This is going to be a long post. It took me much longer to install the rock sliders than I thought it would.
Here's how I installed the Terrafirma T818 rock sliders onto my 2015 Land Rover LR4. I bought the sliders from Lucky8. They didn't come with instructions, just a bag-o-bolts/washers/nuts.
Mounting Hole Alignment
I'd read LR forum posts indicating that the mounting holes on the slider might not align with the holes on the car. In one post, Scott Brady was defending Terrafirma saying that LR seems to be moving the holes on the car. After I removed the running boards, I compared the bolt hole patterns on the rock sliders to the holes I could see on the car. Existing holes used by the running boards appear to align with the holes in the rock sliders. I wondered if I might be able to use the T40 Torx bolts that held the running boards to bolt the sliders into the same threaded holes in the frame. Spoiler: yes.
I made masks from cardboard to check the hole alignment. I simply traced each slider and their bolt holes onto cardboard and then cut them out. I then placed each mask against the rocker panel and looked to see if the holes in the mask lined up with the holes in the frame. I made 4 masks, 2 for each side (bottom holes and side holes). All of the holes appeared to align properly. To do it right, I should have made 1 mask per side, to ensure that the bottom and side holes are aligned to each other.
Initial Fit Check
Then I did a fit check. I balanced the slider on top a bottle jack and raised it up partially into position. Once the jack is supporting the weight (25 lbs) it's easy to maneuver the slider with one hand. I looked underneath and checked for any interference. It looked like it would fit.
I removed the rocker panel trim and tried installing the slider. It's getting easier to remove the trim, now that I know how it's attached. I have a handy Prylon trim pry tool from Amazon that made it super easy to remove the plastic rivets on the bottom of the trim. (To be perfectly honest, I could have done it with a fork.) Popping the trim off the car leaves yellow trim clips attached (the male part of the M/F clip design). It looked like they would interfere with the slider, so I decided to remove them. Just to be safe, I checked online and it looks like I can buy more clips of the same design. The design also suggests that I won't be able to pry or twist the clip from the frame. So I chiseled them off with a putty knife and a hammer.
I also removed the black plastic trim along the rocker panel at the rear of the front fender trim. To so this, I first gained some range-of-motion by unsnapping 2 of the snaps holding the fender trim. I learned a lot by watching this youtube video showing how to remove the fender trim. The black plastic trim is held in place with 2 snap clips.
Another Fit Check
There were a couple interference issues on the passenger side. The AC lines running down the rocker panel (clad in foam insulation) come in contact with the slider. More important, a few hose clamps definitely press against the slider. These clamps are used to attach a joiner section of hose between bare aluminum pipes and insulated pipes. Those steel hose clamps will rub against the slider and might cause problems over time.
I was pleased to see that the slider would clear those big heat sinks that are mounted to the frame. UPDATE: apparently they're not heat sinks, but some kind of crumple device used in conjunction with the running boards I removed. I could have removed those after removing the running boards. The sliders might block my access to the bolts used to attach them. But it shouldn't hurt to still have them mounted - heck, maybe they'll still provide crumple protection from a side impact on my sliders.
Note: I tried using pliers to loosen the hose clamps and just rotate their clocking angle on the hoses. That failed miserably. I checked the local stores for hose-clamp pliers, so I'd have a better grip on the clamps, but I couldn't find any. So I gave up on that idea.
Cutting the Sliders
I decided to cut off a section of the vertical fin on the passenger side slider to clear the AC lines in that area. After a bit of trial and error, it was easy. I used my cordless circular saw with a blade made for cutting aluminum. I was surprised at how easy that blade cut the 0.25 inch thick aluminum slider.
At first, I cut off only a section. Here's a photo of the fit check afterward. You can see that the hose clamps are clear now. However, the insulated line is in contact with the section I left at the end.
So I cut off that last section too. Now even that rear section clears those insulated lines.
Next was the driver side. I was worried because the AC lines running down the rocker panel interfere with the slider on that side also. There's a connector along that line that sticks out a lot and it blocks the slider from going into position.
I marked the location of those AC lines on my cardboard mask and transferred those to the slider. The next photo shows the slider raised for a fit check with the planned cut line marked on painters tape. The slider wouldn't even raise all the way because the hose connector was blocking it.
Then I cut off part of the vertical fin on that slider and re-checked the fit.
Installing the Sliders
Mounting the sliders was now easy. The photos below show the driver side because I took more photos then. I just raised it up and started a few of the bolts. Then added the remaining bolts and tightened them all.
Cutting the Trim
I had to cut away part of the plastic trim right behind the front fender (on each side). That's the only permanent damage I did to the car. Otherwise, everything I did is reversable. I cut away a spacer piece that holds the trim away from the rocker panel. With the slider in place, that spacer is no longer needed and it will cause the trim to stick out. I just cut it off with a small hack saw (any sharp knife would work also).
The red body color makes the Terafirma logo look really nice.
My sliders arrived from Lucky8 with those nicks. You can't miss them since they're right below the driver's door. It's unfortunate, but oh well. I painted those nicks with some Krylon black satin paint (dabbed on with a Q-tip - it's not a super clean job). I'll seal them with Gtechniq C1 and EXOv2 products.
It took me a long time over many days to install these. I decided to not describe all the tests and mistakes I made. I was extra careful because I didn't want to damage my brand new car. Now that I know how things come apart and go back together, I could install them in under 3 hours (in my small dark garage). In a large well-lit bay, I could install them in under 2 hours.