<VV> 5-speed transmission

[The Corvair Kid]

Hi Cliff,

What sort of empirical testing were you thinking of? There was
*experimentation* with different 5th gear ratios, but not what I would call
"testing". One can mix-and-match 5th gears from various T5 applications to
achieve different outcomes. In the T5, first gear is essentially fixed on
the main shaft, so that's the starting point. The various flavors of units
offered had either a 3.76:1, 3.50:1, or 2.95:1 first gear.

With a 3.76:1 first gear, overdrive ratios of 1%, 14%, 19%, 24%, and 28% are
possible. (Not all of these were offered in actual production cars but the
parts are available, so you can "create your own ratio" to a limited
extent.) With the 2.95:1 first gear (which is what I have), there is really
only one usable ratio (IMHO): 27%. The others are much steeper. With 3.50:1
first, 22% and 27% are the "reasonable" ratios among all of the possible
ratios (IMHO).

--Kent

-----Original Message-----
From: VirtualVairs <virtualvairs-bounces at corvair.org> On Behalf Of Cliff
Tibbitts via VirtualVairs
Sent: Tuesday, August 18, 2020 9:44 AM
To: virtualvairs at corvair.org
Subject: <VV> 5-speed transmission

Wowzer, I never dreamed my simple answer to a question would arouse so much
interest.

Kent, was there any empirical testing done prior to your installation?
Just curious because I was not around when these units came out.  The
testing would be nice to have but expensive and who would want to do it?

On the other hand, seat of the pants experience counts for something as
well.  Consider this.  These cars were built in the 60's before most of the
present day Interstates were even built.  The national speed limit for most
thoroughfares was 60 or 65 MPH.  Also consider that these cars were expected
to spend most of their time running around town at speeds of 35-45 MPH.  At
those speeds the engine would have been 2000 RPMs plus or minus
500 depending on gear ratios.  Therefore I think again, that the cooling
should not be a problem unless the RPMS dropped below 2000 rpm.  In which
case, I would downshift.  I do that now with my 4 speed.

Finally, and I don't have the information in front of me, but I read once
that the cooling ability of the fan decreases above 4000 RPM so for people
who like to drive at 75-80 on the interstate, I think a 5th gear would help
quite a bit.
-- 

Cliff Tibbitts
cliff at tibweb.com