
On the left is the new larger rotor. It has been
painted red for clarity in this installation.
Below are the hand tools needed for the conversion.
Tools
12mm, 14mm combination wrenchs
14mm socket
Vise grips or other large pliers
Dead-blow hammer (you can use a soft faced mallet
instead)
Floor Jack, jack stands, Lug nut wrench
Brake cleaning spray, yellow high temperature grease
|
If you can rotate your tires, you can
swap the rotors on a Miata. Ever since the 1994 Miata
arrived, owners of the earlier model years have lusted
for the larger brakes. There has been a common
misconception that this is a difficult process to do. But
in reality, you only need a few hand tools, the larger
rotors, and the caliper brackets from the larger brakes. Mazda
part numbers for the brackets:
NA75-33-291
|
Front Left
|
NA75-33-281
|
Front Right
|
NA75-26-29X
|
Rear Left
|
NA75-26-28X
|
Rear Right
|
These brackets ran about $200 for all
four from Roebuck
Mazda.
You will also need to order new brake pads from your
favorite supplier. I like the Hawk Pads in Blue for the
front and Black for the rear. Make sure
when you order them, you specify that it is for a 1994+
Miata.
|
Side
by side comparison of old vs new An
interesting aspect of the brackets, as shown in
this side by side comparison, the pivot socket
for the calipers (highlighted in red in the
image) is on opposite ends of the bracket. Thus
the need for swapping sides when the brackets are
installed--yes, you understand correct, the part
number listed for the left side is used on the
right and vice versa. In the image are the front
left brackets; original on the bottom, new,
larger on the top.
Warning: don't forget this when
installation time comes.
|
 |
|
 |
The First
Step: Jack
the front of the car up using the standard
methods you typically do. I use a floor jack and
a 2x6 24" long with a 5/8" deep and
wide groove running down the middle of the
length. The seam under the doors that is normally
used by the stock jack fits in the groove in the
wood. I can lift the entire side of the miata
this way. Once the front is up and on jack
stands, remove the wheels and set them out of the
way. Turn the steering wheel to full lock in one
direction (let's start with right) and then go to
the left side--the rear edge of the rotor will be
further out this way.
|
|
Caliper
Removal The
bolts you want to access are all on the inside
surface. The first bolt is 12mm on the bottom
outside edge of the caliper itself. This bolt is
only threaded for about 15mm from the head; the
rest is smooth so that the calipers can move in
and out.
Pull this bolt
out and the caliper will be able to flip up on
its pivot. As it does, the springs that are
attached to the brake pads may cause the pads to
pop off. Watch for this to keep track of which
side and placement everything has. It's ok if
they come off, as you will be removing everything
anyway.
|
 |
|
You should
be able to swivel the caliper back and forth to slide it
out. Place it on the lower A arm for safety. Next are the
two 14mm bolts that hold the caliper bracket to the
spindle. These are fairly tight, so use that 14mm socket
probably a 1/2" drive 6 point is best. Save both
bolts in the same place as the lower pivot bolt you
removed before. Now
is a good time to turn the wheel and do the other side.
Follow the same procedure and make sure that you keep
track of which bracket goes to which side. If you get
confused, don't worry, the curved portion faces the hub
and the straight part goes on the back, with the pivot
hole on the top.
|
 |
Old
into New Match up the brackets you just
removed with their new counterparts. Make sure
that the pivot point and bolt are oriented in the
same direction. Left is right, and vice versa.
You might want to use a little Berryman's
Brakekleen spray to clean off the cruft since you
have to tranfer the clips and rubber grommets
over (for some strange reason, these bits are
only available if you buy a new set of calipers
for mucho dinero)
The image to the left has the four clips and
two rubber grommets oriented to be installed on a
new bracket. The little clips should stick out
rather than in.
|
|
The long rubber grommet is really the
hardest part about this whole thing. The trick is to not
rip the rubber when removing or inserting it. I used a
worn out thin flatblade screwdriver and carefully
inserted it between rubber and steel, then twisted the
screwdriver to break the seal on the rubber grommet. Once
the seal is broken the closed end og the grommet can be
twisted up and then pull the open end through. After
the rubber and spring steel bits are are replaced, fill
the grommets with high temp yellow grease. Now is a good
time to pop the old rotors off. A small whack with a
deadblow hammer might be needed to break the seal if rust
has gotten in there. But a Miata in good condition should
have loose rotors when the calipers are off.
|
Rotor meets
backing plate - Not! As can be seen in
the two images, the backing plate will require a
bit of judicious vice-grip application. The new
rotors are too big to fit clear of the bent lip,
so it has to be straightened out. You don't want
to remove the plate entirely because it also acts
as a duct for air to help cool the brakes and
keep them dry. Spin the rotor to make sure that
it doesn't bind up any place before installeding
the brackets.
|
 |
 |
|
 |
Putting
it all together The only trick to
installation is getting the caliper to flip down
over the new pads with the little V springs
helping to push them out. The clearance is really
tight with new pads but rest assured that the
calipers will fit, the part numbers are
the same for all years of Miata
Bolt the brackets to the spindles with the
14mm bolts. Standard torque for these bolts is 58
ft/lbs. The 12mm bolt that holds the caliper in
the lower pivot should just be hand tight, about
35 to 45 ft/lbs.
|
|
You're basically done. Just slip the
wheels back on, drop the car off the jackstands and go
check out how fast your Miata can slow down. |