Silicone For Roof Rack Install..

So I just installed a Prinsu Cab Rack on my 21' over the weekend. I used clear silicone in the threaded holes in the roof as directed in the instructions, however, my friend mentioned to me that when installed his OEM roof rack on his 19' the instructions did not mention needing silicone.

My question is, what is the purpose of the silicone? Is it to prevent corrosion or leakage of some sort?

 

It will prevent water from getting in.

 

Because Prinsu does not use a gasket, your silicone functions as one. The silicone should go in the tubes, but also under the spacers to effectively "stick" them to the channel. The factory rack uses a gasket, so silicone is not needed.

 

From getting inside the cab? Do the holes extend all the way into the interior of the cab? If so, that seems kind of silly of Toyota to risk leaking water inside of the vehicle for the sake of a roof rack..

 

3rd brake light recall Toyota sometimes don’t think things through.

I don’t know if the roof rack holes are water tight or not.

 

Thanks for the reply, so to clarify, it's to prevent water leakage into the interior? I applied a copious amount to the holes (around and inside) so hopefully it'll stay sealed for a good while. I'll link the silicone I used below. The paranoid part of me hopes that the silicone won't degrade/crack over time and allow leakage eventually..

$15 GE Advanced Silicone Window & Door Sealant Clear, 10.1 oz, 1, Cartridge

https://www.amazon.com/dp/B0000CBJ7W?ref=ppx_yo2_dt_b_product_details

 

From the factory the roof rack holes are taped shut. When you put on the Prinsu you want to seal around the bolts. Silicone does fine- in the hole and a glob around it. I’ve had my Prinsu on and off two trucks since 2015 with zero issue.

Enjoy your rack!

 

You should be good. Back when I had a Prinsu I used silicone on the tubes, then butyl tape to stick down the spacers.

 

The Prinsu rack instruction that I received stated to use silicone:
see page 7
https://prinsu.com/wp-content/uploads/T2-T3-Cab-Rack-2005-Present-Install-Instructions-2-13-19.pdf

 

just put a hershey kiss sized dollop of silicone on the bolt hole, then lay the spacer on top and you should be good.

 

butyl tape and washers from mcmaster-carr are what i used.

i’m not a fan of blobbing silicon in the holes

 

what washers? Picture?

It seems like it would be pretty easy to make a small gasket for it out of rubber, or even use an oring/ac gasket? I plan on doing a roof rack and definitely want to over do the seal protection so I dont ruin my sunroof or headliner.

 

https://www.mcmaster.com/99604A123/

 

I just recently bought a prinsu rack…what is the best silicone out there to use?

 

none at all

 

I was wondering what the actual cross section looks like too, because I don't understand how they couldn't have designed it not to leak even with no screws. No one is really able to say what it looks like in the screw holes.

 

I recently installed a rhino rack which bolted and riveted to the roof. Best I can tell, they are thru-holes which go into the headliner cavity. They are 100% sealed BEFORE you remove the painted membrane over them.
I attached a pic of one, once the seal has been cut away.

 

Get a waterproof silicon and you'll be good. I think this is the one I used..interior/exterior waterproof. Several years later...no leaks.

https://www.homedepot.com/p/GE-Silicone-1-10-1-oz-Clear-All-Purpose-Caulk-2708911/100091111

 

I installed an RCI roof rack a few months ago. Although they say you don't need silicone because of the rubber block used in mounting, I still put a nice glob of good silicone in each one to be sure. We've gotten a lot of rain at my fire station and zero leaks, I was worried but after getting some moisture I'm confident in it.

 

Thanks!!!