PT ragtop has plenty of poke: DaimlerChrysler strategy is to pop no top before it's time

Automotive Industries, March, 2004 by Rob Wilson

Offering both a 180 hp and 220 hp turbocharged engine option, DaimlerChrysler has packed poke a'plenty into its new PT Cruiser convertible, introduced to the automotive press last month. This should expand the potential consumer base for the PT Cruiser to include those who always liked the look of the jaunty" retro mobile but are also looking for a jalopy with morn jump.

That demographic subset just got all hooked up. And so did convertible lovers who find the PT appealing but wouldn't own a hardtop, particularly one without much pep. With the base model MSRP at $19,995 and the top model Cruiser GT at $27,565, there's a very healthy slice of market that can afford to step up to the PT Convertible.

Some industry, analysts think DaimlerChrysler is late getting to the dance with this model, but now that it has arrived everyone has to admit they've got a great looking date.

The car is beautifully executed taking the styling cues of the PT sedan and reinterpreting them width vigorous panache and now it also has lots of punch. We whipped through the mountains outside of Phoenix in the top line GT with the turbocharged 220 hp 4-cylinder 16 valve engine driving through a Getrag 5-speed manual. Acceleration was extremely crisp. For a front-wheel-drive vehicle, handling was supurb.

Sound attenuation was a strong development theme for this convertible. With the top up or down, all you hear from the engine is a soft whisper. So it's a Hummi and not a Hemi. Particular attention was paid to the air induction system, intake manifold, timing belt, shrouded alternator fan and engine mounting to create what DCX calls a "picnic table" conversational environment. It works!

One mason this model took some time to develop was because so much of the car had to be changed in making the transformation from sedan to convertible. Only the front end of the PT sedan was left untouched. "With the exception of the taillights, the convertible is all new from the A pillar to the trunk lid," commented Dennis Krozek, director vehicle development and program management for the small vehicle product team at DaimlerChrysler.

Krozek said the development team used a combining strategy employing high-strength steel, differential thickness panels, and several hydroformed steel parts to achieve a stiff and safe body structure while adding as little weight as possible.

The PT convertible weighs only 150 lb. more than the sedan, which Chrysler says is far less than convertibles from competitors such as VW. Body-in-white stiffness is given at 4693 lb.ft. per degree for twist and 42,800 lb. per inch for bend.

These results were achieved with extensive use of CAE software technology and full body Finite Element Analysis. For NVH control, natural frequencies were separated from the steering column, powertrain and suspension system frequencies input frequencies and transmitted to the body at some 47 attachment locations, tuning each local area individually

A novel body component on the convertible, and another key to body stiffness and NVH reduction, is what Chrysler calls a "sport bar," which function like a roll bar. But this is a very robust steel hydroformed part that joins the body on both sides at the B pillar position and encircles the passenger compartment just below the soft top. With the top down it reduces noise by vectoring wind behind the vehicle. It is also a very attractive styling cue.

But the most impressive component system of all has to be the top itself. This comes from Edscha Roof System (ERS), the Pontiac, MI, subsidiary of the German company Edscha AG. The entire engineering and product validation for the system was performed by the U.S. group and the top is manufactured by Edscha's plant in Toluca, Mexico.

Top system components include: forged main control link and rails, stamped top header and main pivot bracket, a high pressure hydraulic pump and motor, four high-strength steel roof bows on the frame, forged rails, a high-strength steel floating bow, glass stabilized wide tension belts, a sound damping pump cover and two-piece stamped header. The whole system installs with only six fasteners.

All PT convertible models feature the same top, which comes in either black or taupe, but all are powered. There's no manual option. This is a premium textile roof and not PVC. Edscha says the outer skin is the same as is used by BMW, Audi and Ferrari.

The outer fabric is a three-ply composite with an acrylic outer fabric, a rubber inner layer and polyester lining. The headliner is also a three-ply composite, and between the outer fabric and the headliner is a bonded fiber insulation to reduce noise and heat transmission.

The combination of these three elements will provide extraordinary performance in noise and heat isolation as well as longevity for superior appearance over the life of the vehicle. The roof does not appear to "balloon" in motion at all and this is attributed to the way the fabric is connected to the bows.

The roof features a heated scratch-resistant backlight that is urethane bonded in place and can be serviced without disassembling the entire top