launching
 

anyone can explain a good way to launch a STi? any help would be great thanks

good question id like to know also!!

i've got a built wrx, I haven't driven an sti but this may help. I hold it at about 6000 and slip the clutch a little to get it rolling and then dump it. I get consistant 1.73 60 ft

i usally drop between 6 and 65000 rpm.just some light slipping and away she goes!;)

so I guess the launching sweet spot is close if not the same. well... mines not stock, but you know what I mean

I am going to Ennis Friday night to run the 1/4 track. I have never raced on the track before. I am hearing that because of the rubber in the concrete you get alot better launch than Street.

So my question is do you start differently on the track than street? Street I normally take to 6500 and dump it. My concern on the track with the power I am pushing dumping it with alot of traction I will break something. So best to ride out the clutch at first or dump and go that is the question.

WRX-rated.. What your going to want to do (track, prefferably never street) but your going to need to pre-load the clutch to help prevent damage to drivetrain, tanny, differential, drive shafts blah blah... Do this by finding the "cross-over" point on your clutch pedal.
1) Next time ur in first, practice by slowly letting off the clutch time after time, where you begin to feel when you have total controll over the point on which your car begins to "lurch" and the mm's before it when it remains disengaged.
2)Master this cross-over point to where (at track/street) you will find this point even when your nervous (like before the race begins)
3)While at this cross-over point, you slowly begin to feel the car lurch, rev it to about 5k and keep it there, and when the light turns, just dump her and mash that gas.

pre-loading the tranny should always be practiced in every race. its a savior to your drivetrain (this is good for you soobes- who have the glass box!! ) The reason this method saves axles is because when you just "dump the clutch" it takes enertia, and brut, sudden force to get all the power to the fly wheel, then to the gear box, then to diff, then to the drive shafts then to bearings/wheels. Its like a rock hard his to all those parts when you dump the clutch.. But when you pre-load, all the parts are already filled with energy, its merely the weight of the car holding it back, untill you let the rest of the power reach the flywheel after the light turns green. :banana: :cool:

nicely said

So you're basically saying that you should like rev the motor up to about 5,000 rpms and have the clutch pedal in the position where you feel like it's about to engage and just drop the clutch??? I'm alittle confused because like the word "drop" in subaru language i've known is like the worst word! so if you could maybe explain alittle better that would be great. I want to learn how to launch properly. I have had some pretty good slipping launches but I want to know the best way. It's alot harder to launch a AWD car.

Thanks,
Raymond

reply to esracer
 

In theory, yes. But the most critical aspect of this type of launching is that your tranny/drive-train is pre-loaded. Pre-loaded with power that is. In your diff and in your tranny (basically ALL of the drivetrain parts) Example pic of a diff:[IMG]http://cougar.slvhs.slv.k12.ca.us/~pboomer/physicslectures/machines2/differential.jpg[/IMG] See how many teeth there are on just one gear? All those teeth NEVER touch each other untill under power... Meaning there are small (hundreths of an inch) gaps when there is no power driving them to push the other causing the "wheels to turn".
Basically what im trying to say is, when your at a stop (in neutral, or in gear with clutch pressed in etc.) all the gears and essentual parts of the drivetrain are at a stop too. They are "relaxed" and when they are in a "relaxed" position, they have small gap between when they are "relaxed" or when they are "working" (given power when under accelleration)...
When you pre-load the clutch you are taking away that small gap between the teeth that were once "relaxed." Pre-loading, essentually, puts the teeth together, by letting the clutch out to the point where you can feel the car moving merely millemeters, the teeth are at work, meaning the gears are at work. This puts little stress when you let the rest of the clutch out when the light turns green... Because all of the jobs those gears had to preform where all ready, all you had to do was let the rest of the power to the flywheel. Do you understand better? (if not ask questions!!! Its the only way you'll learn.) This method of "pre-loading" goes for FWD,RWD,AWD, less stress means more life for parts.
When you dont pre-load- and let the clutch free- all the gears and teeth have a sudden EXPLOSION of power, to quickly get their job done. This EXPLOSION really relies on those teeth moving the thousanths of an inch to come in hard contact with eachother- causing broken parts over time... With the more HP the more the explosion remember... And no, im not telling you to "drop the clutch at 5k" the RPM that you want to launch at is different on every car- depending on the MODS you have etc. etc.
-Ken

Hey man thanks for that info, that was great!

No prob bro!
 

Anything for a fellow racer!!

great info I too have been having trouble launching my AWD. I am about to take it to the track for the first time so I need all the help I can get....I know everyone goofs at the track and I am prepared to be humble and get some laughs....

i hold @ 4K and slip. i hate the smell of a burning clutch. bah..

this pre-loading stuff is kind of confusing...because if the car starts moving forward aren't the gears partially engaged? so wouldn't it strip the teeth if you apply too much power at that point?

thanks for the write-up 10sechonda!! if only u could come to my house and teach me.


also, is there any way to launch w/o that burnt clutch smell? its kind of embarassing when u pull up and ur car smells like @ss haha.

and finally, which is worse for your tranny, slipping the clutch or dumping the clutch? i heard somewhere that slipping the clucth wears out your gears more...