Due to the body design of each E30 model, doors are generally not compatible between different models. However, doors from identical models of different ages are interchangeable, but attention needs to be paid to the internal mechanisms, including the wiring loom and window mechanisms.
The front doors of each E30 are model specific, and therefore cannot be interchanged. For example, those fitted to a 2-door are too long to fit a 4-door, while Cabriolet doors lack the window frames needed for a 2-door. However, front doors of a 4-door are interchangeable with a Touring.
The rear doors of 4-door models and Touring models are not interchangeable due to the differing shape of the window frames. However, interior window mechanisms and all interior trim including door cards and handles are interchangeable between the two models.
Learn more about removing and replacing doors
Main article: Windows
The internal window mechanisms changed during the facelift, meaning cars up to and including 1987 models have different glass, mechanisms, looms and motors (if fitted) compared to 1988 and later cars. This means that if you are considering installing electric windows to your vehicle, it is important to have the correct mechanism and loom for your model.
If you are planning on installing rear electric windows to your car, be aware that the appropriate wiring for the loom is installed. Look on the B-pillar of your car and locate the small plastic removable panel; inside this should be the plug to which you will connect the door loom when required.
Learn more about retrofitting electric windows.
Wing mirrors are interchangeable across the entire E30 range.
The wing mirrors are electrically operated by a thumb switch on the driver's armrest, mounted to the door card. Power is given by the loom to a motor inside the wing mirrors which controls horizontal and vertical tilt. Some mirrors were fitted with a heating element, but this is automatically controlled and requires no switching by the driver.
The wing mirrors are mounted directly to the door frame using two 8mm bolts. To access them, use a flat bladed screw driver to gently prise off the plastic trim triangle from inside the door. Unplug the four-pin socket, then hold the mirror while loosening the bolts.
If you find your glass is cracked or faded, learn more about replacing the wing mirror glass.
Main article: Locks
Main article: Central Locking
E30 locks are a very simple barrel design, and can be removed, dismantled, repaired or recoded fairly simply. They are held in place with a C-shaped clip what presses the lock barrel against the inside of the door skin. This clip can be pulled sideways and removed with a long screwdriver and some nimble fingers, after removing the door card.
If there is a problem with your locks, learn more about repairing your door locks.
All electric elements of the door are controlled by a one-piece loom, connected to the main vehicle loom by either a C40x plug in the A-pillar (front doors) or B-pillar (rear doors). The loom plugs are different between pre- and facelift cars, but the essential wiring is the same. From the plug, the loom provides power and control to the:
- Door locks
- Door lock heater (if fitted)
- Wing mirrors
- Electric windows (if fitted)
The door pin switch, which senses the opening or closing of the door, is separate from the door loom.
The two main trim elements of the door are the weather seal, which seals the gap between the door and window, and the bump trim, which runs along the middle of the panel.
To remove the weather strip, simply lower the window and use a flat screw driver to prise the weather strip upwards, being careful not to bend it.
To remove the bump trim, remove the 10mm plastic screw from the door jamb and then slide the strip horizontally and away from the door. It is held on with two plastic clips, which can be removed by smacking the middle pin into the door with a screwdriver and hammer. The clip itself will then pop off easily.
Can't Close Door
As these cars age, the latch mechanism can get sticky. When this happens, the latch occasionally jams in either the open or closed position. When you try and close the door, the catch on the pillar smacks into the latch, and the door doesn't close or worse, the latch is jammed open and won't click shut.
To solve this, spray the latch with some penetrating lubricant (such as WD40). Then use a screwdriver to prise the latch arm outwards - it can help to pull the door handle at the same time to help free the mechanism. With some wiggling you should be able to free the latch arm so that it springs into the open position, and closes properly when it hits the door catch.
Due to the nature of the door skin, most E30 doors develop rust along their bottom edge, despite the seam sealer applied there by BMW. Surface rust can be rubbed down, filled and repainted, but more serious rot requires the door to be reskinned properly.
The glass for the windows is raised and lowered by a simple mechanism bolted to the bottom edge of the glass. The sides of the glass then run in two channels, which can accumulate dirt and debris which will affect your windows. If your windows are not raising and lowering probably, learn more about adjusting your front windows.
Electric Windows not working
The electric windows fitted to E30s are a simple mechanism involving a cable and winch system (pre-facelift) or a scissor-jack mechanism (facelift), driven by an electric motor. If unused, these electric motors can become rusty inside causing them to seize up. However, the most common fault of electric windows is simply dirty switches.
To troubleshoot, use a flat screwdriver to prise up two window switches from the centre console, and swap them over. Now test the windows. If they work, the fault is the switch, which is usually dirty contacts. These can be cleaned up with a small (nail?) file or scraper and Contact Cleaner spray. Never use sandpaper.
If none of your electric windows work with the front doors open, check fuse 28. If your electric windows only work with the door open, but not with the ignition on, then check fuse 17. If they still don't work, pull out relay K5 and link together pins 30 and 87 of its socket with a short piece of wire. If this makes them work the relay is either faulty, or there is a problem with the unloader circuit, associated (on facelift cars) with the green/black wire to the starter motor. In this latter case, you will probably have a non-working heater blower and non-working door mirrors as well. A known symptom is that the green/black wire terminal on the starter motor works loose; tighten it up again by hand and refit the wire, and your windows should now work.