jaap74

Given that there is no launch control in the 2017 C43, hard braking then mashing the throttle is the only option.

At what point can doing this damage the transmission ?

How do others attempt this ? At what RPM do you release to get a good start and where is Boost showing as ?

Thanks

jonathan358

2k boost. Hold it for 15+ seconds and you will get your damage...

5ilver-5urfer

Launching before a car has fully warmed up can definitely cause damage. I've never had a Merc with launch control but can confirm that BMW M cars have a stringent set of requirements that need to be met before launch control is allowed. It's not recommended as something the driver should be making a habit of.

AMG C43 3LV6

If youre needing to launch your C43 regularly you probably bought the wrong car. Ive never launched it myself and while its tempting, I also dont want to cause permanent damage to my engine.

jaap74

I got my car tuned therefore just wanted to know my new 0-100 km/h time, it's not a regular event at all.

Pre-tune was 5.1 secs, post tune 4.7 which I think is pretty poor hence my question. My attempts were done at no less than 28 degrees C (82 F) which I think is not optimal, I'll give it another go when the weather cools down :-)

jonathan358

Yeah, you will want cooler, denser air but with warm tires. GL

evoi19

5.1 is pretty high even in 82F temps. What RPM are you launching at?

ShakyTom

Yeah those times are pretty terrible, stock and tuned.

jaap74

Not sure to be honest, will pay more attention at my next attempt

jaap74

I know !

Star4life

don't hold past 2200 rpm and you'll be fine on the brake boost. I don't find my self launching all the time as a courtesy for the driver behind me. I usually try to launch only when its just me. I am tuned so spinning all 4 wheels is not an issue and don't want to throw rocks at the car behind me. as long as you aren't doing it every day I wouldn't worry about it.

evoi19

You're very polite to those behind you!

munis

I have launched the car more than 500 times I am sure. (8 track days with an average of 20 hard launches, and countless dragy sessions of me in an empty road) and nothing has changed so far. Ofcourse how you launch matters a lot. If you hold the RPM at anything above 2000, it is a problem, which a lot of people do. Holding is bad, cant emphasize that enough. The correct way is to press the gas pedal, and when the rpm needle is swinging towards 2200, the moment it reaches it, let go of the brakes. (3.4s 0-60, dragy verified ).

coop16

May not be the launch most are looking for however I find if you activate the "HOLD" brake feature by depressing hard on the brake at a stop and taking your foot off the brake, then when the light turns green go hard on the accelerator you get a more aggressive launch from stand still.

JonWu

Is your technique to keep the brake with your left foot and floor the gas and time the brake release at 2k or do you gently step on the gas to get to 2k slowly, then let go of the brake and floor the gas at the same time?

AhEmGee

So you are still brake boosting/ holding it on the brakes briefly. That is only way possible without launch control.

AMGiggity

Does relatively high RPM at stop get logged by the CPU? Just wondering if dealership can pull it up later and deny warranty repair.

Dalle1985

The car will protect itself if you are getting close to damaging it. The main strain is on the torque converter and drive shafts.

The torque converter is basically a fluid coupling device, meaning there is no mechanical connection between in- and output shafts. Instead fluid is used by means of a pump (input shaft) and turbine (output shaft) to transfer (or convert) torque.

So when you do launch control or brake boosting (holding the brake and mashing the throttle) what happens is that the pump is rotating, but the turbine is stationary. This causes “shear” which results in fluid friction and in the end heating of the transmission fluid. And heat is the enemy of transmissions! So if you do it for long, the transmission fluid will get very hot and this can cause damage to the transmission, but if the fluid gets REALLY hot (we are talking red area hot) the engine will limit torque to reduce the risk of damage to the tranny.

The shafts are under a lot of strain in the split second you release the throttle, so they can be damaged, but most modern, high powered, cars have quite strong shafts.

So in the end, don’t do brake boosting when the tranny is cold (because you should not strain any part of the car when fluids are cold) and don’t do it when the transmission fluid is very hot, but avoid these pitfalls, and it probably isn’t going to do much damage.

Manual cars is a completely different bag of worms as the clutch is a mechanical coupling device so when engaging it, the speed difference between the input and output cause A LOT of friction. If the torque is higher than the clutch friction, it results in slip and more friction which will cook the clutch! So when you dump the clutch at high revs, this causes a huge torque on the clutch and this wears the clutch down!

AhEmGee

Very well explained.

Not all new performance cars are that over built though .
For example the C7 RS6 have weak driveshafts and many tuned cars have broken theirs.

Dalle1985

Well - it is an Audi after all

There are bound to be exceptions but generally these cars are pretty overengineered because they are going to be driven hard. But eventually a bean counter somewhere will say “no need to put 50% over-engineered drive shafts on” and they will end up with lots of failures and lots of dissatisfied high end customers! But look at the power people are pulling out of some of these cars and the amount of extra abuse the whole driveline will have to cope with! And some of those RS6’s are putting out 800+ hp and 1000+ Nm of torque, which is just crazy!