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Stainless steel vs plated steel vs aluminum rivnuts


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I am going to be mounting my flares soon and need to get the rivnuts.  I have read a bunch of threads but was looking for some feedback.  

 

Aluminum

Pros: won't rust.  Easy to crimp down.  Easy to drill out if needed.

Cons: weak threads that can strip.  Galvanic corrosion to steel body?

 

Zinc plated steel

Pros: strong.  Somewhat easy to crimp down.  Decent rust resistance? No galvanic corrosion? Able to be tack welded to body.

Cons: not enough rust resistance?

 

Stainless

Pros: strong.  Won't rust.  Able to be tack welded to body

Cons: hard to crimp down?  Galvanic corrosion? Hard to drill out if needed.

 

Thoughts?

 

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I know this isn't what you asked, but for fender flares I would use rubber well nuts.

 

https://www.mcmaster.com/well-nuts/

 

They seal the holes without damaging the paint, allow for a bit of misalignment (much more than rivet nuts), and IMHO are much easier to use.  I have used a lot of rivet nuts in various applications where there is no better option, but find them pretty temperamental in the sense that they always like to spin and have to be drilled out and replaced.

 

Well nuts also have the advantage, that in any sort of collision they will shear off rather than greatly damage the underlying bodywork.

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I used AL rivnuts all over my build. They work great. I've hit cones at autoxes with the flares hard enough to spider web the gelcoat, but the rivnuts were unaffected. You don't need a lot of torque on 1/4-20 bolts, which is what I used, so that also is a non-issue IMO. I have had a few spin where the surface they were put into wasn't totally flat (trans tunnel for instance). They're easy to remove and redo, I expect the zinc or stainless will be slightly more hassle.

I bought some zinc plated steel ones and they were way too stiff for my Harbor Freight rivnut hand pliers. No friggin way I was going to do that over and over again, and I glued in a windshield with that glue by hand with a caulking gun. Not touting my super strength, just saying I will put up with a lot if I don't have to buy an expensive tool, and I was not going to do the zinc ones by hand.

If you have a pneumatic gun, then maybe consider zinc or stainless if you're worried about it, but AL is fine.

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  • 1 month later...
7 hours ago, AydinZ71 said:

I must be dumb as f***. I’m still drilling holes and tack welding nuts on the other side 🤷🏽‍♂️

I do the same thing depending on the situation. I only use rivnuts where I might need to change the location or where strength isn't an issue. Everything else is welded into the body.

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15 hours ago, fusion said:

In the rear quarter panel, I should have specified.


In some cases when I can’t reach the other side I will drill an over-sized hole and weld-in the nut flush. In other cases, I will drill a through-hole and tack weld the nut right into the hole. This works for low-stress small-size nuts (M5 for example) where a flush-mount is not necessary. For example, nuts for mounting brake or electrical lines. I can’t explain why I never did rivnuts 🤷🏽‍♂️

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Let’s just say I have a lot of experience now 😂. 15 months of continuous rust repair, metalwork and welding. Im pretty comfortable with it. Have not ruined threads or seized a bolt yet. To be clear, nothing wrong with rivnuts. I just don’t use them and don’t have the tool. Being a race car and weight being a concern, I rarely use anything more than 20 gauge. Here are some pics of fabrication I have done with tack welded nuts. Ignition coil mount, oil cooler mount, and 5-pt harness bolting locations 

 

A798ABA2-C159-46C2-8AE2-E4E480AA7D32.jpeg

79E81231-8B3F-4227-B681-E7DE518076D4.jpeg

B6C3242F-A970-433B-A6B0-17C547FEFC72.jpeg

619D8FE0-BEDF-412A-8CA2-26280EB258EC.jpeg

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I often weld my rivnuts, as well.  For this reason, I am usually using zinc-plated steel nuts.  It only takes a small tack or two to firmly secure the rivnut in place.  (For the rear flares, the tack weld is on the outside surface.).  The current set of flare rivnuts have been in place for four years without any signs of loosening or corrosion.  Hope this helps.

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