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Thread: Quad Tail Light DIY

  1. #1
    Join Date
    Oct 2004
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    Quad Tail Light DIY

    I've had people ask how I got quad taillights a few so here are some pics of my setup. The stock US light housing after 1980 has an empty bulb housing, all you have to do is install a socket and wire it up. I had an extra set of tail light housings so I pulled bulb sockets and reflectors out and installed them into the empty hole in the stock US housing. Removing and installing the reflector was as simple as gently bending the tabs out to and back in to lock it in place.




    Since most people won't have extra reflectors and sockets lying around, you can use aluminum foil held in with spray adhesive as a reflector and buy standard bulb sockets from any autoparts store. This can be glued in similar to how I did my euro turns signal housings:



    To wire the extra bulb up I clipped the green power wire, twisted it together and crimped a spade connector on, then ran another wire from there to the new socket. For the ground I followed the factory method by stripping the insulation off just over the ground tab and soldering it to the ground tab.





    Last edited by jrcook320; 01-14-2009 at 04:10 PM.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  2. #2
    Join Date
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    Cool good write up! Jason (jbob) did this a long time ago as well

    I just want to add that the Euro taillights already have this connection as it is a rear for light. All you need to do is switch the wire to the existing brake light and add a bulb to the passenger side. I was able to buy 2 sets of 323i tail light housings on eBay for $15 so it was cheaper to do it this way.

    Love my quad lights!

  3. #3
    Join Date
    May 2006
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    83 320i (M20 Powa)
    this was one of the first things i did on my car since it was free and quite simple. i love the look

  4. #4
    Join Date
    Aug 2007
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    South Bend IN
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    '86 IROC, '89 GTA
    Josh, how many seconds did this mod take off your lap times? haha I kid. Looks great, nice writeup, you should quite Fedmo and be an automotive journalist.
    '86 IROC-Z Camaro 383/TKO600/C4 IRS

  5. #5
    Join Date
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    e21 340i
    haha i always wondered why you had a pic of yourself braking in the bit below all your posts. now i see why. cool, i love cheap mods like this.


    i was going to mod my taillamps but changed my mind and went a bit further and did this...


    haha not everybody's cup of tea, but it certainly looks different
    there is one led array on each side, which does the tail lights (half illuminated), indicators, and stop lights (full illumination). the wiring for it was a nightmare, but i sorted it out and the electrical system i designed works perfectly.
    ps. i dont have reversing lights, which is fine in nz for certified cars.
    also, i've installed leds on the underside of the trunk lid, which illuminate the number plate, but cant be seen.
    Last edited by 340i; 01-14-2009 at 10:19 PM.

  6. #6
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    Quote Originally Posted by 340i View Post
    haha i always wondered why you had a pic of yourself braking in the bit below all your posts. now i see why.
    That was mostly cause I like the pic, background, stance of the car and it shows off the duals...

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  7. #7
    Join Date
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    1975 BMW 2002
    Quote Originally Posted by 340i View Post
    haha i always wondered why you had a pic of yourself braking in the bit below all your posts. now i see why. cool, i love cheap mods like this.


    i was going to mod my taillamps but changed my mind and went a bit further and did this...

    haha not everybody's cup of tea, but it certainly looks different
    there is one led array on each side, which does the tail lights (half illuminated), indicators, and stop lights (full illumination). the wiring for it was a nightmare, but i sorted it out and the electrical system i designed works perfectly.
    ps. i dont have reversing lights, which is fine in nz for certified cars.
    also, i've installed leds on the underside of the trunk lid, which illuminate the number plate, but cant be seen.
    You need to put a build thread on here for that 1uzfe. After putting one in a miata I have tons of respect for that engine.

  8. #8
    Join Date
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    already got a build thread over on bmwe21.net/forum, and dont really want to do another at the moment. maybe one day ill copy it and edit out the crap, then post it up here.

  9. #9
    Join Date
    Jun 2005
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    Penland, NC
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    e21 e36

    Brightening the Bulb Reflectors

    As Josh said, when you are using OEM bulb sockets for the quad brake light mod, you can also bring over the removable reflectors from the donor tail light housing. If the reflectors have lost their shine, you can add the step of painting them with high sheen metallic paint that will improve the brightness of the brake lights and the turn signals.

    Here's how one of the completely revamped housings looks after I added the extra brake light and repainted all of the removable reflectors:



    The process is a straightforward remove, paint, and reinstall:

    Remove the brake light bulb reflectors from the donor tail light housings along with the two reflectors that come in each of the stock USA housings you are going to modify. Straighten out the two thin tabs holding each reflector in place on the backside to let the reflectors pop out of their compartments. I found that a sharp chisel works better than a flat blade screwdriver to bend the tabs.




    The reflectors are made of plain steel that was painted at the factory, but they are probably corroded after 30+ years and may be dull and rough textured. Those corrosion bumps diffuse the light and reduce overall brightness.




    Smooth them with 220 grit sandpaper, then clean them with a mild solvent to get rid of the dust.




    Spray a coat of generic primer to provide a good foundation and improve adhesion of the topcoat.
    Let the primer dry completely (about 15 minutes).




    Follow that with highly reflective silver metallic paint, applying it sparingly to avoid runs and puddling. Hold the can at least 10 inches away and apply two mist coats, about 10 minutes apart. Let them dry at least 8 hours before you handle them. The newly painted surface is easily marred by fingerprints or scratches even after it's completely dry.



    The retaining tabs are very thin and difficult to reset completely, so I used hot glue in addition to bending the tabs when reinstalling them.

    While you're at it, lightly sand and spray the copper bulb contacts with a cleaner like Deoxit to be sure that they will keep working for a long time. You could use dielectric grease instead, but this stuff chemically cleans the surfaces and lasts longer (works well on grounds and in the fuse box too).



    Also, while you've got everything apart, it's a good idea to treat the rubber tail light gaskets with a rubber protectant to keep them supple and sealing out moisture in this rust prone area.

    As an alternative, I suppose you could just install the two additional reflectors, sand and clean the rough areas with everything in place, then prime and paint. The drawback would be masking or removing the bulb sockets and wiring. Either way, you'll end up with brighter lights that look better and are safer.

  10. #10
    Join Date
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    raising the bar, I would expect nothing less! did the bulbs make it in one piece?
    Tom D

    77 e21 - m42
    88 e30m3
    04 330 dinan3
    84 r1000rt
    02 r1150rs
    all of them gray
    14 f800gsa - red headed stepchild!

  11. #11
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    Absolutely!
    And of course, they were perfect in every way, ready to use for the quad brake light upgrade: wires clipped to maximum length, reflectors and bulbs included, all mounting tabs intact.

    Some background info: I put out a request for parts needed for this project and Tom picked up everything I needed on his next trip to the Pick 'N Pull. I recommend staying on this guy's good side, which fortunately is easy to do. Thanks again Tom.

  12. #12
    Join Date
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    1981 320i
    I have a spare set of lights and about to do the mod. I was wondering about brake lights fuse- when adding another 2 bulbs to the circuit, wouldn't it overload the circuit and blow a fuse? Or damage the wiring/fusebox? Do you leave the same fuse or change it to something like 25A? (I believe stock rating for brake lights is 16A). Bigger fuse=possible damaged wiring?

    Thanks,
    Max

  13. #13
    Join Date
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    my 77 uses fuse #12 for the brake lights, radio and horn, the fuse is rated at 8amps. lets say you use a 21 watt bulb times 4 or 84 total brake light wattage. at 12.6 volts the load is 6.7 amps. as far as the radio and horn I would have to measure thier actual load, but I'm sure I'm still more then covered. the radio I never use and the horn is only used after evasive braking when I presenting them with the much deserved bird.

    if you wanted you could use the existing circuit to trigger a relay and run a new dedicated 8A circuit to handle the brakes.
    Last edited by Tom D; 07-24-2013 at 07:34 PM.
    Tom D

    77 e21 - m42
    88 e30m3
    04 330 dinan3
    84 r1000rt
    02 r1150rs
    all of them gray
    14 f800gsa - red headed stepchild!

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