bonzelite

monocoque (French for "single shell"), or unibody, is a construction technique that uses the external skin of an object to support some or most of the load on the structure. compared to older techniques, in which a body is bolted to a frame, monocoque cars are less expensive and stronger.

monocoque construction was first widely used in aircraft, starting in the 1930s, and is the predominant automobile construction technology today, albeit "semi-monocoque:"

a true monocoque refers to a more shell-only/ self-supporting (or nearly so) structure than is current practice, ie, aircraft structure vs. current automobile. heavy frame-type underbodies, and roof structures required today, make a true monocoque layout infeasible.

bonzelite

Mg (magnesium) is used extensively in the aviation industry for structural members as it is extremely lightweight and strong.

as well, as Mg is electrolytically extracted from magnesium chloride in seawater, the production of magnesium requires a great deal of electricity, and the cost of that electricity constitutes a significant part of the cost of magnesium production.

however, it is expected that in the next decade, the automotive industry will begin to use Mg as a substitute for steel. Mg is half the weight of aluminum, one quarter the weight of steel, and stronger than either. as a result, the world demand for magnesium is projected to increase to more than double the present 325,000 tons per year.

however, besides the current expense to process it, magnesium (Mg) is extremely fickle, as the biggest problem with welding it is that it is most often processed by high-pressure-die-casting, as the porosity (void space) levels produced by this process can lead to severe weld disruptions (particularly in common robotic spot-welding seen in current auto manufacturing), and is seldom ever joined in this manner.

moreover, Mg needs to be submerged-welded in a separate atmosphere (under water, inert gas). despite its potentially excellent use as an alternative to aluminum and steel, magnesium is currently impractical for primary structural use in mass-produced cars due to its lack of casting quality, cost-effectiveness, and resistance to being spot-welded.

what is seen today as production parts in cars are typically cast-frame components, ie, single-pieced elements, like straight bolt-ons such as engine valve covers, instrument panel substrates (also called "cross-car beams" if used for reinforcement of dash/cowl area), transmission and differential housings, and numerous engine compartment instrument panel frames, connected to the base material by mechanical means (threaded fasteners and self-piercing rivets).

the use of a "shielding gas" (typically argon or carbon dioxide) is required for arc-welding any material, particularly Mg, if the desired outcome is a high-quality, high-integrity joint, capable of providing long-term durability in an automotive environment.

some methods of welding it are:

-gas metal arc welding (also known as MIG for Metal Inert Gas).
-laser welding
-electron beam welding (both vacuum and nonvacuum).
-friction stir welding (this process does not liquify the base material; rather, it produces softening and "plastic deformation" by means of a rotating tool).

before being welded, Mg typically appears as an alloy metal (ie, mixed with another metal:magnesium-aluminum or magnesium-lithium).

bonzelite

obakemono:

Japanese for "monster." this name has been used, as well as "godzilla," to describe the GT-R.

expect to see it again.

bonzelite

high and low pressure zones associated with a car's body may be quickly pinpointed when considering the following:

-any place where the airflow is turning away from the car (where the windshield meets the hood, for example) will have a high pressure region associated with it.

-any place where the airflow is turning towards the car (where the windshield meets the roof, for example) will have a low pressure region associated with it.

-percentage of total aero drag of these elements of the car's body are as follows:

underbody: 1-7%
engine compartment: 4-14%
brakes cooling: 2-5%

bonzelite

you can cross-reference this post with post #57 to compare and contrast the most stolen cars in California with North America in general:

for California:
-most stolen cars in 2004-
1. 1989 toyota camry
2. 1988 toyota camry
3. 1990 toyota camry
4. 1991 honda accord
5. 1990 honda accord
6. 1991 toyota camry
7. 1987 toyota camry
8. 1992 honda accord
9. 1995 honda civic
10. 1994 honda accord

for California:
-most stolen trucks in 2004-
1. 1988 toyota pickup
2. 1986 toyota pickup
3. 1987 toyota pickup
4. 1985 toyota pickup
5. 1986 toyota van
6. 1987 toyota van
7. 1984 toyota pickup
8. 1985 toyota van
9. 1984 toyota van
10. 1986 nissan pickup

source: AAA, automobile club of southern california

bonzelite

i have noticed a disturbing trend, in that the definition of "platform" is often misused:

originally, a "platform" consisted not only of suspension, but driveline and most importantly (single most expensive component) the "pan stamping" (commonly called floorpan and firewall). this term, then, meant that these components were shared in common between different models of cars under the same manufacturer, using the body-on-frame assembly line process (as is still common today in pickup trucks, but less so in cars).

as time went on, and manufacturing and design technology shifted to unibody, or "partial monocoque" for car body construction, the term "platform" began to somewhat change it's meaning:

today, a platform actually seems to be defined as a collection of fixed hard points, so that different vehicles with the same points can be built on a single assembly line, with similar crash characteristics. hence, the G35 sedan, G35 coupe, and FX45, despite having major differences in appearance, handling, length, height, etc., can be said to be on the same "platform" - and would still be even if they did NOT share very similar suspensions and engines.

confused?

simply, a platform is a basic dimensional design: on the FM platform (for example), the suspension and drivetrain mounting points, and firewall are common. the platform determines body width, firewall height, and, to some degree, the length because of front suspension points being located an established distance from the driver position.

sharing a platform prevents total research & development every time a new model is designed, saving time, and retaining tooling commonality. some drawbacks are the inability to make immediate changes, as issues may arise in styling and customer needs.

however, a platform is not anymore necessarliy a "chassis." in theory, several vehicles may be adpated from a single platform, but not share overall body length, engine, or suspension components (as is true for the 350Z and G35 --same platform, different chassis codes).

Nissan and the FM platform:

the Nissan FM platform is a modern FM layout automobile platform. the name is derived from the "front midships" location of the engine, with it being pushed as far back to the firewall as possible, creating a weight distribution that's close to 50:50. this platform debuted with the 2001 V35-series Nissan Skyline.

current FM platform family (RWD):

Nissan Skyline V35/Infiniti G35 (V35-series chassis)
Nissan Fuga/Infiniti M (Y50-series)
Nissan 350Z (Z33-series)
Nissan Stagea (M35-series)
Infiniti FX (V35-series)

Nissan and the FF-L platform family (FWD):

higher-volume offerings share another platform: the FF-L (front engine, front-drive). first seen on the 2002 Altima, the FF-L now underpins the new-for-2004 Maxima and Quest, and the Murano crossover utility vehicle.

the FF-L platform pushes the wheels out to the corners, allowing a long wheelbase and wide stance within a manageable overall length. along with the platform’s inherent handling and performance advantages, it allows greater packaging and styling flexibility.


chassis codes:

1984-1987
Nissan 200sx
S12

1988-1990
Nissan Silvia
S13 CA18DET

1990-1991
Nissan 180SX
RS13 CA18DET (R for fastback)

1991-1993
Nissan Silvia
PS13 SR20DET (P for SR)

1991-1998
Nissan 180SX
RPS13 SR20DET

1991-1993
Nissan Silvia (K for SuperHicas)
KPS13

1991-1993
Nissan 180SX
KRPS13

1989-1990
Nissan 240SX
HS13 KA24E (H for KA24E)

1989-1990
Nissan 240SX
RHS13 FB

1991-1994
Nissan 240SX
MS13

1991-1993
Nissan 240SX
RMS13FB(M for KA24DE)

1991-1993
Nissan 240SX FB w/ SuperHicas
KRMS13

1991-1993
Nissan 240SX w/ SuperHicas (Canadian market only).
KMS13

1994-1998
Nissan Silvia SR20DET
S14

1994-1998
Nissan Silvia w/ SuperHicas
CS14

1995-1998
Nissan 240SX KA24DE (no specific S14 code for KA24DE)
S14

1995-1998
Nissan 200sx
B14

1995-1998
Nissan 240sx
S14

1999-2001
Nissan 240sx
S15

1990-1996
Nissan 300zx
Z32

2003-
Nissan 350z
Z33

1989-1994
Nissan Maxima
J30

1988-1994
Cefiro
A31

2001-
Nissan Altima
1995-1999
Nissan Maxima
Cefiro
A32

2000-2003
Nissan Maxima
Cefiro
A33

1991-1994
Nissan Sentra
B13

1995-1998
Nissan Sentra
B14

1999-
Nissan Sentra
B15

1989-1994
Nissan Skyline
BNR32

1995-1998
Nissan Skyline
BCNR33

1999-2001
Nissan Skyline
BNR34

1991-1996
Infiniti G20
HP10

1997-
Infiniti G20
HP11

2003-
Infiniti G35 (Coupe)
V35

2003-
Infiniti G35 (Sedan)
V35

2003
Infiniti FX35/45
V35

1995-1999
Infiniti I30
A32

2000-
Infiniti I30
A33

1994-1996
Infiniti Q45
G50

1997-2000
Infiniti Q45
Y33

bonzelite

as if the prior post was not enough, we need some more platform data:

model: platform

Nissan 200SX: NISSAN B
Nissan Altima: NISSAN ALTIMA (pre-2002), then FF-L (2002-present)
Nissan Frontier: NISSAN QW (then became F-Alpha 2005)
Nissan Hikari/Tsuru: NISSAN B
Nissan Lucino: NISSAN B
Nissan Pickup: NISSAN PICKUP (2004 became F-Alpha variant)
Nissan Sentra: NISSAN B
Nissan Vanette: AYMESA CV
Nissan Quest: FORD VX54 (pre-2004), then FF-L (2004-present)
Nissan Tsubame: NISSAN B
--------------------------------

the following all share the F-Alpha platform:

Nissan Frontier
Nissan Pathfinder
Nissan Titan
Nissan Xterra
Nissan Armada
Infiniti QX56

bonzelite

as more companies move over to aluminium body panels, the tooling challenges for mass-production become enormous. welcome to superplastic forming (SPF), ie, superforming:

in the traditional stamping process, sheet metal is deformed between two dies in a heavy press, causing the metal to conform to the shape of the dies. because aluminum is less rigid than steel, aluminum stampings have a tendency to spring back to their original shape.

superforming is a hot forming process in which a sheet of aluminium is heated to 450 to 500 degrees centigrade and then forced onto or into a single surface tool to create a complex three dimensional shape from a single sheet.

"superplasticity" in metals is defined by very high tensile elongations, ranging from two hundred to several thousand percent. the process, conducted under controlled temperature and "strain rates," dramatically increases the formability (plasticity) of certain aluminum alloys, and allows production of highly integrated, net-shape components that often consolidate many parts into one. this reduces the number of parts, fasteners, and assembly operations required for complex automotive and aerospace applications, and enables the use of aluminum in place of steel at competitive costs.

General Motors (GM, along with a myriad of commercial entities and universities), in conjunction with the Department of Energy (DOE), researched this technology during the 1990s for application in typical mid-sized automobiles. the proliferation in subsequent years of the technology has already proven attractive to many sports car manufacturers, and will ensure that future vehicles of all kinds are lighter and more fuel efficient.

since it's inception, the process has undergone refinements:

21st century manufacturing processes (again pioneered by GM and collaborator Alcoa), have further refined "SPF" to what is now known industrywide as the more streamlined and cost-effective "QPF" (quick plastic forming --):

with QPF, as in SPF, a heated aluminum sheet is subjected to high-pressure air that makes it conform to the shape of a hot tool. the high temperature improves the formability so that even complex shapes can be manufactured. dimensionally correct panels are possible because "spring back" is nearly eliminated. the QPF process is math-based, with the dies created directly from design software. the simple, one-sided tooling process reduces development time, and aids in shortening the vehicle development process.

bonzelite

bore x stroke (mm)

VQ25DE: 85.0x73.3
VQ30DE: 93.0x73.3
VQ35DE: 95.5x81.4
VQ41DE: 95.5x95.5

bonzelite

“oni-can” (translated “demon camber” from japanese) was popular in drifting circles years ago. oni-can is when you apply obscene amounts of negative camber to the suspension. as this setup looked aggressive (or dumb), it lost it's appeal after many drifters, wanting to "fit in," wrecked their cars with this unstable wheel setting.