Originally Posted by JoeD
Slow and oil are the key to drilling steel, keep it under 300 rpm.
No kidding on the oil and low RPMs. I just installed the RRO rock rails on a 2014 Trailhawk. Not a complex install, but, the instructions to drill through that pinch is not the best advice. I can't believe anyone is able to do that from the backside especially in a home garage without a lift. Even then, it seems like you be forced to drill at an angle, skid plates are very close to that seam in many areas.
I mounted the rails in place using two hydraulic jacks. I intended to mark the drill spots using a sharpie on the drivers side, but it was too difficult to get a the pen exactly on the drill spot. I ended up using those little adhesive reinforcement discs you stick over the punched holes of loose leaf paper to strengthen them. They were perfect for sliding between the rail and pinch seam, just eyeball the alignment. Once you drop the rail, you just drill right through the center of the holes of those adhesive discs. Did have the jeep up on ramps front and rear for each side when drilling.
Remove the rail and begin the drilling from the outside in. The instructions state have a sharp bit or two. Baloney. I needed way more than an extra bit or two. I drilled 1/8 inch pilot holes, thinking that would make the 1/4 inch drilling smoother. Was using brand new cobalt drill bits. Each bit was good for three, maybe four holes, using moderate pressure on the drill.
Went through four bits, for 12 holes. Took only about a minute per hole with new bit, dipped in cutting oil, very low RPM. I only had 2 cobalt 1/4 inch bits which were good for 6 holes. I had a titanium stepped drill bit left at home and was actually able to drill six 1/4 holes through the pinch seam on the passenger side using that type of bit. It was still drilling effectively on the sixth hole. Once your bit stops producing metal shavings, it's done. You can drill all day, grinding away and you're not getting through that seam.
Once your done, the sure do look good. I do like the mopar rails we have on our Grand Cherokee, but like the RRO rails for the Trailhawk over the mopar version.
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