Seat back bumper installation
Thread Starter
Racer
Joined: Apr 2004
Posts: 292
Likes: 41
From: Falls Church VA
Seat back bumper installation
I am getting ready to install some seat back bumpers (I have an early '72, and these were not installed at the factory). Before a pull out the drill I was hoping to get some advice. I have never drilled into fiberglass and this goes without saying but, "I don't want to screw it up." Appreciate any advice on how to ensure I drill a clean hole.
Thanks,
Steve
Thanks,
Steve
Melting Slicks
Joined: Feb 2018
Posts: 2,324
Likes: 720
From: Marietta GA
I like to cover the area to be drilled with blue painters tap (three pieces on top of each other). DRILL AT A VERY SLOW SPEED. I always use a NEW small bit to start the hole, 1/16. Once the small bit has started to penetrate the fiberglass, go to a little larger NEW drill bit, continue till you are drilling with the final size drill bit. You don’t want to jump to a lot large bit to soon, because it may chip the fiberglass around the drilled hole. Once the final drill bit is used, remove the tape. While this may be overly cautious, just remember how old these cars are. Good Luck.
Thread Starter
Racer
Joined: Apr 2004
Posts: 292
Likes: 41
From: Falls Church VA
Thanks for the info. I read something about also using a countersink bit (smaller than the hole you need.) Maybe that accomplishes the same as your suggestion to use a smaller bit to start out with?
Melting Slicks
Joined: Feb 2018
Posts: 2,324
Likes: 720
From: Marietta GA
Using the smallest size new bit will ensure that you don’t jump/slip off the mark that was placed on the tape. A countersink bit may take too much material off at one time. I used my technique to drill 1/4 holes in the sides of the rear trunk for the hard top bolts. Be sure to use NEW drill bits and run the drill motor at a slow speed.
