Guidance needed for Suburban roof rack install

[RPO677]

I'd like to add a roof rack/basket to my 99 Suburban that lacks OEM roof rails (never had factory roof rails). Has anyone added a rack to a factory rail-less Suburban that can add some insight re: the install? Does anyone know if the inner skin has access holes to the outer skin where either an aftermarket/custom rack or an OEM set of roof rails can be bolted in place?

Thanks.

 

[Mr Eric]

Old body or new body? If a 99 gmt400, then the advise is,...... don't do it.

It's a monumental job to do correctly.

1) You will have to pull the headliner down.
2 ) make a template, hopefully from a gmt400 in a jy.
3) drill holes,
4) ream holes on the inner layer to give access to the mounting holes and bolts
5)remount the headliner.
6) worry the bolt holes don't leak.

Gmt400 Burb w/o roof racks are rare. Consider maintaining a rare version.

 

[DonYukon]

So what I did for mine was simple really . I removed the existing roof rack and then mocked up the mounting points where I could easily access the mounts without going through inner and outer skin. now because of this you will need to use sandwich plate type of mounts so you can disperse the weight evenly. unless like most people you use it for looks then I wouldn't worry about it. I will say if you can mount one and not touch the factory rack do that as the biggest problem I had was actually sealing the old holes

 

[RPO677]

I appreciate the feedback and welcome more comments.

Yes, a 99 GMT400 K2500 (shown in my a avatar). Agree it’s rare. More so in that it’s a factory diesel example with only 42k original miles purchased from the original owner. Rare doesn’t always equate to desirability however and a rack will make it more utilitarian and enjoyable for me.

If there were factory rails I’d make use of the existing holes (or reinstall an OEM system). It was not outfitted by GM with factory rails/rack.

Rivet nuts might be useful as points of attachment if the underlying dead space between the skins is sufficiently deep but I wouldn’t want to blindly try my luck. Cross section photos would help This body style isn’t common in the few salvage yards near me.

 

[1989GMCSIERRA]

Old body or new body? If a 99 gmt400, then the advise is,...... don't do it.

It's a monumental job to do correctly.

1) You will have to pull the headliner down.
2 ) make a template, hopefully from a gmt400 in a jy.
3) drill holes,
4) ream holes on the inner layer to give access to the mounting holes and bolts
5)remount the headliner.
6) worry the bolt holes don't leak.

Gmt400 Burb w/o roof racks are rare. Consider maintaining a rare version.

You don’t need to completely remove the interior. I do some horse trailer work on the side and a little automotive and I use these things called Riv-nuts. They look like a large rivet head without the center long pin. The center is threaded and has a collapsible section that gets squeezed and secures to sheet metal. that’s how I put my dually fender brackets on. They are designed to be installed in sheet metal that has no accessibility for the back side for a nut. The outer edge can be sealed and you can even put a rubber oring under the exterior flange.
Works great. And they can be sealed also. A install tool kit is about 65 bucks and some come with a selection of rivnuts in both standard and metric threads.

for a drill you can use a drill stop so you dont drill too deep.

look them up and you’ll see what I’m talking about if you haven’t seen these.

 

[Mr Eric]

You don’t need to completely remove the interior. I do some horse trailer work on the side and a little automotive and I use these things called Riv-nuts. They look like a large rivet head without the center long pin. The center is threaded and has a collapsible section that gets squeezed and secures to sheet metal. that’s how I put my dually fender brackets on. They are designed to be installed in sheet metal that has no accessibility for the back side for a nut. The outer edge can be sealed and you can even put a rubber oring under the exterior flange.
Works great. And they can be sealed also. A install tool kit is about 65 bucks and some come with a selection of rivnuts in both standard and metric threads.

for a drill you can use a drill stop so you dont drill too deep.

look them up and you’ll see what I’m talking about if you haven’t seen these.

Yes I'm familiar with rivnut, I have used them in airplane applications. I would be concerned about moisture entry points while using this method. In AZ or somewhere dry or otherwise unconcerned about water inside a cab, fine,.... in a burb? I wouldn't, but I have an aversion to the smell of moisture inside my cabs, much less having water drop from where it's not supposed to do so.

Years ago while doing a OSB hunting rig we shot threaded studs on the roof, for attaching a custom track for lights. It seemed like a great idea at the time, but those old cabs were also substantially thicker, I wouldn't even bother with that method with a gmt4/800 cab, and I'd tig mounts if i was building something one off.

YMMV.

 

[1989GMCSIERRA]

Yes I'm familiar with rivnut, I have used them in airplane applications. I would be concerned about moisture entry points while using this method. In AZ or somewhere dry or otherwise unconcerned about water inside a cab, fine,.... in a burb? I wouldn't, but I have an aversion to the smell of moisture inside my cabs, much less having water drop from where it's not supposed to do so.

Years ago while doing a OSB hunting rig we shot threaded studs on the roof, for attaching a custom track for lights. It seemed like a great idea at the time, but those old cabs were also substantially thicker, I wouldn't even bother with that method with a gmt4/800 cab, and I'd tig mounts if i was building something one off.

YMMV.

truthfully once you seal the riv nut you’ll have the roof rack that has a foot that mounts flush to the roof surface. There will usually be a rubber pad. You seal that with a bead some RV roof sealant you’ll never leak. Go look at the factory roof racks and how they are mounted, it’s really no different than using a riv nut. Depending on how much weight youre planning on throwing on the racks you may want to hit the roof cross ribs with the riv nuts. ive installed plenty of those long light bars on friends trucks using rivnuts, haven’t had a issue after sealing the brackets,