E-brake launch??

[Ron]

If you watch like the gymkhana videos or alot of stage stuff the drivers use the e-brake to launch?? How does this work? wouldn't the e-brake be detrimental to launching?? I'm confused :?

[DoWork]

You use the brake to hold the car in place so you are not standing on 3 pedals at once....

[vicali]

Are you sure it's the e-brake?
On some WRC cars the sequential shift knob is there too;
When they start at the line they rev up and push it into gear..


http://www.autorika.com/wp-content/uploads/2011/04/2011-Ford-Fiesta-RS-WRC-%E2%80%93-Interior-View-670x502.jpg

http://www.speedarena.com/gallery/albums//Rally/WRC/2003/00%20Skoda%20Fabia/005.jpg

In the cars with 'flappy paddles' there is only the e-brake lever;
But you still see them push the paddle when it's time to go.
http://image.modified.com/f/17352706/0203_03zoom+WRC_Subaru_WRX_STI+Interior_View_Dashb oard.jpg

[acco205]

It to hold the car in place while you are waiting to launch. Drag racers do it too.

Basically the idea is one foot on the gas to get revved up, one on the clutch (necessary even with sequential gear boxes) and then right hand on the brakes so you dont roll off the line.

You let off the hand brake just before or just as you let out the clutch. The system moves fast enough that if done right it shouldnt slow you up at all. Its also a handy trick when someone gets right on your ass at a stoplight going up hill and you dont have hill assist. Just keep in mind the mechanical e-brake in your car wont react as fast as the hyrdo handbrake you see in the factory cars.

Mike

[409industries]

If you're talking about the Ken Block type stuff, i'm pretty sure its all electronic launch control.

hold brake, mash gas... computer handles everything else.

[LPPrelude]

It is called a "Staging Brake".

Drag Racing, but applies for anyone coming off the line.

You are preloading the clutch and driveline yet keeping the car from moving.
It stops, driveline shock and clutch damage when you drop the clutch.
It also results in better launches and more useful power being put through the driveline.

It is also VERY important for turbo cars as it will allow them to come off the line at full boost.


That is the why.
The how for a normal pedal clutch systems is this.

Push clutch in, put car in gear, pull on staging brake to lock wheels, rev motor to desired rpm, slightly let clutch out until the car starts to want to move forward, let out clutch and release staging brake to launch.

Turbo cars combine this with a two step system and BAM! Neck breaking launches.

[madpanda]

LPPrelude: Thanks for the detailed explanation. What's a "two step system"?

[LPPrelude]

LPPrelude: Thanks for the detailed explanation. What's a "two step system"?

I am unable to get onto youtube as it is better seen than explained.

Basically for turbo cars when you launch off the line you have little to no boost pressure thus resulting in the car bogging untill pressure builds.

Two Step makes launching easier and can be used for both Turbo and NA.
Some people call it launch control.

Example my old drag car was N/A.
When I was on the line at a standstill I would just put the gas to the floor and the RPMS where limited at 4600RPM's. As soon as the car started to move it would then rev out to 7800RPM's.

Now for turbo cars they will also do a spark cut as well.
So not only are you able to just hold your foot on the floor but the car will pick different cyclinders to cut spark to for a rotation and that will then ignite in the turbo itself not the chamber. Hard on the turbo? Yeah, but it also will quickly spin that turbo and create full boost to launch with.


I went ahead and just googled it and found this:
Better explaination than I can give but it is the same.
http://www.enginebasics.com/EFI%20Tuning/2step%20rev%20limiter.html

The other thing is called a "No Lift" or "Flat foot shifting"
Basically, you just plant your foot on the floor the entire race and never lift. More for drag racing than anything else.

You still clutch in/clutch out but the cars ECU controls the rpms when the clutch is pushed in so you don't over rev the motor.

When I had my STI I know that I was able to tune it with my Cobb AP for the Flat Foot Shifting. I don't know if it was able to do the two step out of the box but I am sure Cobb can get you a Map that has it too.


Edit: I REALLY wish I could link the video I am thinking of in my head from youtube. But try and search youtube for Evo 2 step or Evo launching on dyno.

The video has a silver(?) Evo launching on the dyno and just before the car launches you hear this "booog" sound and can see black smoke coming out the exhaust. Then he launches like a freaking rocket.
The hood is open on the video too.

[kold911]

this one?? (http://youtu.be/U2AR5zL_vo)

[madpanda]

Thanks!

The above link is broken, but I think this is it?:
http://www.youtube.com/watch?v=U2AR5zL_voI

[noisycricket]

I do it mainly because it holds the car still. Very useful when the start is uphill, downhill, or deeply rutted and your car keeps wanting to roll...

http://www.youtube.com/watch?v=vGTdsOJ6DKI


I think some WRCars don't have clutch pedals, it's all automatic and holding the handbrake like that also keeps the clutch depressed.

I was going to go so far as to plumb a line-lock in the clutch hydraulics and tie it to a switch so that holding the handbrake keeps the clutch disengaged, releasing the handle = dumping the clutch... but one of the regions I run with has disallowed launching at the start for site preservation purposes. Then I found that the car accelerates quicker if I *don't* launch. Heh.

(wow, watching that video makes me feel old/dumb... I drive so different now, and the car's so much better than back then :) )

[LPPrelude]

Thanks!

The above link is broken, but I think this is it?:
http://www.youtube.com/watch?v=U2AR5zL_voI

Yes it is. At 11seconds you can hear that "bad" sound and see black smoke out the back.

This is in an STI and is more detailed with the tach and boost gauge of what it does.
http://www.youtube.com/watch?v=y_XErSGxpTY

[LPPrelude]

http://www.youtube.com/watch?v=8edSImjg00g

11 seconds
Sound familiar to the WRC style?

Basically, this plus using the e-brake to stop the car from moving and preload the drivetrain.

[tbtstt]

There is very little comparison, if any, between the "launch control" in a road car and the "launch control" in a World Rally Car, rallycross Supercar etc.

The World Rally Car is much more advanced as it uses the handbrake (which disengages the centre differential) and will often be tied into the gearbox as well. For example the launch control on the later Impreza World Rally Cars would launch the car and put it into 2nd gear at the appropriate moment, so all the driver has to do is concentrate on keeping the car in a straight line!

In terms of road cars though the later "fly-by-wire" stock ECU's can have "launch control" enabled, as can a number of aftermarket ECU's such as Simtek, Syvecs, Motec, Pectal etc.

The ECU controlled launch in road cars simply limits the revs when the car is stationary, so you put the clutch in, have the throttle pedal all the way to the floor and the launch control limits the revs to a preset RPM (instead of banging off the limiter). When you drop the clutch and start moving you already have full throttle engaged.

I think some WRCars don't have clutch pedals, it's all automatic and holding the handbrake like that also keeps the clutch depressed.
World Rally Cars have clutch pedals, but they are only used on road sections. As mentioned earlier the latter launch control systems take care of the tricky stuff, leaving the driver to keep the car pointing in the right direction. In stage the gear changes don't require manual clutch input.

[Jblankster]

next time its cold/wet out i will see if i can make a video of my buddys WRX on the antilag+Ebrake launching. its quite good.

[Rex_Saugerty]

i think pastrada did one on this years race of champions. car was on start line but front tires was spinning

[A1337STI]

You can actually do this with heal toe as well, though its a bit tricky.. I definitely haven't mastered it by any means.

left foot is on the clutch

Right foot is covering both the gas and the brake.. I don't actualyl "heel toe" but put the left side of my right foot over the brake, and the right side over the gas.

depress the brake enough to not roll rev it a bit and slowly start to engage the clutch, there will be a point that boost will start to build (and your clutch starts to get abused)

increase braking a touch, increase gas a touch, engage clutch slightly more and you'll start to build some boost, then LAUNCH. you need to slide your foot off the brake as you slam down the gas (I personally seem to get a little stuck when doing that, I'm still faster starting normally.. but i can see how this technique could be faster)

:D

[Jblankster]

http://www.youtube.com/watch?v=qh2J9IETDUQ&feature=youtu.be



theres a quick one we did. think you got the point. lifts the brake to hold the car and slips the clutch which builds boost. also hitting the 2 step to hold the RPMS. once E brake drops RPMS rise and off you go

[noisycricket]

The ECU controlled launch in road cars simply limits the revs when the car is stationary, so you put the clutch in, have the throttle pedal all the way to the floor and the launch control limits the revs to a preset RPM (instead of banging off the limiter). When you drop the clutch and start moving you already have full throttle engaged.


The DSG-equipped Audi TT RS's launch control is evidently fairly sophisticated. Car and Driver noted that the 0-60 acceleration was 1.5 seconds quicker than the 5-60 acceleration, and they never said anything about turbo lag.

Of course, being DSG, the transmission shifts automatically anyway.

(Rather unfortunate that the DSG trans will not make it Stateside, with H-pattern manuals being the only option. Also unfortunate that the car is something like $70k, which is a lot of money for a four-ringed chop-top New Beetle)

World Rally Cars have clutch pedals, but they are only used on road sections. As mentioned earlier the latter launch control systems take care of the tricky stuff, leaving the driver to keep the car pointing in the right direction. In stage the gear changes don't require manual clutch input.I noticed in some cars that the drivers would need to hold the handbrake lever when shifting to Reverse with the paddles. I'd simply assumed that this was manually forcing the clutch to disengage...

[chimchimm5]

If you're talking about the Ken Block type stuff, i'm pretty sure its all electronic launch control.

hold brake, mash gas... computer handles everything else.

Exactly my thoughts. I've been googling to find it but couldn't. There used to be a vid of Chris Atkinson demonstrating launch control. The cars computer knew that if you were at a dead stop, pulled the ebrake, and then mashed the gas, then it used launch control. Releasing the ebrake was the computers signal to GO!!!!

[lance2448]

So I guess I shouldn't try this at stoplights with my dd huh? :p

[Gravel Crew Rally Team]

My AEM standalone has launch control. It works when I'm at a complete stop, clutch in, full throttle and when it hits 3500 rpm it kicks in. Bunch of flash bang! Let out the clutch and as soon as i hit 3 mph it shuts off! Good fun!

[Logic]

Some people use it to stop the car from rolling forward or backwards at the start line .

In some 4wd cars this is counter productive as when you pull the handbrake it opens the center diff. We normally have the diffs programmed that if you come to a stand still for more than 30 seconds it locks the center diff for start mode and pulling the handbrake does not help unless for the GRP N cars now they released a diff control unit that counters that.

For the WRC cars all of the fords except the 01 focus use the handbrake to start the launch sequence , in these diff controllers you have more outputs that you can program in many different sequences .

The subarus S10-S14 (2004-2008) it was all electrical , so you would come ot the start line , push the launch button , until you see LC on the screen , push your left foot onto the brake pedal (over 50BAR of brake force) then release the LC button , put the car into gear with your foot still on the brake , then switch on the ALS and put your right foot to the floor , and when you have the green lights you take your foot off of the brake pedal .

The fords it was more simple , come to the start line , push the lc button , put it into gear , turn on the als , and pull the handbrake back to start the launch and keep your right foot floored , and when the lights turn green you release the handbrake , this was like that for the citroens as well.

[Logic]

i think pastrada did one on this years race of champions. car was on start line but front tires was spinning

because he had the handbrake holding , see my above post to see why.

[Logic]

http://www.youtube.com/watch?v=LpBiZYVfTp8&list=FL939cMALwENEF27bMkULt9Q&index=422&feature=plpp_video

[Logic]

here is the subaru one explained.
http://www.youtube.com/watch?v=xvyVF_ccI2E