Hi all, I've been doing some work on my tractor and encountered a problem. I had to remove the mandrel/spindle assemblies from my mower deck. One came out fine but I broke off one of the three mounting bolts on the second one. It broke off so close to the top of the casting that I couldn't get a pair of vise grips on it. So I went to the grinder and ground it down nice and flat so that I could drill a hole down the center and use an easy out. Well I got the remainder of the bolt out but it WASN'T easy. In the process though I ended up destroying the threads from the original hole. It's an aluminum casting. I have some Durafix aluminum repair rods that I used to repair an aluminum engine block casting last fall and they work great. I was able to fill the hole and get it ground down and cleaned up. I figured I could drill a new hole and tap it. The bolts are 5/16-18 bolts. If I pick up a 5/16-18 tap, would I drill a 5/16 hole? Or is that not correct? Maybe the tap would have directions on the size hole to drill but I just wondered if anyone here might know. Any input would be greatly appreciated. John Wanna kill these ads? We can help!