ACECO

The headlights on my 75 coupe are working OK as far as opening and closing. One does pop up a little sooner than the other, but this doesn't bother me. I know this can probably be fixed with a once thru of the vacuum lines, actuator seals, etc.

My question is that when the lights are open, they seem to bounce/vibrate on rough roads. Nothing too major but when hitting a bump, you can see the light pattern on the road "move/jump" a bit. I was wondering if this is normal or of there is something I need to check to "firm up" the assemblies in the open position.

TIA to all who reply.

:seeya


[Modified by ACECO, 3:54 AM 3/24/2004]

Big Fish

Check the bushings on all the moving parts for wear or possibly missing.

Larry B.

Each headlight assembly has its own vacuum actuator and relay valve. The relays route the vacuum to one side or the other of the actator. There is almost always some leakage at the relay or actuator. Since they are seperate each light moves at it's own speed. That is normal. As for the fluttering (bouncing). When the lights are up they lock via an "overcenter" linkage. If they do not go overcenter and lock then there is an adjustment to achieve this. Check http://www.corvettefag.com and see if there is a how to article on it. If not then a good service manual should explain it. I recommend GM manuals. They are far better than anything else. try http://www.corvettefaq.com


[Modified by bluevetteman, 7:34 AM 3/24/2004]

theoUK

Aceco,
To date, ALL the adjustment information I have read about c3 lights (including the supposed "instructions" in the GM shop manual) has been, well... crap, to be quite blunt.
Most instructions point out where the adjustments are made, but give no detail on which adjustment affects what.
I have just had my lights apart, and have finally sorted out how to adjust them. All up, there are 5 sets of adjustment to make to the lights, but since yours are only "fluttering" the adjustment you need to make is the easiest.

Take off the bezels. On the outer side of the headlight door, you'll see the "j-bar". It's a J shaped bar (no, surely not?!) bolted to the side of the door with two bolts.
The idea of this bar is that its lower end nudges up against the headlight support when the lights have popped up, thereby putting a bit of pre-tension in the system, and stopping it from fluttering. Even with slight wear in all the bushes/linkages etc, this bar should do the job of stopping the flutter, if correctly adjusted.
As far as adjustment goes, I'm led to believe there are two types of J-bar, depending on age (perhaps you could confirm this for me /us?) You want the bar adusted so its bottom end JUST nudges up against the headlight support when the lights are popped up. To tight and the lights won't lock open.
On my 80, the holes in the top of the j bar are elongated, so the adjustment is made at the top end where it bolts up to the headlight door. I've read of older cars having a screw in the bottom end of the bar, which you turn inwards to remove the slack.
I hope that makes at least a bit of sense, you'll probably see exactly what I mean when you take the bezels off. Good luck! :cheers:

Larry B.

Yes I agree that the manuals do a poor job relaying what to do.. I found an article at corvettefaq on the topic. It is from covette fever article and has some pictures but like yo usaid it is kinda vague. The bottom line is just make an adjustment and try it. I had one car that the light operated fine standing still but when I was traveling a hiway speed, the air would push the assembly back just enought to bind in the opening. Then they would make a big "pop" and lock. Of couse this chipped the paint on the surround. I finnaly solved it but it was a real PIA.

theoUK

They're definitely the sort of thing you need to have a go at first, aren't they?!
Reading the vague instructions deosn't really do it justice. BUT, I do think I've got them sorted now, and I've nearly finished writing up an article with some photos. You just need to know the consequences of your adjustments, and remember to do things in order. I'll post the article soon.
:cheers:

HDFLH67

While we're on the subject, mine work fine, but one doesn't close completely; sticks up about 1/8 inch. I can see the stop but can't reach it. Is there a way to get at it?

theoUK

Not sure what your year is, but on my 80, you can reach the stop screw from underneath. Its the screw that goes through the "rear link" this is the cast aluminium link, that the actuator rod is pinned to. You want to unscrew the stop screw a touch, with the headlight down, until it drops down to become flush.
:cheers:

GTR1999

The Glas-Ra volume #4 book for the C3 covers headlight rebuilding and does a good job. If the lights are bouncing all over the place when up the hinge bushings are probably gone. I removed the buckets to rebuild them and made SS hinge pins to prevent them from rust seizing in the future. The hinge bushings are nylon and were gone, I had 1/2" play in them. There are several adjustments to be made for the lights and on the 73+ you have to check the support to be sure it's not breaking away from the underside of the nose. This will cause the buckets to hang low.
Gary

ACECO

Thanks for the tips everyone. The car will be coming out of winter hibernation either this weekend or next so I will post the results after I give your suggestions a try.

Thanks again! :yesnod:

:seeya

Regards.....................George

theoUK

Gary,
What's the Glas-Ra Vol. 4 book? Must have missed that one! Wouldn't mind reading it if you can point me in the right direction.

Luckily, the bushes and pins in mine only needed a clean and grease up. What slack there was in these was then easily taken care of by adjusting the J-bar, hopefully the same can be said Aceco's....

HDFLH67

Corvette repair manuals:

ttp://www.glas-ra.com/v1.html

theoUK

Ah, the body repair manuals - yes, seen them advertised before but didn't recognise the Glas-Ra name. As a matter of fact I want to replace my front bumper at some time, and was thinking of getting hold of a copy. Add it to the christmas list....
:cheers:

Corvette ED

The ears on the housing where they mount to the body break off. They are white metal and break. This will cause your lights to bounce up and down because it is no longer attached to the body.

theoUK

Oh yeah, forgot to mention... part of the problem with mine was that the nose reinforcement bar (not sure which years prior to 80 -82 have this design) had come loose at one end. The front of the headight support bolts to this. Unfortunately it was a headlight removal job to make enough space to re-rivet it. :cheers: