It doesn’t matter what kind of classic muscle car you’re restoring; concealed headlights are a huge frustration to service and repair on any of them. C3 Corvettes are no exception. Like most concealed headlights of the era, C3 Corvette headlights are vacuum operated and a challenge to maintain. Although 1968-’74 Corvette headlight door mechanisms are different than 1975-’82 ones, the basics are the same. We’re going to be servicing the 1968-’74 type here.
Although the mechanical part of the 1968-’74 concealed headlight system is the same, the vacuum system changed nearly every year as Chevrolet tried to work out the kinks. The 1968 vacuum system we’re working with is a one-year-only system. In 1969, there were two versions of this vacuum system: early and late. Chevrolet finally settled on one system from 1970-’72.
When Chevrolet changed the Corvette’s hood for 1973, eliminating the concealed windshield wiper cowl door, changes were made to the vacuum system, which remained virtually unchanged from 1974-’79. Chevrolet came up with an even simpler vacuum system for 1980-’82, which was less problematic.
Your C3’s vacuum headlight door system consists of a vacuum valve or switch at the headlight switch, a check valve (to hold vacuum), a vacuum filter to keep dust and dirt out of the system, a manual override switch at the steering column, a vacuum reservoir to store vacuum, two vacuum relays and two vacuum actuators to open and close the headlight doors. There are also color-keyed vacuum hoses that enable you to install each hose where it belongs in the system. All you have to do is follow the Chevrolet vacuum schematic in order to get everything connected and working properly.
Once you understand your C3 Corvette’s vacuum headlight and wiper door system, it becomes easier to understand the rest of it. The first order of business is vacuum lines, relays, switch and actuators. The actuators must be free of leaks or they will not function properly. Leaking vacuum hoses and related components will not only cause headlight and wiper door malfunction, but also cause the engine to run rough because there’s a vacuum leak affecting the air/fuel ratio.
Before you get into the mechanicals of concealed headlights, you must have a properly functioning vacuum system. If you have one headlight door open and one closed when the headlights are switched on, you most likely have a leaking actuator for the headlight that is closed.
Concealed headlights also malfunction due to mechanical issues. If the vacuum actuators are working fine, headlight door mechanisms can bind and hang up rendering them ineffective. This is when you need to rebuild the headlight door and mechanism to get them working properly again. We’re working with a ’68 Corvette roadster in need of working headlight doors. We’re going to go through each of these headlight door mechanisms and get them working again. We’re looking to Dru Beeler’s expertise at Hot Rods by Dean in Phoenix, along with help from Corvette Central, which has provided all of the components necessary to get our night vision corrected. Vette
1. Here’s the complete anatomy of a 1968-’74 headlight door assembly from Corvette Central. You can order a new reproduction assembly or all of the parts necessary for you to rebuild your existing headlight door assemblies.2. Here’s the flip side of the headlight door assembly from Corvette Central. This is a nice reproduction piece that enables you to get back on the road quickly. We’re going to show you how to rebuild your existing headlight door assembly with authentic reproduction parts from Corvette Central.3. These are the original headlight door vacuum actuators from our ’68 Corvette. The reproduction actuators from Corvette Central bolt right in place of the originals and offer crisp function. You could also replace the shaft seals and press your original actuators back into service as long as the diaphragm isn’t leaking.4. The Corvette’s front fascia houses each complete headlight assembly. Behind the headlight door is this mechanism, which rolls the headlight door open and closed. The only thing missing here is the headlight door.5. To get smooth headlight function, begin the rebuild by cleaning up the actuator roll pins on the doors like we are doing here with steel wool or a scouring pad. If the surface is badly pitted you can fill the pits with a good epoxy resin and work it smooth. You want buttery smooth pin surfaces for flawless function.6. We’ve got the pin’s surface cleaned and the spacer installed. All pitting and corrosion must be removed from the pin for smooth operation. During assembly, dress these pivot pins with white lithium grease.7. Each headlight door assembly gets two of these pivot bushings. Again, lubricate these nylon bushings with white grease for smooth function and longevity.8. It’s a good idea to chase all the threads before assembly begins. Damaged threads can cause binding and, potentially, fastener damage. Chasing them with a thread chaser improves fastener installation.9. Install the headlight door stops next. Allow yourself adjustment room.10. We’re opting for all-new headlight mounting and adjustment hardware from Corvette Central because it looks good and eases installation.11. The headlight dishes are next using the Corvette Central-provided hardware. This is one of two adjustment screws for each headlight.12. This headlight dish tension spring from Corvette Central applies tension to each of the headlight dishes, which keeps the headlight properly aimed once adjusted.13. The headlight door assemblies are complete except for the headlights.14. We’ve installed new Wagner headlamps in the door assembly. If you’re building a driver, opt for Halogen headlamps, which are much brighter than those classic sealed beams.15. These nylon inserts and bushing and pin go together to tie the headlight door actuator rod to the headlight door. Apply white lithium grease to the pin and insert for smooth operation.16. This nylon bushing and pin provide the pivot point for the link that transmits linear motion from the actuator to the headlight door.17. This is the adjuster that limits travel of the link that ties the actuator to the headlight door.18. This nylon bushing and pin are what the link pivots on as the headlight door is moved by the actuator. Apply white lithium grease to the bushing and pin, and assemble as shown.19. The link pivot pin and bushing are installed as shown using a liberal amount of grease between the pin and the bushing.20. The pin is secured with a cotter pin as shown. Expect to have to replace these bushings roughly every 10 years, especially in dry climates.21. Here’s another look at the nylon bushing and pin that join the actuator rod endlink and link.22. Here’s the completed headlight door actuator with springs installed. Yours should look like this.23. Dru Beeler of Hot Rods by Dean installs the headlight door assembly as shown. You have to get underneath to attach the pivots to the body.24. The actuator link is then connected to the headlight door, which is tricky because it’s in a tight spot.25. With the headlights switched on, the headlight door should look something like this. The headlight door stop, not shown here, adjusts how far the headlight door opens.26. With the headlights off, the door should sit flush with the fascia.27. Here’s what the headlight door looks like off and closed below the surface, behind the grille.28. Here’s the headlight door stop, which limits door travel when headlights are on.29. The headlight protector shield, from Corvette Central, is an often left-off piece, especially when there’s repair work after front-end damage to your C3 Corvette. Don’t leave it off. Its purpose is to protect the headlights.30. Make sure to use new attachment clips, as these hold the mounting screws firmly in place.31. Here, the rubber headlight protector shield is in place and ready to go before the front grille work is positioned.
