G's headlight mod - RHD shield mod & Clear Lens swap

Discussion in 'Gen 3 Prius Accessories and Modifications' started by shaotai, Aug 26, 2015.

  1. shaotai

    shaotai Member

    Aug 8, 2014
    Seattle, WA
    2013 Prius
    Hey all,
    Finally got around to taking some pics and putting together these directions on modifying your RHD headlights (Prius G's in this example) to LHD. I will also show you how to paint the shield and swap in clear lenses to help sharpen the output.
    As you are probably aware, the slope in the HID projector shield in RHD cars is designed to output light to be higher on the left side and lower on the right. This ends up blinding oncoming traffic in the US. These directions will show you how to modify the projector shields to output the light completely flat to prevent blinding oncoming traffic. Alternatively, you could further modify the shield to make it output light higher on the right side in OEM fashion for LHD cars.

    1 can of spray paint (your color choice but this is optional)
    1 set of clear lenses (TRS STi-R 3", again optional)
    JB Weld
    Masking tape

    Kitchen oven heated to ~250F (size to fit a headlight)
    Cut sheet of plywood or oven tray to hold headlight in oven.
    Flat blade screw drivers (various sizes)
    Philips screw drivers (various sizes)
    Dremel or other rotary tool
    Flat file of various sizes.

    1. Disassemble and remove as many of the parts off the headlights. Bulbs, HID ballasts, and any covers. This also includes about six screws that hold the headlight lens in place.

    2. Using a flat board or oven tray, place headlights in the center of the oven, verifying that it is not touching the sides.

    3. Bake headlights for about 10mins. Remove headlight assembly and start prying the lense off using the flat screw drivers. You might need to repeat the baking step a number of times as the adhesive cools. (Same directions as other headlight lens removal posts if you need more details) Should eventually look like this:

    4. Pop the projector and framing out by using a screwdriver and looking for the locking clips on the three mounts. Push clips inward on the three mounts and the housing will come right out. (2 clips per mount) (Circled in red below)

    5. Once the projector and frame are out, flip it over to remove the three screws to separate the projector from frame. (Circled in red below)

    6. You can also remove the front lens by taking off the two screws from the front of the projector housing that holds the lens in place. (Circled in red below)
    All apart should look like this now.

    7. Notice the shield and the slope of the stock G's HID projector. The goal will be to flatten this to make it completely even across.

    8. Separate the shield/lens mount from the reflector bowl by taking out the two screws holding the two halves together. (Circled in red below)

    9. Projector housing now completely apart.

    10. Place the bowl in a safe area and now mask the back area of the shield with tape. Firmly verify that the tape is sealing the area where the shield dips.

    11. Mix up the JB Weld and generously apply in area of shield with the "dip". We will use the JB Weld as filler to raise this area up. Set aside and let it dry. (Unfortunately this will take a while)

    12. Once dried, remove the masking tape.

    13. Using rotary tool, start grinding away at JB Weld to same level of the right flat area.

    14. Keep grinding larger areas and then use the flat file to match up to the right side. Eventually, you want it to look completely flat.

    15. Now mask the whole thing up except the front part of the shield. (Like above) You can then paint this area to the color of your choice. (I chose blue) Set aside and let that dry.

    16. Once dried, pull masking tape off and verify everything looks clean and straight. Should look nice and clean all around with just the front part of the shield painted.
    Here is the back of the shield, very straight clean cut off.

    17. Start the reassembly of the projectors halves and lens. This is the original fresnel lense. Notice the bumps/dots in the lens surface. This helps diffuse the light for a softer output.

    18. Here is the TRS STi-R 3" clear lens. Notice the clarity of the lens. This helps produce a sharper light output and with proper spacing, can create a nice hue of blue light right at the cutoff of the projected light.

    19. Place modified projector back in frame. Then pop the projector assembly back into headlight housing. It will snap in place at the three mount points. Place headlight lens cover on the headlight assembly, heat the oven to 250F again and bake for 10mins. Reassemble the rest of the headlight parts. Once installed, it should look like this!

    Although I don't have any output shots yet, the cut off is very sharp with a tinge of color. It is also flat all across and rises slightly to the right, which is perfect for US roads.
    Painting the front of the projector shroud doesn't affect the output of the actual light. It only makes the inside of the projector visible with the color you paint it. Also, only at certain angles is the color of the projector visible, otherwise, it just looks normal. A very nice subtle mod!

    To simplify the modification of the RHD shield, it looks like the Lexus IS350 Bi-Xenon HID project is very similar to the projector used in the G's headlight. (Koito D4S) It is still missing some of the mount points to the frame, but maybe very possible to swap in with slight modification. This will help save some time and the IS350 projectors can be purchased for cheap!

    Hope you find this helpful! Let me know if you have any questions.
    #1 shaotai, Aug 26, 2015
    Last edited: Aug 27, 2015
    RightOnTime, ePrius, AKWSF and 7 others like this.
  2. Dylan Doxey

    Dylan Doxey Senior Member

    Mar 15, 2013
    San Diego, CA
    2014 Prius
    Brilliant write up! I have been curious about the anatomy of these lights and just what exactly I need to do to fix the stair-stepped cutoff.

    Question : Have you seen JB Weld used in an HID projector cutoff plate before? Is it known to be able to hold up to the heat punishment in the long term?

    Also, would it be equally viable to grind down the high side, as opposed to adding material on the low side?

    You mentioned setting the shields aside to dry. I've read in other places that you need to bake painted components dry to ensure there won't be any further outgassing after you've reassembled the light.

    Thanks for taking the time to document this.
    #2 Dylan Doxey, Aug 28, 2015
    Last edited: Dec 12, 2015
  3. shaotai

    shaotai Member

    Aug 8, 2014
    Seattle, WA
    2013 Prius
    Thanks Dylan!
    Yes, the JB Weld was something I saw being done in other forums. It has a very high temp tolerance, about 500F, and seemed easy enough to shape and modify.

    As you mentioned, it could be an option to grind down the higher half of the shield, but this would be grinding and shaping metal, which might be much more difficult to keep nice and flat. Also, the dip that you fill in with JB Weld looks to be slightly lower than the focal point, so grinding down the primary area may change the effectiveness of the optics of the lense/shield positioning. It's really close though and maybe something to try!

    I haven't thought about baking the shields to let the paint cure, but maybe the short period of baking to get the headlight cover back on would help that process. It may be suggested as an additional step, and of course, dependent on the type of paint that you use.

    If we could find an exact match for the projector, that would be the best option and simplify the process great. The Lexus IS250/IS350 Bi-Xenon is very close, uses D4S bulbs and is 3". But there are slight differences, so still some modifications would be needed.

    If I get my hands on another set of G's to maybe fix up, I'll order those projectors to see if we can get them to work... :)
    Dylan Doxey likes this.
  4. xliderider

    xliderider Senior Member

    Apr 19, 2012
    Honolulu, HI
    2011 Prius
    An option to filling in the lower cutoff with JB Weld is to cut a strip of thin aluminum flashing or a soda can and use JB Weld to hold the strip to the front of the cutoff shield with the top edge of the aluminum strip placed evenly against the high edge of the cutoff shield.

    Yes, still using JB Weld, but not relying on only JB Weld to block the light under elevated heat conditions. The JB Weld is only used as a bonding agent, and possibly a filler of small gaps between the aluminum strip and the metal shield.

    Edit: NVM, I see that neither the front or rear surfaces of the G's cutoff shield is flat. Placing a strip of aluminum would be pretty difficult.
    #4 xliderider, Aug 28, 2015
    Last edited: Aug 28, 2015
  5. rrg

    rrg Active Member

    May 18, 2010
    East coast - NJ
    2011 Prius
    Looking for night time pictures?
    Dylan Doxey likes this.