Hello, I looked all over the Internet for ways to use the existing roof rails (2003 Prado VX turbo diesel 4-door) for cross bars. Mostly I wanted to drop the profile of normal bars for wind resistance and noise… and look. But also the existing rails provide a flexible (moveable front to back) and strong structure. I don't do much overland, I'm mostly putting surfboards and luggage up top, and might design a basket/cage that sits between these existing bars.
Here in Peru you still have metal workers, simple machine shops, on the corner of certain neighborhoods so I just made the design and then transmitted it to the metal workers to construct.
Forgive my ignorance in the names and other descriptions of the various parts. I've got pictures which show most of key elements.
For those who haven't disassembled or investigated, the whole OEM rail system is comprised of 3 bases that attach to the roof with 6 (3x2) 12mm bolts for the front and rear bases with a hollow rail internally divided into channels, one facing the inside and rectangular the other facing outside right triangular.
The the other side of the front and back bases partially enter 2-3cm into the outside (right triangular) channel and attach to the rail with 4 (2x2) Tor 30 screws through the bottom of the rail.
The middle base attaches differently. Instead of of the Tor30 screw holes there is a female piece that drops down from the rail that connects with another 12mm screw to the base.
The outside height of the inside (rectangular) channel is 3cm with a 1cm channel running horizontally the length of the channel (visible from roof). The space inside is roughly 2.6cm x 1cm. This allows .8cm of the inside channel height and 3cm of the outside channel height surface area to be used to hold the rack design together.
The design elements are:
- 4 flat pieces (7.5cm x 2.5cm x .5) with two threaded holes that slide into the inside channel.
- 4 angles (7.5cm x 3.0 cm, 3.0 cm) with the same two hole placement as the threaded flat piece
- 8 bolts 2cm threaded length, 10mm head, lock washers, washers to pass through the angle and screw into the flat piece in the channel sandwich the parts around the outside edge of the inside channel
- 2 bars (99.6 cm x 1.9cm) whose ends will sitting on and be welded to the horizontal part of the angle.
- Plastic shims. There was a .3cm difference between the the forward part of the rails and the rear. We decided that we would use plastic shims to make the difference and protect metal on metal inside the sandwich.
With my yankee Spanish, they just welded the whole thing together in one shot (bars on the angles with holes) as I was expecting that they would do the angles and flat piece, we would attach them to the rails, and then quick weld the bars so they would be the exact measurement, compensating any difference of width (for adjustment) with the plastic shims. They then powder coated it all, although some here have recommended zinc primer through electroplating for the Pacific Ocean, humid conditions that we have here in Lima. We will see.
After removing the plastic covers on the front and back bases I realized the access to the outside channel inside of the rail is blocked by part of the base (first photo), much more at the front foot than the back, enough that I couldn't get my flat piece in. I imagine this is to prevent my or similar designs becoming loose and with hard breaking, massive acceleration, keep the whole apparatus from sliding down the rail and flying off the front or back.
As it was my first time working with the rails and bases and I just took the whole rail off on the copilot side so I could see how everything fits together. What is removed is composed of 3 parts: the front base, back base, the screw on the middle base, and rail between them. The middle base stays on the roof.
I only had to unscrew 2 TOR 30 screws to remove one base (doesn't matter which) to insert my 2 flat metal pieces inside the rail, but I did the back base as well to clean the screws up. I reattached the feet (loosely) to the rail and then reinstalled everything (bases, rails, my two flat pieces inside the inside channel) on the roof and then tightened up all the bolts and Tor30 screws.
On the pilot side I just removed the base securing bolts on the front base and then un screwed the TOR 30 nuts to avoid unattaching the whole rail (2nd photo). Tough job on the Tor30 screws as they are underneath and low clearance, almost to the point that the TOR wrench couldn't fit as the screw exiting reduced the clearance and they didn't turn easy with the fingers. Then I slid my 2 flat pieces in and reattached everything.
I then guided the complete bar/2 angles with shims to the placement of the flat piece (inside the channel) and spent a while lining up the bolts with their threads on the flat piece and tightened everything up.
The shims are key as getting perfect measurements didn't happen and you have an inflexible space between the two rails. I just loosen the 4 screws (2 each side) of each bar and slide them forward or back depending on my load.
At the back the clearance over the roof at the angle is 4cm, the worst clearance is 1.75cm (the 2 raised channels at the middle of the roof) and 2cm at the exact middle. At the front bar it's 1.25cm and 1.5com.
Doing it over I would make the flat pieces thicker to get more thread from them and maybe make their length (and that of the angle) longer to have more surface area contact with the rail. I would probably move to 2.5-2.7 cm diameter bars so their tops would be flush with the rails. They would look better too as mine look a little dinky. But for my loads they are fine.
- plastic curved tool (bike tire levers work great) to remove the end caps of the bases to expose the bolts attaching them to the roof. I broke one trying to use a screwdriver.
- 12mm wrench for bolts that attach OEM bases to roof and the middle base to the rail
- Tor30 wrench for bolts connecting OEM rail to OEM base