Please explain Launch Control

[CarGuyOhio]

I have no idea what the default RPM is. I can tell you in about 2 weeks though. This guy said his was 1400

 

[Bambi]

Well, anymore than I was and I'll be going flintstones style, as I'll be going through the floor. Brakes were bottom out. What more can one do than that?

One of the reviews I read said they cut 2 cylinders during LC because the brakes won’t hold more

 

[CarGuyOhio]

One of the reviews I read said they cut 2 cylinders during LC because the brakes won’t hold more

This is correct. There is a cylinder deactivation to help the brakes. You can really hear it while it is revving in this video.

 

[Bambi]

All the cars I’ve driven with LC I do a few times for fun then never again. Power braking or just matting the gas seems more fun

 

[Humzila]

When we had clutches on our mopars it was called dumping the clutch.

 

[Bambi]

When we had clutches on our mopars it was called dumping the clutch.

That too

 

[Bavanew]

All the cars I’ve driven with LC I do a few times for fun then never again. Power braking or just matting the gas seems more fun

Isn't LC essentially power braking, except for not exceeding the desired/set RPM? The idea is to get the rpm into the power band before releasing the brake.

 

[Bambi]

Isn't LC essentially power braking, except for not exceeding the desired/set RPM? The idea is to get the rpm into the power band before releasing the brake.

Basically yes. But in the trx case it deactivates 2 cylinders so brakes can kinda hold, then lets launch rpm to be simple vs you having to manage the throttle and wheelspin

 

[White881]

On my Trackhawk the max RPM setting my brakes would hold was 2300, that was new. Now that my brakes have 23K miles on them the max RPM that can hold is about 2000. And yes you must mash the brakes to the floor (pumping first helps), then absolutely mash the gas fast as well. Not gradually. Consistently cruises me to an 11.6-11.7 quarter mile.

 

[Bavanew]

On my Trackhawk the max RPM setting my brakes would hold was 2300, that was new. Now that my brakes have 23K miles on them the max RPM that can hold is about 2000. And yes you must mash the brakes to the floor (pumping first helps), then absolutely mash the gas fast as well. Not gradually. Consistently cruises me to an 11.6-11.7 quarter mile.

That's good to know about the rpm. Like I said in my original post, it's currently set to 2,400 or 2,500 rpm. I assumed it was factory default. With that said, what's the point of allowing you to set the RPM any higher if the brakes can't hold above 2k? Starting a launch at 3,500-4,000 (provided that you could actually hook up) would certainly be quicker off the line, but that would never be possible with these brakes.

 

[STRADALE]

I have no idea what the default RPM is. I can tell you in about 2 weeks though. This guy said his was 1400

Adam Carolla has a TRX?

 

[Bavanew]

I suspect people are rolling into full throttle. That’s not the right way to do it. You need to quickly go to full throttle. If you watch a lot of these LC videos you can see the vehicles start to move because the rolled into the throttle and did not get LC to set. Basically the brakes are what’s holding the truck in position rather than the computer. And for the record LC has nothing to do with wheel spin. LC is like a stall converter designed to allow the vehicle to hold and launch at a specific rpm. Traction control is what’s used to manage wheel spin to maximize torque and stability control is what’s use to minimize roll over from lateral force. With that said LC and TC work together to give you the best launch by allowing a higher rpm for launch and minimize wheel spin to maximize torque. Once you take your foot off the brake LC is done and TC takes over. SC kicks in when you start going sideways.
Try again by quickly going to full throttle and see if that works for you. Hope this helps.

Hi, thanks for the reply. Some good information you provided. However, as for applying the throttle quickly, there was no pussyfooting, I immediately mashed it to the floor, each and every time. It says right in the information centre to quickly apply throttle, so, I knew from the beginning that it was necessary.

I suspect that, as per White881 inferred, my set RPM needs to be lowered. It's at 2400 or 2500, and others seem to be less than 2k.
I rolled significantly during the first three launches. I don't recall rolling during the following launches, but that doesn't mean it didn't roll at all.

I have a feeling that, I'll have a successful launch when I reduce the rpm. I'll set it at 2,200 and go from there, lower it incrementally until it works.I'll be a little disappointed if I have to lower it less than to 2k.

 

[Hellasaurus]

Hi, thanks for the reply. Some good information you provided. However, as for applying the throttle quickly, there was no pussyfooting, I immediately mashed it to the floor, each and every time. It says right in the information centre to quickly apply throttle, so, I knew from the beginning that it was necessary.

I suspect that, as per White881 inferred, my set RPM needs to be lowered. It's at 2400 or 2500, and others seem to be less than 2k.
I rolled significantly during the first three launches. I don't recall rolling during the following launches, but that doesn't mean it didn't roll at all.

I have a feeling that, I'll have a successful launch when I reduce the rpm. I'll set it at 2,200 and go from there, lower it incrementally until it works.I'll be a little disappointed if I have to lower it less than to 2k.

Good luck, looking forward to hearing how it goes.

 

[Bavanew]

Good luck, looking forward to hearing how it goes.

Seeing as you seem knowledgeable with LC, I know that you can activate it in multiple (Most) drive modes, but does the launch behave according to the drive mode? Or, does LC adjust parameters best suited for LC regardless of drive mode. Alternatively, do I get a better launch in sport mode than, say, in Auto? Sport mode disables TC (I think it does), but launch control is all about TC, that's why I'm incline to think that it overrides the drive mode.

 

[Variable]

It's junk in the Hellcat hopefully Ram stepped it up in the TRX!

It’s not junk in the demon with the trans brake.

 

[CarGuyOhio]

Adam Carolla has a TRX?

Damn, it does sound like Adam. I miss The Man Show!

 

[Troy dunlap]

I've done with my super snake and it's quite liberating, can't wait to try it with this truck.. at 423 miles! I'm starting with 2400 rpm.

 

[Bavanew]

I've done with my super snake and it's quite liberating, can't wait to try it with this truck.. at 423 miles! I'm starting with 2400 rpm.

I had an opportunity to try LC out again yesterday. I set my rpm to 2,200 (from 2,500) and it worked without a glitch on the first attempt .
It's a strange feeling to hear/feel the engine under load, only for it to slowly (felt slow) depart immediately after letting off the brakes, followed by a quick acceleration.
Overall, it was quick, but the slower departure left me feeling like there was more to be desired on takeoff.

I'll experiment this weekend, see how one launch compares to the next, as well as to increase/decrease the launch rpm to see what works best.

 

[Troy dunlap]

I had an opportunity to try LC out again yesterday. I set my rpm to 2,200 (from 2,500) and it worked without a glitch on the first attempt .
It's a strange feeling to hear/feel the engine under load, only for it to slowly (felt slow) depart immediately after letting off the brakes, followed by a quick acceleration.
Overall, it was quick, but the slower departure left me feeling like there was more to be desired on takeoff.

I'll experiment this weekend, see how one launch compares to the next, as well as to increase/decrease the launch rpm to see what works best.

Faie. Keep in mind the 4wd and weight of the beast

 

[Bavanew]

Faie. Keep in mind the 4wd and weight of the beast

For sure, however, if I floor it from a dead stop without LC, it pulls harder off the line. It's probably a result of traction control and whatnot by using LC. In the end, if ppl are getting better 0-60 runs using LC, then the perception of acceleration when not using LC is very misleading.