<VV> Overdrive Transmissions

[Sethracer at aol.com]

Saginaw 4 speed ratios 
1st                    2nd                3rd                 4th 
No lines             2.84    2.01                1.35              1.00 
1  line                 2.54                1.80                 1.44       
       1.00 
2 lines                3.11                 2.20                 1.47       
       1.00 
3  lines               3.50                 2.47                 1.65       
       1.00    
The above numbers are standard Saginaw 4-speed ratios. Lines refer to the  
number of lines on the standard input shaft - It doesn't apply the  Corvair. 
Note that the Corvair trans has some specific Reverse gear  location needs 
that may not match the other available Saginaws, especially later  ones.  
The line for the 3.11 first is the standard Corvair ratio. I  suppose, if you 
shifted to the wider ratio box, starting with the 3.50 to one  first, you 
adjust the rear axle ratio, maybe to 3.08, still have a usable  first gear or 
change to taller rear tires and lower your Cruising RPM. 
- Seth
 
 
In a message dated 10/30/2015 8:59:28 A.M. Pacific Daylight Time,  
virtualvairs at corvair.org writes:

If I  ignore all the engine discussion, I THINK the original question  
essentially was whether you could change fourth gear of a Corvair  
transmission into an overdrive.  The simple answer to that question  is no. 
Fourth is direct drive, yielding a 1:1 ratio by coupling the input  and 
output to each other.  You can add, change, remove gears all day  and all 
it 
can possibly change is everything but fourth.

There are  other options.  However, since the countershaft gears all come  
together in one piece, any ratio changes will start to get complicated  
(read 
as $$$).  To get an overdrive, you could change another gear to  run faster 
than 1:1.  The obvious change would be to make current  first into 
overdrive. 
There are complications.  Your shift pattern  would change.  Going 
sequentially through the gears would mean going  though the current 
positions 
2-3-4-1.  Using an FC transmission might  yield some better ratios for 2 
and 
3 (the new 1 and 2).  There are  some complications.  Using the early 
transmission, you would end up  with a non-synchro overdrive.  No matter 
which transmission you use,  you may not be able to make clearance in the 
case for the extra-large gear  on the countershaft.  Messing with first 
gear 
ratios will foul up  reverse.  It may be easier to change second or third, 
which avoids  both the non-synchro and reverse problems.  The synchronizer 
parts  may limit how small you can go on the driven gear.  Also, it would  
make for an even stranger shift pattern.

Overall, you would  probably be better off to use an FC transmission and 
find 
some 3.08 final  drive gears or have a custom ring and pinion made (if you 
could even find  someone to do it).

Jim Becker

-----Original Message-----  
From: DickR13607--- via VirtualVairs
Sent: Friday, October 30, 2015  9:37 AM
To: virtualvairs at corvair.org
Subject:  Overdrive  Transmissions


I understand the rpm problem, but, as an engineer  whom worked for  FoMCo
for a number of years, I was taught that lower  rpm's meant better  gas
mileage and longer engine life.  Also,  why have various people spent  years
working on possible 5-speed  transmissions for Corvairs?  I thought my  
idea 
was
much less  costly.  Would it work?  I don't know, but I  haven't seen  
anything
that addresses that question.

Richard Royle
66 Corsa  Turbo

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