Hey guys! ChrisFix here.
And today, I'm going to show you how to
rebuild a limited slip differential...
...and install carbon fiber clutches.
So if one of the wheels starts to spin and
slip,
these clutches are going to engage and
grab on to each other
to send power to both wheels,
so you'll get more traction which will give
you better acceleration,
and better handling.
Now, not only are we installing the
clutches, but I'm also going to be installing
a brand new finned aluminum diff cover
which is going to help with the cooling
because it's good to keep the brand new
clutches cool to make them last longer.
Plus, this has a drain bolt and a fill bolt
so we don't have to remove the cover to
change the fluid.
And down the road, if we want, we could
add a temperature sensor
and an oil cooler to our diff.
Now how did I know the limited slip
differential is worn out
and I needed to install new clutches?
Well, it all started at the track when I was drifting.
I was having an epic day, I was learning so
much, and I was just killing it out there!
But every once in a while randomly, the rear
end would feel completely different
and that was making it hard to be
consistent.
Then, I was at the drag strip ready to race
Adam LZ
doing my burnout to get those tires hot
and sticky.
But if you notice, only one wheel was
spinning.
I was doing the classic "one wheel peel."
It was so bad that everybody thought I
broke my axle.
"Your axle's broken."
And that's when I knew my limited slip was
completely worn out and needed a rebuild.
Now, rebuilding your limited slip differential
isn't only for a track car,
it's good for any car where you might run
into a situation where you loose traction.
Maybe you're using your daily driver on the
road
and it's raining or snowing,
maybe you have a truck or an SUV, you're
towing something or you're going off-roading,
or you live on a road where there's dirt,
there's mud.
Any situation where your tires might slip,
a fresh limited slip differential is going to
give you more traction.
Now, how do you know if your car has a
limited slip differential?
Well, one way to tell is to go under the car,
find the rear differential, and look for a tag
like that.
And if you have a tag like this, it gives you a
lot of information.
So we have 3 27 gears in here,
and this is an 8.8 rear end.
In between the 3 and the 27, you can see
there's an L.
That means it's limited slip.
And for another example, if we take a look
under my truck,
we have a similar rear end, and you can see
our tag right there.
And this tag shows 4 10 gears and an 8.8
rear end,
but there's no L here, so it's an open
differential.
Now not every differential still has the tag
on it,
so how do you figure it out if you don't
have the tag?
Just go to your door jamb there is a sticker
right here with your VIN number.
Take that VIN number,
and then type it into a VIN decoder.
Just do an internet search with your car's
make and the word, "VIN Decoder,"
enter your VIN, and it'll give you a bunch of
information
including the options the car has such as a
limited slip differential.
So, those are some ways you can see if you
have a limited slip diff.
And rebuilding your LSD is actually really
simple once you know what you need to do.
So I'm going to give you a step-by-step
guide, I'm going to show you
everything you need to know so you can
easily do this at home
in your driveway with common hand
tools.
I'll also be sure to link all the products and
tools that I'm using
in the description so you can easily find
them.
So, let's begin!
And the first thing we want to do is soak
our new clutches in friction modifier.
So grab all the clutches and put them in a
container and spread them out,
and then pour in your friction modifier.
We want these clutches to soak for at least
15 minutes
so when they get installed, it'll engage
smoothly
and it won't make any noise.
And once these are all covered, now let's
start working on the car.
So with the rear of the car safely jacked up
and supported by jack stands,
the first thing that we need to do is remove
our brake calipers
because we want to slide this axle
outwards.
In this case, I have a dual caliper setup, so I
have two brake calipers, this is custom.
Most cars will have a single caliper or a
brake drum that needs to get removed.
And in order to do that, it's really simple,
there's a bolt holding it in up here,
and a bolt holding it in right down here.
So let's start at the top bolt.
Crack this loose and unscrew it all the
way.
Good.
And unscrew the bottom bolt as well, but
here we have an E-brake cable in the way.
So I'm going to use a box end of a wrench
to loosen this, which will fit right in here.
And once that bolt is loose,
slide the caliper up and remove the bolt
the rest of the way.
Now with the caliper loose, we can slide it
off.
But before we do that, grab a bungee or
something similar
and hook it onto the suspension.
That way when we remove the caliper, we
can hold it up with a bungee
so it doesn't hang from the brake line,
which could damage it.
Now we can remove that second brake
caliper.
That's the top bolt.
Then unscrew the bottom.
Good.
Slide the caliper off, and we can rest it right
on the lower trailing arm.
And finally, let's remove the rotor.
So with the brake calipers removed, the
only thing that's holding in this axle
is the C-clip in the differential.
So let's slide under the car and we're going
to remove this differential cover right here.
It's held in by 10 bolts around the
perimeter.
But before we remove those 10 bolts, it's
important that we slide an oil catch can
underneath the differential so that when we
open this up, the differential fluid comes out
and doesn't make a mess.
Now it's also a good idea to come to the
front of the differential and make sure you
can remove the fill bolt.
Use the box end of your wrench and make
sure it comes all the way out.
You don't want to drain the diff and not be
able to fill it to the correct level.
So with this removed, now we can remove
the diff cover and drain the fluid.
You want to start by removing the bottom
bolts first and work your way up
so if the gear oil starts leaking out, it's a
controlled leak from the bottom,
and it won't make a mess.
And for that last bolt up top, we want to
unscrew this about halfway so it's loose,
but at the same time, the cover won't just
fall off.
Now we can pop open that diff cover and
drain all that gear oil out.
And if your cover doesn't come off easily,
you might need to use a screwdriver to
get it in there and pry it open.
So after all our diff fluid is drained out,
now we can get to that top bolt and
remove it completely,
and get this diff cover out of our way.
Now luckily, most of the gasket material
came off with the diff cover.
But there's still some leftover gasket on
there that needs to get cleaned off.
So cover the gears with a bag so they don't
get dirty,
and I like using a plastic scraper to remove
the old gasket because plastic can't gouge
the flat metal surface on the diff.
Now with the differential gasket surface
smooth and clear of any old gasket,
we are ready to disassemble the rear end.
So to make this job really simple and really
easy for you,
I'm going to be showing you how to do
this without removing this carrier,
which is this whole assembly right here.
Instead, we're just going to be removing
these spider gears and side gears
so that we can get to the clutches.
This is what a clutch looks like, this is a
carbon fiber one.
The stock ones aren't carbon fiber.
But they do have these tabs here, and you
can actually see the tabs there, and there.
So we need to get in there to pull those
clutches out and install brand new ones.
In order to do that, we have to turn the
differential until we find the lock bolt,
which is right there, which is holding this
pin in.
This is an 8-millimeter bolt and a ratcheting
wrench makes this so easy to do.
Also, if we don't put the car in 1st gear,
then you're just going to spin the
differential.
So put the car in 1st gear, or if you have an
automatic, put it in Park.
And now the transmission's going to hold
this so that we can loosen this bolt.
Good.
Now, slide your hand behind the
differential and push on the other side
to knock that pin out a little bit.
And now, we can slide the pin out all the
way.
Beautiful.
Now, we want to put the car back in neutral
and spin the axle
so we have access to our spider gears,
C-clips, and spring.
Taking a closer look, you can see the end
of the left axle
and the end of the right axle.
Next, we want to push the axle inwards,
and that gives us access to our C-clips
right there.
Then we can use one of these stick
magnets to get it in there
and remove that C-clip.
Perfect!
Since we're doing both axles,
you might as well get that other C-clip
while you're in there.
Now we can pull the axle out about 6
inches.
That's plenty of room, and if you want, you
can pull it all the way out.
And now's a really good time...
...to replace your bearing and your seal.
I already replaced these when I did the dual
caliper setup.
It's really cheap, really easy to do, and it's
great preventative maintenance.
But since I already did it, let's go back
under the car,
and we can remove our S-spring, which is
this right here.
Now, this spring is compressed right now,
and under tremendous amount of pressure.
So you have to be really careful and make
sure you have your eye protection on.
And to remove it, we're going to use a hammer.
So I like to use a piece of wood that fits
right over the spring,
and then carefully tap that spring until it
can't move any further, like that.
Then we can spin the carrier and get to the
spring on the other side.
Next, clamp onto the spring and give it a
wiggle and pull it out.
And you might need to use a screwdriver to
help...
...pry it out.
And there you go, that is how you safely
remove that S-spring.
You can see how our clamping pliers did
not let go of it.
So that's a good trick to do when you're trying to get this out.
Now, before we remove any gears, with a
differential, it's always good practice
to reinstall the gears exactly where they
were.
So grab a paint marker and mark the gear
and differential so we know where it goes.
And we can do the same for the side gear
as well.
And for the bottom spider gear, I'm going to
use red.
As well as for the other side gear.
Perfect, with all these gears marked so we
know exactly where they go,
now we can remove this top and bottom
spider gear.
To remove them, all you have to do
is spin the side gear with your finger,
and get ready to catch this as it comes out.
Just like that.
And these spider gears have a washer on the back.
You can see that washer there, make sure
it comes off with the spider gear.
And in order to get that other spider gear,
just spin the side gear again.
And then make sure you pull it out with that
washer on there, perfect.
So, both of the spider gears are out.
Now we have to remove the two side
gears.
Because we have a ring gear here, we can't
get to this side here.
This won't come out all the way.
So we're going to remove this one first.
And to remove this, it's really easy, you just
pull it right out.
Beautiful.
And once thing I noticed is this side gear
doesn't have a washer on the back
and there should be one.
So just make sure you remove the washer
from inside here.
Just like that.
Next, remove the driver's side side gear the
same way.
And it should just slide out like that.
And this one came out with the washer.
So let's go and replace the clutches.
This is really easy to do, we're going to
work on one side at a time,
and the order of the clutches and the
plates on the side gear is very important.
You can see we have that thin washer on
the outside,
so when we separate this, we want to keep
this in order.
What I like to do is lay everything out in
order, we have the washer,
clutch, steel plate, steel plate,
clutch, steel plate, clutch, steel plate.
Then we can grab our carbon fiber clutches
which have been soaking in the friction modifier.
And a little trick that I use is put these in a
sealed bag
because this friction modifier smells
horrible!
So we can grab three of the six clutches
because we're doing one side at a time.
And then we can grab a set of steel plates
and a washer,
and lay out the washer, clutches, and steel
plates in the same order as the stock setup.
So we have the old clutch pack and new
clutch pack,
and I mean, look at the difference in the clutches.
These new carbon fiber clutches are going
to make a huge difference.
Now I'm kind of curious how worn out this
old clutch pack is,
especially compared to the new one.
So you can use a caliper to measure it.
So we'll start with the old clutches.
Grab a C-clamp and clamp them down,
make sure it's nice and tight.
And if the old clutches are worn out, it'll be
thinner than 0.635 in.
And look at that, in this case, 0.632 in.
These things are worn out.
Now, let's check out the brand new
performance clutches.
Now, this should be right around 0.655 in.
for a performance clutch pack.
And it's 0.656 in.
So our brand new clutch pack is thicker
than our old worn out clutch pack.
So, out with the old, and in with the new.
And all we have to do is get the side gear,
make sure our thin washer is on the
outside,
and then just wiggle it right into place.
Perfect, so our driver side clutch pack is
done.
For the passenger side, it's the same exact
process,
so get the new clutch pack on there, and
we are ready to install these in the diff!
Back at the differential, installation is
opposite of removal,
so grab your driver side side gear.
And you see these clutch ears here? We 
want those to be aligned.
So straighten them out,
and slide that side gear into place.
It goes in really easy, and you can see how
the clutch ears need to get aligned
to fit properly.
Perfect.
Now let's do the same for the passenger
side side gear.
Get the clutch ears straight
and slide it into place.
Now we can install our spider gears.
And the back of the spider gear
fits into these little cups here and here.
And what makes installing spider gears
tricky is that
the washers on the back here come off
very easily.
And they have to stay on
otherwise, they'll just fall in the diff.
So a little trick is to pop the washers off the
back of the gears
and then add a little gear oil that you're
going to be using to fill the diff later on.
Then press the washers back on,
and the oil's going to hold those washers
on pretty tight.
Plus, it's always good to lubricate this
anyway.
The next trick to installing spider gears is to install them at the same time.
We remember we have the green which
goes to the top
and the red that goes to the bottom.
And these have to be on the exact opposite
sides of each other,
so get your hand behind the carrier and
push that spider gear in.
Then put the other gear right in the front on
the exact opposite side.
Now, turn the gears so they move into the
cups where they should sit.
Good.
Now, you want to make sure they're in
correctly, so spin the carrier,
and then push the cross pin through the
hole,
and make sure it goes all the way through
both spider gears just like that.
Good.
Now that all the gears are in place,
this next part is probably the hardest part
of this whole job.
And that's installing the S-spring.
Now, on my Mustang, we have to actually
reuse the old S-spring
because the new one's too thick and won't
fit.
But even the old one is too difficult to get in
there.
It's hard to compress, so you can't just
push it in.
So the trick to get the spring in...
...is to use a vise and compress it.
And if you don't have a vise, you'd always
use a C-clamp like this.
It won't be as easy, but you'll be able to
compress it.
But luckily, I have a vise, so get this spring
in the vise
and clamp down as far as you can go so
that spring is completely compressed.
Then, grab a needle-nosed locking pliers
and clamp down on the spring to keep the
spring compressed.
Then open up the vise,
and the locking pliers is going to keep this
spring compressed
so it's small enough to fit in the differential.
So slide the spring into place,
And even though it's compressed, you still
need to get it started by tapping it in there.
And once it's in a little bit, unclamp the spring,
and tap it the rest of the way in so it's as
centered as you can get it
in between the gears.
To verify it's centered, slide the cross pin
into the hole,
And you can see it gets stuck, so tap the
spring a little bit more...
Perfect.
And now, the pin can go all the way
through, so the spring is centered
and correctly installed.
Next, we have to push the left
and right axles back in.
And then grab a C-clip and slide it back into
the slot in the axle.
Finally, pull the axle outwards
to lock it into place.
Do the same thing for the other axle.
Slide the C-clip into the axle,
and then pull on the axle to lock it in place.
Now, turn the carrier so we can install the
differential cross pin,
which you can push into place until it's
flush with the carrier.
Now, we want to install a brand new cross
pin bolt.
Never reinstall the old one because the
new one has thread locker on it,
which prevents it from backing out.
If this bolt does come loose, it will destroy
the differential,
and you definitely don't want that.
So torque this down to 25 ft-lbs, which is
about as tight as you can get it
with this small wrench.
Good.
Alright, we are almost done.
I cannot wait to do a burnout and test out 
those clutches.
So our differential is fully assembled, the 
clutches are in.
Now, it's time to install our brand new diff
cover!
So with the gasket surface completely
clean,
we can either use a paper gasket, or use an
RTV gasket maker.
I suggest a paper gasket, it's a lot easier
and they're inexpensive.
But if you can't find a gasket, or if you don't
have one, you can use this RTV,
and I'll link a video in the description on
how to use this.
So when using the paper gasket, the
hardest part is aligning the bolt holes
and keeping that gasket there, because
when you let go, it's just going to keep falling down.
So a little trick is remove the gasket
and apply a little bit of gasket sealer.
This sealer is a tacky liquid that helps the
gasket adhere to the surface,
and you just need to apply a thin layer, like
that.
Then align the gasket and press down so it
sticks to the surface.
Now grab your diff cover, and it's very easy
to align the cover
and get that top bolt in because the gasket
isn't going to move out of alignment.
Also, since the new diff cover is thicker,
I'm using these longer bolts,
so keep that in mind if you switch to an
aftermarket cover.
So now, let's hand tighten all 10 of these
bolts which holds the cover in place,
and then, grab a torque wrench, and these
bolts should be tightened down to 25 ft-lbs.
A little trick I use to keep track of the bolts I
torque down
is to mark them with a paint marker once
it's torqued.
This helps a lot, because you're going to be
torquing these bolts down
in a crisscross pattern.
That way, the diff cover compresses the
gasket evenly for a leak-free seal.
And with the new diff cover torqued down,
it's good to go!
Now, let's add some differential fluid.
I'm using a full synthetic 75W-140 gear oil
which is made for limited slip differentials.
But it's also recommended that you still run
4 oz. of friction modifier
so the clutches can engage and disengage
properly.
I also highly suggest getting one of these
pumps
which screws right to the top of the
bottle.
That way, you can remove the fill bolt on
the diff cover,
slide the pump hose into the diff,
and very easily pump the gear oil
into the differential without making a
mess.
Keep in mind that the car should be
relatively level when filling up the diff
so you don't overfill it or underfill it.
And since this diff holds about 2 quarts of
oil,
you're going to have to use two bottles of
gear oil.
So once one bottle is empty, switch over to
the new bottle.
And you can always check the back of your
owner's manual
to see how much oil your diff holds.
But to know it's full, just keep an eye on the
fill hole at the front of the differential.
Once oil starts seeping out of there,
stop pumping, because your diff is full.
And we're so close to being done,
so let's screw this fill plug in so we can
stop the leak.
And let's also screw the fill plug in on the
top of the new diff cover so it's snug.
Good.
So with that, our rear end is completely done,
and we have one thing left to do, and that is
the brakes!
So put the brake rotor back on,
then grab a caliper and slide it over the
rotor.
Hand tighten the top bolt, and then hand
tighten the bottom bolt.
And I need to get the other brake caliper on
as well,
and also hand tighten these bolts as well.
And finally, we can torque down all the
caliper bolts to 76 ft-lbs of torque.
Then, install the wheel and torque down the
bolts in a star pattern.
Alright, now we're going to go for a ride,
and we don't just want to go out and do
some burnouts and rip on the car.
For the first 100 miles or so, you want to
drive around regularly,
and let those clutches break in.
That way, they can last a good long time.
And finally after 100 miles, we're heading
onto the track.
Moment of truth, let's see if we can lock up
the rear end and spin both tires.
Awesome! This feels so much better,
and I can see that both tires are spinning
and making smoke
which is what you want to see.
No more one wheel peel!
Now, that's how you rebuild a limited slip
differential
and install performance carbon fiber
clutches.
Hopefully, the video was helpful. If it was,
remember to give it a thumbs up.
And if you're not subscribed, consider
subscribing.
As always, all the tools and products I
used
are linked in the description so you can
easily find them.
