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All automatic transmissions shift based on output shaft speed. That is
where the governor is located, which controls shift speed. Throttle pressure
also plays a part. Light throttle, quick shift. Max throttle, max shifts. The
1-2 and 2-3 shift valves are not the same size, so the trans is timed to shift
before the engine blows up. ALL 727s have a full
throttle downshift, even those with the part throttle downshift. Which didn’t
come out until 72 on big block 727’s. The whole idea was to not have to floor it
when you needed a downshift, but full throttle wasn’t really necessary. If it
doesn’t work right, linkage or throttle cable is to blame. 62 valve body is
pretty much the same as 63-64 with cable shift. Most of the 300 transmissions
had a higher speed governor, along with the other high performance models.
Governors with different weights can be bought to tailor the shift speed to the
engines power curve.
Don
Sent: Wednesday, October 14, 2015 6:39 PM
Subject: RE: [Chrysler300] 300 F axle ratios.
Once again displaying
and acknowledging the many gaps in my knowledge and experience, I never was much
of a drag racer on a timed strip but perhaps the reason for decent performance
from a numerically-low differential ratio in a letter car is that one can stay
in the lower gears to higher speeds. On its own in WOT mode, I think the
tranny shifts more based on engine speed than tail shaft speed. Controlled
by the driver, I would expect the shifting to begin at an RPM where the power
curve starts to flatten. With a TorqueFlite, 2.93 axle and 29” OD tires,
one could get 60 MPH in low and 101 MPH in second at 5000 RPM tail shaft
speed. That ought to just about do it for the quarter mile in any letter
car. Does anyone have additional documented time and speed values for
letter cars on the ¼ mile strips? Numerically low stay in second through
the quarter? Numerically higher finish in high gear? Rich
Barber Brentwood, CA 90+ in the
shade today. From:
Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of
alan miller alangmiller22@xxxxxxxxxxx [Chrysler300] Hey Guys, Back in '67 I drove my 'F' once at Fremont Drags.
Using 2.93 gears, turned a16.38, slow, but not bad I thought. Hot Rod Magazine
had a road test showing 16 flat, 7 years earlier. I don't remember their axle
ratio maybe someone out there has the issue. I'm sure all of you remember 6
seconds to 60 mph was considered a pretty good acceleration time, and about 7
sec. for our Brutes, but a Cobra 5.5 seconds, WOW! Times have changed...now in 2015 my Wife's car.... 2.9 to 60.
We are having the time of our lives! Alan To: rmreed@xxxxxxxxx;
gbarker@xxxxxxxxxxxx He had 9” Le
Car wheels….easy! John From: Michael Reed [mailto:rmreed@xxxxxxxxx] You surprised me on that one, Gary! Drag racing with a
3.31 RAR?!! That would seem to me to uncompetitively long gear ratio, unless you
weren't really serious. I don't recall anyone, even in the NHRA stock classes
back in the 60s and early 70s, running anything taller than 3.90. Most were
running 4.11s or 4.56s, some 5.12. My daily driver/weekend SuperStocker had a
4.56. I drive to the strip these days also, 4.11
gears.
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