So I bought the m10x1.5 fix a thred kit from advance auto parts today to fix a stripped hole in the subframe that my upper control arm goes into. These bolts are crucial as they’re the only things holding the control arm to the frame (and thus the knuckle). I bought the tap because I’m using grade 10.9 bolts that are aftermarket because OEM ones weren’t salvageable (also because the nut at the back of the subframe broke off and I don’t want to cut it open). The fix a thred kit comes with a handle, tap, and helicoils. My questions are: -if I drill the holes out with the recommended 13/32 bit and then run the tap through, would that be enough to strongly hold the new bolts? -do I need to install the helicoils? What purpose do they serve(id really like to just put the bolt into the subframe without these)? -if I need to put the helicoils in, are they strong and reliable enough (like the grade 10.9 bolt) to hold up to the stresses of the suspension?
Thank you for any answers, I want to do this job right with a permanent fix and not a temporary patch up!