The hallmark innovation on Jeep’s 2008 Liberty is the “industry-exclusive” Sky Slider roof system supplied by ASC (www.ascglobal.com). The full-length, open canvas roof system slides both fore and aft to provide an open-air driving experience for front and rear seat occupants. Because the roof can be opened so that the rear cargo area is exposed, it permits moving tall items, such as a fridge or dresser. Constructed from reinforced acrylic cloth, similar to the material used on soft top convertible systems, Sky Slider posed some engineering challenges when it came to maintaining body rigidity—as cutting a humungous hole in a roof tends to cause such problems. “We went through a lot of finite element analysis on the vehicle body to assure proper rigidity. We put a fair amount of structure into the body itself to make sure we had the right stiffness,” says Tony Brenders, Senior Manager, rear-wheel drive vehicle development at Chrysler. A structural member, located overhead between the second row and the cargo area, aligned with the C-pillar, provides added stiffness and crash protection in the event of a side impact. “That was the perfect location to place the structural member without interfering with rear seat occupants or cargo storage,” Brenders says.
Another issue was assuring that the roof system would not leak or cause excessive wind noise when retracted. “We went through a number of refinements in terms of using the proper materials especially when it came to sound quality, because we did not want his thing flapping around. We also spent a lot of time on the overall sealing element,” Brenders says. The roof was designed using a force-sensitive hinge system that folds the canvas only when the proper amount of force is exerted on each hinge. “The last thing you want is this thing bunching up against the rubber seal, so it was engineered to lift off the seal when the proper amount of force is applied and then the roof starts to stack up. It’s pretty complicated when you think about it,” Brenders adds.
Sky Slider is delivered to the Liberty’s Toledo, OH, assembly plant as a plug-in module that’s attached via robot using 14 bolts and a urethane-based adhesive. “It’s fully self-contained so all the assembler has to do is plug in the two motors and it’s ready to go,” he addsKMK