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Thread: HIR backup lights??

  1. #1

    Default HIR backup lights??

    I was wondering what the more informed among us think about this HIR backup light modification:


    It involves using landscaping HIR lights in place of regular 921s. Safe? Effective? Legal?

  2. #2

    Default Re: HIR backup lights??

    Well, it's certainly clever! I don't know if the bi-pin bulb will be securely held in the sockets designed for wedge-base bulbs after some vehicle shake/shock over rough roads or trails, but the worst that will happen there is the bulb will fall out of the socket and roll around in the lamp. The measured temperature increase is significant, so that might be a concern with prolonged operation of the reversing lamps, but most people use the reversing lamps for less than 60 seconds at a time. A circuit designed for 21w bulbs might not be entirely happy with a 67% overload on it, but again, it's not used for long periods of time. They appear to get reasonably good light distribution out of the modded reversing lamps, but they're a traditional optic. Because the filament is a different shape and position in the HIR capsule they're using versus the 921 bulb they took out, this mod might not work as well in newer types of optics with precision reflectors that are focused for a specific filament orientation, shape, and size.

    I would like to try these, but my car uses 7440 for the reversing lamps, not 921, and I don't think the bi-pins will bend in a way that would allow it to work.

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