Automotive Engineering - November/December 2021 - 29

Engineering the
2022 Toyota
Tundra
Chief engineer
Mike Sweers talks
structure, materials
and a different approach
to hybrid power.
by Steve Macaulay
T
oyota's third-generation 2022 Tundra was developed under
the direction of veteran Mike Sweers, who has been the program's
chief engineer since 2010. The all-new pickup is based
on Toyota's F1 platform, shared with the Land Cruiser and the
2022 Lexus LX600 SUV. Sweers, who is also senior VP, Product
Development Office, detailed the new Tundra's significant changes in
a recent interview with SAE contributor Steve Macaulay.
Sweers noted that the new truck gets a fully boxed frame, whereas
the outgoing truck's frame featured open channels. " You've heard
me talk for years about open C-sections and why open 'Cs' are important, "
Sweers said. " My competitors have criticized me for using a
'C' because our current pickup truck has a lot of compliance. " That
benefits ride quality, a key focus of the Tundra development team
and an attribute worth carrying into the new SUV.
" A truck shouldn't ride like a truck, " he asserted. " If you jump out
of an SUV or a car and get into this new Tundra you should say, 'Oh,
that's nice.' " While Sweers admitted that the ride quality with a fully
boxed frame is inherently stiffer than an open-C structure, his engineers
addressed that by replacing the rear leaf spring pack with a
multilink setup with dual-stage coil springs as standard.
When driving some competitors' trucks on Michigan I-94, Sweers
observed their rear ends " kicking out, " a result of their frames being
too rigid and their suspensions configured with heavy leaf packs
to accommodate loads. He acknowledged a dynamic characteristic of
coil springs: With a fully loaded bed or heavy tongue load while towing,
the rear end wants to come down. Toyota is offering load-leveling
air suspension in the rear for those who need the extra capability.
Tailor-welded frame rails
The Tundra's new frame differs from most boxed truck frames in using
laser-tailored steel blanks, Sweers explained, for strength with
optimum mass efficiency. The frame build starts with steel sheet, followed
by blanking out areas that are later filled in - via a wire-fed
laser welding process - with the appropriate types and gauges of
steel. These " tailored " blanks are formed into Cs, then two Cs are MIG
welded together to form the full box.
His team changed the roof design for 2022 and even made the
CHMSL part of the aero package. Now the wind separates as it
AUTOMOTIVE ENGINEERING
PRODUCT DEVELOPMENT FEATURE
The 2022 Toyota Tundra loses
its V8 and gains a hybrid option,
with NiMH battery, rear coil
springs and an SMC cargo bed.
comes off the roof and hits the tailgate spoiler. This
ended an interior " chaff " problem when the power
rear window is down. Toyota's aerodynamics team
- Sweers described as " a riot to work with " and " super-passionate
about what they're doing " - came to
him and said they wanted to rent a 20-foot covered
trailer so they could test it in a wind tunnel. " We ended
up buying it, " he said.
Materials mix
Engineering Tundra's body and cargo bed called for a
mixed-materials execution. Aluminum is used for the
hood, front doors, and deck outer. There are steel
fenders, bumper and tailgate. The bed is constructed
of sheet molded compound (SMC).
" We asked ourselves how we could get mass out of
the back of the truck, " Sweers said. The team looked
at aluminum and high-strength steel for the application.
But they decided on SMC because " it doesn't
dent like steel or puncture like aluminum. It doesn't
corrode, " he explained. And it's lighter than the alternative
materials. " We've used composite on Tacoma
forever, " noted Sweers, who also is the engineering
chief for the midsize pickup.
The downside of SMC, he admits, is that it costs
a lot more than steel and aluminum. " The people in
purchasing weren't particularly happy because the
decision was made to use a one-piece design for the
composite bed, which impacts shipping costs, " Sweers
said, adding, " This will sound like hooey, but our customers
are expecting our stuff to last forever. "
The simple tailgate
Tailgates that have lots of articulation is a current
trend in the pickup segment, and a point of controversy
for Sweers. Are such tailgates answering a question
that no one asked? " Do I really need Dutch doors
November/December 2021 29
TOYOTA
Automotive Engineering - November/December 2021

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