Broken 17mm suspension...Help me
 

Yesterday I was replacing my shocks and springs on my 90 miata. On the fronts there is a 17mm bolt underneath where the bottom of the shock mounts that must be removed from what i've read. They were both very rusty. Both L and R side bolts broke. I got the passenger side out. The other one is stuck. First of all whats the bolt for? And if worst comes to worse could I just replace the part the bolt is stuck in?