Another rear turn signal installation thread...

[mattsz]

I'm thinking about modifying my rear end ...(pause)... I'm hoping to figure out a way of installing the bullet turn signals and the classic British-style taillight from NFG in such a way so that they don't interfere with either my luggage rack or my saddlebags.

I have an idea which would require piece of hardware that I'm having trouble locating, so I'm hoping you brainiacs might have a solution for me.  I would like to find a couple of pieces of hollow threaded rod, like you can buy for lamp repair work - threaded on the outside, smooth on the inside.  Easy to find, but that stuff is too large in diameter for what I want to do.  The bullet turn signals come with hollow mounting bolts, with the "hot" wire passing through it.  Same idea as the stuff mentioned above, but it's smaller (and of course, it has a head on one end).  I'm not sure what size it is, but the outer diameter of the threads is about 5/16 inch, or about 7mm.

I'd like to find 2 threaded hollow rod pieces similar in size to that bolt.  I could go a bit bigger OD, like up to 3/8 inch, but no bigger than that.  Thread doesn't matter, as long as I can get a locking nut to fit it.  Each one needs to be about 1-1/4 inches long.  I can trim longer pieces to length, of course!

Can I buy such a thing, or do I have to fabricate it?  Either drill out a solid piece of threaded rod?  Cut threads into a hollow "tube"?  Or start with a solid bar, and do both?

[Arizoni]

I was going to suggest that you buy some 5/16" brass tubing and thread it with a 5/16-24UNF die but after measuring some I have I find the wall is too thin.

Likewise, a piece of 5/16" steel brake tubing for automotive hydraulic brakes is too thin to thread.

More looking on Google says the standard threaded hollow tubes they use to build lighting fixtures is a 3/8" diameter.
Going to a place that specializes in making custom light fixtures might be your best bet if that size would work.
Either that or tear apart that ugly lamp your wife has sitting on the end table next to the couch? 

[mattsz]

More looking on Google says the standard threaded hollow tubes they use to build lighting fixtures is a 3/8" diameter.
Going to a place that specializes in making custom light fixtures might be your best bet if that size would work.
Either that or tear apart that ugly lamp your wife has sitting on the end table next to the couch? 

Jim- that 3/8" would probably be perfect, but I'm not finding it in my searches.  Which Google are you using?  My only strikes come from UK websites  .  And the results I do find are 1/2" or equivalent sizes, too big.  What did you search for?

Hey... that's MY ugly lamp!

[mattsz]

Never mind...  I'm finding stuff called "Lamp pipe".  Go figure.

"1/8 inch IP" thread has a 3/8 inch diameter - that's perfect.  I should be able to find it locally.

Stay tuned...

[Arizoni]

That sounds like similar tubing to what I found.
I did notice that they said the 1/8 inch IP thread seems to be some sort of special sized thread.
Normally a external pipe thread is tapered so it will seal when it's tightened into an internal pipe thread.  These seem to be untapered threads.
The thread spacing for British 1/8" IP threads is 28 threads per inch.  For American 1/8" IP
pipe threads it is 27 threads per inch.
A standard thread pitch for a UN 3/8" bolt is 16 threads per inch (course) and 24 threads per inch (fine).

Anyway, it looks like you will be stuck with using whatever type of nut is available for those tubes.

[barenekd]

OK, I'm trying to simplify this by asking what are your trying to do? Are you using the stock taillight box and just want to lengthen/shorten the stems? Do you have to use the stock turn signals?
Just a bit of clarification, please, for us dummies! I can think of a lot of things to do there, but they may or may not fit your design criteria.
Bare
 

[mattsz]

OK, I'm trying to simplify this by asking what are your trying to do?

 

Bare -

I wanna put these:



on the body of this:



by drilling a couple of holes in the sides of the housing, kinda like this:



and making extensions for the turn signals using some delrin rod I have, similar to the OEM signal extensions, but not as chunky.  I plan to drill out the delrin for the wires, and screw the turn signal mounting bolt into one end, screw the lamp nipple into the other end, and mount each one with locking washers and nuts directly to the tail light housing.  I've mocked up the installation, and it seems to be the best way to do it and allow room for my luggage rack and saddlebags.

FYI, the mounting bolt from the NFG bullet turn signals is basically a hollow 5/16-18 carriage bolt.

These, from Hitchcocks, would have been nice:



but I'm not sure the length of the stem would be just right.  And, the S&H from them kills me every time...

[barenekd]

Since it has been difficult to a metal tube that has the right ID/OD, try some PCV tubing. It has a bit thicker wall thickness leaving you more room to the internal threads. Not sure what delrin is.
There are a bunch of aftermarket turn signals that come with longer stems from a variety of sources. I usually get mine from Cycle Gear, but they are generally smaller than what you have, although I think they have larger ones, too. the prices are right, too!
Bare

[mattsz]

Thanks for your suggestions, Bare!

Delrin is a sturdy, machinable plastic-like thermoplastic acetal resin, which I have in both 1/2" and 3/4" diameter rods, in black (I use it for hurdy-gurdy axle bushings).  In fact, it looks rather like the black stalk material from the OEM signals, only it's not rubbery.



I'll try it because I have some kicking around, and its a joy to work with on the lathe, so I can get just the length I need.  And I already have the signals.  If it doesn't work out, I can go from there.

Also, I've decided that the 1/2" stuff is too narrow; the 3/4" stuff is plenty beefy enough to accept the 1/8" IP lamp nipple.