Tail light bulb blowing

OK what's up with this?
In the last 500-600 miles I've blown out my 1157 tail light bulb three times now.
Not the brake filament, the running tail light filament.
WTF?
I don't ride at night often nor do I run with the headlight and tail light on very much in the day time.
This is getting too expensive to ignore.
Charge voltage at idle is about 12.8vdc-13vdc and at 4000-5000 rpm it is 14.5vdc to 14.8vdc.
With the four way blinkers on and the headlight (100w Quartz) I'm seeing about 13.5vdc at 3000rpm-4000rpm and it drops way down to 12.3vdc-12.5vdc at idle. Obviously straining to keep up but not over voltaging/charging at high rpms.
I'm thinking it has to be a vibration thing... and has something to do with installing the new 1075cc 10.25:1 piston kit.
I don't think I've changed that 1157 bulb more then two or three times in my life since 1977.
So what... but 3 in the last couple weeks?
Comments please...

No eBay APP ID and/or Cert ID defined in Kunena configurationYou can't get good bulbs anymore. I suggest a LED. They will take a lot more power swings.
Steve

Chinese bulbs? Ed

For $10 or so you can get a 15W LED replacement bulb on eBay that should be vibration proof...

650ed wrote: Chinese bulbs? Ed

I don't know Ed I picked up the first pair at AutoZone and the other set at Checker O'Reilly today... I guess I should go through the trash and see what they say.
Cheap crap I guess..... is there a heavy duty version?

I think the first one blown a couple weeks ago was a GE.... but the OLD from the very early 80's I think ... can't say 100%.
Maybe it was just past it's prime....

The ones I bought are 4 months old and doing fine.
Steve

Went out to my trash and dug them out.... Sylvania China Crap.
Guess I'll go over to NAPA tomo and see if they have anything real.... pissed off now.

Yup.
Steve

possibly a loose connction or bare wire, shorting occaisionally???

Shorted wires:
No, I really don't think so.... the current would bypass the bulb if there was a short in a wire and the fuse would go open instead.

Anyone ever heard of a 2057 or 2057LL looks similar and reportedly "heavy duty".

A bad connection could cause it to go early.
Steve

The 20 57 and the 1157 are interchangeable. The only difference is the 2057 has a slightly lower wattage out put than the 1157. Typically these are used in the automotive industry for daytime running lights...hence the lower wattage and longer life.
Ty