How do you guys launch??
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This is a discussion on How do you guys launch?? within the Motorsports Talk forums, part of the Community - Meet other Enthusiasts category; So I was driving around today, running some errands when I found myself stopped at an intersection, no other cars ...

  1. #1
    Registered User BenS's Avatar
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    How do you guys launch??

    So I was driving around today, running some errands when I found myself stopped at an intersection, no other cars around in an industrial area. Something inside me kept poking at me to do a launch. So beings I'm still in my break in period and don't want to ruin my tranny, I tried to do a conservative 3k launch. I rev'd to 3k, held it there and dropped the clutch. Drop meaning I lifted my left foot off the clutch as fast as possible. Then I heard a huge THUMP coming from I believe the rear of my car and my car did not take off as expected.

    So, not sure what to think here. Am I not supposed to launch this way? Is the thump normal? Could it be possible that it scared me and I naturally eased off the gas when I heart it? I felt myself being pushed back into the seat but I think I must have let off the gas being shocked by the thump noise.

    Curious if anyone else has experienced this in their 09-10? How do you guys launch?
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    Registered User kbrownmann's Avatar
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    since i have never tried to launch my car, im not so sure about the technique. but i believe the thump was the driveshaft ( someone please correct me)
    the thump happens because:
    in a fwd car when you drop the clutch you get a burnout, but with awd the wheels wont lose traction, so some of that extra energy was absorbed in the driveshaft.
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  4. #3
    Registered User BenS's Avatar
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    Ouch, I'm too scared to try to launch my car again.
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    The Fruit mangostick's Avatar
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    Quote Originally Posted by BenS View Post
    Something inside me kept poking at me to do a launch.
    next time tell it "NO" when it pokes you ..

    Am I not supposed to launch this way?
    Its not advised..
    Is the thump normal?
    You've now experienced what is called "diff clunk" ..
    Could it be possible that it scared me and I naturally eased off the gas when I heart it? I felt myself being pushed back into the seat but I think I must have let off the gas being shocked by the thump noise.
    no that was the traction control snipping the balls off because you scared it.. well not quite but if its on and a wheel spins.. it backs the throttle right off. Besides, launching is not good for trans no matter how lightly you do it. There are more effective ways to come off the line quick without shock loading the drivetrain.

    Curious if anyone else has experienced this in their 09-10? How do you guys launch?
    yep, once.. and it wasn't a launch but catching 2nd too hard on a combo of slippery and not slippery surfaces. Scared the crap out of me and to boot at same time the tc kicked in and snipped the balls off.. I thought I broke it, a quick second later though all was fine. I was already rolling so not as bad but launching really isn't good for any awd car.

    turn in concepts makes a anti clunk kit for the earlier cars, its caused by the diff mount bushings being soft and allowing the diff to move around under load. If you call them I'm sure they can help with a rear kit. When I get motivated I might do this with my 2010. I'm thinkin between that and the sti motor/trans mounts it will smooth out the driveline nicely.
    Last edited by mangostick; 06-09-2010 at 09:39 PM.
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    Registered User kbrownmann's Avatar
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    from what ive heard, it takes practice. its more of an art of "slipping" the clutch. its less stressful to the transmission. id say wait till the break in is over and try a few techniques. see which one works best for you. also since i am not too firmiliar with it, there is a thread on it here somewhere
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    Registered User kbrownmann's Avatar
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    Quote Originally Posted by mangostick View Post
    next time tell it "NO" when it pokes you ..

    Its not advised.. You've now experienced what is called "diff clunk" ..
    aha so i was wrong. the differential was my next assumption lol thanks for clearing that up
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    The Fruit mangostick's Avatar
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    Quote Originally Posted by kbrownmann View Post
    from what ive heard, it takes practice. its more of an art of "slipping" the clutch. its less stressful to the transmission. id say wait till the break in is over and try a few techniques. see which one works best for you. also since i am not too firmiliar with it, there is a thread on it here somewhere
    Pretty much.. well with any turbo car you dont want to just wind up and dump.. since you're not making boost you're not making power. Effectively all you would be doing is shock loading the driveline without any positive outcome. The old saying goes "make power IN gear not between them". Granted you're in gear during a "launch" but that impact wrench effect when the driveline is shock loaded is what blows gears apart. Getting a good slip to build boost and start the car rolling without toasting off the clutch IS tough to learn.. but very doable. In 19K mi I've gotten pretty good at it now.

    regardless the better bushings or at very least inserts for the rear are the way to go. That way even if you slip and boost off the line you're diff isn't doing the "wiggle n bump" all over the place.
    Last edited by mangostick; 06-09-2010 at 09:48 PM.
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    Registered User BenS's Avatar
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    Ah that explains a LOT. Thanks mangostick. +1. -1 to me for being a dumbass. Might have to look into that anti diff clunk thing. I used to drive a rwd with decent hp & torque so dropping the clutch would just cause it to squeak and take off... 1st time with an awd car. MUCH to learn for me.
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    The Fruit mangostick's Avatar
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    I'm coming from a fwd daily driver and a 400hp rear drive euro ford. ( I wanted a car similar to both.. so I got a wrx)

    The merkur (odd euro ford) has a bushing mounted subframe/diff and irs kinda like the scoobies do, just older and a little less functional. With factory bushings they clunk like HELL if launched.. as well as a crap load of wheel hop. Mine actually had a mark on the floor pan where the diff flange had whacked it a few times. Same reason some of the old muscle cars have a large "snubber" on the diff housing. Even with a straight axle.. stuff still wants to move when sharp force is applied.

    oem's use a soft bushing to keep noise and vibration out of the cabin.. they're great for grandma but terrible for spirited use. (goes for any and every car)

    The bushing kit will take the clunk out and sharpen things up.

    Just remember about launching, you're developing momentum at one end and all of a sudden trying to stop it with the weight of the car at the other end. That energy has to go someplace whether the car moves or not. The weakest link is whats going to give. Most times its traction.. but with awd, we have lots of traction.. so some part of the driveline will give just like a fuse.

    Next time the launch demon comes knocking at your ego remember something always has to give. Either the car moves, tires spin..or El Kaboom pays a visit.
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    Registered User Graham46's Avatar
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    Mango I have a question-

    Do the bushings really eliminate the problem or do they just transfer the shock to somewhere else? Im not positive, but I think I remember reading that replacing the bushings may get rid of the noise, but if the same driving habits are still being used, it would just transfer the same negative shock/energy to somewhere further up the car? If you can swat this theory down, Ill def look into getting those bushings in the future
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    Registered User Heide264's Avatar
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    Been reading around NASIOC a bit on the subject, seems like there are a couple common ways they do it over there.

    The general idea is to make a weak spot SOMEWHERE in the system that isn't the most expensive part. Normally the clutch or the tires. One of those 2 has to "give".

    You need to go balls to the wall with you launches to get tires to spin (ballsy) if you are going to dump it. There is a few techniques on this threat people use to get boost to help spinning those tires... I lied can't find it, will post it later if I find it. Otherwise, the idea is to slip your clutch, so the clutch takes the heat. Literally, a lot of heat =P. Both techniques seem to work well. Everybody on the forums was commenting how their soobies were the hardest cars they've ever had to launch correctly, so don't get frustrated.

    ...If you plan on doing this a lot, plan on replacing a lot. It's not cheap, but after you get it down a lot of people over there seem to be doing okay.
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    Registered User tarmacsti's Avatar
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    This is how I do it...

    1. Make sure you are on a level road, launching on downhill or uphill is dumb... esp when you still learning!

    2. Rev up the car to 4500 rpms

    3. Let out the clutch to take up the slack of the diff and any components that may get a sudden shock.(but make sure you dont move and inch, this can be done by pulling up the handbrake - slightly till you find the sweet spot then let it down and put both hands on the steering)

    4. In a single motion let out the clutch as quick as you can blink and put your foot flat on the gas! (I exhale when doing this for better concentration/transition)

    5. Be careful at this point since you might have to hold on pretty tight and be ready to change gears quickly, to soften the blow you just gave the car shift into 2nd and only then let go of the gas.

    note:
    if you smell clutch you doing it wrong
    if you hear the prop/diff hitting the undertray you doing it wrong.
    getting off the line quick and smooth is the trick (art) it can be done with any car without damaging it.
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  14. #13
    The Fruit mangostick's Avatar
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    Quote Originally Posted by Graham46 View Post
    Mango I have a question-

    Do the bushings really eliminate the problem or do they just transfer the shock to somewhere else? Im not positive, but I think I remember reading that replacing the bushings may get rid of the noise, but if the same driving habits are still being used, it would just transfer the same negative shock/energy to somewhere further up the car? If you can swat this theory down, Ill def look into getting those bushings in the future
    Oh not thats not a theory... its a fact and you're correct. That force HAS to go somewhere, so yeah after you strengthen one area it will travel to the next weakest link. Bushings though wont make enough difference to put anything at risk that wasn't already.

    That 5mt has a big bullseye on it anyway.. its not likely your going to break a driveshaft (or prop shaft as they call them over seas) and the diffs in these cars are very strong despite small size.. so the trans is next in line excluding the clutch. It is literally the HUB of the driveline. All roads meet at the transaxle.
    .. not that I've heard of anyone breaking a 5mt yet on the 08+ cars.... but that doesn't mean its not possible.

    Now that being said though, doing the bushings does a couple things. Removing the slop in the driveline makes power transfer smoother. Minimizing shock loading and unloading prolongs life of components. This includes the trans. Only risk is a slight bit more nvh into the cabin but most people dont even notice.

    Driving habbits and abuse will have a lot more negative effect on the trans/clutch/diffs. There really aren't any negatives to doing the bushings.
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    i too think that Getting a good slip to build boost and start the car rolling without toasting off the clutch IS tough to learn..



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