mikapen

This is a cross post that I first put in the AMG GLE 53 forum, but no replies yet.
Since this forum has a lot higher activity, I'll try posting here to see if somebody can help me in understanding ARC.
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I have the AMG Active Ride control (ARC) on our GLE 53. It's part of the AMG DYNAMIC PLUS Package, which is standard on the GLE 63S models. I like it a lot.

I am trying to figure out just what the car uses as input and controls, to actuate the active sway bars.

We had a 2020 GLE 450 with E-ABC, and the mechanism is entirely different.
The E-ABC uses a camera and adjusts or relaxes the suspension when it sees an approaching bump or dip.
The ARC doesn't use cameras, but it must use some sort of an accelerometer at the suspension, to sense a quick suspension movement from a bump and relax just that corner.
Whatever its mechanism, it does make a smoother ride than E-ABC, while increasing roll stiffness and improving handling.

Here's a screenshot of the Mercedes online configurator, with a description of the suspension.

"AMG ACTIVE RIDE CONTROL with roll stabilization
In addition to the capabilities and modes of AMG RIDE CONTROL+, the 48-volt architecture of the GLE allows for an enhancement offering active roll stabilization. Each axle employs an independently operating electromechanical actuator with an integrated planetary gear. The system can help reduce body roll and allows for more precise damping adaptation when cornering. In straight-line driving, it can enhance comfort by helping adapt to asymmetrical wheel movements such as bumps on one side of the road."
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And some text from a Daimler announcement with description of the suspension on a 2021 AMG GLE 63 S Coupe https://media.mbusa.com/releases/rel...rt-from-116000
"A number of new features in the 2021 AMG GLE 63 S Coupe also make it more agile and more dynamic than ever before. These features include innovative technologies such as: active roll stabilization, known as ACTIVE RIDE CONTROL,....
The ACTIVE RIDE CONTROL system uses two independently operating, electromechanical actuators at the front and rear axles, each with an integrated planetary gear. This means that the stabilization system not only reduces body roll when cornering, but also increases ride comfort while driving in a straight line, as stimuli from one-sided road bumps are balanced out."

I'm more interested in "How does it know what to do?" than "how the 48v suspension works," but any input that helps me understand the ARC would be nice.
Note - this isn't the same as older suspensions with the same name.
TIA

mikapen

I know that this sounds like an esoteric question (above). But I have reasons, other than pure curiosity, to try to understand the mechanisms at work with the ARC.

I did some track days with the 53. It was stellar - much better than I expected for a 2 1/2 Ton, six foot tall car with all-season tires. Learned the vehicle, learned what it feels like At The Limit.
However, I had an off-track excursion, and the suspension went into protective mode. It was 101F, and my tires just melted. I slid sideways, on two wheels for a bit, but kept the shiny side up.

The Dealer has had the car for a while, and it's not responding to the fixes that diagnostics or test drives are suggesting.

I suspect that the ARC is causing the issues, and that some sensor or algorithm is on the fritz.
I'd like to understand just how that 48v suspension works. How does it know what to do?

I'd appreciate it if somebody would revisit post my #1 and maybe shed some light on this new 48v suspension.
Thanks.

chassis

I have been in the factory that makes the components for this system.

The stabilizer bar is in two pieces.

Each half of the stabilizer bar is attached to either end of a planetary gear set and 48V electric motor (servo actuator) system.

The motor produces torque in the direction and magnitude it is instructed to by the control module. The motor torque is multiplied by the planetary gear set according to MB’s specifications.

The control module takes input from the usual cast of characters in the vehicle: steering wheel angle, vehicle speed, accelerator pedal position, vehicle roll angle, yaw rate, lateral acceleration and I’m sure a host of additional sensors. The sensors communicate via CAN to other modules, including the ARC module.

It’s a safe assumption that the 48V device additionally has internal sensors for its own position and current.

If the shop can’t fix it, and they are focused on the ARC system, my guess is it’s the control module, actuator or 48V power supply to the actuator. Everything else that affects the system is shared by other systems in the vehicle. If the vehicle is having no other faults, it’s likely the ARC module, power supply or actuator.

The actuators are expensive and maybe hard to obtain in the wonderful supply constrained world we now find ourselves in.

I can imagine that a high speed off road event would have called for fast and large ARC actuations which may have burned something somewhere, if only a tiny electronic device on a control board.

chassis

Planet carrier for the system. The long flutes interface with rubber on a mating female component to insulate the vehicle from noise and vibration coming from the motor and planetary gears. The planet gears rest in the round structure on the right side of this component.

chassis

Bentley Bentayga system

chassis

Porsche PDCC Sport system

https://presskit.porsche.de/specials...rung-pdcc.html

In the Panamera, the new Porsche Dynamic Chassis Control Sport (PDCC Sport) system optimises driving dynamics through the integration of electromechanical anti-roll bars. One electromechanical actuator – consisting of a direct current motor and a three-stage planetary gear set – on each axle connects the two halves of the centrally divided anti-roll bars. Depending on the lateral acceleration, the actuator turns the two anti-roll bar halves in opposing directions, with the result that lateral inclination of the body is almost completely compensated for. The electromechanical system responds considerably faster than systems with hydraulic actuators, but requires a 48-volt power supply due to the high actuator dynamics and forces.

Prior model Cayenne:

mikapen

Thanks, @chassis AFAIK their initial focus was steering gear, since that's the codes thrown. Then they agreed that the rear end was the unstable part, and checked for damaged or loose subframe. Don't know the outcome yet.

But I think it's hyperactive ARC. Watching the AMG Track Pace display, the left front shows a lot of activity, the LR less, and Rt. F&R are quiet, on curves at 40mph. And that's kind of what it feels like - nervous.

Here's the symptoms - lane changes at 60 are erratic and it "jumps lanes," in the words of the Tech and SM. Under braking, the rear end is squirrely.

Good thoughts about the quick actuations and big forces.
I wonder how they could be tested, if they aren't showing up in diagnosis.

chassis

Can they force actuations in XENTRY? They should be able to see inside the ARC module, or whatever module controls ARC functionality.

They need to diagnose proper condition of the front and rear stabilizer bar actuators. Squirrelly rear end can only mean a few things. If the vehicle departed the roadway at speed, several of these could be suspect.

Damage in:
- wheels or tires
- halfshafts or differential
- control arms or knuckle or toe link
- springs or shocks if these have active elements
- stabilizer bar system

mikapen

Excellent question about XENTRY. Thank you!

Your list of possible damage distills it pretty well. These days, however, we probably should add software to just about anything.
The bold items are things that have been, or are currently being checked. Maybe more. They're more focused on suspension integrity, so far. They swapped wheels and tires with another vehicle, too.

I expect the ARC to enter into the discussion pretty soon.
So it's a work in progress and why I'm trying to learn more about this. Want to be conversant.
This is helpful.

Ron.s

Sorry to see that happening to you particularly after the E-ABC issue on your 2020. Did it occur at the track? There are a fair number of ARC units out on the road if you count the similar Audi SQ8, RSQ 8’s and no similar posts until now.

mikapen

Yes, it was at the track. Luckily I went off track on a low speed corner, so I was only sliding sideways at 60 MPH, on dirt.

Right now they're focused on a damaged or bent subframe. They are at a couple of adjustment limits when performing an alignment, so maybe it's out of tolerance enough that the ARC can't compensate.
Part of the delays are the interface with insurance company, who wants documentation at every step. It may end up on a frame machine for better measurements. I'll bet the labor on a subframe replacement is expensive. So far they are accepting coverage, which I cleared before participating in the HPDE.

This reminds me of a friend's VW Cabriolet, that she drove through a rock slide while it was happening on Wolf Creek pass. Her car was still drivable, but it ended up totaled with only a few thousand miles on it. Hidden damage.

The only other car I've driven with a similar suspension is the Cayenne. It's just not as fast a suspension or as strong at resisting roll movements. Plus it does nothing to smooth the ride, which Mercedes solution handles well. IMO Mercedes has built a better Cayenne, with the ARC.

I couldn't find an Audi with their active suspension to test, but it would have been another $25,000 minimum over the GLE 53, so I didn't pursue that. I was already well over budget.

I am amazed at how well the 53 worked at the track, handling transients in the cornering, braking, and kerbs. The car was a lot more capable than the All season tires, or the driver for that matter!
It outperformed the gaggle of WRXs, prepped 944 and RX7. I was no match for the thousand horsepower Corvettes and the GT3s with Sparco seats and numbers on the side. Closest competition was a Honda 2000s, at half the weight.
An AMG 53 is no slouch on the track.

My lesson, as Martin Brundle says, is to obey track limits!

chassis

Something is bent if they are out of adjustment on the alignment rack.

Control system (ARC, suspension and ESP) expect the underlying mechanical systems (suspension parts, subframe, body) to be in proper working order.

If the ARC is working overtime now, and the alignment process has run out of adjustment, something must be bent. The underlying mechanical components need to be verified first, then the diagnosis should move to the control systems.

mikapen

That's what we've been working on, after addressing the steering rack codes. It aligns, but just barely. The LR eccentric is at its limit, which is the clue.
Insurance objected but I opened my wallet for additional diagnostic time, so we can pursue the most obvious needs.
After it is back in mechanical spec, we'll see if everything is happy. I hope so, but I'll be able to ask better questions after your posts. Thanks.

ObliviousFool

Can you get a 2021 GLE 63s without ARC? Was watching this video, and I could have sworn at one point they said their test model did not have it, but I could not find the part where they say that.

Ron.s

It’s standard on the 63… best part of the suspension, IMO.

mikapen

They said that it didn't have E-ABC, which isn't available on the 63S, but ARC is standard.

I don't think they understood the controls on the SQ8 or 63S. They seemed to think the seat adjusting display on the GLE was a suspension setting.

One of them owns the BMW, they had the Audi for testing several times, I don't think they have been in a 63S.
As with most reviewers, they're confusion over settings impaired their review.
Fun, though.

IMO the ARC improves the ride at all settings, and the only high performance SUV that approaches the ride quality, in Sport+, is the Cayenne.

ObliviousFool

Right on thanks was bothering me that I could not find the part in the video. Are there models that use both?

mikapen

They are entirely different mechanisms, and can't exist on the same vehicle.

E-ABC is for passenger comfort, and ARC is for performance.

The side benefit of ARC is that it allows a softer suspension (better grip and handling) while better resisting roll.
It's attributable to the 48v electrics that drive the active sway bars.