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DISCUSSION => Electrical => Topic started by: colin86325 on February 29, 2012, 08:51:50 PM

Title: Rebuilt my door lock actuators
Post by: colin86325 on February 29, 2012, 08:51:50 PM

I'm fixing up a 1991 318i for my girlfriend and both of her rear door locks were inoperative with the central locking system, so I used a DIY article I came across
here (http://forums.bimmerforums.com/forum/showthread.php?t=1596941) to rebuild the lock actuators using common $3 electric motors.

Basically I followed the steps outlined in the excellent write-up I linked above. But in this case the actuators were from a 1991 318i, so the device is a little different than shown in the article above. I took some pictures and made a few notes along the way in case anybody is interested.
 
Here's the actuator viewed from the side.  I used a hacksaw to separate the plastic portions and it took a really long time.  A Dremel tool with a cut-off wheel would save a lot of time. Because of the way mine were glued there was no way a small screwdriver was going to work to pry the pieces apart, as suggested in the article.


(http://i287.photobucket.com/albums/ll139/colin86325/actuator/actuatorside.jpg)

Here's what it looked like with the top removed. Note the location of the parts in case you do decide to use a Dremel.  You don't want to damage anything, especially the PCB. Also shown is the actuator rod with its teeth to engage the gear driven indirectly by the drive motor.

(http://i287.photobucket.com/albums/ll139/colin86325/actuator/actuatorapart1.jpg)

I removed the drive gear and the dead-lock bolt, along with its small spring.  The spring fits into a small hole in the body of the dead-lock bolt, and the other end of the spring is tensioned against the inside of the actuator body. When the dead-bolt function is used, this dead-bolt engages an indentation in the plastic actuator rod and prevents its travel.

(http://i287.photobucket.com/albums/ll139/colin86325/actuator/actuatorapart2.jpg)

I further removed the brass locating plate for the drive motor, and the plastic clip that keeps the wiring in place. You can start to see the rust on the motor case.
(http://i287.photobucket.com/albums/ll139/colin86325/actuator/actuatorapart3.jpg)

Here it is fully disassembled.  The drive motor was badly rusted.  The smaller dead-bolt motor was in worse shape, but I didn't really care about the dead-bolt functionality.  (I also did not have a part number to source a replacement motor, as this motor is a bit smaller than the drive motor.)
(http://i287.photobucket.com/albums/ll139/colin86325/actuator/actuatorapart4.jpg)

Here's a closer look at the rust.  Because of its position when the actuator is installed, any water collects against the dead-bolt motor and puddles against the plastic housing.  In hindsight, the manufacturer should have drilled a tiny weep hole and added a thin drain hose to the actuator at this location.
(http://i287.photobucket.com/albums/ll139/colin86325/actuator/actuatorapart5.jpg)


That's basically it.  I transferred the brass gear from the old drive motor onto the new motor, soldered the connections to the new motor, and tested the assembly before I sealed the actuator back up.  I used a plastic adhesive and C-clamps to hold the pieces in place while the adhesive dried. I followed up with a bead of silicone along the seam.

The original actuator had a rubber boot that extended and contracted with the actuator. This boot even had a built-in drain to divert water that collected inside the boot, but after 21 years I have to report that the rubber boot was absolutely crumbling and no longer provided any protection from water.  In lieu of this boot, I cut the fingers off a heavy-duty latex glove and slit the finger tips to slide them over the actuator rod.  I doubled the fingers up (that is, I used 2 fingers, one inside the other) and sealed the slit in the tip to the actuator rod with more silicone.

Title: Rebuilt my door lock actuators
Post by: Geoff on March 01, 2012, 06:21:51 AM

way to get into the nuts and bolts of it, bro.   I freely admit to not having the patience for that kind of stuff,  but my hat is off to you:)
                                                                      Geoff

Title: Rebuilt my door lock actuators
Post by: DesktopDave on March 01, 2012, 10:40:02 AM

That is an awesome write-up.  Reminds me of all the little hobby motors I built into models as a kid!

I'm going to have to try this myself!

Title: Rebuilt my door lock actuators
Post by: colin86325 on March 02, 2012, 03:06:06 PM

Thanks guys, thank goodness for small victories.  This car has been fighting me all the way!

Title: Rebuilt my door lock actuators
Post by: DesktopDave on March 02, 2012, 03:50:55 PM

Amen to that...but you should see my e24.  Small victories include "making it run" and "stopping the rust."  I'll need a broom for the sea next...

IMHO the e30 is a far better put-together car!

Title: Rebuilt my door lock actuators
Post by: wannam42 on March 03, 2012, 06:43:54 PM

Double amen to that! Thanks for taking the time to write and post!