can someone please explane to me how to let the clutch "slip" on launching.
i've just been dumping.
my best time so far is 13.5 @103mph ,60' 2.0
and also any other help and advise would be great. going to WAW the comming up wednesday and really wont a 12 pass.

Info taken from wrxfanatics:http://www.wrxfanatics.com/index.php?showtopic=22007
I've never run the 1/4 so cant offer any personal advice

Hope its of some help....otherwise I'm sure a few other folks have tried and true techniques.





QUOTE There are two things you need to accomplish to get a good launch in the wrx.
You need to launch under some boost,
and you need to control the load on the engine so it stays near max torque rpm for the first few feet without banging the clutch and shock loading the drive train.

There are several variations on the theme and each person will discribe it slightly differently but you want to engage the clutch quickly and smoothly so it slips just a bit with out just side stepping the clutch, or frying the clutch by holding it at partial engagement. The newer 2003 cars have a flow limit valve in the clutch line so you cannot just let up on the clutch and break things. It slows down the engagement just a bit. On the 2002's you'll have to do that yourself.

One of the top WRX drag racers in the country describes the technique where you stage, and then let the clutch out a bit until you can tell it is just ready to engage (the friction point) is just a fraction of an inch away.

Hold at a moderate fast rpm (everyone picks a slightly different number) I use about 3000 3500 rpm.

Now comes the key to launching under boost.

You can only build boost under no load conditions when the engine is accelerating at WOT .

Just as the second yellow comes on, stomp the throttle to the floor from your stage rpm, the engine will take about a second to rev to red line. There is only .500 seconds between each of the yellow lights.

Watch the tach and as the rpm swings by 5000-5500 rpm let up on the clutch quickly.
(you can't wait for the green light you have to start leaving on the last yellow)

Since you prepositioned the clutch right at the friction point there will be very little clutch motion, or shock, your engine will be very close to 5500 rpm when the clutch engages and under some boost because you floored the throttle a fraction of a second earlier. If you get all that coordinated you should have enough torque and energy stored in the flywheel so the engine does not bog.

Hang on !!! you will be accelerating at over 1 G and hit red line in low in about 1.5 seconds.
Be ready to shift !!!!!
The biggest time loss that keeps folks at 2.x seconds is a slow shift, you have to shift quickly to get back under power in second gear before you complete the first 60'.

Shift quickly and firmly but NOT VIOLENTLY !!! your not trying to break anything just be quick.


I tell folks to hold the shifter in their fingers not to grab it like a club, this gives you more feel and makes you less inclined to try to rip the shift knob off the console.



2. Shift Points for Drag Racing.

This is debatable as to what is the best way. Pretty much there are two schools of thought. One side believes you should just run everything out to redline, and than shift. The other school of thought is that you should short shift, right before the cars starts to lose power.

HERE is a link to a discussion about this from this forum. It also leads to another link that has a optimum shift point calculator.

There also seems to be a change in shifting between the WRX and the STi. I have found that I get the best acceleration redlining 1st, and than shifting at around 6200-6500 in the rest of the gears. This also seems to have gotten favorable reviews from other STi driver sources.

3. Double Clutching

Again, another LINK to a source on this forum that discusses this. Here also is a LINK to an outside source for info on Double Clutching.

The biggest thing in learning to do this is practice. Eventually with practice it will become second nature.

4. Tire pressure for the track

Once again, another LINK to a discussion on this site.

As a note about tire pressure, when at the drag strip with a WRX or STi you are better suited in INCREASING pressure. This will help brake the tires loose a bit. This helps reduce the shock on your tranny, among other things. I have had my pressure as high as 45psi all around when at the drag strip with stock tires.

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meh

thats gold due, perfect
thanks!

what do ya think is best rpm takeoff ? so it dosent bog and dosent wheelspin either?

Thanks for those links, Maniac.
I've been double-clutching with heel-toe around the tracks, and it works a charm, but the instructor said to do it BEFORE i start turning. I tend to do it just as i start to turn, which obviously is bad. I can't grasp rev-matching and then letting the clutch out without my foot on the accelerator, just feels abnormal. Anyone got any tips? Should my foot still be on the brake when heel & toeing as i let the clutch out?

Sorry to go off topic. I'm no launching pro Hi-Voltage, but slipping the clutch has worked well for me when the occasion arises.

I'm no Colin McRae but yeah the idea is you grab the lower gear before you enter the corner. That way your also using the gears to wash off the speed. There's enough stuff going on in a cnr with trying to get the right line, making sure the weight is balanced ect, ect. So if you can get the gear change out of the way that’s one less thing.

As you say it is instinct tho to put the clutch in when shit goes down. I remember a crash I was in, after everything had stopped spinning I realized the clutch was in & the engine still running.

Double clutching is just practice, you get into the practice of doing it every cnr you take & after 6 months you won't even think about it. You'll rev the shit out of your car or bunny hop till you get them right. You also feel like a bit of a wanker doing it all the time but it does pay off. When you get one spot on it’s an awesome feeling.

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Ho's gotta eat too

Picking the revs is just experience I guess....I'm not a heel-toe expert, but I learnt to down shift using double clutch in trucks many moons ago....so I can usually get the revs right that way. Heel and Toe is a newish trick for me so still getting the hang of that.

I'd say most of the time you would still be continuing the braking manoevure with the heel-toe after releasing the clutch...theres gunna be some corners and situations where you may need to be back on the noise instantly, so guess how you handle it is up to you and your car.

Get everything sorted before iniating the corner - keeping everything smooth is the key. Concentrate on being smooth above and beyond everything....getting faster will happen as a result.

I'm sure some of our erstwhile instructors on here can clarify better than I.
In the mean time....another link from my collection: Heel-and-Toe Guide

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meh

Higher than 4000rpm so it doesnt bog, lower than 7000rpm so it doesnt spin.
Depending on how the track and your tires are, depends on if it spins too. I know a couple of ppl that have gotten 1.6 60" in a rex by holding revs on limiter and sidestep clutch with new tires tho.

Hard launch
Flat shift
Good tire tread
Good track
Boost....

This will help you get a 12!!

NB: If you want a good time, you gotta be prepared to punish your car and gearbox.

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09 Evo X

Haha yeah i double clutch/heel & toe on the street. I think some people wonder what you're doing, but it makes everything THAT much smoother, and you know your car is loving it with no jerky transitions.

Cheers for the advice boys.