Miata Window Regulator Replacement (manual & power windows)

Technical

Miata Window Regulator Replacement (manual & power windows)

By John Kuykendall

Introduction

Replacement
of the window regulator is usually required due to symptoms such
as an inoperable or balky window. The causes may be broken regulator
cables, malfunctioning regulator gearbox, lack of window guide lubrication
or (in the case of power windows) a burned-out motor. To repair
any of these problems, the same door and window disassembly is required.
This repair may be undertaken by any careful, moderately experienced
DIY mechanic, although it involves trim that requires care to replace
neatly.

 

Step 1:
This is a typical Miata door assembly. The inner panel shown is
for a Miata with manual windows. Note that not all Miata’s will
have the same door panel – some earlier models may not have the
door handles, map pockets, or they may have extra items such as
arm rests. Models equipped with power windows will not have the
manual window crank.

 

Step 2:
Close-up of door, showing four Phillips or crosshead screws which
must be removed. Two screws secure the door handle – the top screw
is under a plastic cap that must be carefully pried out of the handle,
while the bottom screw is exposed. The screw at the rear of the
door/map pocket is under another cap, so pry this up (but not completely
off, as it is attached) and remove the screw with the cap intact.

The final screw
is a small one in the center of the door pull trim cup. Remove all
screws and place the door handle and various parts aside. Note that
there may be variations from year to year and model to model. Just
make sure you have removed all the fasteners before trying to pry
the door panel off.

Step 3:
While holding the door pull open, remove the trim cup over the pull
handle and set it aside. Note that in this picture, the door winder
handle is already removed – see the next step for procedure.

 

Step 4: Manual
Door Winder Removal: Using a door trim removal tool (available at
Advance Auto and other places) or a thin rag or piece of string
wrapped around the door winder crank, carefully remove the spring
clip securing the crank handle onto the gearbox shaft. Don’t lose
the clip or the round plastic trim washer! You may have to pull
the handle out smartly to remove the handle and clip. Set the handle
and parts aside.

Step 5:
Here’s a shot of the window crank with the clip re-installed for
illustration, and the round plastic trim washer that goes behind
the crank handle. The regulator gearbox shaft is shown beyond, again
in this case for a Miata with manual windows. Note that on some
(older?) models with separate speaker grille panels, you will need
to remove the grille prior to removing the door panel.
Step 6:
Use the door trim removal tool (or similar flat tool) to release
the numerous push-clips (about eleven on a typical Miata) holding
the interior door panel onto the door. Most of these fasteners are
around the outside of the panel, but a couple of them are in towards
the center. Try pulling the panel out a little first, to visually
locate the fasteners, so that you can pry as close to them as possible.
If you encounter any resistance, check again to make sure you’ve
removed all the screws fastening the panel to the door. Remove the
door panel carefully over the door pull handle, pivoting the handle
outward as necessary to clear the panel. Place the door trim panel
aside where it won’t get walked on!
 

Step 7: Door
with the interior panel removed. Note that there is a clear plastic
dust/moisture barrier under the panel, which is adhered to the door
with sticky, nasty, very hard-to-remove black adhesive goop (mastic).
You can fold the liner upon itself as you remove portions of it
for access, thereby partially covering the goop and maybe preventing
it from getting all over you – avoid it like it was poison ivy!

Step 8: Here’s
a shot of the plastic liner folded up and stuck together. Depending
on your particular model and what areas you’ll need to access, you
may want to remove only portions of the liner, or the entire thing.
Assess your particular situation and decide. Total removal means
you will have to realign and re-adhere the liner when you’re through,
not a simple task!
 

Step 9: To
remove the window regulator, you need to remove the window! In order
to remove the window, you’ll need to remove the black plastic window
trim at the top of the door on the outside of the glass. First you
must remove the screw or plastic pop-fastener at both the front
and rear of the door. Roll the window all the way down (assuming
this is possible with your broken regulator – you may have to manually
work it down). Then CAREFULLY release each of the series of plastic
clips along the top of the door by prying the tab inwards.

Use
a padded, flat pry tool (like a small-bladed screwdriver wrapped with
tape) working between the trim and the door over the top of the window,
being careful not to scratch the paint. Avoid bending the trim piece
(i.e., don’t do what you see in the picture) in the process of removing
it, keep it as straight as possible. A neat re-installation will be
nearly impossible if you damage or bend this trim piece or break many
clips. If this happens, you will probably have to purchase replacements
(ask me how I know this). Removing this trim clears the opening at
the top of the door for the window and other parts to be removed.
 

Step 10:
Mark the location of the two 10mm window stop mounting bolts at
the top edge of the door (#2 and #5, respectively, from the rear
of the door). Use a “sharpie” or similar permanent-type
marker to clearly mark around the heads of the bolts. You want to
re-install the stops in the exact same location to avoid having
to make window realignment adjustments later. Temporarily re-install
the window winder and roll the window down so the top is about 7.5″up
from the top of the door. Locate the three crosshead screws holding
the glass to the window regulator, and remove them. Once removed,
you can carefully lift the window glass as a unit up out of the
door, and set it aside where you, the kids or your cats can’t break
it!

 

Step 11:
Mark the location of the four 14mm nuts holding the window regulator
to the door, by marking around the head of each nut with a marker.
There are two nuts located near the top of the door (#3 and #4 from
the rear of the door), and two on the bottom/center of the door.
Again, you want to re-install the regulator in the same location
that it was removed, to avoid later adjustments. Remove the three
10mm nuts (or two, in the case of power windows) securing the window
regulator gearbox to the door.

Also
remove the 10mm bolt on the bottom/front of the door, which secures
the front window track guide, allowing it to be moved aside slightly
for clearance to remove the gearbox. Unplug any connectors to the
power window motor/gearbox. Pry the three push-fasteners that fit
into holes in the door and secure the regulator cables. Now twist
and work the regulator gearbox (or motor/gearbox) past the front window
guide, and remove the entire regulator assembly (with cables and guides)
through the large cutout opening in the side of the door.
Step 12:
Here’s the new (manual) regulator assembly, ready for installation.
In my case, my manual regulator gearbox was starting to make “crunchy”
sounds, like either some of the gears were broken or the cable was
coming unraveled on the gearbox pulley. Power window regulators
are similar, only the gearbox portion includes an electric motor
and electrical connector. Oh, and another difference – the manual
regulator assembly costs about $40 from Mazda, the power regulator
about $250! If your cable breaks and you have power windows, you
may want to look into replacing just the cable (not available from
Mazda) with something like a bicycle or motorcycle control cable
to save major bucks.

Install
the window winder crank (or connect the regulator to connector in
door) to check the operation of the new (or rebuilt) regulator before
taking the trouble to re-install. Now, install the regulator in the
reverse order as removed, being careful to match-up the marks made
at the four mounting points. Check for free operation of the regulator
again, and try loosening one fastener at a time if there is any binding,
as the regulator may be twisted slightly. Be careful to reinsert the
push-fasteners that secure the regulator cables and keep them away
from the moving window. Don’t forget to re-install the bolt holding
the bottom of the front window guide.
Also, here’s
a shot of a typical Power Window regulator assembly, for those of
you so equipped.

Step 13:
Clean the window of any accumulated dust, dirt and grease. Check
the front and rear window guides and grease them with white lithium
grease, as needed. The new regulator should come pre-lubricated,
so just wind it up to a point where the window fastener holes are
accessible through the door openings. Insert the window carefully
into first the rear, then the front window guides. Work the window
down until the three fastener holes line up with the regulator.

Reposition the
regulator as needed. Make sure the plastic pads are correctly positioned
on the window, and reinstall the three cross-headed screws snug
but not overly tight. Align the two window stops at the top of the
door where marked upon removal, and tighten the 10mm bolts. Check
window operation again, by running the window fully up and fully
down several times, checking for binding and noises. Loosen and
move regulator mounting nuts slightly, one at a time, as needed
to free up any binding. With the window fully raised and convertible
top up, check for proper fit of the window along the weather strip
at front, back and sides. Adjust as needed.


Step 14:
Replace the plastic window trim at the top outside of the door neatly
(GOOD LUCK!), making sure the trim snaps into the door by engaging
each clip. Secure the front and rear of the trim using the push-fastener
or screws, as applicable. Replace the door interior panel, speaker
grilles, trim, handle, pull cup, and crank handle in the reverse
order as removed.

Note that you
insert the top of the panel into the door window gap first, then
push the panel down until fasteners “snap” into place.
You may need to lightly pound the panel down all over with your
fist to make sure the fasteners snap into place, particularly in
the center. The panel should fit flat and neatly against the doorframe
along all edges. Check the window operation one more time, to make
sure you didn’t screw something up when you installed the panel!
Clean up any stray black goop or grease, and you’re done!

ADDITIONAL
THOUGHTS ON REPLACING BROKEN POWER WINDOW REGULATOR CABLES:

Here’s a common
reason that many power windows on Miata’s need repair – a broken
regulator cable that prevents the window from being raised or lowered.

Apparently,
Mazda does not sell a replacement cable by itself, so you must buy
the entire motor/regulator assembly for about $250 per side! Assuming
your motor/gearbox is still working fine, it is possible to replace
just a broken cable without buying an entire new regulator assembly,
but it requires a bit of ingenuity and patience.

A very detailed
procedure for doing this is included in the Miata Enthusiast’s Manual
by Grainger, available from most Miata parts places (PBC, Finishline,
Moss, etc.), and thus I’ve not attempted to cover it here. Replacement
basically involves partially dismantling the gearbox and re-threading
a new cable onto the motor drive and through the regulator. The
ingenuity part comes in with finding an appropriate replacement
cable (motorcycle or bicycle shop?) with the correct end fittings.
But, it could save you a bunch of money. Good luck!!.