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Launch your Evo they said, it will be fun they said....

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43K views 312 replies 71 participants last post by  pturnerIV  
#1 ·
Well, this weekend I thought I would perfect my launch on my Evo! After getting my failsafe changed up and letting me use launch control without going off I thought I would give her a rip!

Well the first time I did it on Friday night I took traction control off and everything pushed the clutch in, put it in first- and romped on the gas... Well with my set up I haven't launched it much to perfect it and get the best place for launch control and with how big my turbo is we set launch control at 7000rpm to start.

As I hammered my foot down on the throttle I watched anxiously as the rpms rapidly accelerated to 7000rpm and proceed to bounce right there. After about 1-2 seconds I let loose of all 400ish ponies I was on and she took off- but once again she completely bogged down like it always had done in the past, but it felt better and I could tell that this time it wasn't the failsafe going off- it was the lack of power to keep the tires spinning and boost rolling in before she bogged down!

So I started thinking about it, and I had an idea: maybe if I romped on the accelerator and let it go a little longer before I let it loose I could build some boost (Looking at my boost gauge it always appeared to be a '0' when I launched).

Well I picked up my girlfriend took her out to lunch and went to a safe place to practice a launch. As I sat there with her I took all traction control off once again, pressed in the clutch, pushed it into gear, wiped the nervous sweat off my brow and proceed to hammer down once more! Well sure as shit I was right! I watched the little needle proceed all the way up to 7000rpm to be sure it was behaving, then quickly switched my gaze to my boost gauge. I watched for what seemed like a quick second and all of a sudden a magical thing started happening- the gauge started reading off boost! 1, 2, 3, then 4lbs of boost started appearing in the tiny digital numbers. As the gauge hit 4lbs I couldn't hold back any more I was so excited so I dropped the clutch! Well for a split second I was amazed, I thought for sure everything was going perfect and I wasn't going to bog down at all! Then it happened... BOOM!

I went about 10ft then I proceeded to coast a little ways down the road.. As I let go of the throttle in disbelief I started running scenarios in my head- Did I just blow my clutch apart? Is there a new fancy window in my block? Did I leave my transmission 20 feet behind me? I was horrified! When I finally stopped I hoped out and looked underneath my car and saw a huge puddle of oil pooling up on the ground coming from my rear differential! I was so disappointing. I never even thought of something like this happening! I tried looking underneath my car at it to see the damage but I couldn't see anything as the car was too low.

After a while I thought that I should walk back to the place of launch up a ways and see if I could see anything of significance up there- well I found half of my plug to my rear diff. So I thought well maybe I just put too much pressure on it and it blew out with all the oil. (More of a hope rather than a guess). I also found a trail of oil about 1 1/2' wide by 10' long!

Well after a long process of getting a trailer and getting the car home I finally got underneath and saw the damage:











Well now that I know I have to replace/fix my rear diff... What do you guys recommend? I want to be able to launch my Evo at the drag strip still, but I am terrified of this happening again! I've heard of people doing a 8/9 swap, maybe that's a good idea? Or just getting a used one and putting better bushings and things in it? Or trying to send it to Jack's Transmissions to see if the can fix it still? Their ad says they can do it even if it is cracked, although I think I completely snapped mine in half!
 
#2 ·
Wow, that's scary...
 
#3 ·
Who advised you to set your launch at 7000 RPMs? I'm not very knowledgeable on how high the LC should be set, but that just seems like a bad idea to me.
 
#8 ·
It was a joint decision between my tuner and I. He is very knowledgeable on this platform and I trust his judgment 100%.

I don't even blame him even a fraction for what happened!

But my car doesn't even spool until like 4200rpms- so with the launch control set at 7000rpms I could build boost, and even if it did bog down a lot I was thinking that it would still be in the range of spooling boost and it would still launch hard!
 
#5 ·
That's the stock setting. I know that we've had the ability to change it for a long time. I just wonder why you would.
 
#6 ·
I thought it was 'go ahead and launch an MR because it has launch control built into it, but launch a GR with care and caution because you can break expensive things if you mess it up'?

My practice has always been - AWD cars like my STi or this car, aren't for launching, they are for autocross and handling. If I wanted to launch something I'd get a Mustang or something else RWD.

Good luck with the repair, hopefully you didn't trash your transfer case (4600 to replace), or anything else besides your rear differential.
 
#9 ·
Holy shit! Now that is how you break a diff. Forget cracking, leaking. Blow that bitch in half!!! lol.

So when you are launching the car... Do you just hit the gas and let the clutch go? If so, I would recommend letting the clutch out slightly until you feel the grabbing point, then smoothly letting the clutch out the rest of the way.

Either way sucks that this happened. But man if you are going to break something, don't half ass it, go all out like this!! lol.
 
#12 ·
Hahaha if I am gonna go out, I am gonna go out with a bang!! ;)

Yeah I definitely need practice and teachings on how to properly do it! (If I ever do it again! Haha)

When I did it I find the engaging point of the clutch and go just past it, then when I dropped it, it was right there to engage. But yes I just solidly dropped it, no smoothness in it at all really! I definitely need some coaching haha
 
#10 ·
Sorry to hear this story... There's a proper technique to launching these machines over and over again without failure.

BTW,, I have a used rear diff in stock if you want to replace this one quickly.
 
#19 ·
Also quoting this incase you missed it^ Got a used Diff for you right there, unless you have the money to upgrade :D.

Good luck to you bud. I have launched my car a total of 2 times. Once in stock form (messed it up horribly) Then I went and researched it, tried it the second time after being tuned at Kozmic. I knew what to do and how to do it... But my clutch didn't. LOL!!! The stock clutch really cant handle any power above stock levels hahaha.
 
#11 ·
Damn that sucks. Sorry to say but this is a simple case of driver error, not the 7000rpms. You clearly didn't preload your drivetrain and just dumped your clutch. You should have been taught how to do this before trying. The fact you didn't know it would build boost means you didn't know what you're doing. Expensive mistake.
 
#14 ·
Sorry to hear about this, back to drawing board?
 
#18 ·
I guess some people misunderstand launch control. This thing is not intended to spin tires at take off. This thing is to build boost to accelerate you faster without (or a little) tirespin.

I wish I could ever use it. But no way with my carbon clutch I only have to options: to spin tires or crack diffs.
 
#20 ·
Damn, may be it's better to let the stock clutch burn to hell than to break the diff in halfs...

I launched quite a few times on tarmac, and trickiest thing was to balance the clutch release vs bogging. Eventually I got it right, but I am still very nervous every time I am about to launch... it's $1200 on the table every time(if you are not lucky then $$2500).
 
#22 ·
See stuff like this scares the SH*t out of me for even trying to lunch my car. Sorry about what happen hope there isn’t anything else that broke that you can see. Best of luck sir, and keep us updated.
 
#23 ·
But when you launch hard and successfully, it's a feeling worth trying for :) I would say it feels times better then airplane take off ;D
 
#28 ·
Just a launch technique question: Suppose you have an infinitely strong drivetrain that can absorb all punishment. With an AWD, would you then just dump the clutch from redline?

And is the reason why you clutch slip to absorb all the shock that would be transmitted to the drivetrain and prevent breakage of the non-infinitely strong drivetrain components?

For MR owners, any pros to increase the stock rpm launch threshold? Any cons?
 
#29 ·
In this case either your tires will give out and you will spin the wheels, your your engine will bog down and you will just loose power - you need some slip to transfer the power to the wheels without bogging down.
 
#31 ·
Yeah I think everyone agrees that I am horrible at launching, and that I need a lot more practice! Haha

So obviously I need a new rear diff! But my question is what to do? I have had a few people talk to me about selling one they have, but I also heard an 8/9 swapped rear diff will be stronger than a X's rear diff! Opinions on what to do from here?

Also while fixing my rear diff what else should I look at that could have also been busted during my time of stupidity! Haha
 
#38 ·
DAMN man! That just makes me cringe. At least you got a good shop to help you out! Buy a used diff from one of these guys, swap it out, inspect/feel out the rest of the drive train. After all that, if the used diff isn't to spendy, grab a second one and send it in for some strength. From what I know of you, this Will NOT be your last launch, you enjoy the car too much. Then switch in your beefed up unit and sell the second. You are up and running and getting seat time the whole time.

Come up here and I will let you help burn my clutch to learn. :rock:
 
#40 ·
Whoa! This is insane. Glad mine didn't look like this. I'm sending my T-case and tranny to Jack's this week.

As for launching. How far do you have the clutch down while you're bouncing off the launch control limiter?

I had the same bogging issue when I first started learning to launch. I found that it helped a lot to have the clutch pedal JUST far enough to get the trans in first gear.