Best way to launch in NO4?

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

On dirt what's the best technique for launching in a 4WD? Should one floor it? Start lightly on the gas, and then build up speed slowly? What amount of wheel spin is optimal?

Sorry for the basic question; just trying to gain a little time at the start.

KouroshNeshat · **Posted:** Wed Nov 18, 2009 11:00 am

have you seen mark Hoerath (sp) launch his wagon? spraying dirt everywhere? lol.

I just rev mine up and go (cant recall the RPMS)... others drop the clutch. i try to take it easy a bit on the car.

try different approaches at the line. just dont bog.

RichardNuss · **Posted:** Wed Nov 18, 2009 11:08 am

In the GL-10, we would rev it up and drop the clutch, launching as hard as we could.

In the Audi we take it easy on launch because there's a clunk in the rear-end that we haven't figured out yet.

Time-wise, I would say launching as hard as you can is good, especially in an AWD with race tires.

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

Now the engineer in me wants to find a field to do a little experimentation with a stop watch.

Vincent Keene · **Posted:** Wed Nov 18, 2009 11:20 am

Michael I thought your Subaru was an automatic? If so there is no good way to launch it.

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

Vincent Keene wrote:

Michael I thought your Subaru was an automatic? If so there is no good way to launch it.

I just bought Keith Vail's '93 Subaru Legacy from Brian Herring.

http://www.thscc.com/phpBB/viewtopic.php?t=9756

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

The new license plate will read "DIRTBOMB", which strangely enough was available. Not only is it street legal, it doesn't have to be inspected until 11/2010.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

IIRC I drop the clutch at 4k.

The launch is one of the more gratifying moments of rallycrossing AWD on rally tires

Vincent Keene · **Posted:** Wed Nov 18, 2009 11:43 am

Michael Czeiszperger wrote:

Vincent Keene wrote:

Michael I thought your Subaru was an automatic? If so there is no good way to launch it.

I just bought Keith Vail's '93 Subaru Legacy from Brian Herring.

http://www.thscc.com/phpBB/viewtopic.php?t=9756

OK cool. I didn't know that. In that case the best way to learn to launch an NO4 car is to watch Mark Hoerath. If you are worried about damaging the car then don't expect to do as good as he does.

KouroshNeshat · **Posted:** Wed Nov 18, 2009 12:02 pm

Vincent Keene wrote:

Michael Czeiszperger wrote:

Vincent Keene wrote:

Michael I thought your Subaru was an automatic? If so there is no good way to launch it.

I just bought Keith Vail's '93 Subaru Legacy from Brian Herring.

http://www.thscc.com/phpBB/viewtopic.php?t=9756

OK cool. I didn't know that. In that case the best way to learn to launch an NO4 car is to watch Mark Hoerath. If you are worried about damaging the car then don't expect to do as good as he does.

exactly!
but i do believe he has a beefed up trans (not sure if the 6spds beefier).

come to think of it, i think i do launch around 3.5-4K.

Vincent Keene · **Posted:** Wed Nov 18, 2009 12:09 pm

KouroshNeshat wrote:

but i do believe he has a beefed up trans (not sure if the 6spds beefier).

Technically on dirt the stock tranny should fair just fine. Even on a high RMP dump of the clutch. Think of it like this. When the clutch engages and the wheels spin it's all good. On pavement when the clutch engages and the wheels don't spin at all, well all that torque has to go somewhere...usually into the diff resulting in carnage.

Dustin Fredrickson · **Posted:** Wed Nov 18, 2009 12:23 pm

Vincent Keene wrote:

KouroshNeshat wrote:

but i do believe he has a beefed up trans (not sure if the 6spds beefier).

Technically on dirt the stock tranny should fair just fine. Even on a high RMP dump of the clutch. Think of it like this. When the clutch engages and the wheels spin it's all good. On pavement when the clutch engages and the wheels don't spin at all, well all that torque has to go somewhere...usually into the diff resulting in carnage.

This is my theory as well, I aim for 4-wheels-spinning at launch on race tires, prob 3-4k at full clutch engagement.

Pete Guthrie · **Posted:** Wed Nov 18, 2009 12:52 pm

micheal, simply come to the setup day on friday, we can "field" test you car there. i may be there in my wrx if we can get the toyota running by then.

KouroshNeshat · **Posted:** Wed Nov 18, 2009 1:26 pm

Good point with the dirt haha. I've got the same theory, just wasn't thinking strait.



Keith Vail · **Posted:** Wed Nov 18, 2009 3:19 pm

Vincent Keene wrote:

OK cool. I didn't know that. In that case the best way to learn to launch an NO4 car is to watch Mark Hoerath. If you are worried about damaging the car then don't expect to do as good as he does.

I seem to remember for the longest time you told me I was one of the few that would actually launch my AWD car off the start. :lol:

I used to rev the Legacy up to about 4500-5k and dump the clutch. You get wheelspin so it is not hard on the driveline at all.

RichardNuss wrote:

In the Audi we take it easy on launch because there's a clunk in the rear-end that we haven't figured out yet.

Richard that noise is probably from the rear diff moving when you dump the clutch. STi's do it on pavement when you launch them if you haven't upgraded to stiffer mounts. The stock bushings allow the diff to move and hit the floor. I have driven a few STI's that will do it on a hard 1-2 shift if the bushings are getting worn.

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