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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
? Temporarily locking headlights down?
I'm trying to track down a vacuum issue with my headlights. I'll get it figured out eventually, but I need an immediate short term way to lock the headlights down. At the last track day the headlights popped up at about 110 mph and stayed there for the rest of the session. Manually closing them between sessions was only good until the first long straight again (obviously). I've got another track day coming up soon. Are there any sure ways that are a bit more sophisticated than my current plan to run a short small cable or chain from each headlight down to the radiator support? (Still uncertain if I can safely swap out a couple headlight linkage springs for a solid link or loop to prevent movement.)
I'm trying to track down a vacuum issue with my headlights. I'll get it figured out eventually, but I need an immediate short term way to lock the headlights down. At the last track day the headlights popped up at about 110 mph and stayed there for the rest of the session. Manually closing them between sessions was only good until the first long straight again (obviously). I've got another track day coming up soon. Are there any sure ways that are a bit more sophisticated than my current plan to run a short small cable or chain from each headlight down to the radiator support? (Still uncertain if I can safely swap out a couple headlight linkage springs for a solid link or loop to prevent movement.)
Thanks for any constructive suggestions.
Disconnect and plug the vacuum line that opens the headlights and replace the check valve in the main vacuum line coming off the intake which maybe causing this issue. Good luck on the track, which one? Check valve
My headlights have been in manual mode for years. Near where the springs connect at the linkage hinge, there is a metal pull tab with a hole in it. Perhaps tie some 550 cord from that hole to the front bumper reinforcement.
Disconnect and plug the vacuum line that opens the headlights and replace the check valve in the main vacuum line coming off the intake which maybe causing this issue. Good luck on the track, which one? Check valve
Take the check valve off and suck through it. It should only let you suck one way,the engine side. That might be your problem. Plug that line for track time and no vacuum will go to the rest of the car except power brake booster and that is a different vacuum line.
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Guys, thanks for the info and recommendations. It's greatly appreciated. And Mel, I appreciate the vacuum diagram that was included in the check valve link. I will be working on the system again tomorrow.
These days I pretty much only do track days with the car (no night time or rainy day usage), so I have no idea how long this issue has been around.
An aerodynamic question. If you disconnect the vacuum hoses from the canisters...and of course plug them up......will the headlights still pop up at 110 mph? In other words, if the headlight assemblies are disconnected from any vacuum source, will air pressure cause the headlights to pop up? If so, this is another source of a problem in human kinds unrelenting battle to solve problems with the C3's vacuum controls even though 50 years has passed since these cars appeared on the roads.
Guys, thanks for the info and recommendations. It's greatly appreciated. And Mel, I appreciate the vacuum diagram that was included in the check valve link. I will be working on the system again tomorrow.
These days I pretty much only do track days with the car (no night time or rainy day usage), so I have no idea how long this issue has been around.
Back in the day I did time trials at Bridgehampton, Long Island, NY, 2.5 mile incredible track. Now a golf course.
I think they pop up at high speed because the air pressure overrides the vacuum system if that is the case perhaps a couple small vice grips strategically placed would be a benefit.
Like others have said just unplug and cap the vacuum source at the manifold. Matter of fact mine is disconnected now since I've switched over to EFI and I wanted to eliminate any possible vacuum leaks which tuning. I'll eventually hook it back up but I rarely drive at night and can manually open the headlights faster than the vacuum system can. LoL
In the STICKY section above, at the bottom of the list, there's one labeled "CONSOLIDATED FAQ'S"
Nice Willcox vid in there explaining and troubleshooting the headlight system.......
If you do not have nice paint to worry about you could always use "racers tape" (duct tape) over the headlamp doors edges. This process has been used for years in racing and wind tunnel testing. All you need to do is tear the tape into 1/2: strips apply then do your run(s) then remove tape at the end of the day.
Last edited by Mr E's C3; Oct 2, 2025 at 01:41 PM.
Reason: add word
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Originally Posted by MelWff
Back in the day I did time trials at Bridgehampton, Long Island, NY, 2.5 mile incredible track. Now a golf course.
I recall hearing the Bridgehampton name several years ago. It always sounded like an exotic track to me.
The closest track (Heartland Park Topeka) closed a few years ago, so the only one within acceptable/regular driving distance is Raceway Park of the Midlands in SW Iowa. It's a modest complex, but the 2.2 mile road course has a nice mix of fast and slow sections, and decent runoff areas if needed. Track day fees are also very reasonable.
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Originally Posted by Richard454
Back in the day when my car saw a 1/4mile at the time-
Disconnect at the intake manifold- as to stop ANY vacuum leaks in the system ( hoses/tank/actuators/valves)
and
THIS- around the linkage
Well, that looks like a time efficient method. I've got some of those heavy duty ties on hand.
I'm also blocking off more of the air entering the grills. I don't have much overheating issues, and I'm constantly trying to reduce the amount of air entering the engine compartment and getting under the car. It ought to reduce the amount of air trying to lift the headlights as well.
I recall hearing the Bridgehampton name several years ago. It always sounded like an exotic track to me.
"The Bridge" was a really neat track in a pretty location, but being at the far northeast end of Long Island it was a tough place to get to even 45-50 years ago. Professional racing ended there in 1970, but SCCA club racing continued into the 90's. Sitting just about on the beach, the wind and blowing sand made things interesting there at times. As the Hamptons continued to grow as the summer playground of the "beautiful people" it got harder and harder for Bridgehampton to survive, but through the efforts of a small group of devoted fans it managed to hang on probably 20 years longer than it had any right too. Much of the credit for it becoming a golf course (that preserved a portion of the track including the Chevron bridge) instead of a housing development was through the efforts of the track's many supporters.
The racer I crewed for in the late 70's and 80's only made the trip there once, for an SCCA Regional around 1980.
? Temporarily locking headlights down?
