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Wheels - The Nuts and Bolts of Whatever Moves You
December 1, 2008, 4:53 pm
Launch Party Is Over for Nissan GT-R
By Ezra Dyer

We Americans just can’t have nice things.
Nissan GT-R, soon without launch control.

As Exhibit A, I give you the Nissan GT-R and its soon-to-be-discontinued
launch control feature: A bunch of people bought GT-Rs and fried their
transmissions using launch control. Said customers then hit Nissan with
warranty claims, at which point Nissan took its toy and went home. Thus
the 2009 GT-R will be the only vintage of the car with the
factory-sanctioned ability to perform a high-r.p.m. clutch drop from a
standstill. I’m not sure whether that will make 2009 GT-Rs more valuable
on the used-car market, or less.

With the proliferation of dual-clutch sequential manual transmissions
comes a thorny issue for car companies — whether or not to include
launch control, and how to design the system if they do. Launch control
systems address a major performance issue inherent to sequential manual
transmissions, which don’t have clutch pedals to drop: namely, how does
the driver execute an aggressive takeoff from a standing start? Usually,
through an arcane button-pushing routine to initiate launch control.

Nissan’s system was the real deal, an automated version of the sort of
machinery-abusing takeoff that a human driver might attempt on a drag
strip. There’s a certain video-game-cheat quality to setting up the
system, like the button-pushing sequence you’d use to get 30 lives in
the old Nintendo game Contra. Set the suspension to “R” mode, set the
transmission to “R,” turn off the stability control, left foot on the
brake, right foot hard on the gas, pop the left foot off the brake … and
hold on. The motor would wail, followed by a violent clutch engagement
and all four tires clawing frantically under maximum power.

Now, I don’t know the specifics of the warranty claims that caused
Nissan to discontinue the GT-R’s launch control system. For instance,
were people doing right-angle burnouts while running over manhole
covers? (I include that example because an engineer at a car company
once told me that he had to duplicate that exact scenario to figure out
how customers were causing a certain drivetrain part to fail.) Were
people just doing occasional drag strip runs? And at what point does
responsibility shift from the customer to the automaker when something
breaks? That’s the question plaguing the growing number of companies who
offer some form of launch control.

If you own a manual-transmission performance car and you abuse the
clutch and transmission to the point of failure, you as the owner have a
pretty direct responsibility for what happened. If you take, say, your
Subaru WRX STI into the dealer for a new clutch, and they take it apart
and discover that you’ve inflicted 90,000 miles worth of wear in 5,000
miles, well, your left foot is the obvious culprit. But in a car with
launch control, there’s a philosophical difference. Sure, you may have
initiated the launch control sequence 20 times in a row and fried the
clutch, but ultimately the car itself was the one doing the dirty work.
So if something breaks, why is it your fault simply for using a feature
that’s built into the car? It’s an argument that Nissan, at least, has
decided it doesn’t want to get into.

Launch control systems in the United States have a history of either
being omitted entirely (as in the United States-market Ferrari F430) or
dumbed down. For instance, the launch control function on BMW’s
single-clutch sequential-manual gearbox, SMG, was a modified version of
the system used in Europe. The European SMG would slip the clutch to
provide the fastest takeoff possible, at the expense of clutch wear. The
American system would quickly — but completely — engage the clutch,
which tended to spin the tires and probably cost a few tenths of a
second on zero-to-60 time. The rear tires were the circuit breaker of
the system, the place where excess energy could be dissipated in a
manner conducive to avoiding warranty claims.

But all-wheel-drive cars like the GT-R, Mitsubishi Evolution and Porsche
911 C4, which usually have too much traction to generate significant
wheel spin, put the stress on the clutch. And that’s an expensive
circuit breaker.

There are different ways of handling that stress. With Mitsubishi’s
twin-clutch Sportronic transmission in the latest Evo, the launch
control mode restricts full engine power until the car is rolling and
the clutch can fully engage. The system also monitors clutch temperature
and will call a timeout — forcing the driver to pull over to let things
cool down — if multiple launches raise clutch temperature too high (the
launch control feature on BMW’s new DCT dual-clutch transmission also
keeps a careful eye on temperatures and will take a hiatus if it gets
too hot). The Evo with Sportronic does 0 to 60 in 5.2 seconds, while the
five-speed manual version is a few tenths of a second faster.

The difference is purely down to the violence of the launch and can be
traced to the first 60 feet of an acceleration run, where the manual
Evo’s launch r.p.m. and clutch slip are restrained by nothing more than
the driver’s penchant for mechanical sadism. In the case of the
dual-clutch Evo, the programming is calibrated to err toward longterm
drivetrain survival rather than ultimate drag-strip heroics. Mitsubishi
points out that, while the dual-clutch car is slower than the five-speed
from rest, the Sportronic car’s quicker shifts and extra gear ratio make
it faster around a road course. So the virtues of either transmission
and the relevance of launch control depends on whether the word “track”
conjures in your mind a drag strip or the Nürburgring.

Then there’s Porsche’s new PDK dual-clutch transmission. A base Porsche
911 Carrera with a six-speed manual can go from 0 to 60 miles per hour
in 4.7 seconds. The same car with PDK and launch control is actually
four-tenths of a second faster. There are no restrictions on how often
you can use launch control, and the warranty is identical to that of
non-PDK cars. I suppose time will tell whether Porsche, unlike Nissan,
has designed a transmission tough enough that launch control doesn’t
lead directly to legal damage control.

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