Roof Rack

I wanted to install a roof rack to transport my bike. From what I could tell, the only OEM option ever sold was for the Toyota version of the car (the Altezza Gita) outside the US. These are hard to find and expensive. I found a few owners had modified the roof rack from a 2008-2012 Toyota Rav4, which are much more plentiful and less expensive.

Roof rack installed on Toyota Rav4
[Image source]
Summary of modifications required:

  • Shorten (grind down) end-casting bosses to fit shallower roof channel
  • Drill new front hole in front brackets
  • Expand rear hole in rear brackets
  • Shorten longitudinal rails; drill and countersink new holes at cut end
  • Shorten cross-beams; drill and tap new holes at cut end

The challenge: it’s difficult to ensure the end castings point the right direction without being able to join them with the rail, but the rail might end up too short if cut to length before the castings are low enough in the roof channel. Additionally, the rails have to end up parallel, which is hard to ensure without the cross-beams in place. But they can’t be placed without being cut, and their proper length depends on where the castings end up. So the modifications were an iterative process. The operations are in rough chronological order below, but one side was built at a time, sometimes going back and forth between steps to ensure everything ends up fitting.

I ground down the front-casting bosses to sit down into channel better.

  • I used a flap disk on an angle grinder, but the belt sander I have now would work better
  • I ground them down until the height and angle were right (has to “point” at the rear boss so the rail fits between them). After that, I trimmed the rubber boot-like piece to fit right between the casting flange and the roof.

Then I drilled a new hole in each front casting since the IS300 roof bolt pattern is different than the Rav4’s.


The rear bolt pattern is closer to fitting, so the rear casting’s rear hole just has to be extended rearward. I used a rasp (shown) and smaller burr for this.


I cut the rails slowly using a chop saw, but it would have been better to use an aluminum miter-saw blade. I had to go very slowly, in short plunges, with the composite chop-saw blade to keep the heat down. If the aluminum heats enough, it just melts and mashes. I read some about using wax on the blade, which I assume helps keep the heat down, but I didn’t try that.


I cut the front of each rail, but I don’t think it matters which end you cut.

Once I tuned the length in, next came drilling and countersinking new holes for attachment to the boss.


After getting each side’s bosses reshaped and the rails cut, I was able to mock up and cut cross-beams.


Here again, it doesn’t matter which side is cut (the beams have constant curvature). I used the chop saw again.

I drilled and tapped new holes in each cut end.


I cleaned up the cut edges of the rails and cross-beams w/ a fiber disc on the pneumatic angle grinder.


Then I applied black touch-up paint to hide the bare Aluminum (Krylon satin black spray paint – nothing special)

I applied Blue Loctite on the threads of both the crossbeam and rail screws.


Cut roof trim to fit around rack mounts. Added some weather trim adhesive underneath.


I applied weather-trim adhesive (Permatex Black Super Weatherstrip Adhesive 81850) around the mounting holes to keep water from seeping through the threads.


I attached the castings to the roof with stainless steel security fasteners (Amazon). I needed 45mm for back and 40mm length for front (I just cut down 45mm ones).

I put a split lock washer and a flat washer under each mounting screw.


The plastic covers for the end castings had some broken retention tabs, and replacements are expensive. What I did was applied some “Plastic Bonder” epoxy where the tabs had been, then I ground the blobs into a tab shape after the epoxy cured. They’re not pretty, but they’re hidden and worked perfectly.