So I ordered a rack and now I am looking for hardware.

[Signal]

So I was surfing somewhere and I saw someone posted about installing a no drill rack and not using silicone they used something like silicone washers or something from Mcmaster parts or from fasenal. Does this make some sense or was I miss reading ?

 

[MrSmartypants]

They are probably available from those industrial suppliers.

However you would need to make sure the sealing washers actually seal the potential leak point. Sherpa uses a rubber block underneath the foot along with the bonded washer to address both leak paths.

Sherpa also sells the parts direct on their website.

Roof Rack Components
– Sherpa Equipment Company

 

[Signal]

They are probably available from those industrial suppliers.

However you would need to make sure the sealing washers actually seal the potential leak point. Sherpa uses a rubber block underneath the foot along with the bonded washer to address both leak paths.

Sherpa also sells the parts direct on their website.

Roof Rack Components
– Sherpa Equipment Company

Is this what you are talking about?


Bonded Washers
– Sherpa Equipment Company

and

Adjustable Leveling Mounts
– Sherpa Equipment Company

 

[Teamoatmealpie]

You want to search for user name. Mynameistory. He did good write up with part numbers from McMaster-Carr

Yes dont use plain old Home Depot silicone or RVT- those use acid to cure and will etch your paint resulting in bare metal/rust. If you do use any sealer go with Sikaflex 221.

 

[jbtvt]

Doesn't your rack come with hardware? The Sherpa racks are rubber and very hard, I wouldn't/didn't count on them to seal my rack. Couple posts on that in this thread: Destroyed Factory Roof Mounting Locations

If you do need to order sealing material you might try silicone setting blocks, they're available in a bunch of sizes. I would just use sealant though. Bonded washers go on top or rack mounting brackets, sealant, or blocks if using them, goes between brackets and roof.

Fastenal is usually a ripoff unless you buy huge volume, like 10,000+/yr

 

[danyo492]

This is the McMaster Carr part number for the silicone washers. They are UV and weather resistant. I used these and haven't had any issues.

P/N 99604A123; 0.355" ID, 0.812" OD

 

[jbtvt]

Yes dont use plain old Home Depot silicone or RVT- those use acid to cure and will etch your paint resulting in bare metal/rust. If you do use any sealer go with Sikaflex 221.

FTR, acetoxy silicones will not etch paint, and for most applications you'd be better off using a GE silicone from Home Depot than you would be with a polyurethane like Sikaflex 221. Certainly any smooth surface like painted metal, almost any silicone is a much better choice for adhesion and lifespan. My recommendations are in the link above.

 

[Signal]

FTR, acetoxy silicones will not etch paint, and for most applications you'd be better off using a GE silicone from Home Depot than you would be with a polyurethane like Sikaflex 221. Certainly any smooth surface like painted metal, almost any silicone is a much better choice for adhesion and lifespan. My recommendations are in the link above.

Thanks I don't mind using Silicone I just never did this before so I would like to not have rust and seal it. I did a baslet on my Xterra and we had a bad seal somewhere and water came in. It was no fun.

 

[danyo492]

I used Permatex Ultra black when sealing my rack. Worked like a charm. I put a bunch in the OEM holes and on the bolt threads. Also used butyl rubber to seal the OEM hole locations.

 

[Teamoatmealpie]

FTR, acetoxy silicones will not etch paint, and for most applications you'd be better off using a GE silicone from Home Depot than you would be with a polyurethane like Sikaflex 221. Certainly any smooth surface like painted metal, almost any silicone is a much better choice for adhesion and lifespan. My recommendations are in the link above.

So you are saying long established companies that build out high end Sprinter type vans for $150K+ that use SF221, would be better off using home-depot acetoxy silicone??? Yeah - No thanks - I'll take my buddies advice.

 

[jbtvt]

Thanks I don't mind using Silicone I just never did this before so I would like to not have rust and seal it. I did a baslet on my Xterra and we had a bad seal somewhere and water came in. It was no fun.

Wipe the surface with alcohol and clean portion of a rag until spotless, then repeat one more time for good measure. Make sure sealant is sticking to surface, don't just blob it on. I've seen a lot of leaks where installers think that because they put a blob of sealant blocking their view of the hole that they've blocked water, but they've left a channel underneath the blob for water to get in.

If doing a spot seal and not a full length bead I usually dab the sealant, then pull away a little, like 1/8", and make sure the sealant is adhered and forming a convex shape, like a nice weld, then dab right next to it, pull away, etc, all the way around the hole. Final product should look like a weld, not a blob. One tiny gap in the sealant is all it takes for a leak

So you are saying long established companies that build out high end Sprinter type vans for $150K+ that use SF221, would be better off using home-depot acetoxy silicone??? Yeah - No thanks - I'll take my buddies advice.

Specialty glazier here, 15+ years of working with every type of sealant in the book. Good neutral cure silicones are better than any butyl for most purposes. You can get skinning or non-skinning butyl sealants and they do have their place, esp when it comes to bonding to rubbers. I'd pick them over a polyurethane and maybe even some hybrids for weatherproofing a truck. But for painted or non-ferrous metals you won't do any better than a neutral cure silicone like Dowsil 795 (1st choice) or 995, GE Silglaze or SCS, Durasil, etc.

I've peeled neutral cure silicone out of joints 30+ years old in full southern sun exposure that was still fully adhered, and installed hundreds of systems up to 30k sq ft of full exterior exposure sealed only with NCS. I've also seen it fail almost immediately if not properly installed, like any sealant, mostly related to issues that wouldn't arise in automotive/homeowner situations - too thin over a wide joint, not bonded to edges of joints, not accounting for metal expansion over a long run of flashing, and so on. Prep is important, clean with alcohol, naptha, or other residue-free solvent if not dealing with fresh surfaces.

Even most of the acetoxy silicones around today are pretty durable, and very UV resistant. Years ago that wasn't always the case. Never used Permatex for anything other than gaskets though.

On the main topic, years ago I built a custom roof rack, sealed the 4 holes in the roof with 795 and never had a leak, owned for years. I've also used it around several windshields in place of weatherstripping. But that's just a footnote compared to the thousands of gallons of the stuff I've used in some of the most extreme conditions you could imagine.

Windshields are installed with urethane, not butyl.

Do what you want, no skin off my back

 

[Signal]

This is the McMaster Carr part number for the silicone washers. They are UV and weather resistant. I used these and haven't had any issues.

P/N 99604A123; 0.355" ID, 0.812" OD

Which rack did you get?

 

[Signal]

This is the McMaster Carr part number for the silicone washers. They are UV and weather resistant. I used these and haven't had any issues.

P/N 99604A123; 0.355" ID, 0.812" OD

Also thank you I ordered them.

 

[danyo492]

Which rack did you get?

I have the Prinsu, full length non-drill rack. Really really happy with it and we have been getting hammered with rain the past 3 days here in north Georgia and not a drop of water has made it into the interior.

 

[Signal]

I have the Prinsu, full length non-drill rack. Really really happy with it and we have been getting hammered with rain the past 3 days here in north Georgia and not a drop of water has made it into the interior.

Thanks, That's what I ordered, I am just waiting for my 6-10 days for it to ship and I am trying to make sure I have anything extra I am going to need on hand when it gets here.