Saudio

First, I'm still figuring out the search function here. I know this subject must have come up before. Is there a way to search ONLY the AMG GT forums and not the whole site?

Anyway, launch mode in my GTC only seems to burn tires and doesn't seem to me to get the car to 60 faster than just flooring it. Also, there seems to be a significant lag between releasing the brake and the car starting to move. I like to take my cars to the strip now and again, am I using launch incorrectly or it is just for smoking tires?

Thanks.

superswiss

In Advanced Search you can narrow down your search to specific forums.

So, this is not specific to the GT, but the main purpose of launch control is to let the engine build boost and get the rpm near peak torque, so it develops maximum torque once you let go of the brakes and the clutch drops. The delay could be if you let go of the brakes too early before boost has built fully. Keep an eye on your boost gauge. As far as traction is concerned, launch control doesn't handle that. That's where traction control comes in. What did you have your ESP set to? Launch control does communicate with TC, but if you turn it off completely then it all comes down to how much grip your tires have and you are likely just lighting them up. You'll likely get the best launch if you put ESP in Sport Handling mode, which will try to extract as much traction from the tires as possible. With the GT R and ESP fully turned off you would have the ability to dial in TC to try to get the best launch possible, but the GT C doesn't have the 9-stage TC, so you only have the option of leaving it fully on, put it in Sport Handling mode, or turn it off completely.

Skilly

he's right on the delay in launch - if you were looking at reaction time and competing against someone else it has a delay that makes it almost feel like a hesitation in the driveline after you release the brake. Its significant and pretty much a wash from just mushing on the pedal and using reaction time rather than building pressure in the turbos. My 911 was instantaneous and violently threw the car forwards immediately....its not a deal killer, but it was a surprise.

Saudio

Two cars ago was a McLaren 12C. The launch control in that car was as you describe in the Porsche. Instant, and brutal. The GTC seems to have to think about things for a moment and that is a very long moment at the line.

Saudio

Thanks for the info! I have tried both letting it build boost longer, and intentionally not letting it build as long, and neither seems to produce an effective launch. I'll keep experimenting but for now it seems like human input would get me to 60 quicker.

sodhigtc

maybe try adjusting the rpm for the launch by holding one of the paddles for a few seconds with race start engaged. I think there is a thread on here with more info

superswiss

Totally forgot about that. Yes, on the later models you can increase/decrease the launch rpm by a 100 at a time using the shift paddles before releasing the brakes. Our instructor at the AMG Driving Academy actually recommended to take it down about 300 rpm. I think the default is 3500, so take it down to 3200. He said otherwise you just end up spinning the wheels. We were asking him specifically about the C63S due to RWD, but he even took it down on the GT63S when he demonstrated launch control and drift mode.

sodhigtc

thats awesome! I am also yet to try it out but can’t wait too! I believe our cars launch around 5000rpm ish so will be interesting to see how much it can be lowered by!
I know my buddy with a new cla 45 launches at 3500rpm with the 4matic!

let us know how you get on!

Keon

The GTC struggles for grip on launches - it's simply the nature of a powerful, FMR car. Try launching the car on a prepped surface with and without launch control - you'll probably see the difference there. I will certainly be comparing them when I get a GTC and take it to the drag strip. I'd love to take my SL but it's starting to feel like it's made of glass and I don't want anything to break.

sodhigtc

Make sure you use the drag timer too that’s in the track pace setting! I used it once and got a 3.88 but thought the car was a little slow to get going also! This could be an amg think as my buddy who has a 2020 cla 45 complains of the same delay using race start!

superswiss

+1...RWD AMGs are simply not drag race cars. That's not what they are built for. They are better at drifting than they are at 0-60 and 1/4 mile. First order of business to get the GT C to hook up better would be a stickier tire like the Cup 2. The PSS and PS4S are good all-around street performance tires, and I love the PS4S, but they'll never hook up like a Cup 2 or other R compound tires. Part of the charm of an RWD AMG IMO is breaking the rear wheels loose and drift or manually short shift to get it to grip. It's a ton of fun! I don't get the appeal of straight line racing. A proper race track has turns, in both directions!

Skilly

I dont disagree. That said, its not the grab that impacts the launch as much as it is the gentle transfer of power once you release the brake. Compared to a 911 or a 12c that feels like you just dumped the clutch, the GTC feels like a good half second while it figures out how to move from stall to go time! From there, its all sorts of tweaking on the wheel grab, but launch just seems lacking. Would I trade back to my 911?....NOT A CHANCE. But, if I am being fair, the MB gets a fail here while Porsche has it dialed in.

canucklehead

The delay in launch is the car's built in torque management to save the life of the drivetrain. I experienced this when I took my car to the 1/4 mile track.
Normally with other cars I leave on the last amber, with the GTR I would have to leave early on the second amber to cut a good light.
Makes road encounters iffy, always going to lose the 60 foot race, and will be playing catch up to the 1/8.

Keon

The appeal of straight line racing is that it's a hell of a lot easier on the car than a track day. I'll take it to the track, but I don't like having to shell out a lot of money for new brakes.

doulehr

ESP Sport actually limits the traction control to allow the car to break traction/drift before the system intervenes....I think for a good launch you would want the traction control fully on.

AMG 17GT

Race start is not good on this car. Best way I’ve found to launch is ESP all the way off and mash paddle 1/2 for a 1/2 second and then floor. Obviously tires are crucial for hook up. P4S was a lot better than SS.

superswiss

Actually, you do want some wheel spin. The friction coefficient is not a constant. For street tires, it peaks between 10-20% of wheel slip and then falls off. A good traction control allows just the right amount of slip to maximize friction. The 9-stage TC in the GT R, GT R Pro, GT BS and '19+ C63S does an excellent job at this in Sport Handling mode and if you like you can manually dial in the amount of desired wheel slip in 9 stages. The traditional TC in the GT C is not as good about it, because it mostly uses the brakes to slow down the spinning wheels and that comes with delays and is not smooth. The 9-stage TC is directly integrated in the ECU's torque management and rather than using the brakes it manages the engine torque to keep the rear wheels at the desired slip ratio while balancing traction left to right via the locking rear differential. It actually works amazingly well from personal experience. It manages traction very smoothly and consistently.

Here's a graph of how the coefficient of friction develops as a function of wheel slip ratio. It also shows you in what range ABS operates. Both TC and ABS have the same goal to maximize friction for either maximum acceleration or maximum braking.

Saudio

You mean do this in race start? As in, brake on, half throttle, then release brake and go to full throttle at the same time?

Skilly

I messed around with that - it doesn't really work. You can't get the turbos spooled up effectively and you get this spongy 'half baked' launch. The car just over protects the launch while its transfering power to the drive train. Incredible car, but this isn't one of its strengths.

AMG 17GT

no as I said race start is no good I’m talking about pressing and holding the ESP button until it turns completely off not sport completely off and then do the throttle as I said which will generate some wheel span which is as others have said it’s necessary to hook up

Saudio

Got it. Worth a try, thanks.