7.5" Differential Tips:

[h-bot]

From: twelve_second_vega_REMOVE_733924_THIS_@yahoo.com


I am really starting to like the 7.5"
differential more & more. They may not be the strongest unit
available, but the selection of gears are vast and parts are
cheap.

Here are some of the tricks I am using on my 7.5"
axle. I thought some of you might be interested in
hearing about them.

One of the first things I do
is insert a carrier bearing race into the housing
and place the cap over it. I then carefully sand the
mating surfaces of the cap, with #400 grit paper on a
piece of glass, until I can insert a .001" feeler gauge

between the cap and the housing on one side. This will
ensure you have the right amount of crush on the bearing
race.

Many times, you will see the right side gear
bearing race has spun in the housing from too little
crush. I really think this works and its easy to
do.

I also debur all the teeth on the gears including
the heel. I think this adds some stress releiving
properties to the gearset.

On the Cone Type Posi
Units, I pull everything out and polish or debur all the
parts, including the ends of the springs. I will usually
check the fit of the cross shaft and sometimes I will

sand a few thousandths carefully off the mating
surfaces of the carrier halves until I have a stiff,
sliding fit.

I use coarse valve grinding compound
and lap the cones into their seats using an old axle
as an arbor. Once I have a perfect gray surface, I

switch over to a fine lapping compound. I think this
really extends cone life and improves seating and heat
dissapation.

I polish the ends of the side gears
where they contact the spring plates and dress the
plates themselves on a grinding wheel. Don't forget to

debur and polish the spider gear's thrust
surface.
In stock condition, the spring plates are very wavy
and the side gears only contact them in 3 places!


It only requires about .010" of material removal
and it makes for a very slick mating surface.
I
will usually perform a final polish (by hand) to every
contact surface with #400 grit wet-or-dry paper and a
light solvent. This yields an almost mirror finish and
makes the unit smooth and long lasting.

Before
assembly, I will coat all the parts with a moly type engine
assembly paste and drop them into a fully deburred
housing.

I use Mobil 1 Synthetic 75 w 90 axle lubricant
exclusively. It already has the clutch-type limited slip
additive in it. There is no need for
additional
additives.

I complete the installation with one of Summit's
Aluminum Support Covers. I like the added capacity, but I
think their calim of adding
strength is probably
far fetched.

I fill the differential until
lubricant is level with the bottom of the axle bearings.
This makes sure they have lubricant all the time and
prevents them from running dry until the spinning axle can
sling lubricant out to them. So far, I have no sign of
any leakage either.

I install a hose barb in
place of the vent cap and run a piece of fuel line up
to the floor of the car. I install a clear, plastic
fuel filter
in this hose. It acts as a vent filter
and gives you protection should you ever go through
deep water.

I cannot take credit for inventing
some of these tricks and techniques, but I am using
them with good results and I wanted to shre them with
you.

Best of luck on your project...Robert



 


[This is message #19 by user twelve_second_vega on Yahoo! Club V8 Vega Conversions: http://clubs.yahoo.com/clubs/v8vegaconversions ]

[h-bot]

From: twelve_second_vega_REMOVE_109797_THIS_@yahoo.com


The use of a National #8610 Pinion Seal is
recommended when converting to the S-10/Camaro Style 7.5"
ring and pinion. No one around here
stocked the
#8610 seal and my cost on it was around $27.00.


I discovered the difference in the O.D. of the
sealing surface on the S-10 and Monza Pinion Yokes was
only about .012" so there is no need for
a
'special' pinion seal.

I used CR Seal #15305, which
was a normal stocking item at Pep Boys and it only
cost me $6.99. It did not add any measureable preload
to the differential assembly.

The following
parts will be needed on an S-10 Ring & Pinion
Conversion. These are GM part numbers unless otherwise
noted:

9785792 Crush Sleeve

344171 'C' Locks
(2)

26041321 Cross Shaft w/ (4) Machined Flats

14056196
Cross Shaft Screw

88891763 Pinion
Nut

553023 Pinion Shims .030" to .034"

559755 Pinion
Shims .020" to .024"

The average pinion shim(s)
required for the installation of an S-10/Camaro 7.5" Ring
& Pinion in a Monza/Sunbird/Skyhawk Housing is
.082" to .092" respectively.

I recommend
pressing the pinion bearing on without shims and leave an
approximate gap of .125" between the rear bearing and the
pinion.
Take an old pinion nut and cut/grind off the portion
that locks onto the pinion stem. Install the pinion
with bearings, set rotational preload
(24-32
in/lbs w/ new bearings, 8-12 in/lbs w/ used bearings)
and take a tooth pattern/backlash check.

This
procedure will assume you are using the side shims from the
donor car. Be careful. They are cast iron and you will
need a plastic hammer
to install them without
breakage.

Using this method, you can easily pop out the
pinion and press the bearing on a little at a
time
until backlash and contact pattern are where you want
them.

Now, simply remove the pinion and
measure the distance between the bearing and the pinion.
This measurement is the correct pinon shim(s) needed
for installation.

I hope this information is
helpful...Robert


[This is message #42 by user twelve_second_vega on Yahoo! Club V8 Vega Conversions: http://clubs.yahoo.com/clubs/v8vegaconversions ]