im scared to launch

[razrman8]

Alright guys. I have a 99 gsx.. and I've been wanting to launch it for quite some time.. only thing is.. I'm scared that Im going to BREAK something. Like launch to hard and transfer case... BOOM. How do you guys launch. Do you suggest just not doing it

 

[razrman8]

Very nice input guys. I installed a new slave cylinder, bench bleed master-cylinder, bled master , and bled slave and my car is driving so good its scaring me.. Especially on downshifting. It's so smooth

 

[gusu]

The best results for launching are USUALLY this.

Rev up to 4500 but kind of surge it a bit so you build boost. Don't do it for very long and don't do much more than 4500 or in most DSMs knock may be logged.

You want to granny the clutch out like a normal shift while you go WOT.

If you have a logger I'd check to see how much you can get out of your car but any more than 4500 RPMs I have just chirped the tires and not taken off any faster.




Totally forgot to mention you don't really want to launch on a stock clutch.

 

[VETTE_50_TH]

Where can i get some sink-rows? Does sears sell them??

 

[jjrock5]

How to launch:

1.Press clutch in, shift to 1st gear
2.Rev engine to ~8000 RPMs
3.As soon as RPMs are reached quickly let off the clutch pedal
5.You are only now a true DSM owner since your car is on jackstands

 

[BIGBLAZE79]

My stock clutch did not last long launching. I got about 10 to 15 launches out of it and about 30k miles. It gets very hot quickly when you launch. Once its hot it slippes worse so don't continuously launch on it with out giving it some time to cool down. That being said I could not emagine having an AWD and not launching the car. It gives me the shakes sometimes it's so fun, oh wait that's cause I'm so scared of exploding my 3rd tranny oh BTW I have an ACT 2600 clutch.

 

[niddydsm]

How to launch:

1.Press clutch in, shift to 1st gear
2.Rev engine to ~8000 RPMs
3.As soon as RPMs are reached quickly let off the clutch pedal
5.You are only now a true DSM owner since your car is on jackstands

Sad to say but very true i have owned 4 now in the last 5 years and every last one of them has broken a major component. This is my first AWD and i burnt my clutch up within like 2 weeks don't know how good the clutch was when i got the car but definitely gave out. what i've learned from this AWD is gas before clutch !!!!

 

[TheMitsuGS-T]

How to launch:

1.Press clutch in, shift to 1st gear
2.Rev engine to ~8000 RPMs
3.As soon as RPMs are reached quickly let off the clutch pedal
5.You are only now a true DSM owner since your car is on jackstands

1... 2... 3... 5???

 

[razrman8]

Thank you you guys for all of your input its greatly appreciated

keep this thread going!

 

[2gmummy]

1... 2... 3... 5???

i think 4 is: pick up your pride and drivetrain parts throw them into you dsm and call for a tow

 

[jjrock5]

haha. I can't count or type.

 

[TimIacobucci]

I noticed everyone(well not everyone) mentioning setting up launch control on the ECMLink. What about us poor sod's that don't have ECM, any "rev limiters" out there that aren't using ECM??
Just curious as I'm building a car for the drag strip and eventually will maybe go to ECM, but with the budget going on new engine and clutch, plus all the other nice things for the track, I don't have $1000 spare for EPROM and ECM.

The issue with that is being able to tune for engine modifications. If you are building the car specifically to drag race it I assume you are not using a stock engine and turbo. Tuning is what will make a powerful engine/car fun AND reliable.

I've heard horror stories of guys demolishing the center diff ( are they talking about the transfer case or something else), as I thought we only had 2 diff's front and rear and the transfer case was a gearbox of sorts that split the power for the axles. Just a little confused over the terminology some guys use and would like to have some solid facts as whether the "center diff/ transfer case" is going to hold up to launching on the strip.

And awd car has 3 differentials, to differentiate front side to side, rear side to side and then a center differential front to back. Our center differential is inside the transmission along with the front diff. The output shaft from that center diff feeds into the transfer case, which is just a geared 90 degree turn to connect to the driveshaft and on to the rear diff and rear wheels.

This is confusing because most transfer cases on trucks that are full time awd and other cars which are awd do contain the center differential in them.

The weakness of the center differential is the 2 stock spider gears, this is why aftermarket transmission companies make 4 spider differentials. This still uses the stock viscous lsd.

The alternative to this is welding them together to essential spool the center diff. This is a good setup for a pure frag car because it is strong and puts more power to the back sooner rather than relying on the stock viscous coupling to do so as the front tires loose traction. These are a speed sensing type of limited slip device and do not react very quickly especially if old and worn.
The downside is the tires need to slip to turn because there is no longer and front to back differentiation. This means tire chirping and squealing and pain the ass parking. Find a friend with a 4x4 truck (non awd, just 4wd) and lock in the 4wd and drive around town some, turn slow and park and see how it feels. Most all car manufacturers specify NOT to use this system unless off road for this very reason.

The other $ alternative and probably best all around solution is to get a kaaz or quaife center diff.

The other side of this is putting more power to the back will stress everything from the transfer case to the rear axles more. Putting more power to the back will make the car hook harder and launch more like a rwd car than a fwd, this will transfer more weight to the back and load the driveline even harder. With enough power this is when you start to break things like transfer cases and rear axles.

ALSO, it was said, that the the transfer case wouldn't give up at HP less than 300, which is comforting to know, but is that a general rule or pretty good numbers to take to the bank. I'm running a 4bolt LSD rearend with what will eventually be a 6 puck clutch on the stock transfer case and stock front diff'.

The front diff will not be the problem as the weight transfer puts more load on the rear in a properly functioning awd system, you will not strain the front driveline as hard as the rear. The first part of that system is the center diff and it's stock 2 spider gears.

There are lots of guys running 4-500+ hp on the stock transfer case and 4 bolt rear.

The 6 puck is the debatable part. It will work well for hard launches and quick times but it may also be good at breaking things. Like many people have emphasized in this thread already, the key to launching while not hammering driveline parts is preloading and a progressive clutch engagement. 6 pucks are not known for doing that very well, you want something that will slip, or an automatic.

Another good tip for preloading on the launch of a an awd car is using the ebrake. Engage it at the line and let the clutch out just a bit until it is slightly dragging against the brake then drop the brake and let the clutch out quickly without dumping it. This keeps the whole rear driveline tight and can mitigate the massive shock loading manual cars can have.

 

[LKWTSI]

Thanks for the reply "TimIacobucci". That's exactly the knid of response I was hoping to get.
As for my plans. yeah the motor is a rebuilt 6 bolt with a 0.020" overbore, stock cam and pistons, going to be running MAF/MAF-t and eventually 650 injectors and SAF-C. EvoB16G on a aftermarket O2 and 2G mani All ported and such. pushing the fuel up with a 255 HP and AFPR.
The drivetrain will be on a Fidanza flywheel and the clutch was still in the decision stage, but thought the 6 puck would be the best at handling the torque as I've heard guys saying the springs on disc clutches break easier.
I think I'm going to be fine on the drivetrain from what it sounds like (for the moment) until I start pushing some serious horsepower and then I'll take a look at the options of an aftermarket center diff'.
I appreciate the advice and input.

 

[pj91gsx]

You would rather burn the clutch rather than launch hard. The 1st thing to break if you launch it like JJrock says, is the tcase splines.

release the clutch til you feel the car start to move and let out, it will spin the tires most likely then take off.