In a message dated 5/20/2007 9:57:57 A.M. Mountain Daylight Time,
wester6935@comcast.net writes:
So what does the change in the shift point when I go from stock
settings to a stronger shift point with the chip in my truck do?
Wes
Hi Wes
The chip reprograms the transmission electronically just like a chip for
higher performance in your engine does. Instead of changing fuel and timing
curves for the engine, they change the trans shifting characteristics.
Your valve body has sensors that sends pressure signals to the trans
computer. Typically the trans computer is separate from the engine computer but
it
does share engine control signals sent from the speed sensor and throttle
position sensor on your engine. This eliminates the sensitive mechanical
throttle
valve cable like the 700R4 and 4L60 must have to control shift points and
kick-down. The computer also eliminated vacuum modulators on those
transmissions.
Your shift linkage still moves a mechanical valve in the trans to select a
gear. There are also valves for 1 to 2, 2-3 and 3-4 gear shifts. The only
difference is when first gear shifts into second in a hydraulically controlled
trans, it's spring pressure that is overcome and allows the up shift. In a
computer controlled trans, it's sensors telling the trans computer when it's
time
to shift. At this point the computer signals a solenoid in the trans to open
allowing oil to flow to the 2-3 shift valve train and out to the clutch pack
and/or band servo. When it's time for the next shift, the computer signals a
different set of shift valve trains to move allowing the clutch packs and/or
band servos to engage while other clutch packs/bands used for the initial
shift disengage. During the subsequent shifts, 1-2 is closing while 2-3 is
opening. Timing is everything to maintain smooth shifting without flares or
harsh
shifts.
Otto
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