The two headlight mechanisms will have identical worm gears (Stainless Steel) and worm wheel gears (Nylon Part# 51072-41 for a 1989 Corvette, for example) which houses the clutch bushings (Nylon) I believe the two mechanisms (output shafts) left and right, turn in opposite direction to rotate the headlights up or down in unison. This means that on the passenger side the worm wheel lip will be below the worm (as seen in the video), on the drivers side the lip will be above the worm. The worm wheel gear cannot be removed if it is not worn (just the bushings are bad). Often to remove the worm wheel gear the motor has to be pulled out, which is a huge task to put it back together. I know how to do this because I work on motors so it is not a problem. But, beware you may not have enough clearance to remove the gear housing as seen in the video, I think it depends on the shaft stack-up (length) which varies slightly due to factory adjustment. While I have the motor apart I clean the commutator and housing. You will need a motor brush jig to retract the brushes while you reinstall the worm gear and motor shaft. Be careful because there is a thrust ball at the end of the worm gear shaft, it is easy to lose. After cleaning use grease to hold the ball in place during reassembly. You can then confirm it is in place through the witness hole in the housing casting. The screw adjust on the case is to set the motor thrust clearance. There are two lubricants used in the assembly; plastic gear and bushing grease (I used Molykote 33 Medium) and light machine oil (I used Chemours Krytox GPL105) for the bronze bushings and metal shafts (I do not think bushings are made from Sintered Bronze). Try not to intermix the two lubricants. For the other moving parts external to the motor and gear assembly I used Liquid Wrench Silicon Spray (This is an excellent coating thin penetrating lubricant). For the slotted pin I would recommend: 420 SS 5/32 Dia. 7/8 inch length slotted (McMaster-Carr# 92383A714), or a 420 SS 5/32 Dia. 1 Inch coiled (McMaster-Carr# 93740A269. The one inch length allows witness length above and below the knuckle. I think the coiled pin is stronger and has a slightly higher retaining outward force. The original pins looks like they are made from 18-8 Stainless, 5/32 inch diameter and 7/8 inch length. Before reconnecting the harness connectors clean with Deoxit spray. As seen in the video the T30 Torx bracket bolt nearest the actuating shaft may be frozen in place, and it also may have loc-tite applied to the threads. It can be extremely difficult to back-out this fastener. You may have to put the frame in a vice and then apply considerable force after applying penetrating fluid (I used Liquid Wrench Penetrant and Lubricant) until the screw starts to move. When it does, move the fastener in and out to aid the penetrating fluid, and add more each time it moves further out. I actually had the shorter T-30 Torx motor mounting standoff screws come loc-tited from the factory. The amount of force needed to get them to move was ridiculous. Using a long 3/8 inch ratchet wrench and T-30 Torx bit socket. You may have to use this same procedure on the one or more of the gear cover 8-32 screws, if you don't, and the screw is frozen, you will shear the head off. The problem with the cover screws is they are painted and treated steel. If the threads rust while seated, you will not get it out. You will have to drill the fastener out oversized, tap and put in a Heli coil (for 8-32) if the housing ear survives, that is. If you are able to remove the 8-32 screws, chase the holes with a tap and cutting fluid, then lubricate the holes. You can just reinstall the original screws, however the better option would be to use new 18-8 SS serrated flange hex head screws, which will not rust and are strong enough for this application. Mounting the headlight in the vehicle can be a challenge in centering it in the hood cutout. You can snug it in place (make sure it can still move on its mounts, and use hardwood shims to even the space around the outside. I think from the factory (1989 C4) the bottom space was just slight larger than the top and the sides are equal. It looks better if both headlights have the same relative gaps. Make sure and tie-wrap the wire harness to the vehicle side wiring frame so the wires do not interfere with the headlight shroud when in the down position. I hope some of the information above is of some help.
This how to video of the headlight assembly is clearly the best one out there. I like how you showed in detail the correct way the stop is positioned. I do have a question though. While the one end of the stop is on that bump or rivet does the other end rest on the aluminum block or will it just fall into the correct position. Thanks for your effort.
The stop just rests there. If it isn't in the right spot the motor will only come up half way or not at all. When you take yours off just look at how it is on there for reference, or even take a picture of it. If you have it wrong you'll have to take it all apart again to fix it. Glad you liked the video.
@@C3Stingray Looks like I will be taking it apart again. The stop must have moved as I drove the role pin back in. I'll watch your video a few more times and I'm sure I'll get it right. Thanks for the reply.
Thank you for posting this video. I found it very helpful when I did this project. I did have a question about the headlight housing. I noticed even before I started this job, there was "play" in the headlight cover. Meaning, you can rock the housing back and forth and it did not sit flush with the hood ( up slightly at the front). I did make sure of the placement of the "stop" shim you mentioned, and the headlight rotates as it should. My problem is the "play" and the cover does not sit flush with the hood. I did notice a nut on the end of the motor, I was wondering if that might have something to do with the problem ? Any ideas you might have would be greatly appreciated.
