Upon installation of my 9006 hid kit into my 1-piece headlights, I decided to dremel the 9006 bulb base to fit into the H4H housing (rather than dremeling the H4H housing which takes 10 times longer). This mod is easy and just took a few minutes to do with a dremel, and is great for those who wish to install 9006 HID kits into their 1-piecers. THE RESULT IS A PERFECT FIT!
WARNING! Do this at your own risk! Keep in mind that you most likely will not be able to return the bulbs after tampering!
(For those who do not know, USDM headlamps use 9006 bulbs and JDM headlamps use H4H bulbs. The differences are that the USDMs have seperate high beams and low beams, where as the JDMs have H3 fog lights where the USDM high beams would be and they use JDM H4H bulbs which contain dual filaments for the purpose of low and high beams in one bulb. And by doing this mod you are replacing the H4H dual filament bulb with a 9006 bulb, losing the high beams, no big deal bcuz 9006 HIDs are bright enough in my opinion)
The 9006 base is the same circular size as the H4H base, but the difference on the 9006 bulb base is that two out of three of the 'legs' are not in the exact positions as the H4H bulb base, plus there is not an 'indent' on that one side needed for fitment.
So we must dremel the two 'legs' that do not fit, trimming it and leaving just a tip of the 'legs' left so that the bulb doesnt fall thru; plus we need to carve an indent on the one side of the base where the H4H housing has a bump there requiring the indent (there is only one bump in the H4H housing even tho the H4H bulb has two indents, as shown in the pics below)
easy as 1-2-3...
1. Observe both 9006 and H4H bulbs and identify the differences, notice where to trim!
2. Wrap the bulb with plastic wrap and a rubber band, then use your dremel to trim away!
3. Clean up and go install your newly modified 9006 bulbs into your 1-piece H4H housings!
(If the bulb base still doesnt fit perfectly then identify the spot where you must trim some more)
Here are some sample images to make it clear and simple...
Pic of 9006 bulb AFTER DREMELING:
[notice the trimmed indent and how much of the 'legs' i left (just enough so the bulb doesnt fall thru and that it clears the walls for fitment)]
Pic of H4H JDM(/VDM) 1-piece housing
Pic of a perfect fit:
Dremel tool i used:
(the gas pocket in the 9006 hid bulb lines up with the filament in the H4H bulb, so the beam pattern was about exactly the same before and after)
enjoy ur lights and GOOD LUCK!