944 Cowl 3rd Brake, Anyone using this fixture? Options

[Spoke]

A 914/944 owner asked if I could add LEDs to the 944 cowl 3rd brake fixture. He said this same fixture is also used on some Corvettes. Anyone use this on their 914?





For such a nice exterior, the bulbs are crappy push-in bulbs with even worse sockets. As always, I'm looking for a way to connect wires to this fixture w/o cutting, gluing, splicing. I could solder steel piano wire to the pigtails and plug in to the existing sockets but Steve doesn't think that will work well. There's 2 grommets to this fixture, one to the sealed lens and one to seal through the cowl.




There's almost enough room to get a 5mm LED on a board between the reflector and lens. You can see the edge of the reflector is curved. The LEDs don't fit at the top and bottom so the boards will have a cutout there for relief and for securing the boards.

The length is 11 inches so I'll make the board span the entire interior of the lens. I'm thinking 36 LEDs which will be quite bright.

[Steve]

I'm using this setup as well as others. One of my lights is intermittent.

[Root_Werks]

Would this be mounted on the targa bar behind the rear window?

[andys]

Corvette.....Forgot what year, maybe late 80's?

Andys

[Spoke]

@Andys

Corvette.....Forgot what year, maybe late 80's?

Andys

What lights do you have in in?

[Spoke]

Not a 3rd brake light but something I designed last week. Not sure how it would look. Basically just an outline of LEDs. Many new vehicles use the LEDs in a pattern of some sort. Why not the 914?



Trying out the new light.



Looks interesting with a round turnsignal and an outline brake.

[mepstein]

I’m not a fan of the outline. Looks too modern to me.

[Spoke]

I'm contimplating using surface mount LEDs for this board but the board is too large to fit into my IR oven. I'll have to print this out to see how it fits in the enclosure.




Getting this arc of the board to follow the curve of the fixture was not trivial. First I had to determine the the amount of arc over the length of the fixture. I measured 85mil arc over the length of 12.5 inches of the lens. Using trig I calculated the radius of the curve of the fixture to be 229 inches.

I could have used an arc of 229 inches in Altium for the board outline but the maximum PCB workspace is like 10 x 10 feet. 229 inches is just over 19 feet and I couldn't get the arc to work. So I ended up using small sections of straight lines to make the arc.

[Spoke]

Printed the board and placed it in the fixture. I got the curvature right but the board is too tall. It fits between the reflectors and the lens but the lens needs to be pushed out a bit to fit the board+LEDs.



The reflector hugs close to the exterior and you can see the indentation the lens makes to the sealing gasket. Notice too the extruding braces. These might contact the board when assembled. I think I'll have to leave a relief in the board to accommodate these ridges.

[Geezer914]

I purchased one off eBay a few years back for $25. 86-95 Corvette. Tapped into the tail light wires running under the relay board. Used quick connects so I could remove the engine lid if needed. Mine has a one piece gasket that covers the entire bottom of the light except for the 2 mounting holes and 1 for the wires.

[Geezer914]

Corvette.....Forgot what year, maybe late 80's?

Andys

86-90 Corvette, and 90-95 ZR-1. 86-90 had 3 bulbs, 90-95 had 4 bulbs.

[andys]

@Andys

Corvette.....Forgot what year, maybe late 80's?

Andys

What lights do you have in in?

Whatever came with it. Geezer914 seems to know.

Andys

[Geezer914]

The bulbs are 891. Super Bright LED bulbs sells a G4 LED bulb for 3.99. 180 lumens vs 145 for the 891 bulb.

[Spoke]

The bulbs are 891. Super Bright LED bulbs sells a G4 LED bulb for 3.99. 180 lumens vs 145 for the 891 bulb.

@Geezer914

Is this the G4 LED you're referring to?

G4 Bi-Pin LED Light Bulb - 20W Equivalent - 180 Lumens - 12V - Dimmable

If so, did you do the warm, natural, or cool version? I'd like to purchase a few to test them out.

If these are not the ones you used, please point out which one you used.

Thanks,
Spoke

[Spoke]

Decided to take another route on the boards. Instead of one 11 inch long board, I'll do 2 smaller 5.25 inch boards. The boards can now fit in the IR oven so I'll do surface mount high power LEDs with focusing lenses.

[Spoke]

Boards are in.



Designed some clips to hold the boards in the fixture.



Seem to fit well. The boards + clips drop right in.



The first boards have been populated. So glad I went with 2 small boards instead of one long board. These fit into the IR oven and makes assembly much easier. Waiting on the lenses for the LEDs. The Carclo 10415 lenses are as expensive as the LEDs.

The connectors will be interesting. The easiest method would be to solder some piano wire of the correct gauge onto the wires then push them into the existing sockets. Steve who was the catalyst for the project does not want to use the existing bulb sockets because of oxidation/corrosion but I'm not a fan of cutting/splicing or any way damaging the fixture.

If someone would like to try these out, please contact me. I'm giving Steve a set and someone else to try. No charge; I just ask that you report back how they fit and work.

[Steve]

Boards are in.



Designed some clips to hold the boards in the fixture.



Seem to fit well. The boards + clips drop right in.



The first boards have been populated. So glad I went with 2 small boards instead of one long board. These fit into the IR oven and makes assembly much easier. Waiting on the lenses for the LEDs. The Carclo 10415 lenses are as expensive as the LEDs.

The connectors will be interesting. The easiest method would be to solder some piano wire of the correct gauge onto the wires then push them into the existing sockets. Steve who was the catalyst for the project does not want to use the existing bulb sockets because of oxidation/corrosion but I'm not a fan of cutting/splicing or any way damaging the fixture.

If someone would like to try these out, please contact me. I'm giving Steve a set and someone else to try. No charge; I just ask that you report back how they fit and work.

Are you referring to me? Otherwise, I would also be glad to try it out.
-Steve

[Spoke]

Are you referring to me? Otherwise, I would also be glad to try it out.
-Steve

@Steve

If you're not the Steve I've been working with and sent me the fixture, then yes, I'd be glad to send you a set. Please PM your contact info. It will probably be a week or 2 before I get these out the door.

[burton73]

Would this be mounted on the targa bar behind the rear window?

I had PMB put this one in for me. Does not mess with my view and it is as high as it can go

Bob B

[Steve]

Are you referring to me? Otherwise, I would also be glad to try it out.
-Steve

@Steve

If you're not the Steve I've been working with and sent me the fixture, then yes, I'd be glad to send you a set. Please PM your contact info. It will probably be a week or 2 before I get these out the door.

PM sent