zordak Reader
8/12/18 5:52 p.m.

Zordak's guide to broken fasteners

I am seeing a large number of posts with a mention of broken easy-outs in broken fasteners. I am going to share my experience with working on broken fasteners.

First lets break this down to 2 catagories, 1) Broken while tightening or sheared off and 2) Broken off on removal.

1) Broken while tightening or sheared off.
    As long as the fastener did not tighten up in the threads a very small chisel or punch can be used to back them out. Be careful damaging the top of the hole can cause a problem, not a big one but will need use other methods.
   if the chisel/punch does not work a left hand drill is next. Carefully use a center punch in the center of the fastener and drill. If the drill catches it will back out the fastener. If not use an easy out.
2) Broken off on removal.
    The first thing to remember is if the head broke off while trying to remove the fastener a smaller easy out will break as well. The only way to remove these is to start with a very accurate center punch, even more so if a steel fastener in aluminum. Sometimes using the tap drill size and a tap can clear out the broken fastener but be careful here as a broken tap cannot be drilled out with a carbide drill, way too hard and an interrupted cut. Trying this will just get you a broken drill. The best solution is to use heli coils or a thread insert.

I hope this helps. 

pinchvalve MegaDork
8/12/18 7:06 p.m.

My $.02: a slot cut into the exposed bolt/screw can often allow you to back it out with a standard screwdriver.  A Dremel with a cutoff wheel is ideal.  

nutherjrfan SuperDork
8/12/18 7:36 p.m.

I learned number two recently with a sheared off caliper bracket bolt and then a sheared off easy out.  I also learned a little later that evening that autozone sells reman caliper brackets.  blush  Still it's fun stuff when you have two registered back up vehicles.  smiley

zordak Reader
8/13/18 9:31 a.m.

Yes it is much less stressful when when you do not have to stay up all Sunday night finishing up an engine swap started Friday after work so you can get to work on Monday. 

pinchvalve MegaDork
8/13/18 9:53 a.m.

There is also a scale you can use to estimate the likelihood of a fastener breaking.  


Plenty of time, plenty of money, Other cars to Drive              1am, night before the big race, hotel parking lot, no stores for miles


           Fastener will NOT break no matter what.                                                        Fastener will DEFINITELY break. 

jfryjfry HalfDork
8/14/18 12:07 p.m.

Welding a nut to a broken fastener is often a successful option. 

There are plenty of options I would employ before trying an ezout 

boxedfox Reader
8/18/18 11:05 p.m.

I've had success drilling a relief hole all the way down the bolt, then cutting a slot at the top as pinchvalve suggested. Having the hole in the middle seems to give the fastener room to shrink as undoing an overtightened bolt often means that the stretched fastener needs to be compressed back into shape.

When that doesn't work I usually keep increasing the size of the hole until I've completely drilled it out. That's when I call up McMaster-Carr and order up some thread inserts.

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