The Art of Conversation Isn't Lost on the 2005 Chrysler PT Cruiser Convertible

- Quiet convertible top up or top down based on driving experience - "Picnic table" conversation capability at cruising speed - Top up and top down wind noise reduction enhancements

AUBURN HILLS, Mich., Jan. 29 -- Regardless of whether the top is up or down, one thing convertible customers typically have to sacrifice for their day in the sun is the ability to carry on a conversation. Not so with the very "untypical" 2005 Chrysler PT Cruiser Convertible.

"One thing we know from our experience with convertible customers is that convertibles are 'social vehicles,' which means passengers want to be able to talk to each other when riding in them, much like they would around a kitchen table," said Steve Bartoli, Vice President-Strategy. "So, we made sure Chrysler PT Cruiser Convertible passengers could carry on an open-air, 'picnic table' conversation while driving, something other convertibles would be hard pressed to offer."

While the ultimate proof is on-the-road experience, extensive wind tunnel testing contributed to Chrysler PT Cruiser Convertible's "picnic table" conversation level of quietness. As one of the first Chrysler Group vehicles to benefit from the company's full-scale Aero-Acoustic Wind Tunnel Test Facility in Auburn Hills, Mich., PT Cruiser Convertible engineers were able to accomplish the following:

  *  World-class wind noise reduction with top up and down
  *  Significantly reduced rear compartment turbulence through ideal sport
     bar tuning and placement
  *  Optimal boot fastening and attachment integrity
  *  Enhanced mirror design for minimal turbulence-induced noise
  *  Surfaces tuned for reduced noise and turbulence

Several critical sections of the new Chrysler PT Cruiser Convertible were reviewed for opportunities to reduce noise levels in an effort to make it a quiet convertible, top up or top down. From the glass to the engine compartment, potential NVH issues were identified and eliminated or reduced, with the ultimate goal of making the vehicle "picnic table" conversation capable.

Body

The Chrysler PT Cruiser Convertible body provides tight sealing against wind, road and aspiration noise. While a stiff body structure contributes to low NVH levels, tuning the complete structure to minimize transmission of outside noise and vibration into the passenger compartment also adds to the PT Cruiser Convertible's quietness.

Chrysler PT Cruiser Convertible engineers used full body Finite Element Analysis (FEA) models to determine dynamic bending and torsional characteristics that would meet the team's performance criteria for NVH control. The natural frequencies of these characteristics were then separated from steering column, powertrain and suspension input frequencies and transmitted to the body structure at forty-seven attachment locations. Tuning each local area individually to separate its natural frequency from that of the input virtually eliminates the area as a potential noise and vibration transmission path into the passenger compartment.

In addition to a unique styling cue, the Chrysler PT Cruiser Convertible's sport bar serves an important noise-reduction function by directing wind vectoring behind the vehicle. The sport bar design, location and height prevent air from circling back into the rear seat vacuum, moving it over the passenger compartment instead.

Inside the cabin, extensive application of acoustic treatments help absorb, dampen or block noise from entering the passenger compartment. Steering column stability is achieved through robust mounting of the instrument panel structural beam and a lightweight tubular steering shaft, which also reduces NVH levels. Local stiffness at the rear shock attachments was increased by inserting bulkheads inside the longitudinal rail to minimize noise transmission. Mounting the rear spring seats on the cross member suspended between the longitudinal rails also helps isolate the passenger compartment from noise transmitted through the rear suspension.

  In addition, the following body features contribute to NVH control:
  *  Seatbelt turning loops that sit in a shallow pocket for less wind noise
     around the turning loop and attachment bolt
  *  Unique "C-channel" weather stripping between the convertible top and
     side windows
  *  A stiff front bumper beam and attachments to the longitudinal rails
  *  Optimized stiffening bead patterns on all inner panels
  *  Heat-expandable foam baffles in the longitudinal rails
  *  Pass-through sealing on the cowl side inner wiring
  *  Full-perimeter hood weather stripping

  Powertrain

As is the case with all Chrysler Group powertrain systems, the engine, transmission, driveline and engine accessories on the Chrysler PT Cruiser Convertible were engineered to minimize the levels of noise and vibration they create. Their mounting systems also were refined in conjunction with the body structure to separate input and response frequencies.

The PT Cruiser Convertible's air induction system also was engineered to reduce airflow resistance and minimize induction noise. The large air cleaner housing mounted in the left front corner of the engine compartment dampens incoming airflow pulsations. A tuning chamber in the cover enhances its noise reduction ability. Body mounting prevents the housing from becoming a potential engine noise amplifier, while rubber mounting keeps it from transmitting induction noise to the body structure.

  In addition, the following powertrain features contribute to NVH control:
  *  Low-rumble intake manifolds
  *  Counter rotating balance shafts
  *  High-volume air induction system with tuned resonators
  *  Sealed timing belt covers
  *  A "torque axis" engine mounting system with right side hydro-elastic
     bushing
  *  A rigid front suspension cross member
  *  Rigid accessory mounting brackets
  *  A shrouded alternator fan with low pulley ratio
  *  A front power plant bending strut
  *  A linear fuel vapor-purge solenoid
  *  An isolated shifter base plate on manual transaxle vehicles

  Suspension

Similar to the powertrain components, the PT Cruiser Convertible tires, wheels, brakes, suspension and steering systems were tuned to separate their natural frequencies from each other and from those of the body structure. In addition, their mounting systems were refined in conjunction with the body structure to isolate them from the passenger compartment.

Top, Door, Decklid Weather Stripping

Extensive use of weather stripping, combined with rigorous sealing of body panel seams and gaps on the Chrysler PT Cruiser Convertible resulted in one of the most tightly sealed bodies of any DaimlerChrysler Corporation convertible. Unique C-channel weather stripping completely wraps the top edge of the side windows at the sealing edge of the convertible top. This weather stripping's unique design dramatically prevents wind noise and water leakage compared with conventional weather stripping. An anti-stick coating on this section of weather stripping makes it easy to open and close the door.

Extensive door weather stripping also helps seal the PT Cruiser Convertible against wind and water. Body-mounted tubular weather strips seal the sides and lower edges of both doors, while inboard lips overlap the interior trim for a continuous appearance. These lips and the carrier that attaches the weather stripping to the door opening flanges include a co- extruded rubber. The door-mounted weather stripping also comes in contact with the upper edges of the body sills to prevent road splash and road noise.

Finally, a body-mounted, one-piece tubular weather strip seals the circumference of the deck lid.

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