*Courtesy of Ian Maddison
& 86mister2 from the MR2
Twosrus sells replacement
motor gears for power windows, which is a very common failure
on the aging MR2s. However, the regulator gear could be the
one causing your problems. This gear is irreplaceable and
you must purchase a new regulator (either from Toyota, junkyard
or another MR2 owner). Below is a great writeup from Ian which
details replacing the regulator. But first, 86mister2 explains
how to tell which gear is broken before tearing into your
Here's how you can tell which gear is broken without dissasembly
of your doors:
1) If the window pauses for a second but continues on its
own to move up or down, it is a bad motor gear. What happens
is when the motor gear moves to it's bad spot, it obviously
won't turn the regulator gear untill the motor gear spins
back to where it still has teeth. Then it will re-engage the
regulator gear untill it comes to the bad spot again. This
will cause the window to stop for a second or 2 each time
it passes the bad spot, but will continue again on it's own.
2) If the window pauses and doesn't resume by itself, but
just makes a horrible grinding or repetitive clicking noise
and you have to give it a little push or pull to resume operation,
you have a bad regulator gear. What happens is the motor will
spin the regulator untill it hit's the regulator gear's bad
spot. Since there are no more usable teeth on that spot of
the regulator gear, the motor gear will just keep spinning
against it causing the grinding noise and the window stops
moving. When this happens, you need to give the window a little
help so that the busted regulator gear turns enough to re-engage
with the motor gear with its remaining teeth. This scenario
IS NOT REPAIRABLE with twosrus gears.
3) Another problem that can happen which will lock the window
in place would either be a power failure, or the window cable
gets wrapped around a piece of metal. There is normally a
little plasitc piece on these metal tabs that the cable rests
against so as not to get intertwined with anything. Over time,
the plastic tabs can pop off or break. If this happens, the
cable may slip around the metal tab that once held the plastic
and jam the window. Repeated attempts to raise or lower the
window in this scenario may damage your cable, causing it
to start to fray or snap. If you believe this could be your
problem, I would recommend removal of the door panel and checking
it out to make sure the cable isn't stuck on anything.
Before starting the job, you should consider the possibility
that not only the motor drive gear teeth are broken, but the
regulator gear may be broken, too. You may need the complete
regulator. It happened to me. I found very useful a screw-driver
with replacement bits, including hex and star drives, particularly
if it's a 'T-bar' type. A square drive mm. socket set with
a 3 inch extension is also nice. The BGB is very helpful,
but is unclear on a few fundamentals.
- First, you need to be able to move the glass to different
positions while you are removing components. (O.K. I know
that, at this point, it's broken, but...). You will need
to have the window switch separate from the door trim. It's
only held with two screws and is easy to remove and replace
in the door trim panel. The relay is also re-sited after
removal of the door trim. This is because the window needs
to be all the way down to remove the outside weather-strip
from the door and mid-way to separate the window glass from
- Secondly, and most importantly, the plastic 6mm hex socket
in the large toothed wheel of the regulator will not move
the wheel (and the regulator) when the electric motor is
- The green manual (BGB) is not really clear about window
adjustment, particularly with the 4mm hex drive in the regulator
The immobility of the regulator gears is quite reasonable,
when you think about it. The glass must remain in any position,
where it is stopped. The importance of this point is that
you must position the regulator in mid-position with the 6mm
hex drive before attaching the electric motor so
that you can bolt the glass to the regulator through the holes
in the door. You do this positioning as the motor is attached
again to the regulator, after replacing the broken gear wheels
and before the regulator is replaced in the door.
If you attempt to move the power window mechanism without
the glass, then you will break something. I recommend disconnecting
the battery, so that every time you supply power to the window
regulator, it is intentional. When you remove the window relay
and mirror power cable, the connectors
are fairly obvious.
1) Generally, the green manual (BGB) is clear on the window
removal process. They advise you to remove the door-trim,
but don't mention the tendency for those little plastic discs
that cover the three screws to fly everywhere in car or garage.
I suggest using some electrical tape over each as you lever
it out with your taped-over screwdriver. They also don't mention
the need to remove a small screw from the plastic inside handle
trim to get the door liner off. The water-proofing plastic
liner to the door can gently be pulled off its tarry glue,
after removing the power-window relay.
2) The rubber mouldings at each end of the door can be detached
by removing their two screws and the two screws that fix the
outer weatherstrip are fairly obvious. If, like me, you drop
any of them in the door, they are small enough to push to
the door drain hole and fall through it.
3) The rear-view mirror and its triangular lower frame will
need to be removed from the door. The frame is fixed with
two bolts, outside, and one nut, inside. Note the room for
movement, allowing this frame to be adjusted to the position
of the window-glass and prevent those annoying whistles at
4) The manual says to remove the inside door handle and
its links to the lock, but later implies that the regulator
can be replaced with the door handle mechanism in-place. I
managed to remove the regulator and replace it without removing
the inside door handle, but removing it will give you a little
more room, especially if you feel the temptation to be forceful.
There have been complaints that the regulator channels and
metal parts are weak and that bending any of these causes
5) At this point I recommend the use of white paint (I used
typing correction fluid, White-Out) to mark the present position
of all regulator adjustment bolts and window stoppers and
6) There are two glass stoppers to determine the final height
of the closed window-glass; one is two inches from the rear
view mirror and the other is above the door lock. Both are
on the inside and are marked by a 1.5 inch oval defect in
the metal. You can check the location by looking for two plastic
hooks in the window glass that fit into the window stops.
7) There are two door trim supports with felt that hold the
window-glass against the outside weatherstrip. They are bolted
to the inside panel of the metal and are more central in position
at the top of the door than the door stoppers. The green manual
(BGB) does not make a clear distinction between stoppers and
door trim supports. The difference becomes important at the
window adjustment stage after re-installation. There are 4
plastic clips in the door; 2 hold cables in the regulator
and 2 position the power-cable to the mirror.
8) Once you have marked the position and removed the window
stops and felt supports, you can remove the bolt and 2 nuts
that hold the window glass to the regulator. It is fairly
easy to remove. Note the plastic-tipped metal hook that goes
in the channel of the regulator frame nearest the door hinges.
You will need to relocate that hook when you reassemble the
window. Removing the 4 large nuts that hold the regulator
channel arms and the smaller three bolts that hold the gear
wheel assembly to the door will permit removal of the regulator.
Check that you have unplugged the power connector,
first. The regulator does come out, but it's a bit difficult
although it should come out without the use of any force.
The door space is not equal throughout and, by looking, you
can choose the widest space for each particular component
as it presents on its way out. Here, midwives and obstetricians
may have a particular advantage.
9) The motor can be disconnected by removing the three screws
that hold it to the regulator gear holder. The screws have
star-shaped sockets and you must have the right size,
because these are hard to undo and have to be tight. If the
motor gear wheel is the only component with missing teeth
then you are lucky. Otherwise you will have to fit a new regulator.
Both gear-wheels are plastic. The Toyota part comes with all
gear wheels and the smaller is a better fit to the 7 toothed
metal motor drive than is the MR2 club part that is available
separately. Both will be a tight fit and may need to be lightly
tapped in with a plastic faced hammer.
10) Assembly of the window mechanism is the reverse of its
dismantling, except for the nuts that go to the upper studs
of the regulator; these, like the bolts for stoppers and felt
supports, are only finger-tight. You must remember to
adjust the height of the window-glass mounts so that you will
see them through the holes in the door. The spring mechanism
is designed to help take the weight of the door and if you
screw on the electric motor without pre-positioning, the window
will be at the top and its holding bolts, inaccessible.
11) Fold the regulator without twisting or overly forcing
distortions in the cables. The cable to the motor drive lies
on the inside of the car, relative to the rest of the regulator.
Note that it is attached, by a plastic clip, to the inside
of the door. All cables will perform badly when distorted,
ask any motorcyclist. You will need to be patient as the regulator
goes back into the door, it takes lots of tries.
Adjustment of the Window
- Locate the studs of the regulator in their respective
holes in the door
and tighten the nuts to finger-tight at the top and fully
at the bottom. Use your earlier paint marks to site things
in their original positions.
- Hold the motor assembly so that the hex drive in the
center of the gear is visible through the round
hole, presumably for the handle in non- power-windows.
The three nuts that hold it can be seated and tightened
- Replace the front lower frame that holds the mirror,
but do not tighten the nut and bolts. It will be moved so
that there is no air-leak between it and the final position
of the window glass.
- Put back the door stops in their original position and
replace the external weatherstrip and the rubber belt moulding,
being careful not to drop any of the 6 small screws into
- Reconnect the power and raise the glass to its mid-position.
Here, in theory, the window trim at the top of the door
and the trim supports will operate at the mid-point of the
curve of the window-glass.
- Adjust the felt covered door trim supports so that the
glass is gripped between the elastic pressure of the weatherstrip
and the felt door-trim supports (2). There must
be a small gap between the felt underneath the rubber edge
on the weatherstrip and the glass. The purpose is to use
the elasticity of the weatherstrip rubber and not
to grip the glass between the felts on both side of it.
That way lies motor burn-out.
- The door trim supports can then be fully tightened. They,
and the outside felt in the weatherstrip, will act as the
for the lever that is the window glass in its final position
against the rubber around the door way.
- Raise the window glass to the top to 'close' the window,
but do not close the door. You will need to check the height
of the door relative to the roof side weatherstrip and roof
drip moulding. The green manual specifies a 1 to 4 mm gap
between top of glass and roof drip moulding. They say to
remove the weatherstrip to check this, but you can get a
working approximation by comparison with the other side,
provided that no-one has changed it from the factory set-up.
- Note the distance of adjustment needed and lower the
window. Adjust the height of the door window stoppers to
bring the top position of the glass to within the specified
distance from the roof drip moulding. Several tries may
be needed. Finally tighten the bolts on the door window
- The position of the window glass can also be adjusted
by changing its position in the moveable mounts at the bottom
of the regulator.
- The two nuts near the door lock allow the glass to
be moved forward. The green manual specifies a distance
of 7.5 to 11mm from the glass of the closed window to
the center pillar moulding, behind the door.
- The nut nearer the door hinge permits the window
to tilt as it rises. The green manual specifies that,
when closing, the front of the window stops first and
the rear rises a further 5-10mm. I had no trouble, but
I wonder if there might be a need to adjust the door
window-stopper positions twice if the window doesn't
move as expected.
- If you have a new regulator or the window position has
been changed, you will probably need to adjust the prominence
of the studs that hold the upper parts of the regulator
channels. The alignment of the final position of the regulator
with the door will have been done with the usual Toyota
efficiency at the factory, but there is sufficient variation
door-hanging to allow the possibility that the raised window
may not exactly match the line of the roof moulding.
You may have noted that the upper regulator studs have a
flange on them which holds the glass against the upper nut.
By screwing or unscrewing these studs, the regulator channels
are tilted and the window glass can be made to tilt at the
top of its travel. To do this you will need a 4mm hex drive.
The window glass acts a lever
with the regulator fixing at one end and the roof moulding
at the other. The final position of the top of the glass
can be made to tilt in towards the rubber by unscrewing,
anti-clockwise, the bolts to move the lower end of the window
outwards. Conversely to get more clearance at the top of
the glass, when the door is closed, the studs need to be
turned clockwise. With each set of two studs at the top
of the regulator, you must make the same degree
of rotation. Also move each pair of studs to the same degree.
This implies that the tilt of the window in the door is
correct. If the final tilt is wrong with more clearance
at front or back, then adjust one set of two studs. If you
do not move the two studs together, then, theoretically,
you will stress and break the glass. More probably, you
will merely incrase the friction in the channels of the
regulator. A "T-bar" screw-driver is particularly useful
to measure the degree of rotation.
- When you think you've got it right, tighten the appropriate
nuts and bolts to fix their position.
- Before you finish, you'll need to make a check of window
movement with the door closed, particularly to check if
the window tends to roll-up the soft rubber sealing weatherstrip.
- Reposition the front lower frame that holds the mirror,
so that there is no air-leak between it and the final position
of the window glass. Tighten the nut and bolts.
Once the window is done, the replacement of mirror, the
installation of plastic seal, door trim and replacement of
relay and switches is a straightforward reverse of dismantling.
Hopefully, you will have working window with relatively
silent dry motoring.
Ian Maddison Jan 2004