Does vent above rear windscreen communicate with interior? 3rd brake light?

DaveMcKenz · 10:14 AM

Hi guys,
I was considering various ways of rigging a 3rd brake light for my 84. One suggestion was to put an exterior LED strip in the vent above the rear windscreen. I see the exterior slots, but no sign of them leading anywhere. Has anyone done this or could you tell me if I can run a wire from inside to the rear vents?
Thanks,
Dave

wwest · wwest's Garage

I used a 3rd/middle brake light assembly from an '88 series, ran wire from rear brake to the new light. vague memory is I used the rear defrost wire grommet.

Otter74 · 12-07-2015, 09:23 AM

I believe these are cabin vents to relieve air pressure inside the cabin.

DaveMcKenz · 12-07-2015, 09:23 AM

Yes thanks. The defrost grommet is one way from the engine compartment to the interior. I was considering the roof vents for a more stealth appearance. I am looking for a place to probe for passing a wire from these vents.
Dave

DaveMcKenz · 12-07-2015, 09:38 AM

Success!! I unzipped my sunroof access and put a light in there. From the outside I found a crack of light at the very top of the vents. I was able to get a 16" zip tie through there. If I go this route, I will be able to pull a wire to that location.
Thanks,
Dave

DaveMcKenz · 12-07-2015, 10:17 AM

I have seen others do this 3rd brake light in the past, and I think it it the least invasive, most subtle option. I have ordered a waterproof light strip with 5630 SMD LED's:
http://www.amazon.com/gp/product/B0145YY71Y?keywords=5630%20led%20strip&qid=1449514731&ref_=sr_1_15&sr=8-15
I think I can now connect this through the roof lining to the engine compartment where the brake light harness is located. When I get the light strip, I can get close to 25" of bright LED brake lighting above my rear window. I will post some pics as I get this done.
Thanks,
Dave

ganun · ganun's Garage

Cool idea Dave, while the 3rd brake light in the top is very bright and visible to those following its also right in line with the rear view mirror, kinda of annoying, but I wanna be seen. Something else.......
This was interesting, with a quiet garage and doors closed, when I slammed shut the cars door, the garage door would make a noise. WHAAAT????? The air rushing out those roof vents would push on the garage door. OF course only with the car sealed up, ie windows up, vents closed, where you have to push to get the doors to close.

wwest · wwest's Garage

Quote:

Originally Posted by ganun

Cool idea Dave, while the 3rd brake light in the top is very bright and visible to those following its also right in line with the rear view mirror, kinda of annoying, but I wanna be seen. Something else.......
This was interesting, with a quiet garage and doors closed, when I slammed shut the cars door, the garage door would make a noise. WHAAAT????? The air rushing out those roof vents would push on the garage door. OF course only with the car sealed up, ie windows up, vents closed, where you have to push to get the doors to close.

Also what damages, long term, the door mounted speaker(s), driver door speaker most often first.

Quicksilver · 11:50 AM

Yes you can do it but you either need a sunroof so you can open the zipper in the headliner or you will have to pull the headliner. I got this setup installed the week before this year's Targa Baja.

--------------------------------
Here is my first attempt in 2002 which used normal loose LEDs pushed through rubber grommets. The narrow beam meant that they were pretty much invisible unless you were low and a couple feet from the rear of the car. (This is because the rear vent surface is angled downwards.)

I put the grommets in place, inserted the LEDs, soldered them together using the grommets as a jig, and then insulated the mess. I then popped the LEDs out put the string of them inside and managed to pull the LEDs in from the rear. Looked good but was worthless from usable light output.

Oh BTW, the install is pretty much invisible until the lights come on.

DaveMcKenz · 12-07-2015, 12:15 PM

Very cool, Wayne. I am hopeful that the newer high output 5630 LED's will be an improvement.
I think I may have got the idea from you in some old posts.
Thanks,
Dave

wwest · wwest's Garage

The LED bulb (1156?) (EBAY) I found to put in the '88 fixture is seriously...

BRIGHT

Also used the device from Super Bright LEDs to flash the LED on and off rapidly upon initial brake application.

Not recommending SBL for ANY other part source.

Quicksilver · 12-07-2015, 08:23 PM

DaveMcKenz - A 5630 is a good choice but the problem is it isn't side emitting so either the tape will need to bend (won't really work) and it will block the vents (bad idea).
You could set up some way to mount them on their side but I think they rely on being surface mounted to act as a heat sink.

With the rate of development in LEDs I would suspect that someone will come up with a side emitter that is more powerful then a 335 pretty soon.

Sicklyscott · 12-08-2015, 04:53 AM

Wayne - how did you attach the lights to stay put? What lights did you use?

DaveMcKenz · 12-08-2015, 04:57 AM

Hi Wayne,
I am planning on using just the central 12-16" of the vents. I will fabricate a slightly curved aluminum sheet and attach the LED strip to that. We'll see how the details develop.
Thanks
Dave

Sicklyscott · 02-02-2016, 09:18 AM

Any updates to this?

DaveMcKenz · 02-02-2016, 11:28 AM

Updates. Yes and no. I went with an 8" waterproof LED strip. The roofline has a gentle cuve, and the shorter strip looks o.k.. My car is up on a lift for storage now, so I will finish the installation in a couple of months. Pictures then.
Thanks
Dave

DaveMcKenz · 11:46 AM

Hi Guys,
The Spring weather is finally here and I had time to finish this up. I bought a sealed LED strip:
Amazon.com: Chrome Glow 4200-60RR LED Flexible Array Motorcycle Auxiliary Running and Brake Light Bar with Red Lens 8 Inches: Automotive
I fished the wires through the vent openings above the rear window, aided by opening the zipper for the sunroof motor access. I wired the strip in place, then ran the wires from the black/yellow at the brake light connector by way of the defroster grommet. It's pretty stealth until the brakes go on.

Thanks,
Dave

DaveMcKenz · 04-18-2016, 11:48 AM

Here's a picture with the lights on. The strip is bright.

Thanks,
Dave

Steve W · Steve W's Garage

I modified the LED 3rd brake light from a 2015 981 Cayman which fits high and tight across the upper edge of the rear window with a 26" beam spread like on a Tesla. On my 86 coupe, I didn't like the stock rear brake light placement because it blocked the primary view of the traffic when looking through the rear view mirror. With the Cayman light, I had to modify the light to fit a little, and I also cut a shadow mask out of black vinyl with a vinyl cutter, which went on the inside of the window between the window and the LED strip for a clean finish:

DaveMcKenz · 04-18-2016, 01:52 PM

Very cool Steve. I did not want to look quite so modern, but your light looks fantastic.
Dave