Just make sure to not bog it right?! Plus.. Just before the launch, let your car roll a bit..then make some rpms .. and fly off

Or am i saying crap right now lol

 

Not sure if you are talking to me Ravens, but yes, at an autocross I usually take off at 2,500-3,000rpm and am not at full throttle until the clutch is fully engaged. I will maybe chirp the rear tires, but I get no significant wheelspin.

 

i launch at autox when i can. my clutch hates me for it either way. poor clutchy. prolly poor diffy too.

 

I launch at every autocross. Look for 'coreydyck' on youtube.

My technique (no CDV)
1. Rev to an RPM where you won't bog in step 4*
2. Release clutch quickly but not a full dump, someone described it as the action you do when you just realized you stepped in dog poo)
3. Increase throttle at same time to keep engine revs at same level as step 1.
4. Modulate throttle to keep engine revs at step 1 level until vehicle speed catches up to wheel speed.

The key is to shock the tires free (as gently as possible ) before the weight shifts rearward on to them. If you slip the clutch and weight transfers back before the tires start spinning you may blow the diff/axles instantly. If you bog a little way down the line, that's also risky but less so.

* On slippery pavement 5k and part-throttle is all that's needed. On grippy stuff 9k at full throttle is needed. We pull a sustained 0.4 G from launch to when the road speed catches up with the wheel speed. That's with Hoosier A6 tires on pavement.

You WILL eventually break a diff and/or axles doing this. Carry spares in your trailer or bring your gold card to the dealership. I'm at around 200 of these launches on my car (25 events with 8 runs) with no broken diff/axles so far.

 

So you are saying, 9k rpm launch on dry?


the-moss, no wasnt directly to you .. I do this to my Turbo'd GC8

Let the car roll (Te get the diff rolling etc..) Then, get the rpm's and fly off! 99% of the time I only do it in the wet or near dry pavement!

 

If it's sticky concrete and you have good tires, you may need 9k to keep from bogging in step 3 or 4. If you just sit there and spin then that was too much. It needs a fair bit of experimentation and practice to do it right. It feels really wrong the first few times you do it, once you get some practice it actually feels less stressful on the car as long as you keep the tires spinning. Obviously it eats tires quickly in exchange for saving the diff/clutch/axles.

I bogged a bit in my YouTube video from June 20th, that was launching at about 7.5k on grippy pavement with Kumho V710 tires. I launched at 9k the next run (no video on YouTube, sorry) and spun like crazy before lifting out of the throttle a bit.

There was something like 45 drivers in S2000s in A-Stock at Solo Nationals last year taking 6 runs each over 2 days, all that I saw launched like this with only one breaking a diff.

Don't even bother doing this if you can't afford to replace your clutch, diff, and/or axles if you get it wrong. You will get it wrong eventually.

 

DON'T DO IT your car will blow up.