Automotive Engineering - August 2021 - 11

ROAD READY
2021 Jeep Grand
Cherokee L grows all
around
When engineering an upscale, 3-row
Jeep SUV, the development spider charts
must get pretty crowded. You'll need lots
of in-cabin technology and thoughtful
features for the third-row family customer.
No-joke off-road capability is simply
part of the brand. And a cosseting ride
with real on-road dynamics is a must for
competing with luxury brands.
" This architecture is 100% brand new, "
explained Fil Grado, chief engineer for
the Grand Cherokee L. " Every part on this
all-new vehicle is mission-specific for the
Grand Cherokee L, which is an excellent
place to be if you're an engineer. "
Thanks to the new platform and a dedUnderpinning
the new Bronco is a fully boxed steel ladder frame with seven crossmembers made by
Magna that is also slated (with some modifications) for the next-generation Ranger pickup. This is
the top-line Sasquatch-spec chassis. Tires are Goodyear.
on our experience, in its 4x4 drivemode
control. Ford engineers specified
a rotary dial module that also includes
pushbutton Hi/Lo Range selection. The
rotary control falls easily to hand, located
on the center console next to the
driver's right thigh. Rotary dial transmission
controls have a natural operating
feel, making them the new standard
in passenger vehicles and even sports
cars. By comparison, Jeep Nation still
demands a stick-type range control
that looks and feels increasingly obsolete
and clunky
Bronco's overall human-machine interface
and driver/passenger ergonomics
are more contemporary and well
considered than found in Wrangler.
Basic driver-to-pedals and driver-tosteering
wheel geometries deliver more
roominess and comfort, compared with
the remnants of the old sit-up-and-beg
attitude that Jeeps have endured since
the Willys-Overland era.
The third key area in which Bronco's
engineering is superior to Wrangler is
in the overall refinement of subsystems.
AUTOMOTIVE ENGINEERING
As Jeep engineers will discover when
they wring out their first Bronco for
competitive evaluation, the Ford systems
are electronically sophisticated
and unobtrusive. The automatic swaybar
disconnect makes and breaks a hydraulic
circuit to connect/disconnect
the " bar without the 'bang' " found in
some competitive technologies. It uses
pressure sensors to detect leaks.
Bronco's clever Trail-Turn Assist is a
handy feature for use on tight trails. It
relies on steering-angle sensing and discrete
use of brake pressure to help spin
the vehicle, effectively shortening its
turning circle by 40%. The Dana locking
differentials are mostly invisible in their
operation. The same attention to detail
is engineered into Bronco's slick-operating
1-pedal drive and the deft mapping
of the ZF electric power steering. " We
have all these discrete components that
we treat as an orchestra, " noted Jamie
Groves, the vehicle engineering manager.
Think of this new 4x4 as a symphony,
expertly conducted by Ford.
Lindsay Brooke
icated engineering team that " fought like
family " to accomplish an ambitious
breadth of program targets, the all-new
Jeep Grand Cherokee L (GC-L) appears
ready to meet its wide mission. Adding a
third row to the fifth generation of Jeep's
segment-leading SUV seems long overdue
(as is a 4xe hybrid due before year's
end) and will almost certainly expand its
appeal. Off-road ability in its segment will
likely remain unmatched, but a keenly
sorted chassis brings surprisingly adept
on-road dynamics to the expanded
Grand Cherokee lineup.
All-new platform, sophisticated
suspension
Known internally as the WL75, the
5-door, 6- or 7-passenger, 3-row GC-L's
unibody platform is composed of more
than 60% of the latest grades of advanced
high-strength steels. The
" Generation 3 " steels permit the cold
stamping of more complex shapes, reducing
part counts and mass. Aluminum
is used for the hood, tailgate, front cradle,
engine mounts, steering gear, suspension
arms and shock towers, with those front
towers netting their own brace that improves
local lateral stiffness by 125%. The
cross-car IP beam is magnesium.
The vehicle architecture is supported
by novel coil- or air-sprung, multi-link
independent front and rear suspensions.
July/August 2021 11

Automotive Engineering - August 2021

Table of Contents for the Digital Edition of Automotive Engineering - August 2021