Truck cap diy track installation help

Hi, I'm having a difficult time understanding something here. I own a DCSB and I want to add some Thule tracks to the canopy so that I can mount a roof rack on top of it.
I don't know what size I need? I've read everything from 50" up to the full 60" (with 55 being an option as well) for the tracks. Where I bought my cap they said take a 60" and cut it to size but that doesn't seem right to me (and they have pretty bad reviews) Can anyone give me a clear answer?
Here's a picture for funzies

 

Are you mounting them? Might need a tape measure and a step ladder to start with and figure that part out. I cant remember what size I used, but there arent usually holes up there already. I had to decide where I wanted it mounted and how, and then drill holes and bolt it on.

Probably not the answer you are looking for, but most here arent going to make the decision for you other than saying what they did, and that may not be what you need to copy in your own use.

I imagine you will need to take into account the size of rack you are getting so it will span and support it well.

 

There have been several threads on mounting tracks in the Tonneau Covers, Caps and Shells forum.

 

Bar length has nothing to do with the mounts. They are independent. Thule should be able to tell you what mounts you need for that cap. Most likely you are going to want the 60” bars. Stretch a tape measure across you cap and you’ll see where the different lengths land.

 

also check with the MFG and see if they have a suggested mounting locations, and what the weight limit is.
I bought my Ranch topper used, and it is supposedly has a reinforced roof, designed to carry weight (can't remember how much). That would lead me to assume, some may not be designed to mount/carry at all, but I would want to hear such things straight from the MFG.

 

I would think the tracks need to be a litte shorter than the cap length as you don't want to mount them right to the front/back edges. 55" for the short bed (60") sounds reasonable.

 

Cascade Rack has a Youtube video on track installation, as do other posters. Might be worth your time to see what's available there.

 

not sure if this helps but here is a photo of mine that were factory installed on an ARE cap. they are about 41 1/2 inches apart and 58 1/2 inches long. i have the 6 foot bed.

 

If you look inside the cap, you may see a reinforced (thicker) area on the roof. If so, that's where you'll want to drill for the risers.

 

The thicker area is where there's a corrugated filler between the layers of fiberglass. So, although this helps with the overall rigidity of the cap, it's actually not a good place to mount the tracks. You want to drill outboard of the thick area. The bolts should go where there's solid fiberglass, and not a corrugated filler.

My Leer factory tracks are 42 inches apart, center to center. That's how far apart the bolt holes should be drilled. (The distance between the edges of the tracks is going to be about an inch less.)