Anson SA6 roll hoop

[Lastminuteracin]

In the process of restoring the Anson. The roll bar has been removed due to damage before I got it. I do have a replacement. Originally it was epoxied and riveted. It’s been replaced before and some of the rivet holes don’t line up or are wallowed out some. Any reason I can’t replace the rivets with proper AN bolts and nylocks? If so should I still use epoxy too? While I’m no engineer I’m thinking that I’ll be adding a slight amount of weight but the strength in both shear and peel will be greatly increased.
I’m trying to get it all fitted before sending it for powder coating.

[jrh3]

This could be a very important part. Take a look at Carrol Smith- Prepare to Win.
If it were my car and head I’d add an oversized doubler with aircraft rivets.
Honeycomb , probably pull rivets for doublers. You might want to make friends at the local EAA aircraft chapter.
Vans RV builders have lots of aluminum skin experience. Zinc. Chromate primer between the steel and aluminum is nice. A strap duplicator can be useful for spotting the holes.

[Lastminuteracin]

This could be a very important part. Take a look at Carrol Smith- Prepare to Win.
If it were my car and head I’d add an oversized doubler with aircraft countersunk bucked rivets.

I do have all his books and have tried to determine the best course. Do you think the bucked rivet will be stronger than an AN bolt? And yes I'm seeking opinions as I strongly believe in safety.

[J Leonard]

Are there bobbins or spacers the thickness of the honeycomb where the rivits used to be? I think a full backing plate would be good to sandwich the honeycomb and spread load.

[Lastminuteracin]

Are there bobbins or spacers the thickness of the honeycomb where the rivits used to be? I think a full backing plate would be good to sandwich the honeycomb and spread load.

Yes sir, the round things with the extra holes are what you describe. I have already made a batch of them and removed the one side. The side with the single holes should still be useable. I was planning on bonding a backing plate to the underside. Im just hung up on the actual attachment method. Thank you for the response.

[Fred Michael]

Structural blind rivits are just fine as long as they are properly installed and sized correctly, as long as you have corrected the oversize holes with a new panel or bobbins

[bobmic]

To answer your original question, yes AN bolts would be stronger in tension and shear. All other comments are good and for sure a backing plate is the right choice. Epoxy would give you a joint that won't start moving around after years of vibration but with that many bolts I doubt that will happen anyway.

One thing to think about is the fit of the bolts. Bucked solid rivets will expand slightly to fit the holes when they are bucked. Bolts need to fit properly!

[Lastminuteracin]

Bringing this back as I’m finally there. All bobbins replaced, new hoop mounted and drilled for proper NAS shear bolts. Do I still need epoxy or are the bolts, large backing washers and backing plates sufficient?

[bobmic]

Bringing this back as I’m finally there. All bobbins replaced, new hoop mounted and drilled for proper NAS shear bolts. Do I still need epoxy or are the bolts, large backing washers and backing plates sufficient?

I would say properly fitted bolts are adequate and epoxy is a bonus.