Drilling holes for rear light guards

[khatadin]

I am about to attach rear light guards to my d-90. Is there anything I should know about drilling the holes in the exterior panels before I start? For example, should I prepare the metal by tapping it first? or just line up the holes and start drilling with an appropriately sized metal bit.

Lastly, once the holes are drilled, should I apply some sort of subtance on the bolts to help prevent rust? thanks.

-Scott

[javelinadave]

I measured about 20 times before I drilled anything.
I then put masking tape over where I was going to drill.
I then marked the masking tape and hit each mark with a punch (You don't want your drill bit walking across your paint)
I then drilled a pilot hole with a small bit. Then drilled them to size with a larger bit.
It helps to have second person “eyeball” things for you while you hold the guards in place. I didn't coat the exposed metal with anything but if I lived in snow country I would shoot the back of the nuts with paint or undercoating (not my area of expertise, I live in Phoenix).

[khatadin]

thanks..exactly what i was looking for. -Scott

[popeohana]

I just drilled holes in my 90 to install a rear seat. Any suggestions on what product(s) are available to treat the holes for rust prevention.

[khatadin]

I was given the following advice, which may apply to your situation as well.

"if you can get to the thread I would coat with rust proof compound, or anti-rust paint/primer.(once installed of course) if you should judge that no access to the bolt threads is possible once installed, i would consider using antiseize compound on the threads prior to installation."

Separetely, any advice on the type of drill bit that works well?

[Mike Hippert]

I second Anti Sieze! That stuff is great! I use it on almost everything. You could try and get a reverse drill bit, they will try and back out the bolt like an easy out will.

[Roadsiderob]

Scott,
I like to use a planing bit...instead of a tapered point it has a small point in the middle to center and cuts more like a small hole saw...makes perfect holes with little cleanup required and doesn't chew up the aluminum. Also, after installing several sets of light guards and wing protectors I quit trying to fit the nuts on the back and started installing threaded inserts in the body instead. This is much easier. Take a look at where they expect you to fit the nuts (and your fingers) before you drill...
Rob

[khatadin]

Rob, thanks. Dumb question, but are planing bits and threaded inserts relatively easy to locate at hardware stores? Or is there somewhere else I should look?

thanks again

[Roadsiderob]

Scott,
The bits will be available at the hardware or home store...Black & Decker, Snap on and others make them. The 6mm x 1.0mm threaded inserts (Riv-Nuts) are a specialty item. I would look for them at an industrial fastener store or try Wurth. You will need to either make or buy an installation tool as well. To make one, take a piece of flat steel 1/8" x 1" x 6" and drill a hole in one end big enough for a 6mm bolt to fit through. Get a 6mm bolt about 25mm -30mm long and thread a 6mm nut all the way up to the head of the bolt. Put the bolt/nut through the hole in the flat steel and then thread the insert on until the bolt is flush or a little past the end. Put the insert into the prepared hole and tighten the nut down onto the flat steel while holding the bolt and the flat steel stationary. Further tighten the nut to expand the body of the insert in the hole. I'd get a few extra and do one on some scrap for practice to judge the feel of it so you know when to stop expanding the insert...you can damage them if you go too far. Inserts are available in either steel or aluminum...I'd use the aluminum ones for lamp guards or wing protectors and go with steel for more structural applications such as holding a hardtop in place.
Rob