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We're
replacing the original M-21 Muncie 4-Speed with a new Richmond Street
5-Speed manual transmission. "Why?", you may well ask.
One of the limitations of the
old 4-speed design was the choice we were all forced into making between
eye-popping acceleration off-the-line or reasonable R.P.M.s at highway
speeds.
The addition of the extra
gear in the Richmond solves this problem, even without an overdrive
gear. (NOTE: 5th gear is still at 1.00:1 just like in the original Muncie 4-speed).
Here's a spreadsheet I made up to
demonstrate the results of using different rear gears and transmissions.
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You see, by changing out the
formerly-installed 4.56:1 rear gear set for a highway-liveable 3.08:1 rear end, we
solve the highway cruising problem (just 2,300 R.P.M. at 60 mph).
And
because 1st gear in the Richmond is a stunning 10.10 overall ratio (3.28
times the 3.08:1 rear gear) we get astounding off-the-line performance
too....slightly better than a 4.56:1 rear end combined with the 2.20 1st gear in
the old Muncie 4-speed....Tada!  |
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The
Richmond 5-speed has arrived. Here's a comparison between it (on the
left) and the
original M-21 Muncie 4-speed (on the right).
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The original
transmission mount, used with the Muncie 4-speed is in place in this
photo.....but with the Richmond 5-speed. As you can see to the right, the mount
boss (marked A when you enlarge the photo) on the Richmond is further to
the rear (left in this photo) than where the Muncie mount boss sits on
the mount (marked B on the enlarged photo). |
Click on photo to enlarge. |
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After careful
measurements and marking, we cut 2.75" out of the original mount
with the band saw. When measuring your car, be sure to allow for things
like the scattershield "block plate" if you're going to use
one. |
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We're
going to discard the entire centre section, replacing it with a piece of
1/4" plate to give us something to weld the two remaining pieces
to.
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Now that it's welded together, all that remains is some
cleanup and painting with POR-15. |
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It's
installed..........and the Richmond 5-speed
is finally home where it
belongs. |
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A
big thanks to ML67 (Corvette
Forum member) and RichsCorvettes
(CF
and
Corvette Action Center member) for excellent advice on
modifying the transmission mount bracket.
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The
Hurst Shifter to the left is part #407 0009, but the stick is all wrong
for a 1967 Corvette. It should be shorter and straight with a round chrome
shaft and ball and a reverse lockout "t" handle.
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In order to
replicate the appearance of the original shifter on the Munice 4-speed,
we ordered #407 0015 (shown fresh out of the box above) and replaced the
straight (but flat) stick with the original-appearing stick to the right.
The reverse lockout "t" will be non-functional with the
Richmond 5-speed. It will, however, look like a 1967 shifter. The part
number is ST-327 from Zip Corvette Products. |
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I couldn't resist
installing something on the day after Christmas, so I snuck out to the
garage.
You wouldn't know
there was a Richmond 5-speed hiding under there, would you? |
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The decision was
made to fabricate a completely new driveshaft. The Richmond 5-speed
output spline required the use of a TH400 yoke on the front of the
driveshaft; much larger than the stock yoke. We wanted additional
strength, so a new shaft with thicker walls was used. |
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A heavy-duty Spicer
u-joint
was used at the tail-end. |
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Click on
the above images to see larger photos
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Balanced and ready for paint. |
