Molding headlight covers - problems with moisture?

[zeeboost]

I'm planning on molding in some headlight covers on my '82 280zx. I vaguely remember talking to my bodyshop about this a few months ago, but it's not bondo they would be using - it's some sort of flexible filler. I don't remember exactly. But anyways, I'm going after a smooth, flush finish, and won't be using the weatherstripping that comes with the covers. So now, my main concern is if I'm going to have any problems with moisture collecting on the inside of the headlight cover due to temperature changes, rainy conditions, etc. I don't know if there are any types of preliminary measures that should be taken before these get molded on. If anyone can share any insight on this, please chime in. Thanks

[Challenger]

Wouldnt some sort of vent fix any issues? A vent somewhere not obvious.

[zeeboost]

I'm not sure - I thought about using a small rubber hose that was hidden in a lower corner, but I don't know if that would help/hinder anything.

[ZR8ED]

You could drill a small hole in the bottom of the headlight bucket to give water a place to drain, and air to get in there to dry it out. Then all you have to do is remove the headlight to get in there and clean once in a while.

 

Just a thought.

Scott.

[zeeboost]

Then all you have to do is remove the headlight to get in there and clean once in a while.

 

Just a thought.

Scott.

 

I've been keeping this project pretty hush-hush for now, but I may not be able to remove the headlights once I'm finished. If I can, it won't be an easy task at all. It's not going to have the original 7" headlights, basically. How do other cars get away with this? Are they completely sealed, not having a drain tube or anything?

 

Some examples of the headlight cover finish I'm going after:

 

Ferrari 360

 

 

Ferrari f50

 

 

Aston Martin:

[Avernier]

^ All of the above are three piece designs with industrial strength rubber based adhesive. You have to bake those headlights at 250-275* for about 7 minutes to open them. They are fully sealed. The clear part fits into a v shaped groove thats filled with the adhesive. Once you press the clear part into the groove at room temperature (the adhesive is fairly pliable at room temp.), bake it for about 7 minutes at 250, then press it all the way together and clamp it with "C" clamps or vice grips until it cools. now it is fully sealed from the elements. if you want to recreate that, you need to make a housing that the cover can fit into to seal.

[zeeboost]

What if I mold the headlight cover on and seal off the headlights using a rubber gasket of some sort? If I bond the covers to the bucket, and use a body filler to smooth the transition from the bucket to the cover, this should create an air-tight seal, correct? Thus, leaving the moisture's only area of entry to be the gap between the headlights and the bucket? So basically, if I completely seal this off, I won't have to worry about trapping moisture inside and running a vent tube, correct?

 

edit:

 

Also, I don't mind if I need to run a concealed drain tube for moisture, but only if it will keep the headlight covers from fogging up. If I'm still going to have those issues, I might as well go through the trouble of sealing it all off (again, if that will keep the moisture from collecting on the inside).

[cygnusx1]

A completely sealed module or well ventilated will work. Well ventilated will probably get dirty and require internal cleaning regularly. Sealed (airtight) will be more difficult but will not get dirty or foggy as long as there is little or no moisture in it the air when it's sealed. Partially vented with a small hole will probably get enough moisture in it from daily temp swings to cause internal fogging.

[Avernier]

What if you make a groove in the body around where the cover meets the body, that way you can just use a heat gun to attach the cover directly to the body.

 

I'm making a fiberglass housing built around an infinity q45 projector that bolts into the stock mounting bucket, and has the cover fitted to it. The whole unit slides into the hole and blots to the bucket..

[zeeboost]

Cygnus - Thanks, it looks like I get to figure out the best way to seal this beast.

 

Avernier - I'm painting part of the headlight cover to make it look like part of the car, hence why I'm wanting to mold the covers and flush any gaps.

 

Even though I love this car (minus the stripes someone drew on it...?), I do not want to be able to see the shape/outline of the covers through the paint:

 

 

...but to make it look like one with the body, such as Darius did:

 

[cygnusx1]

There are some hot rods that I have seen that have tail lights that look like they are behind the paint. In other words, there are no seams or pockets, the paint is continuous right over the light and the lights shine through the clearcoat. I am not sure how it's done or what it's called. Anyone?

 

I think that's what you want to pull off here. Just like Darius's car but the headlight corners are clear, but look like they are seamless, flush with the paint, with zero trace lines.

 

Here is a somewhat poor example:

 

[kiwi303]

what you can do is fit the small drain pipe in a concealed area, and glue some copper piping to the underside of the headlight buckets and link that into the water system. the hot water through the copper piping will heat up the bucket interiors and drive out any condensation.

[Guest Gr8White]

A completely sealed module or well ventilated will work. Well ventilated will probably get dirty and require internal cleaning regularly. .

 

 

You could minimize the dirt, bugs, etc. by using a PVC coated reticulated open cell foam baffle glued with silicone to the underside of the vent/weep hole. If you used a weep tube you could stuff some of the baffle material into the tube and not affect how it drains, but significantly affect any infiltration of dirt/debris...It's commonly used for weep holes in custom skylights, good stuff.

[zeeboost]

You could minimize the dirt, bugs, etc. by using a PVC coated reticulated open cell foam baffle glued with silicone to the underside of the vent/weep hole.

 

There's a mouthfull - I'm guessing it operates like a check-valve? At this point, I'm still thinking my best option might be to seal it off. Kiwi - that sounds like a great way to keep the moisture out, but I think I'll see if I can completely seal it off first, and see how that goes. It's such a crazy, over-engineered way of doing the job, I like it...just not as practical

 

I was talking to the body guys about this earlier, and they're not sounding too confident on this any more. The guy doing most of the work to my car told me the best way to do it would just be by using the brackets, since it would be 100x easier to change out if something did happen to the cover, not to mention cheaper. He said that the flexible filler the owner of the shop told me about, probably wouldn't be a good idea because when it heats up (good ol' Texas heat) the plastic headlight cover would end up expanding slightly, or something like that, basically resulting in being able to see the outline of the cover. We're looking at other options, but I'm kinda bummed out. This headlight project was the main reason I took the car to this bodyshop, because the owner told me they could do it...and now I'm getting conflicting points of views. The body guy said he could do it, but couldn't guarantee anything on it

 

We'll see...

 

Cygnusx1 - do you have any other info on your seamless covers?

[zeeboost]

Well, it's starting to look like the cost is greatly out-weighing the benefit of having a flush cover, so it looks like I'll just be installing it using the brackets. Bummer...I'm not sure if I'm going to use the weatherstripping around the cover just yet.

[Dan Juday]

I saw a heavily modified S30 at an MSA show several years ago that the owner had done something like this to. It looked "O.K.". Actually it looked like a lot of work/money for just an o.k. result. It did get me thinking though.

 

I hate those brackets. Exposed screw heads and double back tape, arg!

 

So I was thinking: You could paint the clear covers about an inch or so in from the edges the same color as the car. When mounted it would look like you had smaller than normal covers. Then glue acrylic blocks to the backside, behind the painted areas, as mounts. In the blocks drill holes and glue in dowels that would fit into matching holes drilled into the headlight buckets. If you were carefull, and clever about where the mounts are located, you could get a nice tight fit without any exposed hardware. The covers could be installed and removed by squeezing them enough for the dowels on one side to clear the holes. Use some small felt pads on the mounts so any movement won't mar the paint.

[zeeboost]

I saw a heavily modified S30 at an MSA show several years ago that the owner had done something like this to. It looked "O.K.". Actually it looked like a lot of work/money for just an o.k. result. It did get me thinking though.

 

I hate those brackets. Exposed screw heads and double back tape, arg!

 

So I was thinking: You could paint the clear covers about an inch or so in from the edges the same color as the car. When mounted it would look like you had smaller than normal covers. Then glue acrylic blocks to the backside, behind the painted areas, as mounts. In the blocks drill holes and glue in dowels that would fit into matching holes drilled into the headlight buckets. If you were carefull, and clever about where the mounts are located, you could get a nice tight fit without any exposed hardware. The covers could be installed and removed by squeezing them enough for the dowels on one side to clear the holes. Use some small felt pads on the mounts so any movement won't mar the paint.

 

Dan, that's an idea and a half right there! That may be my best way to approach this. The only other potential problem I'd have is the weatherstripping around the covers. I'm sure using them would help reduce dirt/moisture/other crap from getting inside, but on the other hand, the rubber will look out of place on one section of the cover. The cover has two streamlines (for lack of better word), one on the upper portion and one on the lower portion. I was planning on painting the cover the same as the body from the lower streamline to the bottom of the cover. Pictures would probably help more than an explanation:

 

A crude rendering:

 

 

This probably is the closest resemblance of what I'm going after:

 

 

And originally I had intended on using black pan-head mounting screws, and having a black ring outline the cover (think aston martin vanquish). Another crude sketch of that:

 

 

So if I use the weatherstripping around the cover, it will look awkward where it sticks out in the painted area of the cover. I could paint the rubber the same color as the body and cover, but it would still look odd sticking out like that. I'm not sure of a better way to seal the cover and still have it removable, so I may just end up cutting the rubber out of the painted areas, and just have it seal of the rest of the bucket. I don't know how efficient it will work, but it's the best I can think of at the moment. Again, the dowel pins are an awesome idea! When you mentioned the felt pads, which paint are you saying would be damaged?

[zedevan]

if you want to go that extreme, why dont you buy two lots of the headlight covers and do the following:

 

paint one body colour - cut a whole in it so it has a small lip the whole way around it, and mould it into the bucket, so it sits completely flush

 

cut out the bottom (or entire inside face) of the headlight bucket, and turn it into a false bottom so you can remove it as required to gain access inside

 

install the other 'still clear' one from the inside - hold in place with double sided tape, tabs, dowels, whatever, lots of options

 

so effectively the clear area is recessed the thickness of the outter cover. the seal is not important as the bottom can have small gaps/holes at the edges where you can't really see it?

 

my small experiance trying to completely water seal bits on my zed's headlights highlighted just how much water gets thrown on the area from the wheels so if you are going the completely sealed way make sure its sealed at the back too - and dont forget to put some silica gel packets in there to absorb any moisture which will get heated by the globes and cause condensation on the inside (possibly not that large an issue with the air volume and temp difference?)

[zeeboost]

Sounds like a good idea, but the headlight bucket is already molded to the fender, and the front bumper is molded to the headlight bucket, so it's not too feasible right now. At this point, I don't think I'll be going the sealed route - I'll just have the covers removable so I can clean the gunk out of the buckets. Hence, why I'm trying to figure out what I should do with the headlight cover weatherstripping.

[Dan Juday]

 

When you mentioned the felt pads, which paint are you saying would be damaged?

 

In my plan I wouldn't use the weather striping at all. Just sand a nice clean edge on the acrylic cover before it's painted. The felt pads would go on the mounting blocks, between them and the painted bucket. Since the cover would not be fastened with screws it would probably move around slightly even if every thing was fabricated to tight tolerances. Thermal expansion, wind, and vibration while driving. This movement of the mounting blocks, even slightly, may mar the paint on the bucket.

 

Without the weather strip you would get more dirt and grime under the cover. But with dowels at least the covers would be easy to remove for cleaning.

 

BTW, I really like the look of that rendering.