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GMI
Platform Guide
Last Updated: March 16,
2006 |
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Delta |
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The Delta platform in GM’s premium
front wheel drive small car platform. First introduced on the Saturn ION
(to not-so-rave reviews), Delta is now coming into it's own
under-pinning Chevy's new Cobalt small car. Suspension wise, Delta uses
a independent front, and twist beam rear setup with various states of
tune depending on the application. Pretty much every flavor of GM's
Ecotec I4 is offered with the Delta, starting with the base 145 HP 2.2L
Ecotec and being punctuated with the supercharged 205HP 2.0L Ecotec (ION
Redline and Cobalt SS). Transmissions include a 4 speed automatic, and 5
speed manual. The ION Redline and Cobalt SS receive a specially tuned
version of the 5 speed manual. Currently the Delta platform underpins
the Chevrolet Cobalt, Chevrolet HHR, Pontiac G5 Pursuit, and the Saturn ION.
Things to know-
●GM benchmarked VW's last generation Jetta when designing the new
Cobalt.
●The high end Cobalt SS and ION Redline are the performers of the
platform, featuring not only great straight-line
performance, but decent handling.
●Saturn was going to get an all-new Delta car (GMX-002) in 2008, but the
program was canceled.
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Kappa |
Kappa is GM’s
small rear-wheel drive platform for mid-performance cars. The platform debuted on the Pontiac Solstice, followed
by the Saturn Sky and Opel GT. As of right now the Kappa is a
low-production platform, but that could change to underpin some
much-needed sport-compact cars for GM. Like the Delta platform, the
Kappa is capable of acquiring all of the Ecotec 4-cylinders mated to a
specially-tuned 5-speed manual and all Kappa’s are carried by
independent front/rear suspension with a near 50/50 weight distribution.
Things to know-
● Solstice GXP and Saturn Sky Redline performance Kappa’s are set to
arrive with a turbocharged Ecotec 2.0L in 2007.
● Kappa allowed GM to enter the roadster market.
● A Pontiac sport-compact could be a future Kappa candidate.
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Epsilon |
The Epsilon was
introduced in the United States in 2004 and is GM’s bread-and-butter sedan platform. Epsilon
is able to be powered by nearly all of GM’s V6 family, plus the Ecotec
4-cylinders mated to 4-speed automatic transmissions (hopefully 6-speed
soon!). The platform is used worldwide, for the Saab 9, Opel Vectra and
Cadillac BLS (Europe only). State-side the platform underpins the
Chevrolet Malibu, Pontiac G6, and Saturn Aura. All Epsilon
vehicles employ 4-wheel independent suspension.
GM also utilizes an extended version of the Epsilon. That version of the
platform is used on the Chevrolet Malibu Maxx, Pontiac G6 and Saturn
Aura.
Things to know-
● Pontiac G6 is will be available in coupe and hard-top convertible
versions.
● An updated version of the Epsilon will debut with an all-new Saab 9-5. |
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Epsilon II |
The replacement
platform for the current Epsilon platform is going to be the ultimate
global platform for General Motors. It will be utilized for use around
the world; in Europe, North America and possibly in other markets after
the platform goes online. Epsilon II will likely be slightly larger than
the current Epsilon, however it will be more versatile and be all-wheel
drive capable. E-II will debut in 2009 on the Saab 9-5.
Things to know-
●There were rumors that E-II would be FWD/RWD/AWD capable. That has not
been confirmed, however it is likely that they can tune the AWD to send
more power to the rear wheels for more performance-oriented handling. |
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Y-Body |
The Y is GM’s super
performance chassis. Occupied by only the Chevrolet Corvette and
Cadillac XLR, it is geared to perform. The rear wheel drive Y-body
employs a four wheel independent suspension and an innovative drive
train layout. The Y-body uses a drive train layout where the engine is
mounted longitude-wise in the front, as on most RWD cars, however the
transmission is mounted in the back as a transaxle. Power is then
transferred via a central torque tube.
The Corvette is powered by means of nothing other than GM’s family of
small-block V8’s. Corvette ZO6’s are now powered via a hand-built 500-hp
small-block. Cadillac’s XLR is powered by their Northstar V8, both a
supercharged version and non-supercharged are used. There is and 6-speed
automatic and 6-speed manual offered.
Things to know-
● Y-Body is one of the best platforms in the world.
● Don’t expect to see this platform obtainable on any other GM vehicles |
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W-Body |
Also known as the
‘mid-lux’ platform, the W-body is one of the most used platforms in GM’s
stable. It currently supports the Pontiac Grand Prix, Chevrolet Impala,
Chevrolet Monte Carlo and Buick LaCrosse/Allure. Approximating the
Epsilon, all of GM’s V6 powertrains can be used on the W-bodies amid
4-speed automatics. Performance W-bodies now use a 5.3L small-block V8
that is mounted laterally. All mid-lux cars have 4-wheel independent
suspension.
Things to know-
● The W-Body is likely on its last generation of use.
● There are rumors that the platform will be replaced by the ‘Chi’
platform. |
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Sigma |
The Cadillac-only
platform underpins the rear-wheel drive CTS, STS, and SRX. The Sigma
vehicles use a 4-wheel independent suspension design that utilizes a
short/long arm, coil over strut with anti-sway bar in the front, and a
modified multi-link with anti-sway bar. Of course, Sigma vehicles use
GM’s high-end V6’s and Northstar V8’s mated to 5-speed automatics or
manual (in CTS).
Things to know-
●Sigma is widely liked by the media for being a solid, well-mannered
chassis.
●Even two years after launch, the SRX is
considered the best-driving luxury crossover on the market.
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G-Body |
The G is used for the
Cadillac DTS and Buick Lucerne. All G cars use GM Pushrod V6’s or
Northstar V8’s transferred through 4-speed automatics. The front-wheel
drive platform sports 4-wheel independent suspension, however the DTS
features Continuously Variable Road-Sensing Suspension (Delphi's
Magnetic Ride Control) that reads the road for changing conditions
within milliseconds.
Things to know-
● Before the announcement of the Lucerne, the G-Body’s future was
uncertain.
● The dying Pontiac Bonneville was also a member of the G-Body family.
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Truck Platforms |
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M-Body |
M-Body is the basis
for the Pontiac Vibe, and is a joint platform with Toyota. The Vibe
itself is built alongside the Toyota Matrix, which also utilizes the
M-Body. The only powertrain is a 1.8L VVT-i mated to a 4-speed
automatic, 5-speed manual or 6-speed manual. The Vibe is supported with
front independent suspension among rear torsion beam includes front and
rear stabilizer bars.
Things to know-
● It is hard to tell what the future of the M is because of the Toyota
partnership.
● The Vibe shares many components and parts with its Toyota cousin. |
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Theta |
The unibody crossover
platform holds-up the Chevrolet Equinox, Saturn Vue and Pontiac Torrent.
Theta’s have front/rear independent suspension and are powered by a
4-cylinder (Saturn Vue), a Honda V6 (Saturn Vue), or GM’s ‘good-ole’
3400 V6 (Equinox and Torrent). All of which use a 5-speed automatic,
however the Vue can be had with a 5-speed manual or a specially tuned
5-speed manual in the Vue Redline.
Things to know-
● Theta is such a good platform, Cadillac may use it for a future
crossover!
● Expect the platform to be used for quite awhile. |
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GMT-355 |
This architecture is
used for the Chevrolet Colorado, GMC Canyon and Hummer H3. The Colorado
and Canyon come standard with GM’s I-4, but all of the vehicles use GM’s
Vortec I-5 powertrain, along with a 4-speed automatic or 5-speed manual.
Colorado and Canyon models use A-arms and a 28mm front stabilizer bar.
Firmer urethane jounce bumpers are used on all Z71 models in place of
the softer rubber bumpers used on the Z85 2WD Suspension. Both Z71 2WD
and 4x4 have front torsion bars that help supply performance, handling
and stance. The H3 uses front independent suspension with multi-leaf
rear suspension.
Things to know-
● The GMT-355 could be the basis for a Jeep Wrangler competitor.
● There are rumors that a V8 will hit in the 355 vehicles.
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Lambda |
General Motors has
made it clear that they want a very large piece of the crossover market.
Lambda-based vehicles will be crossover vehicles that are slotted
between midsize and large. The first Lambda to arrive will be the Saturn
Outlook, followed by the GMC Acadia and Buick Enclave. After the current
minivans are done, their Chevrolet and GMC replacements will be
Lambda-based as well.
Things to know-
●Hybrid versions of the crossovers are possible.
●The Lambda program has been over-budget. |
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GMT-360 |
GM’s midsize SUV platform underpins the Chevrolet Trailblazer, GMC Envoy, Buick Rainier, Isuzu Ascender and Saab 9-7x. All of the
GMT-360’s are powered by GM’s I-6 or 5.3L V8 with Active Fuel Management. For 2006 the
Trailblazer will get a dose of SS with an optional 390 HP LS2 V8
(standard on SSR).
Suspension wise the Trailblazer and Ascender have front independent with
a five-link rear, while the rest of the 360’s have front independent
with load-leveling air suspension in the rear. The only transmission
available is a 4-speed automatic.
Things to know-
● GMT-360 has an uncertain future. With competitors like Ford and
Daimler Chrysler thinking about moving their midsizers to unibody
platforms, GM is considering the same.
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GMT-800 |
This
is the most-used platform in the world, underpinning the Chevrolet
Silverado, Chevrolet Avalanche, Chevrolet Tahoe/Suburban, GMC Sierra,
GMC Yukon/Yukon XL, Cadillac Escalade/EXT/ESV, and Hummer H2. All of the 800’s use
GM’s family of Vortec V8’s or Duramax diesels mated to 4-speed automatic
transmissions.
Things to know-
● This is one of the most rugged platforms in the world.
● GMT-800 vehicles have made it through the ultra rugged Humvee
test course.
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GMT-900 |
When
the GMT-800 platform retires in 2007, this will be its successor.
Underpinning all of the vehicles the GMT-800 currently does. It too will
use Vortec V8’s and Duramax diesels. Along with new 6-speed automatic
transmissions, a new 6.0L hybrid using GM’s new two-mode system will
become available.
Things to know-
●A new, fully boxed frame that is significantly stronger and
stiffer with hydro formed front and rear bay sections.
●Wider front and rear tracks – approximately 3 inches (76.2 mm)
in front and 1 inch (25.4 mm) in rear – enable increased stability, as
well as a smoother, more controlled ride.
●New coil-over-shock front suspension delivers linear, responsive
ride and handling characteristics.
●Highly refined five-link rear suspension (with variable-rate
springs) delivers damped, isolated road feel and supports a variety of
load-carrying capabilities.
●Use of monotube Autoride shock absorbers for more controlled,
real-time damping capability.
●New rack-and-pinion steering system delivers precise, responsive
steering and contributes to the vehicles’ “drive small” feel.
●All-new four-wheel disc brake system larger vented discs,
stiffer calipers, more robust apply system and standard next-generation
Bosch ABS system provides shorter stopping distances, better pedal feel
and quicker brake response.
●Larger-diameter standard and available wheels and tires,
including segment-largest, 22-inch designs available on Cadillac
Escalade.
●Standard StabiliTrak electronic stability control with
first-time GM application of rollover mitigation – a software algorithm
technology that uses system sensors to proactively predict vehicle
“tip-up” and applies appropriate brake forces to prevent rollovers.
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