Another Roof Rack Thread . . .

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Mazda 5
Greetings all,

I know that there are other roof rack threads. Some of them are long and tend to meander a bit, so I'm starting a new one. :D

Following is a description of my installation of a Lund cargo rack atop the Mazda-branded Thule rooftop bars. I chose the Lund rack because it's size fits my needs the best. It's pretty much the same width as the bars. Any smaller and it wouldn't hold as much as it could. Any wider and I'd be bumping my head on it every time I got out of the car. ;) Another plus is that it is made of round rather than square tubing. My prior experience with roof racks is that those made of rectangular tubing will sing like a banshee in the wind.

For those who haven't done it, installing the cross bars is very easy. Removing the four plastic covers on the roof will reveal threaded holes into which the rooftop bar hardware will attach. To remove the covers, slide in the direction of the arrow. Oddly, they are removed in a different direction on the left side of the car than the right. The contoured pads which give the bars a custom fit to the Mazda 5 roof line are conveniently labeled on the bottom for each corner. Beware that the two bars are of slightly different length. The wider one goes up front.

RoofandPad.jpg

Left: the threaded mounting under the plastic cover. Right: the pads of the rooftop bars are individually labelled.


The bars are held to the roof by the hardware shown below. It's interesting to note that the screws for the front bar go in at an angle. It can be a chore to line up the bars on the roof and start the screws. The best way I've found is to open the doors and stand on the door sill so that you can look down through the mounting hole in the bar end and see the mounting hole in the roof.

MountingHardware.jpg

The mounting hardware. In the photo on the right you can see how the screw installs at an angle relative to the rack.


Once the bars were mounted, I test fit the rack on them. My goal is to be able to remove and replace the bars and rack as a unit without having to tweak anything. Considering the way the bars mount to the roof, that might be ambitious. The one-size-fits-all hardware that came with the rack was unequal to the task, so I sourced some new hardware that might make the installation a little cleaner and better my chances of having trouble-free subsequent mountings of the rack and bars.

The hardware list:
4 each 7/8" stainless steel vibration-damping tubing clamps
8 each 1/4-20 x 1 1/2 inch stainless pan head machine screws
8 each 1/4-20 stainless nylock nuts
16 each 1/4 stainless flat washers

My best chance for success, I felt, was to assemble in a specific order.

Mount bars.
Set rack on top of bars. Center with measuring tape on front bar.
Mark holes through mounting hardware on front rack only.
Remove rack and front bar.
Drill four 5/16" holes in front bar as marked.
Attach rack to bar with mounting hardware, but leave the nuts a little loose.
Return bar and rack to roof.
Mark holes through hardware on rear rack.
Remove everything from the roof and drill four 5/16" holes in the rear bar.
Attach the rack to the rear bar, leaving the nuts a little loose.
Lift the rack and bars, now a unit, onto the roof.
Attach bars to roof. Snug up hardware holding the rack to the bars.

It may seem that there is a lot of redundant removing and replacing of the bars and rack on the roof, but the reason I bolted the rack onto the front bar before measuring for the holes on the rear bar was because I felt the chances of the rack being perfectly square were slim. (In fact, as it turns out, the rack is out of square by 1/8". I hate oval holes.)

Process.jpg

From left to right: Test fitting the stainless steel vibration-dampening tube clamp to the rack. Markings for the holes to be drilled - I used a silver Sharpie. The pan-head screws, nylock nuts, and washers - all stainless. The rack clamped to the roof bar.


Well, as they say, even the best laid plans of mice and men often go awry.

I found that when I mounted the assembled rack and bars on the roof, the rack prevented the plastic end covers of the bars from closing. I took the assembly off the roof, removed the rack from the bars, and cut down the plastic end covers. A hacksaw and some sand paper did the job.

ModdedEndCaps.jpg

Left: the shortened end cap clears the rack just fine. Right: modified and unmodified covers side-by-side.

I put the rack/bar assembly on the roof, attached the bars to the roof with the hardware, and finally I snugged up all the nylock nuts holding the rack to the bars. Success!

The finished product:

Finished.jpg


Sources:

Roof bars for Mazda 5 (part no. CC43-V4-701G):
http://www.mazdaparts.org/mazda5roofrack.html

Lund 601011 Cargo Basket; 39 in. x 44 in:
http://www.streetsideauto.com (enter 601011 in the search field.)

Tubing clamps (4 required):
http://www.McMaster.com (Enter 11355T66 in the search field.)

Stainless hardware as described above:
Your friendly neighborhood hardware store.
 
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Hi,

Really nice walk through.

I own a Canadian M5 and looked into the fix points on the roof. Needed to use them occasionally for something other than a roof rack, so I needed to know the exact size and step for screws.

A friend of mine (machinist) used some tools and told me that the screws needed are 6mm with a 1.0 step. Went to Home Depot and bought 6mm 1.0 screws (50mm long) and they fit tightly into the hole.

You spoke of 1/4-20. Is there a difference with the Canadian version of the M5?
 
You spoke of 1/4-20. Is there a difference with the Canadian version of the M5?
I used the 1/4-20 screws to attach the rack to the bars. It was the logical size to use given the mounting holes in the tubing clamps. I'm sure the hardware that attaches the bars to the roof is the same 6mm x 1.0 pitch as you described.
 
I can't help to wonder if something might beak (in medium/long term time frame) if there is something loose - even if only slightly. Maybe both are the same size...

For example - 1/2 inch wrench and 13mm wrench. Basically almost the same size, but for some jobs, you need the exact tool...

I'll have to research this.
 
I think there might be a misunderstanding. It sounds like you think I'm using the 1/4-20 screws to attach the bars to the top of the car, where certainly metric screws were meant to be used. Although I will admit a bit of a fetish for stainless hardware, I in fact used the hardware that was supplied with the rooftop bars, which no doubt matches the metric specs your machinist friend gave you.

The 1/4-20 screws that I mentioned were used to bolt the Lund rack to the Mazda rooftop bars.

BoltExplanation.jpg


BTW, the instructions for the rooftop bars specify that the screw be inserted all the way, and then backed off 1-1/2 turns, and then the gray knob is snugged up. The knob acts as a jam nut. You might want to consider that for the purpose of whatever custom rooftop application you have.


ETA: maybe the confusion stems from my (perhaps incorrect) use of terms. What Mazda is calling a roof rack, I am calling rooftop bars. What I am calling a roof rack, others might call a basket.
 
Can someone slap me on the back of my head?


Guess I was confused - I focused on the roof rack nuts instead of the basket installation on the roof rack.

Dang concentration...

(attention) (oops)​
 
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