One of my students accidently snapped one of the rear main cap bolts on our Shop SBC. It snapped off an inch down in the hole, so it's hard to get to. I don't have any left hand drill bits, and the bolt is hardened anyway. Any suggestions? -Shop Teacher Jeff
Sure, one of your students.... Drill into the bolt with a slightly smaller drill bit, and then use a small screwdriver & hammer to chip out the remainder. Run a tap down when you're done to clean up the threads. Ed
[ QUOTE ] Drill into the bolt with a slightly smaller drill bit, and then use a small screwdriver & hammer to chip out the remainder. Run a tap down when you're done to clean up the threads. [/ QUOTE ] To keep the drill straight during drilling and protecting the remaining good threads. Get a thin walled bushing to fit into the hole to insert your bit into. Better you than me.
They all have fancy names, like Techniques of Welding, but basically I do Auto 1&2, Auto Body 1&2, Welding 1&2, sometimes small engines. I'm the new guy here, and I'm still aquiring tools. -Bugman Jeff
Time for some new cariculium. I'm thinking "Extracting 1&2. Aactually i like the sleave idea to protect the remaining threads and with a good bit starting with 1/8 inch you should be able to drill it enough to use an easyout on it. Or better yet just call MEL I bet she could have it out in no time.
petejoe & roadevil got it the sleeve in the hole will not only protect the threads, it'll help keep the drill bit straight use a cobalt or some hard bit and extractor. or just toss the block, and get another, aren't SBC cores like about a buck apiece?
Hold a nut on the end of the broken bolt and fill the nut hole with weld. In other words weld a nut to the broken bolt. Use a socket to extract the bolt!
[ QUOTE ] Hold a nut on the end of the broken bolt and fill the nut hole with weld. In other words weld a nut to the broken bolt. Use a socket to extract the bolt! [/ QUOTE ] Hard to do when the bolt is 1 inch below the surface. You may try a copper sleeve and by using a mig welder, build it up to the surface and then use said technique. I haven't tried that but may work. The hard part would be to try to keep the wire straight as not to hit the sleeve.
You're a teacher, man! Do something to foster self-reliance! Lock the kid and the block into the shop, tell him he gets out when the bolt is out with no damage to the block, and go to lunch! Desperation and stark terror are the best teachers!
did it break when you tightened it or when you were taking it out? how much of the bolt broke off in the hole? its the remaining bolt bottomed out in the hole? all of these are things you have to consider before you start messing with it. especially with a bolt as large as that. when i used to remove broken bolts that were too tight for extractors, i would drill the hole off center. get it close to the threads with out hitting them. then put a nice sharp angle on old punch. i would use the angle of the punch on the thin side on what was left of the bolt. i would crush and then "peel" the bolt out of the threads. once the thin side of the bolt was gone the other side usually knocked loose. WARNING. this method could be very harmful do the block if you are not careful. i used this method many times while i worked at my old machine shop and never once harmed a thread. BE CAREFUL. oh yeah, if you do use extractors, make sure to drill all the way through the bolt. why you ask? if you break that extractor off in the bolt, then you are really screwed. those things will dull, a million drill bits before you can drill through the broken extractor. if you drill all the way through, you can knock the extractor out the bottom of the bolt and try again. hope this helps. diego
[ QUOTE ] Hard to do when the bolt is 1 inch below the surface. [/ QUOTE ] Get a nut small enough to fit in the hole and still be able to put a socket around it. The weld the nut to the bolt like I said.
[ QUOTE ] Desperation and stark terror are the best teachers! [/ QUOTE ] Aint that the Truth. I started doing my clinical rotations at the hospital and now work on live people! This quote will now become my motto!!!!Thanks BL this was what I needed after today!
Cap bolts don't go much deeper than an inch into the block anyway... Is it the block that it's an inch into or do you still have the cap on the broken off stud? In which case wiggle the cap back off....
Isn't the hole threaded right to the top? I don't think I've ever snapped a bolt DEEP inside a threaded hole! Weird. NO WAY your gonna weld a nut on it when its that deep. Hard to get weld penetration with so much metal sucking away the heat anyway. I like the bushing idea, with a reverse drill bit/easyout. Was it being installed when it broke or was it being removed? Did it turn at all? Gonna be interesting to watch... Bill
This is going to sound like a Bullshit story but... There is a Welding Supply Company Called "X-Ergon" that make a special Rod just for that problem. According to the Salesman that came by our Shop a while back, you stick the rod straight down into the hole, start the arc on the center of the bolt, then keep welding until it builds out the top of the Hole. According to the salesman, the Rod is covered with a special Flux that builds around the Filler metal as you weld and keeps the weld from sticking to the threads. It holds the molten metal and forces it to climb straight up like a Column. Once you are out the top with it, you weld a nut to that Column, then let it cool. After it cools off, the Slag supposedly crumbles into dust when you apply pressure with a Wrench, and the broken bolt comes right out. The salesman declined to demonstrate it for us, so it is debateable as to whether it performs as they claim. He did demonstrate this "wonderful" solder that would solder Copper to Aluminum. He soldered a penny to the bottom of a Soda can and told us that there was no way we could break the bond. I stuck a screwdriver in the can underneath the Penny, smacked it on the table, and the Penny popped right off along with all the solder. We haven't seen him since.
Thanks for all the suggestions. No luck so far. The bolt was comming out when it snapped. Judging by the length of the other bolt, this one may be bottomed out. It's not loose in the hole, and won't spin. The hole isn't threaded for the first inch on an SBC rear cap, so damaging the threads with a drill isn't a real big issue. I think I'll try to find some lefty drill bits this weekend. It is a hardened bolt, so I don't know how well it will drill. Can anybody think of a was to cut a slot in the bolt so that we could get a screwdriver to hold? That may spin it out. We've had nothing but trouble with this motor since we got it. If it wasn't free, I'd probably be pissed -Bugman Jeff
Shouldn't need to cut a slot in it, JT, if you use a left hand drill bit. I'd drill the sumbitch all the way through and into the block material, taking away the pressure of the bolt being bottomed out. It should spin right out then If not, a simple EZ out should remove it, now that the strain is no longer on it.
Thats seems kind of odd to me for a Main cap bolt to break off like that. I have rebuilt probably 15-20 SBC's since I first got into Cars and I have never seen one that was even remotely hard to get out. You sure one of your Students wasn't cranking on it the wrong way? Hang a Big sign on the shop wall that says "Righty Tighty, Lefty Loosey"...
The Jalopy Journal
