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This is another shot of the rotary mechanism which converts the linear input of the push-rod
to a rotary input to the Hall effect position sensor (located on the opposite side
of the housing). A look at the various parts inside the throttle pedal assembly makes it
quite obvious that the infamous "sticky throttle pedal" syndrome is caused by friction in
this rotary mechanism. All the other parts of the mechanism are very friction free by design.
This particular pedal assembly is one of the early SMG units which did develop the sticky pedal.
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Now on to the dreaded kick-down detent. Probably because E46 M3's with SMG II have an automatic mode,
BMW has seen fit to equip these cars with a different throttle pedal than the 6-speed manual transmission
cars. The SMG throttle pedal has a "detent" at the end of its travel. One can push the pedal all the way
down to full throttle, and then push it a bit further past a high mechanical resistance detent to get
full throttle plus a little bit extra. The mechanical resistance to the last portion of pedal travel
is induced when a protrusion on the rotary mechanism (1) contacts a mechanical spring-loaded "button" (2).
This button is purely mechanical and it has no electrical output. It is not connected to the Hall effect
throttle position sensor - it merely adds effort to the last portion of the throttle pedal travel. Quite
a bit of effort actually, which is what makes it so annoying to many drivers.
Although there is a change in the electrical output of the pedal when
the kick-down detent is engaged (from a 112% reading in output on BMW diagnostic equipment, to a 133% reading in output),
there is no apparent
change to the behavior of the engine (this impression is generally confirmed by most SMG drivers).
This might indicate that the DME interprets any signal above 112% as indicating a full throttle
command from the driver, with readings close to 133% being used only to signal the SMG software to initiate
a downshift.
However, with the SMG software in automatic mode, and in the lower program
levels (say 2 or 3), engaging the kick-down detent *will* cause the tranny to down shift, where it *will not* downshift
when
merely at full throttle without engaging the kickdown detent.
In the higher automatic programs (say 4 or 5) however, the SMG tranny
will down-shift simply by quickly depressing the throttle, without needing to push past the kickdown detent.
In this instance the detent is largely superfluous.
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It is possible to install a throttle pedal assembly w/o the kick-down detent from a manual E46 M3 into an
SMG II car. This eliminates the kick-down detent and makes the car more enjoyable to drive on
the track. At the track the car is at full throttle much of the time. The driver with an SMG
car will often be in a "zone" between full throttle w/o the detent engaged, vs. with the detent engaged.
This does not sound like a big deal, but it can be bothersome. With the manual throttle pedal installed this is
no longer an issue, and full throttle is full throttle - simple as that.
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The throttle pedal assembly from the manual version of the E46 M3 is a drop-in replacement into
an M3 with SMG II. Everything functions identically except that you lose the ability to force
the tranny to downshift through throttle input when in automatic mode in the lower programs.
Everything else is unchanged - or is it?
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