bushing change in 91 headlights: surprisingly easy

[joe paco]

bought two bushing kits and replaced the broken/granular bushings in my '91 headlights today. one was making racket, but I changed both, a smart move. I did not get the gears, based on other people's experience, and it was a good decision. I have to wonder about the wisdom of spending $60 for a bronze gear, when the bushings apparently fail before the plastic gear. the gears were like new, even viewing with a magnifying eyepiece.

I followed the instructions from several threads here, removing the assemblies from the hood - a 5 minute job at the most- except that my parts came with slightly different instructions, like loosening the two #6 screws from motor to gearbox, to facilitate removing/reinstalling the drive gear to worm gear. one motor screw broke, and I had to drill a new hole and use a drill point screw, which worked fine. any self threading #6 would do, if you even needed it. the one screw was holding ok.

both motors came with 4 washers, but both were in different locations -either 3 under the shaft bearing in gear housing, 1 on top of the gear, or just the opposite. not sure if these are used to set height of gear or what. probably are not critical. ("critical" and plastic don't go together.)

as usual, the engineers designed the assembly such that at least one screw is inaccessible, the bottom motor mounting screw, but the bracket under it can be loosened enough to get access. the drift pin is easy to remove and install, and you simply turn the manual dial to spin the drive shaft so it aligns with the counterweight to reassemble.

compared to changing spark plugs, this is 80% easier.

of course, the headlights work "perfectly." (Corvette and "perfectly" don't go together, either.)

saludos, joe

 

[TedC]

Congratulations. In most cases, you don't need to replace the gears. It is the bushings that fall apart. I found this job more time consuming than difficult. Those washers are spacers, so the key is to remember how many went in which location. Totally agree about changing the spark plugs.

 

[aklim]

Gears can get stripped too. Plastic gets old and brittle. Mine were fine but I replaced them. Later on, I did fine a hairline crack in one of them

 

[joe paco]

Gears can get stripped too. Plastic gets old and brittle. Mine were fine but I replaced them. Later on, I did fine a hairline crack in one of them

I hear you, aklim. People get old and brittle, too.
Plastic gears are in many low torque motors, such as refrigerator timer motors, which have 8 gears or so, also icemakers. Some timing chain gears are plastic. That headlight motor seems to be low torque, and the gear is pushed into the worm gear, so it should break a tooth, rather than strip several of them, if it fails. Out of the sunlight, plastic should last indefinitely.

I was basing my decision on four differnt instructions, from people who had actually experienced the problem, rather than "must be a stripped gear, need to order some bronze gears."

I'm retired, in no hurry, and if a gear had been defective, I would have ordered gears. I reckon I'm just lucky.

saludos, joe

 

[timbila]

Headlights

Hi
After car stored for winter ,headlights only open half way. Is that what your problem was?
Thanks Tim B

 

[joe paco]

Hi
After car stored for winter ,headlights only open half way. Is that what your problem was?
Thanks Tim B

no, Tim. my "problem" was the symptom of a coming issue, one light chattered on closing, motor continued to run even when closed, 5-8 seconds.
if mine did that I would suspect a sudden loss of current flow through the motors, perhaps a relay, actuator, whatever. something common to both (switch, power). not sure if both have the same ground point -to the chassis- but they have individual ground wiring at the motor, so I doubt it.

there are some threads here that address the problem.

saludos, joe

 

[TedC]

Hi
After car stored for winter ,headlights only open half way. Is that what your problem was?
Thanks Tim B

There is a manual control knob on each headlight assembly. You should be able to open and close the light assembly by twisting this knob. You should feel distint stops when fully opened and closed. This way you can manually verify if your gears (including bushings) are working properly.

 

[aklim]

Maybe it won't be too bad to just take it apart so you can visually see the condition of the bushings and see if they are near the replacement point or not? I did that and found one set to be powder and the other to be elongated. Both my gears looked ok but I replaced them anyways since I was already there. Also, later on I did happen to see a hairline fracture on one of the "good" gears. I replaced them with bronze gears and got rid of the plastic.

Worst case scenario, you get to clean it out and change the grease in it. Can't hurt.