Mercedes readies new 4Matic for transverse fwd architecture

 

 

The new 4Matic for transverse-engine fwd applications features a PTO integrated into the 7G-DCT automated dual-clutch transmission.

Mercedes-Benz is preparing to introduce a new version of its 4Matic all-wheel drive transmission aimed at transverse-engined front-wheel drive powertrain architectures, starting with the 2014 CLA 45 AMG. Featuring fully variable torque distribution, the new gearbox is described by the company as a “completely new development." Its innovative aspects include power take-off (PTO) to the rear axle which is integrated into the company’s established 7G-DCT automated dual-clutch transmission and a rear axle with integrated, electrohydraulically controlled multidisc clutch.

The CLA 45 AMG is a new high-performance A-segment variant based on the automaker's CC architecture that underpins A- and B-segment vehicles. It is due to enter production later this year. At 70 kg (154 lb), Mercedes claims the new 4Matic system is lighter by about 25% compared to systems used by competitors. This is particularly due to the use of a compact PTO unit integrated into the main transmission, which supplies lubricant. Rival systems branch off power via an add-on component with its own oil circuit, states Mercedes. The PTO unit uses tapered roller bearings.

Fully variable torque distribution is achieved via the multidisc clutch positioned in the rear axle gear unit. With the clutch open, the car behaves virtually identically to a front-wheel drive vehicle, with almost all torque sent to the front axle. With the clutch closed, the rear axle is also driven, with torque balance available between axles on demand according to overall conditions.

ABS application sees the rear powertrain deactivated and subsequently no torque delivery. Drive torque to front and rear is used to counter under or oversteer under load, with chassis electronic systems actioned in a secondary role.

System pressure to introduce the rear axle is supplied via a rotor-type pump in the axle’s gear unit with an ESP controlled proportioning valve looking after pressure.

Torque distribution is also dependent on the activated shift program (Eco, Sport, or Manual) of the dual clutch transmission. In Eco, the front axle gets the most torque in normal conditions, while Sport and Manual see activation times reduced and the rear axle receiving more torque, to provide the driver with required rear-biased dynamics. Mercedes states that on AMG versions, adaptation of the 4MATIC controller takes place in accordance with the three-stage ESP.

All CLA models will be available with 4MATIC. The production CLA will look very similar to the Mercedes Concept Style Coupe previously seen at international motor shows.

The high-performance CLA 45 AMG will have a 2.0-L turbocharged gasoline engine capable of producing peak torque in excess of 400 N·m (295 lb·ft).

Although Mercedes has long offered AWD on some models, its application across its entire model range has not been as comprehensive as Audi’s Quattro. The new system for fwd transverse-engine architecture will help redress that situation.

Each of Mercedes’ SUVs and ATVs (all-terrain vehicles) including M-Class, GL, and G-Class, has standard all-wheel drive but use a torque converter system. The only Mercedes models at present offering dual-clutch technology are the A- and B-Classes and the high-performance SLS AMG.

Stuart Birch

Superbike 1199 Panigale - Ducati

Technical specification

Engine

Type: Superquadro: L-twin cylinder, 4 valve per cylinder, Desmodromic, liquid cooled

Displacement:1198cc

Bore x Stroke:112x60.8mm

Compression ratio:12.5:1

Power:143 kW (195 hp) @ 10,750 rpm

Torque:132 Nm (98.1 lb-ft) @ 9,000 rpm

Fuel injection:"Mitsubishi electronic fuel injection system. Twin injectors per cylinder. Full  ride-by-wire elliptical throttle bodies."

Exhaust:2-1-2 system with catalytic converter and 2 lambda probes. Twin stainless steel mufflers with alumimum outer sleeves

Transmission

Gearbox:6 speed

Primary drive:Straight cut gears, Ratio 1.77:1

Ratio:1=37/15 2=30/16 3=27/18 4=25/20 5=24/22 6=23/24

Final drive:Chain 525; Front sprocket 15; Rear sprocket 39

Clutch:Slipper and self-servo wet multiplate clutch with hydraulic control

Chassis

Frame:Monocoque Aluminium

Front suspension:Marzocchi 50mm pressurized and fully adjustable usd fork with hard anodized aluminum lightweight slider

Front wheel:10-spoke light alloy 3.50" x 17"

Front Tyre:120/70 ZR17 Pirelli Diablo Supercorsa SP

Rear suspension:Fully adjustable Sachs unit. Adjustable linkage: Progressive/flat. Aluminum single-sided swingarm."

Rear wheel:10 spokes light alloy 6,00”x17”

Rear tyre:200/55 ZR17 Pirelli Diablo Supercorsa SP

Front wheel travel:120mm (4.72in)

Rear wheel travel:130mm (5.12in)

Front brake:"2 x 330mm semi-floating discs, radially mounted Brembo Monobloc M50 4-piston callipers ABS optional +2.5kg (+5.5lb)"

Rear brake:245mm disc, 2-piston calliper

Instrumentation:Digital unit with TFT colour display: rev counter, speed, gear selected, odometer [Menù 1: trip 1, trip 2, trip fuel], coolant temp [Menù 2: average and actual fuel comsumption, average speed, trip time, air temperature], lap times, selected Riding Mode, DTC level, EBC level, DQS status, ABS level, DDA status (only if mounted), GPS status (only if mounted), SERVICE, diagnostic, clock, full status and/or management of Riding Modes, ""Parking"" mode. Display lay-out: ROAD/TRACK (integrated with Riding Modes). Display backlight colours: DAY/NIGHT (manual or auto selection). Warning lights: oil pressure, neutral, EOBD, turn signals, fuel reserve, high-beam, ABS (if oem), over rev, DTC intervention, immobilizer (in Key-off). Light control: automatic shutdown while engine start, automatic shutdown after 60s from key-on without engine ignition. All funtions integrated and managed by left and right handlebar switches

Dimensions and weight

Dry weight:164kg (361.5lb)

Wet weight(KERB):188kg(414,5lb)

Seat height:825mm (32.48in)

Wheelbase:1437mm (56.6in)

Rake:24°50'

Trail:100mm

Fuel tank capacity:17l - 4.5 gallon (US)

Number of seats:Dual seat

Equipments

:Standard Equipment

Riding modes,DTC,DQS,EBC, Fully RbW

Warranty

Warranty:2 years unlimited mileage

Maintenance service intervals:12.000km

Valve clearance check:24.000km (15,000m)

Emissions and Consumption

Standard:Euro 3 (Europe) - USA: follows the US Federal Regulation

Exhaust System:

"The layout of the exhaust manifolds is 2 into 1 into 2 with twin tailpipe under the sump. The design of the exhaust assembly is a work of highly refined engineering: the ends have a complex exterior shape due to the size restrictions necessitated by the "deep sump" of the engine (on the interior) and the leaning angle (on the exterior). The primary manifolds have a Ø 55 mm diameter, the central manifolds a Ø 57mm; they are built in stainless steel and have a thickness of 0.8 mm, with only the two short exits from the cylinder heads having a larger thickness (1.0 mm) to better resist vibrations. Even the silencers are in stainless steel with exception of the outer sleeve (or outer jackets) in aluminium alloy with a 2 mm thickness (result of a process of pre-deep drawing, rolling and longitudinal welding). The reflection silencers have three chambers; in this application the chamber layout is especially complex with respect to the traditional design (used for the 1198) because the exhaust gas enters from the rear (with respect to the direction of travel) inside the silencer and exits again from the outside rear. From a construction perspective, this also implied a complex design, and at several stations of deep-drawing of the aesthetic rear endcap, the catalytic converters are positioned at the inlet of the silencers and have dimensions of Ø 80mm x 74.5 mm.

 Monocoque Technology:

The 1199 Panigale's chassis marks an enormous innovation: different components have been integrated to give shape to a single compact and lightweight element that enhances the rider's posture to perfect the riding position. The monocoque structure in cast aluminium for increased strength uses the Superquadro engine as a structural element and aids in reducing the bike's total weight by 5 kg. The monocoque frame is fixed directly to the cylinder head, and at front are two aluminium bushings inserted with the steering tube bearings. In addition to performing the traditional function of frame, the monocoque also acts as an air-box and significantly contributes to lowering the overall weight of the motorcycle. Housed inside, besides the air filter, are the throttle bodies and fuel circuit complete with injectors, and the bottom of the aluminium tank (lighter by 1.9% compared to the 1198) is used as a cover for the airbox.

Advanced out-of-autoclave composites process accelerates curing, enhances adhesion of fasteners

Kubota Research has developed a very rapid bonding process based on P-Wave/PTIR technology for curing two-part epoxy adhesive to bond fasteners onto metal and composite surfaces for the manufacture and repair of composite structures.

A new IR-assisted advanced out-of-autoclave (OOA) process from Kubota Research Associates Inc. reportedly enhances adhesion properties and “significantly” accelerates the curing speed of thermoset resin systems for installing adhesive bonded fasteners (ABFs) such as Clickbond studs and standoffs from Click Bond Inc. onto composite fuselage and metal structures.

The P-Wave/PTIR process technology invented by Kubota Research—which was founded in 2000 and is headquartered in Hockessin, DE—is a core technology for the development of new continuous fiber-reinforced thermoset and thermoplastic composites that promise cost/performance benefits compared to conventionally manufactured composites, the company claims.

For the OOA manufacturing technology, PTIR prepreg films are laid up on a mold, and an IR transparent vacuum bag applies pressure on the prepreg. The P-Wave radiation system is scanned across the prepreg and emits a selected range of infrared radiation, which passes through the vacuum bagging material and is absorbed by and heats the PTIR prepreg under pressure for consolidation. The P-Wave system and PTIR method can be used in the tow and tape placement process.

Core technology of the P-Wave/PTIR out-of-autoclave process was developed through National Science Foundation grants, #0512869 in 2005 and #0711789 in 2007, according to CEO Mike Kubota, who shared the development timeline and other details with Aerospace Engineering. The company then applied this core technology to rapid-bond ABFs starting in September 2008 through the U.S. Navy Naval Air Systems Command (NAVAIR) SBIR N08-030. Phase II of that program, which ended in September 2012, saw the TRL 7 (technology readiness level) process jointly evaluated at Bell Helicopter and the University of Delaware Center for Composite Materials (UDel-CCM).

“The project had two subcontractors, Bell Helicopter and UDel-CCM, to validate performances including the cure speed of Bell and NAVAIR prequalified epoxy adhesives, the flatwise tension strength, bending strength, shear strength, and the hot and wet tests compared with baseline,” Kubota explained. Specific performance results could not be shared since the project was developed under the ITAR (International Traffic in Arms Regulations) NAVAIR program.

OEM-qualified room temperature cured structure-grade two-part epoxy adhesives such as Henkel Hysol EA9394 and Magnolia Plastics Magnobond 6398 are used to install Clickbond fasteners, for example, onto composite fuselages. These adhesives typically set in 24 hours and cure in 5 to 7 days at 25°C (77°F). Kubota Research claims that its P-Wave/PTIR process, used with the same qualified adhesives, can bond and cure the fasteners onto the substrate in less than 10 min. The process can be applied under a range of operating temperature conditions from -20 to +50°C (-4 to +122°F).

“The main challenges are heating the bond-line temperature higher than the first surface and not producing thermal degradation on both upper substrate (fastener) and bottom substrate (fuselage),” Kubota shared. “Another challenge was Bell and NAVAIR prequalified epoxy adhesives such as Hysol EA9394 and Magnobond 6398 had to be used without modifying the formulation.”

The process enhances wettability between the adhesive and substrates, resulting in increased fastener-to-substrate bonding strength. The P-Wave/PTIR ABF installation fixture also is reusable and replaces the disposable one-time-use pressure application fixture.

“Legacy technology is using a mechanical and disposable fixture,” Kubota noted, explaining how his company’s process is unique. “P-Wave/PTIR IR-assisted advanced OOA heats adhesive in the bond-line instead of the first surface and cured in less than 10 minutes. The rheology of the adhesive was optimized to enhance the wettability.”

Kubota Research is a member of the UDel-CCM University-Industry Consortium, a center of excellence for research and knowledge in the advanced composites industry. Kubota notes that his company and its global partner Bell Helicopter plan to continue collaborating with UDel-CCM to advance the development of P-Wave/PTIR technology “to bring a new generation of cost-effective composite parts manufacturing methods to the industry.”

The advanced OOA process is in the premarketing stage, according to Kubota, and is expected to be fully commercially available in January 2013. The rapid bonding technology can also be applied to boat and ship manufacturing.

Ryan Gehm

Active wheel shutters show Ford’s aero focus for 2015 F-150

Ford's new active wheel shutters in the closed (left) and open positions on the Atlas concept pickup.

Ford’s Atlas concept pickup, unveiled Jan. 15 at the 2013 North American International Auto Show in Detroit, provides a glimpse at some key fuel-efficiency technologies engineers are readying for the 2015 F-150.

Besides the shift to high aluminum content in the front end and cab, aimed at reducing the 2015 trucks’ curb weight by up to 700 lb (317 kg) versus the current F-150, and a next-generation EcoBoost powertrain featuring auto stop-start, Ford is putting a serious focus on reducing aerodynamic drag, said Raj Nair, Group Vice President of Global Product Development.

The Atlas shows a few of the results of “our extensive aero development” on the next-generation pickup, Nair told AEI.

An unexpected feature on the Atlas is active wheel shutters. The shutters are in at-rest position behind the wheel spokes when the vehicle is stationary and at up to moderate road speeds. As vehicle velocity increases to above 60 mph (97 km/h), its wheel-speed sensors signal a dedicated battery that powers the shutters. They deploy in a fan-like pattern (think of a Chinese fan being opened), closing off the openings between the wheel spokes and thus enabling smooth airflow across the wheels.

Active grille shutters and an automatic-deploying active front air dam work in conjunction with the active wheel shutters, Nair said. The Atlas concept truck also features power running boards that tuck in close against the truck’s body at speed, also helping reduce drag.

Ford’s simulations and early testing indicate the aero package as shown on Atlas is capable of providing a fuel-efficiency gain of more than 2 mpg (0.85 km/L) at highway speeds without diminishing towing or hauling capability. Full-line automakers Ford will have to improve their light-duty trucks’ fuel economy to approximately 32 mpg to comply with the new U.S. CAFE regulations that require a 54.5-mpg fleet average by 2025.

The 2015 F-150 also is expected to feature a 10-speed planetary automatic transmission, currently under development, according to Ford and supplier engineering sources. As previously reported by AEI, Ford and General Motors are in discussions on sharing advanced transmission technology as they have done with the highly-successful six-speed transaxle program.

Other technologies revealed on Atlas that have potential for the 2015 production truck include a 360° point-of-view camera that provides the driver a “bird’s-eye” view of the vehicle; driver-controlled trailer-backup assist; dynamic trailer-hitch assist that helps line up the hitch with the trailer coupler; a dual-purpose tailgate step/cargo cradle; and LED headlamps and taillamps.

Lindsay Brooke

Schaeffler fuel-smart concept vehicle to employ several technologies developed in North America

Schaeffler's all-wheel-drive disconnect clutch will be a key technology on its upcoming demonstration vehicle.

In the coming weeks, technical specialists will equip a MY2013 Ford Escape with several fuel-smart innovations from Schaeffler, including its thermal-management module, AWD disconnect clutch, permanently engaged starter/generator, and latching valve. The latter three technologies were conceived and developed in North America.

“We think we’re under $40 per percent of fuel-economy improvement,” Jeff Hemphill, Vice President and Chief Technical Officer for Schaeffler Group North America, said in an interview with SAE International Magazines at NAIAS.

The thermal-management module to be fitted on the vehicle demonstrator (called Efficient Future Mobility North America) will be similar to the Schaeffler unit used by Audi in some production vehicles.

“But this version won’t have quite as much functionality,” Hemphill said about the module that allows the optimum engine temperature to be reached in the shortest time possible and allows temperature balance to be precisely controlled.

Integration of a thermal-management module can provide a 1% reduction in fuel consumption for city and highway driving.

Schaeffler’s AWD disconnect clutch, which decouples the unused drive axle from the drivetrain depending on the driving situation, can generate fuel savings of up to 2% in city driving and up to 6% in highway driving. The permanently engaged starter/generator with a wrap-spring one-way clutch can provide up to 6% fuel savings in city traffic.

The AWD disconnect clutch, the permanently engaged starter/generator, and the latching valve are all second-generation, under-development technologies. “These technologies could start production development later this year [and] enter production in the 2017 model year based on their maturity,” said Hemphill.

Schaeffler’s SUV demonstrator is expected to be ready for ride-and-drive evaluations in the summer of 2013.

According to Hemphill, the initial demonstration vehicle with its conventional powertrain and fuel-smart Schaeffler technologies is designed to meet CAFE standards for 2020. The company's follow-up demonstrator vehicle will add hybrid systems, with the goal of fulfilling CAFE requirements for 2025.

Kami Buchholz

Electronics diverge in engineering Ford's hybrid C-Max and plug-in Energy

Large cell compartment for plug-in holds electronic modules, which are (1) battery temperature sensor; (2) junction box; (3) battery energy controller; (4) DC-DC converter controller; (5) secondary on-board diagnostic module.

Turning a hybrid electric vehicle (HEV) into a plug-in hybrid (PHEV) is more than adding cells to a battery pack, reflashing the controller, and installing a charger. The 2013 Ford C-Max and C-Max Energi are examples of what it takes to develop conventional hybrid and plug-in versions of the same vehicle—that is, many specific parts, software, and validation.

Both cars have lithium-ion (nickel-manganese-cobalt oxide) cells, which are chemically very similar. But those in the plug-in C-Max Energi, which has a 21-mi (34-km) EV range, have thicker electrodes and store more energy.

Why wouldn’t the C-Max conventional HEV have the same electrode thickness? Because thinner electrodes have less impedance, so the cells (of which there also are fewer) can deliver electric power faster. HEV batteries are a power source for acceleration assist, only minimal EV operation.

Designing for dual function

PHEV batteries, however, primarily are an energy source and, for EV operation, must be able to discharge deeply and take repeated recharge cycles over many years. But once EV energy is depleted, plug-in cells also must function in HEV mode. So electrodes’ design and other aspects of energy cells are a balancing act.

The prototype Prius PHEV evaluated the idea of a pair of cell packs: one type, larger for plug-in EV operation, the other (smaller) engineered for hybrid mode when the larger one's capacity was depleted. But the production model has one pack doing double-duty and controller software to optimize each function. That's the approach all other makes including Energi also have taken.

The “full” or conventional HEV version of the C-Max has 76 of the power cells wired in series, rated at 1.4 kWh. The plug-in Energi has 84 of the energy type in series, rated at 7.6 kWh. The plug-in uses 6.5 kWh for EV range and allows a residual of 1.1 kWh for HEV operation.

The physical size of the Energi PHEV pack, of course, is much greater. The HEV cells are each 120 x 85 x 13 mm (4.72 x 3.35 x 0.51 in); the Energi's are 148 x 91 x 26 mm (5.83 x 3.58 x 1.02 in). And the Energi pack has higher peak voltage (361 vs. 327, during regenerative braking). There's comparable HEV capacity for such operations as idle stop/restart, Ford engineers said.

Battery temperature controls

Battery temperatures are important factors for PHEV range, cell life, and performance. According to Gilbert Portalatin, Ford's Chief Program Engineer, Electrified Powertrain Programs and Integration, tests are run at extremes of -35ºC (-30ºF) and 82ºC (180ºF).

EVs such as Ford's Focus and the Chevrolet Spark variants, and even the plug-in Chevy Volt (all with much higher-capacity battery packs), have an active electric-pump-driven heating and cooling system using liquid coolant and siamesed in a heat exchanger with the vehicle HVAC. The object is to keep pack temperatures within 0-30°C (32-88°F), a protective range for fast recharging systems.

C-Max and Energi employ only fan-driven air-heating/cooling systems, relying on a sensor to monitor battery compartment temperatures. The Energi employs control strategies to direct cell temperatures to within 0-45ºC/32-113ºF for maximum EV driving range.

If the battery pack temperature is lower, the Energi will operate in EV at reduced power until the cells warm up during normal cycling of electricity between generator and battery pack, from drive operation and regeneration. There also may be heat provided by airflow through ductwork from the cabin if the climate control is in the heating mode.

There certainly will be heated air blown into the battery compartment from the cabin if the Energi's engine is started.  This occurs when the defroster is turned on or if the weather is extremely cold (the 2013 Chevy Volt also may employ a similar engine-start algorithm for battery pack heating in extreme cold).

For hot weather, the C-Max fan draws in what will be cooled cabin air provided by the vehicle A/C. During Energi-recharging, the fan draws in outside air, which even in hot weather is likely to be cooler than the cabin of a parked car in a hot soak. The Energi also will have a preconditioning mode using A/C for cabin cooling during plug-in, enabled through the Sync or MyFord Touch modules.

Ford has seen no durability problem with its battery pack from hot soak itself, Portalatin told AEI. So long as the vehicle is parked, peak temperatures in the battery compartment don’t affect battery capacity or longevity. Once the Energi is in use and the A/C is turned on (which can be assumed in very hot weather), pack temperatures quickly lower to an acceptable level.

This approach contrasts with the pre-2010 Ford Escape HEV, which used nickel-metal hydride batteries susceptible to deterioration if operating temperatures exceeded 140ºF (60ºC). It employed a second, rear HVAC system with an evaporator and a refrigerant flow control circuit that would chill the fan-driven airflow to the battery pack.

Innovative algorithm

In addition, C-Max Energi has algorithms that can adjust the EV range for the driver’s chosen route or operating choices, one of which is particularly innovative.

It can recognize a familiar route that is very close to the maximum EV range of the vehicle and do “smart discharge.” Using GPS from Sync to determine location along the known route, the system controls power output to extend range without changing the maximum percentage of discharge. This may make it possible for the car to reach its destination without gasoline engine operation. Other algorithms, similar to those in competitive PHEVs, permit the driver to choose when to use plug-in power, including reserving it, such as for lower-speed urban operation.

Ford limits the Energi to a 3.3 kW charge rate with a Level 2 (208-240-volt) system, which is part of the thermal balance with the protection from air cooling. The small battery pack takes just 2.5 hours for full recharge. By comparison, the Focus EV, with its active liquid cooling, accepts a Level 2 charge at a 6.6 kW rate.

Motor electronics for all full and plug-in hybrids rely on liquid cooling, typically with a dedicated electric-pump circuit, under the hood.

Paul Weissler

The Ducati Dry Clutch and Its Distinctive Rattle

Just as you can tell when a Harley is somewhere in the vicinity by the distinctive rumble of its V-Twin, so can you tell when a Ducati has just pulled up next to you.Although many might think that the rattling sound coming from a Ducati is a sign that the bike is in dire need of a tune-up, the bike is in fact perfectly fine. What you are hearing is the signature sound of the Ducati dry clutch, which is music to the ears of many a Ducati enthusiast.

Dry vs. Wet Clutch

It may seem obvious to many of our readers, but let us remind you of the difference between wet and dry clutches. The wet clutch, which you’ll find on just about every bike, is bathed in oil and completely sealed off. Dry clutches, on the other hand, are totally free of oil and do not need to be sealed. Many dry clutches are exposed so that the spinning clutch plates are visible to any passerby.

Pros and Cons of a Dry Clutch

Since Ducati employs the dry clutch on most of their bikes, we’ll take a quick look at the pros and cons of such a set up.

Pros:

1. Easy access for repairs. There is no need to drain the oil before removing the clutch cover if you need to service your clutch. This is especially important in racing where clutches are regularly burned out and need to be replaced immediately.
2. The dry clutch does not share oil with the rest of the engine and thus any debris from disintegrating clutch plates will not harm engine internals.
3. Submerging a clutch in oil creates drag which will diminish the engine’s horsepower; it might not reduce the horsepower by much, but every little bit counts on the track.
4. Heat generated by the clutch plates does not heat up the engine’s oil, which is especially important for bikes in which oil is used in the cooling system.

Cons:

1. Much louder, but this is a matter of preference.
2. With an exposed dry clutch, the springs will eventually rust. This can be prevented by installing stainless steel springs.

Why Does Ducati Use Dry Clutches on Most of its Bikes?

As you’ve probably gathered from the above list, dry clutches are most useful on race machines. For that reason, many will argue that Ducati’s use of a dry clutch on street bikes is only for marketing purposes.
In the past, Ducati has claimed that they build all their bikes to racing specs and that means using a dry clutch. However, in recent years, Ducati has produced bikes whose specifications are more in line with the target audience.
Today, bikes such as the Ducati 848 and Monster 1100 Evo are equipped with a wet clutch for easier use.

Why The Ducati Dry Clutch Sounds Like Rocks in a Bucket

If you’re still wondering what exactly it is that makes the Ducati dry clutch sound like someone put marbles in it, here’s your answer. The sound you’re hearing is the clutch plates bouncing off of one another when the clutch is disengaged.You’ll hear this sound when a Ducati rolls up next to you at a stop sign and the rider has pulled in the clutch lever, freeing up the plates to knock into each other.
Without any oil surrounding the clutch pack to lubricate the plates, you get that distinctive sound of rocks in a bucket.
So next time someone pulls up next to you on a Ducati, you’ll know better than to yell to them that they should get their valves adjusted.