H7 vs. H3 lights

[FJRocket]

Believe it or not, I don't know if the H4 and H7 have the same base, I.E. are interchangeable in the same lens. I figure that they aren't. But I thought I should ask.

I'm trying to find some reflectors that are pretty small and rectangular. Hella FF75 driving lights are about the size I'm shooting for. However, they take the H7. I want to put H4's in there (the old Bixenon HID's). If they are compatible, well, that's great. If not, then can the base be changed or an adapter made to put the H4's in the H7 receptical?

 

[Ignacio]

I think you're SOL. I'm having a hard time finding a big chart, but this little graphic leads me to believe besides being different bases...you've got other dimensions (like focal length of the filament) to worry about. Doubtful it would be cost effective to pursue the rebasing route.

....now that I know a chart exists...maybe I can find a bigger version of it somewhere.

Also, be aware that Warchild and I tried a similar thing with H7 correctly based HID bulbs in a set of Hella FF50. He reported that the light pattern was really bad compared to an H7 Halogen.

And I'm going to assume we're talking about adding on lights to an FJR. That's not at all off-topic. Moving to Parts and Accessories.

UPDATE: It seems to get more and more complicated. Bases of H4's come in P43T and P45T.....but can't find where H7's base has any variations. Interesting stuff, but hard to find definitive answers.

 

[Warchild]

The two bulbs have absolutely different bases. They are not even close.

The H7 base is considerable smaller.

The focal points between the two bulbs are also significantly different.

Recommend you seek another approach....

 

[FJRocket]

Thanks Gents. Now I know I'm REALLY talking apples and oranges. Bummer.

And I'm going to assume we're talking about adding on lights to an FJR. That's not at all off-topic. smile.gif Moving to Parts and Accessories.

No actually I'm trying to use the Bi-Xenons removed from my FJR as landing lights in my kit plane (which is why it was in other discussions). The wing's leading edge is so narrow, about the only thing I can wedge in there is a reflector like the FF75. Haven't found anything near small enough to accept a "dual filament" H4, let alone an H3. The FF75 comes with the H7.

OK, maybe I'll just wedge the HID's back into my '04 and go with the FF75's with the stock H7 as landing lights.