2003 Rs6 Broken Rear Strut mount bolt- Ok to replace captive nut with regular nut?

[74norton]

I am working on the Koni swap in my shop. My car came from Michigan and many fasteners are corroded. In removing the rear strut tower mounting bolts, 3 out of 4 of mine snapped. In retrospect I should have stopped after the first break and reevaluated my approach to removing them. I am sure I could have gotten them out in one piece.

But here I am.

I am considering just chiseling off the captive nut welded on to the body and replacing with a non captive nut.
I am wondering though if this may be a bad ideal since these bolts take alot of impact from the suspension. Maybe they are captive because it helps them from working loose?

I can drill out the broken studs and extract them but it is a harder process and I have to remove the UCAs which is extra work.
On one I drilled it out but could not clearance the UCA to get the drill straight so the hole is off center a bit. I am going to have to drill and retap that one. So the UCAs have to come off anyway.

Im seeking expert input on this question:

Drill and retap the captive nut with one size bigger threads (or insert helicoil) vs. just whacking off the captive nut and replacing with grade 8 nut? Id prefer to just whack the nut off and use a regular but but I dont want to compromise anything. There is a reason Audi didnt use a loose nut here.

I wish I could get in there to weld the nut on, but I am not sure there is enough room and it will be impossible to get to the back. Plus the welder might set the liner fabric on fire.

Advice appreciated

thx

Charles

[GreggPDX]

I'm not an expert, but I believe you'd be OK with a non-captive nut. There are many fastners on the suspension that don't use captive nuts, so I don't see why this one would be any riskier than those. There are likely multiple reasons why Audi would choose that fastener setup, and it could just be related to ease of assembly. A locking nut would be a good choice (lots of these on the various control arm bolts anyways), and some red loctite if you're really concerned.

Good luck!