Deformation of joined Al panels by using blind rivets with steel anvil?

[cc2Arider]

Hey Y'all,

I'm considering getting some "ultimate" blind rivets to fasten the Al panels to the frame members. These supposedly have a much-improved gripping capability because the back side is deformed more uniformly, etc...

I think the by-product of that is that the panels are joined much more "snugly" due to the steel anvil (versus Aluminum) and I'm concerned about the possibility of deforming the panels since the joined flanges will also have some silicone in the joints.

Is this a valid concern? Any builder use something like this in your builds (steel anvil blind rivets versus aluminum anvil)? Does having silicone in the joints cause the deformation?

Thanks for the feedback,

Craig C

[narly1]

Given that the sheet metal panel's primary function is to "close in" the engine, passenger, and trunk compartments and that they contribute very little in terms of overall structural strength, I'd say that anything more than standard pop rivets is unnecessary.

All they really do is hold the panels in place on the frame until the silicone cures.

Earl

[edwardb]

I frequently used the ultimate rivets on my builds. They don't deform the aluminum. Extra strength required? Probably not. But I like the larger head and wider grip range.

FYI: I point this out whenever I see a post in this forum. Factory Five tech doesn't actively monitor here. An occasional answer maybe. But mostly you'll get answers from regular forum members.

[cc2Arider]

Thanks Paul! You are a Gentleman and a Scholar

Craig C

[cc2Arider]

Given that the sheet metal panel's primary function is to "close in" the engine, passenger, and trunk compartments and that they contribute very little in terms of overall structural strength, I'd say that anything more than standard pop rivets is unnecessary.

All they really do is hold the panels in place on the frame until the silicone cures.

Earl

Thanks Earl

My use of them is for aesthetics and my OCD...

Craig C

[narly1]

The only upgrade I would consider over the standard pop rivets supplied would be to maybe use the type that are sealed from the back side.

Earl

[cc2Arider]

You know Earl, I also had considered that in my planning phase...but then learned from others that a sealed floor acts like a bathtub if caught in the rain. So, I thought maybe having an opportunity for moisture weeping might not be a bad thing. It's funny how you can get into the minutia pretty quickly

I like the idea of the closed end rivets, and I actually used them on my motorcycle mufflers that I repacked about 20yrs ago... I think they were originally designed for aircraft fuel tanks.

Thanks for the perspective!

Craig C

[narly1]

a sealed floor acts like a bathtub if caught in the rain

Craig C

Well there is that

Maybe a couple of removable hole plugs with a bead of silicone around them that push in from the underside of the car might not be a bad idea?

Earl

[AC Bill]

I used rubber hole plugs for both footbox floor, The MK3.1 had the dropped front floors, so naturally that's where they went. I can remove them from under the car so I don't need to piss around with the carpets. I also added one to the trunk floor at the very rear, where it steps down by the latch pin. Never needed to pull them thankfully..

[cc2Arider]

Yep! I was considering that...plus I like that idea for the inboard lap belt brackets, too, so that the bolt doesn't squeeze or pinch the tunnel sides

Craig C

[edwardb]

The only upgrade I would consider over the standard pop rivets supplied would be to maybe use the type that are sealed from the back side.

Earl

You know Earl, I also had considered that in my planning phase...but then learned from others that a sealed floor acts like a bathtub if caught in the rain. So, I thought maybe having an opportunity for moisture weeping might not be a bad thing. It's funny how you can get into the minutia pretty quickly

I like the idea of the closed end rivets, and I actually used them on my motorcycle mufflers that I repacked about 20yrs ago... I think they were originally designed for aircraft fuel tanks.

Thanks for the perspective!

Craig C

I'm building an airplane right now and coincidentally just pulled 200+ closed end rivets for one of the fuel tanks yesterday. While they obviously make sense in this case, I really don't think they're necessary for a Factory Five build. The typical open ended pulled rivet is still closed by the piece of mandrel that's left inside once it breaks off. Once you complete all the rest of the finishing (insulation, carpet, etc.) it's closed off enough and fine. Routine moisture isn't an issue at that point. If you do want to pursue closed end rivets, a couple observations from my experience. (1) They're not quite as reliable. Even with the high quality (at least they're supposed to be...) Gesipa rivets I'm using, I've had several pull failures the few times I've used them. More than regular rivets. (2) At least for the brand I'm using, the mandrel is one size smaller than usual. For the 1/8" rivets I'm using the mandrel is the same size as used on a 3/32" rivet. These small mandrels tend to jam in my Milwaekee rivet puller if I'm not careful. (3) Haven't priced them, but have to believe they're more expensive. Plus you would need several lengths as I don't think they're available in multi-grip style.

As someone who's driven these cars for 12+ years and been caught in my share of rain, I find the "bathtub" comment a little over the top. We've been soaked for sure. But never to where there was that much water inside the cockpit. In fact, even in a driving rainstorm, if you keep moving, surprisingly little water gets inside. It's when you stop that it gets interesting. We generally head for cover if in stop and go traffic. Go for the drain holes if you want. But we haven't found them necessary. Since we're currently only driving the Coupe and Truck, both with roofs over our heads, the naysayers are going to point out of course we're staying dry.