What you *don't* want to do is sidestep it. That's what doesn't work.

Exactly. Based on my experience, launching at 4000rpms like was suggested is just too low. The method for the launch was explained perfect but I think the rpms are too low. Maybe launching at 4k works for some, but from my experience it's gotta be 5500 or so.

[The Black Beauty]

I like to launch from 5k and slip the clutch. Its hard, but I'm getting there

[Mykl]

Originally Posted by Hitman83

Exactly. Based on my experience, launching at 4000rpms like was suggested is just too low. The method for the launch was explained perfect but I think the rpms are too low. Maybe launching at 4k works for some, but from my experience it's gotta be 5500 or so.

My technique is to rev it at 5000 RPM's. I try to time it so that I engage the clutch while the RPM's are on the upswing so boost builds immediately. Done right the RPM's don't drop and you get just the right amount of wheelspin. The car doesn't lunge forward, it just pushes you back in your seat gently until it's time to shift.

I don't launch it much anymore since I don't autocross much these days.

[page2334]

use to launch at 7K on stock clutch, around 6K on stage 2 clutch, everything else stock, car still soild with 62,000 miles of abuse

[Mykl]

Originally Posted by page2334

use to launch at 7K on stock clutch, around 6K on stage 2 clutch, everything else stock, car still soild with 62,000 miles of abuse

A testament to just how insanely well built our drivetrain is. Thank you Subaru.

There are guys around here and NASIOC that have been launching their cars every other weekend at autocrosses with 275+ width race tires for years who haven't had any issues.