this is a demonstration of the proper
setup of a ring and pinion gear set in
the rear differential of just about any
vehicle out there this particular
differential is out of a 2007 Toyota
Tundra pickup truck with a ten and a
half inch ring here we have right here a
couple of examples of pinion gears the
pinion gear itself right here this is
the pinion gear out of an axle just like
this and we have opinion bearing in the
rear an opinion bearing that's going to
go in the front with an oil splash
shield and then your pinion flange that
your u-joint hooks to and then not in
between the two pinion bearings we have
a spacer with a couple of selective
washers right here there's two washers
that you put together in certain
thicknesses to control the spacing
between these two bearings the spacing
between these two bearings when you
tighten the opinion nut down on this
particular axle is going to give you a
certain rotational torque on the pinion
gear itself so we have this exact setup
installed already in this housing and
the rotational torque with the pinion
nut tightened to specification needs to
be measured with an inch pound torque
wrench the inch pound torque wrench this
particular one a half goes from zero to
thirty inch pounds and of course it
takes 12 inch pounds to equal one foot
pound the specification for the
rotational torque of this particular
axle is thirteen to nineteen inch pounds
of rotational torque so as I rotate this
with this inch pound
torque wrench I can read whatever this
specification is I'm sorry read whatever
the torque wrenches is telling me I'm
gonna need this type of a dial torque
wrench or a flexible beam torque wrench
the clicker style torque wrenches or the
beeping vibrating type will not work for
this it's very important that we get the
proper rotational torque set because
that is what's called the bearing
preload we're gonna put a lower on those
bearings that's going to hold the pinion
gear from moving when we are driving
down the road because the pinion gear
will want to move towards the front of
the vehicle when you accelerate and
towards the rear of the vehicle when you
decelerate well we don't want that to
move at all
so we have to put the proper load on
these bearings and that load on this
particular type of axle is controlled
with controlled with what are called
preload shims now this pinion right here
is out of a different axle and instead
of having preload shims we have what's
called a crush sleeve and this crush
sleeve goes between the two bearings
it's not reusable and the crust leave as
is a certain height when you first
install it and then you're going to put
the pinion bearing the oil slinger the
pinion flange and the nut don't on and
you're gonna slowly tighten the nut
until it hits the crush sleeve and you
slowly tighten it to where it crushes
the crush sleeve and gets to a point
where we have that same rotational
torque now every vehicle manufacturer is
going to have a certain rotational
torque specified just for the pinion
gear itself the pinion gear with pinion
bearings you must have the pinion
bearing preload set properly before you
can move on to installing the rain gear
of differential case or any other parts
nothing else matters right up front
until you get the proper bearing preload
on the pinion gear itself and it's
typically one of two ways one way is
with the crush sleeve and another way
with bearing preload shims that you put
together that come in a variety probably
30 different thicknesses and you're
going to add the two together to get the
proper distance between the two bearings
now once you get once you've gotten the
preload set properly then we can move on
to installing the ring gear so I'll turn
this housing or cut-down pinion gears
out of the way this is the ring gear out
of this particular Toyota Tundra pickup
truck we have the ring gear itself we
have the differential gears with the two
side gears the two differential pinions
we have on this particular axle these
side bearings are going to have bearing
cups they're going to sit down on both
sides and then those bearing cups are
controlled as far as how far in or out
they go with shims and these shims come
in a variety of different sizes these
shims are what is going to control two
things the first thing is
but the load on the side bearings itself
we need to compress or load these
bearings and put a preload on them so
that the differential case isn't moving
all over when we accelerate and
decelerate driving down the road so I'm
going to install this right now
we've got the shim that goes on one side
and then we've got a shim for the other
side these shims are not just gonna fall
into place
as a matter of fact I probably ought to
put this other side in first to show you
what I'm talking about
let me get that now we'll move it over
get this shim in first okay it's down in
now this shim has got to fit down in
there in the housing also but the reason
it doesn't just fall right down in is
because it's actually got to put a load
on those side bearings and so we have to
carefully tap it in place where we don't
damage it and that's going to put the
load on the the side bearings itself one
way to do that is if I can get it all
together here kind of put it in as an
assembly on both sides easier and then
use a plastic hammer
driving into place we don't want to use
a steel hammer we don't want to damage
the bearings or the spacers we'll put
that down into place so these shims once
again control actually going to control
two things the first thing is the
preload on the bearings to keep the rain
gear from moving back and forth as we
drive down the road the second thing is
is these bearings are these shims are
used to control the backlash I don't
know if you can hear that but there's a
backlash that has to have some space in
between the ring gear and the pinion
gear itself and that backlash is
measured with a dial indicator and we'll
do that here in a few minutes
but we're as long as we have backlash
right now
we can put the bearing caps on and the
bearing caps are left and right specific
I've got them marked as to which way
they go so I'm going to put these
bearing caps on and tighten them down
[Music]
we're going to torque the bearing cap
bolts to specification and once those
bolts are torqued to specification then
we can turn it over and with that same
inch pound torque wrench we're going to
marry it measure the bearing or the
pinion bearing preload again but this
time it should be more because we've
added the preload of the side bearings
and the pinion gear has got to turn the
ring gear which is held in place by
these side bearings so I'm going to
tighten those down and turn it over and
take a measurement okay
I've now got the bearing caps torque
down to specification we still have some
backlash
I don't care how much the back that
backlash is right now as long as I have
backlash and now I'm going to turn the
axle over in this holding fixture and
use the same torque wrench and measure
the the preload again and now the
specification in the book and it's
different for every vehicle
manufacturers to look up what yours is
but it should be whatever the pinion
preload was when we first started plus a
little bit more for the side bearing
preload
on this particular axle that calls for
two to three inch pounds more of preload
as major death opinion but this had this
gear ratio is four point three zero to
one for 30 to 1 gear ratio and that
makes it four point three times easier
to turn the pinion than it is to turn
the ring which means the actual preload
that we added to the side bearings is
four point three times higher than what
we measured here so let's say we added
three more inch pounds of torque as
measured on this torque wrench four
times three is twelve four four point
three times three is twelve point nine
so we've added about twelve inch pound
twelve thirteen inch pounds of side
bearing preload on the side bearings
here so let me turn this over if that's
within specification for your particular
axle then great you don't need to change
the shims anymore to tighten the
bearings down to increase the preload
however what we need to do next is to
measure the backlash once our bearing
preload is within specification which
this one is but if it weren't we would
just change those shims equally to
a thicker shim on each side the next
thing we need to do is measure the
backlash so I'm going to get the dial
indicator and hook it up okay I now have
a dial indicator hooked up we want to
have the dial indicator for measuring
backlash be at a right angle with the
the gear tooth as much as we can so the
plunger is going to come down the gear
tooth we've got a flat spot on the gear
tooth right here and we want to want to
be on a right angle now the dial
indicator is going to as we move the
ring gear back and forth indicate our
backlash we're going between zero and
about a negative four that's four
thousandths of an inch backlash the
specification on this truck I believe is
anywhere between four and seven
thousandths of an inch and every vehicle
manufacturer is going to have a
different backlash specification but
most of them are somewhere in that four
five six seven thousandths of an inch
area now the backlash that we're
measuring here is just on the one tooth
and it's not this tooth where we've got
the dial indicator it's it's the actual
tooth that's down touching the pinion
gear itself and you should never just
rely on the backlash reading of one
tooth we can't measure this one tooth
and say the backlash is the same on
every single tooth there are 43 teeth on
this ring gear and out of those 43 teeth
can you guarantee without measuring that
every single gear tooth has equal depth
which will give us equal backlash
there's no way and so at bare minimum
that the Toyota manual says measure in
at least three places but if you're
hunting a noise or a vibration
remember the ring gear turns the same
speed as the tires
so if you had a noise of vibration that
seemed to be tire speed related you may
actually want to check the backlash
backlash on all 43 teeth I know that's a
lot of work but it only takes one gear
tooth to have no backlash at all or even
negative backlash where it's binding up
to cause a noise or vibration now there
are two types of ring and pinion gear
sets out there there are ring ring and
pinion gear sets like this one where the
depth of the tooth is equal all the way
from the heel which is on the outside of
the tooth to the toe which is on the
inside of the tooth and that one is
called a face hobbed gear tooth where
it's equal depth all the way in other
older ring gears at the toe side the
depth of cut on the gear tooth is less
than it is out here on the heel so it's
real deep at the hill in at the toe it
gets more shallow and that's called a
face milled gear set so there's face
mills gear set gear sets which are the
older ones that are unequal depth and
there are face hobbed gear sets like
this one where it's equal depth all the
way in well that's a difference in
manufacturing procedures on a face hop
gear set like this all the gears are
ground at once there's a cutter that
comes in and rotates at the same time
the gear rotates and it cuts each
individual tooth all at once as it as it
rotates wear a face hobbed gear each
tooth is cut one at a time I'm sorry a
face mill gear each tooth is cut one at
a time and they can actually be there
have some differences depending on how
old worn out the Gleason machine is that
cuts those gear teeth and so I tell you
this because it's important to know the
difference between those two gear sets
because
our next step is going to be to paint
the gear teeth with Prussian blue or
some sort of gear marking compound and
look at the contact pattern now the
everything we've done up to this point
we've set the the pinion depth or the
pinion preload or forgot there's a
pinion depth shim in between the pinion
bearing and the pinion gear is a shim
called the pinion depth shim that shim
controls how far up in this housing that
pinion gear sits and our contact pattern
check that we're going to do is is going
to tell us is that pinion too high too
low or is it okay it's also gonna tell
us is our backlash too tight or too
loose
or is it okay now you might be thinking
well of course it's okay it's within
specification but that just because it's
in specification does not mean it's set
up correctly what you need to remember
is that as long as your bearing preloads
are set correctly and your backlash is
set correctly then you can paint your
gear teeth and run the contact pattern
check but that contact pattern check is
what's going to tell you whether you
still need to adjust the backlash the
back-and-forth movement of the ring gear
or if you need to change the pinion
depth with that shim that I told you
about which is a real pain because you
got to totally disassemble everything
you're gonna ruin the pinion seal if
it's a crush sleeve type axle you'd have
to replace the crush sleeve again
because they're not reusable but up to
this point our pinion bearing preload is
correct our side bearing preload is
correct
our backlash is correct and so the next
thing we're going to do is paint the
gear teeth and run a contact pattern
check one thing you should also do
because it's adjustable is down here in
the differential itself remember there's
two sets of gears in a different
assembly we've got they set a ring and
pinion gear set but then we have to cite
gears and turn it right down in here
we've got the psyche ears and the
differential pinion gears there's a
backlash measurement on those that I
have a different video on youtube it's
called measuring differential gear set
cycle your backlash we're not going to
do that in this video but that backlash
is just as critical as this one for
proper setup of that differential so I'm
gonna paint the gear teeth up what I'm
gonna do is paint every single gear
tooth the con vex side of the tooth the
part that sticks up is the drive side of
the tooth the the concave side the side
that caves in is the coasts side so we
have a coasts side and we have a drive
side we're going to paint both the coast
and the drive side of the gear teeth and
then look at the contact pattern I
forgot to mention one thing on our
backlash measurement if our backlash was
incorrect we would have to change those
two shims on the side bearings we would
let's say we wanted to move the ring
gear closer towards the pinion we would
have to put a thinner shim in on this
side of the side gear and a thicker one
on this side by the same amount let's
say we wanted a add to thinner
let's see subtract two thousandths of an
inch from this Jim over here and add two
thousands of an inch over here that
would bring the pinion over closer to
the I'm sorry that bring the ring gear
over closer to the pinion if we want to
move it away we would add a thicker shim
over here and a thinner shim over here
and there are a couple of dozen
different sizes of side gear shims but
remember we've got the bearing preload
that has to stay the same as long as we
change the shim thickness by an equal
amount we subtract 2000's here we add
2000s here our side bearing preload was
still
be okay okay I have painted some of the
ring and pinion gear set through some of
the ring gear I'm sorry with two
different types of gear marking compound
the yellow is pretty standard in the
industry this particular compound is
Mopar chrysler gear marking compound but
it's the same as General Motors and some
generic gear marking compounds the
yellow iron oxide based gear marking
compound and then you can also get
what's called person blue from Permatex
which is what I've painted here the
darker teeth now to run a contact
pattern check the gear actually needs to
be loaded in other words it shouldn't be
just a free spin of the pinion gear and
ring gear because there's no load on the
gear itself we need a good solid load on
the the ring gear to be able to have a
good contact pattern well if it's a
typical rear axle that doesn't have a
removable differential housing like this
one where the housing stays in the
vehicle you can put your axle shafts in
and write the brakes and you'll have to
use a wrench the socket and a ratchet to
turn the pinion gear you want to turn it
forward and backwards so that we get
both the drive and the coast the side of
the teeth for a contact pattern check on
this particular type of axle I'm not
aware of a way to load it heavily other
than to come in with a pry bar and kind
of pry against the ring gear at the same
time that somebody else so you want to
go the other way is turning with a
wrench
the opinion so if I pry against the ring
gear then it's going to make it harder
to turn and that would be
loaded as far as I could get it in this
particular type of axle
I know Ford has some axes like this
Chrysler I'm sorry older crisis and GM's
had some like this
this is Toyota Nissan has some that are
similar but I'm going to in this
demonstration
since it's I don't have a way to load it
properly I'm just going to rotate the
ring gear around just to get a contact
pattern it won't be a valid pattern
because I haven't loaded it but I ran it
I've run it one way I'm gonna run it
back the other way
and if that have been loaded if I would
have had somebody here to help me load
and turn the ring gear then we can come
in and take a look at the contact
pattern next and I'll need to zoom the
camera in for that okay we've
repositioned the camera so we can get a
better look at the the contact pattern
I'm going to zoom in it even more here
and I want you to see right now we are
looking at the coast we'll see right
here we're looking at the drive side of
the gear tooth and the contact pattern
kind of starts in the middle and works
its way back it's fairly centered on the
the drive side of the gear tooth if it
was more towards the toe we would want
to make an adjustment if it was more
towards the heel we would want to make
an adjustment but if it's centered which
is what we're looking for then that's a
great contact pattern but we need to
look at more than just the drive side of
the gear tooth we have to look at the
coast side also
let me bring this up a little bit more
if we look at the coast side now this
back side notice it's also pretty
centered it starts by right here and
ends about over here on the coast side
that's that's about a good of a pattern
as as you're going to get which means
the shims that are in the side bearings
here that control the preload and also
control of the backlash are correct and
the pinion depth must be correct but it
let's let's take a look at or let's go
through some examples of incorrect
contact pattern and see what we do for
that on the remember on our gear teeth
out here on the end the sand here is the
heel and this end is is the toe and then
the drive side right here is convex the
coast side right here is concave if we
had a pattern that was on the toe on the
drive and on the toll on the coast that
tells us that the backlash is too tight
and we would need to loosen the backlash
if we had the contact pattern out here
on the heel on the drive and the heel on
the coast that would tell us that the
backlash is too loose and we have to
adjust the backlash to get that pattern
here in the middle like we've got it on
this axle if we had on the drive side
the pattern was too close on the drive
on the toe and too close to the heel on
the coast then that's opinion depth
problem and that tells us that the the
ring or the pinion gear down in the
differential case is up too high if on
the coast side with the pattern was on
the toe and the drive side the pattern
was on the hill then that tells us that
the pinion depth is too low and that
shim that goes in between the rear
pinion bearing
and the painting gear itself is what we
adjust to change the pinion depth some
axles have a pinion depth shim behind
the bearing race rather than the on the
bearing itself on the gear but either
way the contact pattern is the final say
of what we do with the ring and pinion
gear set to see if it's set up properly
but remember you cannot I'm sorry you
should not run a contact pattern check
unless you're bearing preloads all your
bearing free loads your pinion bearing
preload your side bearing preloads
are first within specification and then
your backlash is within specification
then run your contact pattern check and
see where the where the pattern tells
you to make the final adjustment this
particular one is set up just right if
this were the loaded contact pattern
this would be ready to put back in the
vehicle and drive but if you put one
back in that does not have a centered
gear set or your marking with the gear
marking compound a gear pattern contact
pattern it could make noise and it might
make noise while it decelerates it might
make noise while it accelerates might
make noise all the time just depending
on how it's set up
and I'll have a chart you can download
through our weber automotive website to
interpret these gear patterns and so
this has been a demonstration of the
proper setup of a ring and pinion gear
set look for my other video on youtube
for a differential gear set backlash
adjustment and good luck with your
differential overhauls