<VV> Posi? (lengthy but includes alternatives and safety suggestions)

[RoboMan91324 at aol.com]

Ralph (I assume)
 
Three alternatives,
 
1.)  With either manual of auto trannies, jack one rear wheel just barely 
off the ground and the other  remaining on the ground.  With the tranny in 
neutral and the parking brake  off, try to turn the elevated tire.  If it 
turns, you have an open  rear.  If you can't turn it, you have a posi.  The 
reason a posi won't  turn is that both wheels always need to turn in the same 
direction and the  grounded wheel prevents this unless the car moves.  That is 
a  very important point.  Always chock the front wheels to prevent  rolling 
in either direction.  This is a good idea  whenever jacking a car up for 
any purpose.
 
2.)  If you have a manual tranny, jack both wheels off the ground with the 
tranny in any gear and the parking  brake off.  Try to turn one wheel.  If 
it does not turn, you have a  posi.  If the other wheel turns in the opposite 
direction, it is an open rear.
 
3.)  If you have an auto tranny, you can verify what rear  you have by 
jacking both wheels off the ground and with a partner, try to  turn the wheels 
in one direction or the other.  If it is a posi, both  wheels must turn in 
the same direction so if you and your partner try to turn  the wheels in 
opposite directions, you can't.  If the rear is open, you can  turn the wheels in 
opposite directions.  If you do not do this with a  partner, there is a 
remote possibility that an open rear will let both wheels  turn in the same 
direction.  For this to happen, you probably have undue  friction in the 
differential spider gears.
 
As long as you chock the front wheels,  alternative number 1 is preferred.  
I assume you will chock the wheels no  matter what.  It is valid for both 
manual and auto trannies and has the  benefit of being easiest.  In general, 
you do not want to jack up the whole  rear end of the car from the center of 
the drive train.  The  motor/transaxle mounts are designed for the drive 
train to be hanging down on  them.  Effectively, the car body holds the drive 
train up.  If you  jack the car up by the drive train, the forces on the 
mounts will be  reversed.  Effectively, the drive train is holding the car up.  
 Especially with aged mounts, this could cause failure of the mounts or the 
 attachment points of the mounts.  Therefore, to raise both rear wheels off 
 the ground, you need to jack up one side and support it and then jack up 
the  other side; more work and risk.  Of course, you can jack up the front of 
 the car from an appropriate center point without concern for mounts.  
 
Under all situations, do not work under a car supported by a  jack.  
Mechanical jacks are flimsy and can easily tip over.  Hydraulic  floor jacks can 
develop a leak and come down very fast.  Bottle jacks have  the risk of leaks 
but also tip over very easily.  Jack stands are much  safer especially 
those with large supports with lips up top and wide bases to  minimize the risk 
of them tipping over.  Always jack the car up to the  lowest level that will 
allow the necessary work.  In  any case, always use extreme caution when 
jacking up a car.  Other than  on-the-road accidents, more injuries and deaths 
result from carelessness with  the car off the ground than anything else.  
Err on the side of  caution.
 
Doc
 
1960 Corvette, 1961 Rampside, 1962 Rampside, 1964 Spyder  coupe, 1965 
Greenbrier, 1966 Canadian Corsa turbo coupe, 1967 Nova SS, 1968  Camaro ragtop

~~~~~~~~~~~~~~~~~~~~~~~~~~
 
In a message dated 8/28/2014 7:40:53 P.M. Pacific Daylight Time,  
virtualvairs-request at corvair.org writes:

Message:  2
Date: Thu, 28 Aug 2014 21:45:58 -0400 (EDT)
From: Ralphsebrell  <ralphsebrell at aol.com>
To: virtualvairs at corvair.org
Subject:  <VV> Posi?
Message-ID:  <8D191421D979ECA-1420-735 at webmail-va048.sysops.aol.com>
Content-Type:  text/plain; charset="us-ascii"

How do I know if I have a Positraction  in my Vair?