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Post Info TOPIC: Corvette C4 Headlight Motor Gear Repair - Headlights making noise - hanging up - not working 1988-1996


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Corvette C4 Headlight Motor Gear Repair - Headlights making noise - hanging up - not working 1988-1996


Well, recently I had a customer coming in with what can only be described as a "lazy eyeball" when it came to his right passengers side headlamp. As I am sure you already known about the flip up headlights on the Corvette, they rotate around to open and close. After awhile they will start running on for awhile, clicking and making all sorts of odd sounds well after they are open and closed, then eventually they will get lazy to where you have to manually roll them into position. I was not sure what I was going to find when I dug into this motor as this is my first one, however from what I have seen they offer two repair gears, one for the 1984-1987 C4 Corvettes and another for the 1988-1996 Corvette. It's also worth noting that the 1988-1996 repair gear also fits in other models such as the 1988-1991 Buick Reatta and the 1987-1992 Pontiac Firebird, not that it matters, but incase some day these parts can't be located at least we know what to pillage to fix the 1988-1996 Corvettes! LOL

Anyway, it was odd to find this particular later model gear setup in a 1986, as the customer ordered the earlier gear thinking, naturally, that he had 1986 motors in his 1986 Corvette C4... Two things happened here, one is he does not know the proper year of his vehicle or two, they have been upgraded at some point. Which one I don't know because the car just came in for me to remove the headlight to perform the repair.

That said, YES you do have to remove the entire eyeball as I call it. This is a pretty easy task and you just disconnect two wires at their harness connectors and remove the four nuts that holds the bracket to the body and the hole assembly just comes right out of there. Be mindful of the shims on the outer most two nuts as you will need to place these in the same position to ensure it sits proper when the time comes to re-assemble. I use tape to tape up the shims which I know will go on top and let the others sit loose in a bag. In this case there were 4 shims per stud/nut for a total of 8 all together.

Once the headlight assembly or "eyeball" as I like to call it is out of the socket it should look something like this

You remove the motor by removing the several T-35 torx screws that hold it on but first you must punch the dowel out of the arm that attaches to the motor. This is somewhat easy providing you have a center punch just a tad bit smaller than the dowel and a nice little hammer. Once it's out about 1/4 of an inch you can use some diagonal cutters or pliers to remove the pin the rest of the way, or just drive it the rest of the way out with your center punch if it's a loose fit and isn't getting bound up in the hole. Once that is done move on to all the T-35's that are holding the motor attached to the bracket and it should separate something like this

Once that is done you will use a 1/4 socket to remove the three bolts holding the cover on. Once these are removed you will gain access to the gear. 

Amazing enough this gear turns on a worm gear that is attached to the motor and it's somewhat of a booger to get it out of there. I though for sure the gear was going to be stripped but it did not appear that way. It takes a little working with a small screw driver but eventually you will work the gear out and learn, at least in this case, what the real culprit was. As I said it looked like the gear was in pretty good shape once I got it out, but then as I looked into the housing this is what I seen

It would appear that the three bushings that go inside the gear to take up the slack and act as a cushion get brittle and completely shatter into bits and pieces! I can only imagine this causes an incredible amount of play and is the reason they run on and on... I would also imagine that due to this play it's the reason why eventually the worm gear looses contact with the gear at some point as it flexes and causes the "lazy eye" which requires you to manually roll it over.

This is what the proper gear looks like for 1988-1996 models, but the customer got me the earlier gears which you will see are different. I will have to wait for him to order up the newer style to re-assemble but I will post both with part numbers for comparisons sake. Here is the gear for 1988-1996 and in the center you can see the three bushings that become brittle and break into pieces.

In this case I am sitting here with two different gears, both for the early 1984-1987, however I am unsure why the customer has gotten me two. I am attaching photos of these earlier gears for reference, even though they don't appear to have any bearing on this particular motor I am working on, but it may help someone with earlier models.



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State of Michigan Certified Master Auto Mechanic +2

Specialty Certified Since 1994

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