What are peoples thoughts on replacing a self-tapping/tri-lobe bolt (like rear lower shock bolt) with a regularly threaded bolt of same size and grade?
Would the thread contact be the same?

 

FYI: The R56 lower shock bolts are "regular" bolts (not tri-lobe), and the shoulder is the right length, which is challenging if you try your local Fastenal fastener store. Thread length is a bit longer, but they can be trimmed.

Untrimmed will be perfect if you decide to switch to the aluminum R56 trailing arms too.

 

On the Aluminum trailing arms I just swapped on to my R53, they came with tri-lobe lower shock bolts. Maybe there are differences in the years, I’m not sure what car they came off of.

Ah, yes, I didn’t think about the shoulder for that bolt though. I wasn’t going to worry too much about length since it is open on the back.

I’d really like to replace the top shock mount bolts but not sure on the thread situation.