C39TS

hotdognobun

C39TS

Thanks!

Glad to hear I'm not the only one experiencing this.

have you tried turning traction control all the way off to see if it works? That's what my dealer is recommending but I haven't had a chance to try it yet

skim7x

That's... Really weird. I thought it should do the opposite as well. Traction control has to be OFF to let the LSD work?? Smells funny

C39TS

I know right !??!!? That's what I thought. To me it's LSD 101. One wheel on mud/ice/dirt/in the air should NOT spin but instead transfer power to the wheel with traction.

chrisridebike8

I think there may be a misconception of how an LSD works. A helical, or gear type LSD, needs some pressure on each wheel. in situations where one wheel has very little or zero grip (think lifting a wheel after hitting a curb at the track or one wheel on very slick ice), the LSD may act like an open diff. A clutch type LSD should always have some power going to each wheel. For example, if the diff has basically 20% lockup, that amount of power should be sent to the wheel with grip. Will that be enough to move the car? unknown. A torque vectoring diff does just that. it vectors torque. their action varies based on software and how the diff is built. my understanding is that the C63S has a torque vectoring diff. there may be some failsafe in there that says "hey, the car is trying to put too much power to one wheel...act like an open diff." keep in mind these diffs can be augmented by systems that brake the spinning wheel like my w204 does. that helps in the situations where one wheel has zero/little grip. the brake adds pressure to it basically making the diff think the wheel on ice/in the air is actually on the ground

C39TS

Thanks for taking the timeout for such a detail post! That makes a lot of sense.

I have a work colleague who suggested that applying a little bit of brake pressure may have caused the wheel with traction to kick in. I wondered where that logic comes from but your post supoorts that. I will try that too when I get the car back.

By the way – I found this blurb on the LSD in the C63S;

“In contrast to a conventional differential, the AMG rear-axle limited-slip differential uses multi-disc clutches and two thrust rings. The clutch redistributes the drive torque to the wheel with the better traction, and thus the spinning of the inside wheel is prevented.

The electronically controlled AMG limited-slip differential on the rear axle ensures more agility and greater driving pleasure. While offering all the advantages of a mechanical limited-slip differential, it also guarantees increased driving stability in slaloms or when changing lane at high speed.”

Jimmy_c63s

Yeah my coupe does this when I enter driveways at an angle especially the "rolled kerb" type like below

amg8

Yeah this happens to me as well so whenever possible when I am turning into a driveway, I try to let the momentum push me through instead of using the accelerator. Not always possible though if you're following slow traffic.

C3504matic

Mine does it on right turns into a inclined driveway sometimes

36EGMA

Thought it was just me too lol

amg8

Yeah its quite embarrassing really. When one rear wheel is off the ground, even if you give it more gas, it doesn't move and only the RPMs go up sounding like you don't know how to drive a "manual"...

Jimmy_c63s

Haha that's exactly how I feel when it happens. Sometimes at the right angle the car will sort of get stuck, do a see-saw and bobble around for a bit while one wheel is spinning. That's when you start getting the sweats

superswiss

At very low speed this can happen. Even with the electronic locking differentials, the wheel sensors do have to detect first that the wheel is slipping in order for the differential the start locking and the slower the wheels turn the longer it takes for them to detect the difference in rotational speed. Having said that, I don't find this situation to occur in my '19. I know they improved the diff in the facelift and it's even faster acting now than before and more proactive. Just last weekend I went for a drive and ended up parking on an incline with one rear wheel in the sand and the other still on pavement. When I parked, the unfavorable traction situation didn't even occur to me. I was also facing uphill, so getting out meant to get enough traction to move the car. There was a pickup truck parked right behind me. When I started to pull out of the spot, I could feel the wheel on the sand just turning with practically no traction, but torque was immediately sent to the wheel on the pavement and the car smoothly pulled forward. I was actually quite impressed at how quickly the differential reacted and sent the torque to the wheel with traction. I remembered how with previous cars, this situation would have resulted in traction control scrambling to slow down the wheel on sand in order to get the opposite wheel to move the car, but in this case it managed everything by simply quickly locking the differential.

tobeit

You guys drive on some strange uneven roads. Would not even think about that.

bfstunoodle

So have anyone found a solution to better pull up a ramp or coming down from one when the car goes into a “three-wheel” situation? I feel my tire is going to wear out very quickly since this happens to me every time I go in and out of the garage 😂

Jimmy_c63s

It's a strange thing isn't it haha. Just be careful when pedestrians are around and you're pulling into a busy car park driveway and one wheel starts spinning making that weeuwww sound. They'll give you the stares 😂

superswiss

Build up momentum while both your driven wheels are on the ground. I'm not sure what folks are expecting here. If one of your drive wheels goes airborne, it will spin until the system detects it and sends torque to the other wheel. Works much smoother in this car thanks to the locking differential than a car with only an open differential where the brakes have to slow down the airborne wheel. Unless you have AWD where the front wheels can pull you up in a situation like this, you'll have to let the system deal with the wheel slip.

tobeit

Don’t go where not all four wheels touch the street....just asking for trouble.