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Re: Gear ratio

To: "Bennett, Cullen" <p21988@gegpo8.geg.mot.com>
Subject: Re: Gear ratio
From: Steve Laifman <laifman@flash.net>
Date: Wed, 23 Jul 1997 11:06:50 +0100
I would be careful of using the "World Class" Ford 5spd OD, or the
earlier model. The size will not fit your tunnel, and it is not very
strong. Find shelves full of broken ones at repair shops. Just can't
take the torque. There is nothing stronger than your top loader, which
is virtually the same as the Cobra 427. That .63 overdrive was not meant
to allow good highway cruising. It is much too low with any rear end you
would want to use in the other gears. They choose that ratio for CAFE
(Corporate Average Fuel Economy) government requirements, not for your
cruising benefit. A good performance overdrive would be a 0.8, or a 20%
rpm reduction. This is what the Alpine OD, and all other sports OD's I
know of. With the normal 185/70 R 13 tires on 4.5" 13" rims the 2.88
rear end gives about 26 mph/1000 rpm. This is about 78 mph at 3000. The
motor should feel pretty unstressed at that rpm, and purrs very nice and
contented. If you had an 80% OD it would drop it to 2400 rpm, OK but not
much torque. A .63 rear OD would put it at 1890 rpm. There is now
reasonable way you could touch the gas pedal, or climb an incline,
without a shift. OK for economy. This is about what the OD automatics
do, but they up-shift the instant you demand any power.

Steve Laifman         < Find out what is most     >
B9472289              < important in your life    >
                      < and don't let it get away!>

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