Well Sunday I had a mishaps with a curb and well busted the lower a-arm up...I have an S4 NA... and well one of the bolts that hold the lower ball joint on broke, bent the bracket and the other bolt is just hanging on...
And this all happened on a wet day going only 35 mph into a righthand-upward slopeing turn.

now to the Question...Will a S5 Arm bolt up without problems?

 

no

you'd need both sides plus the S5 endlinks and maybe sway bar aswell.

 

you should be able to find a plentiful amount of S4 parts many places start with your local junk yard, the S5s are all one piece with the ball joint connected to the controll arm....wow I hit a curb understeering at prolly 35 to 40+ was kinda messed up at the time, and only ended up bending spindle on the knucle, it was about 10 degrees
down to what it shoulda been, I've since learned my lesson, though I think I also bent the frame cause the shop could never aline it, Lol I remeber I ran over a stop sign to, go outa my car started cursing myself, and bent the stop sign back up to the normal position....my skid marks are still there, I belive it was about a year ago, I prolly was going faster than I thought, I hit a run off from a damn sprinkler in JAN!!! (Only in TEXAS) but I did deserve a eye opener, though my car didn't, and man my rim was FUBAR!!!

 

IM pretty sure I would have s4 LCA's in stock pretty cheap.