Quick question on H4 vs H5 on fiberglass fenders..

[rattlsnak]

Quick question, I'm looking to get some H5s to mount in early style fiberglass fenders (GT racing style) but have been told I have to use H4s by a few people as most, if not all, fiberglass fenders dont have the four threaded mounting points inside the bucket to mount H5s, or any style SC/Carrera type headlights. I know the H4s are held on by the one trim ring screw at the bottom. I dont have them in front of me so the question arose.

Anyone for sure?

[TRE Cup]

H1 and H 4 euro lamps are indeed held in place at the top of each h/l bucket by the flange there. And at the bottom by the threaded plate.

H-5 and usa lamps 1968-1994, have 4 threaded tabs in the roughly 1,4,7, and 10 o'clock positions.
With either set up you have problems using the fiberglass buckets to mount your lamps. The issues are having a strong enough part of the 'glass to support the metal flanges installed on them. It may be nice and tight today, but some time from now, dismount/mount, and road vibration may loosen the metal tabs. This results in the "oh S**T!" moment when you hit the brakes hard coming to a stop; your expensive lamp surfing, lens down of course, across the intersection (yeah, been there, done that )

A better long term solution , when fitting 'glass fenders, is to install steel buckets in them. Then you have a more reliable mounting position (not that the central screw mounting is perfect in any case ! .
One option that we have used, when access to the back of the bucket is easy, is to attach a retaining cable from the lamp, thru the back of the fiberglass bucket. We affix a cable stop to the cable in the fenderwell. Makes for a theft deterrent as well

[rattlsnak]

Thanks for the reply. I figured as much, but I'm away from home and just couldnt remember how they are made. I'm going to go the route of putting metal buckets in the glass fenders.

And yes, too funny. I HAVE had an H4 go slingshotting across an intersection after popping off the fender!!!