The Stovebolt Site Forums The Shop Area Engine Shop Broken Bolt in Fly wheel Help!

Okay so I was installing the pressure plate and clutch onto the flywheel and I broke a bolt in the fly wheel. So I tried to drill it out and use a bolt extractor/easy out tool and what a ya know I broke that in there. I tried drilling more and I think I am already into the threads and I can't drill it out. I'm thinking of taking off the fly wheel and going to borrow my uncles drill press and drill it out bigger from the opposite end and retap the threads. Any ideas?

Getting the flywheel out where you can work would be a big help. What is this fly wheel off of?

Most manual flywheels for the old Chevy sixs that I have worked on have the hole drilled and tapped all the way through.

If so you may can drill from the back side with the drill press. Might get lucky and the bit catch the bolt and take it right out.

If you have to drill the hole bigger, then heli coil it so that you can go back with the same size bolt as the rest of them.

Pull it off and take it to a machine shop, the easy out is to hard to drill.
The easy out will have to be ground out.
This is one of those classic going from bad to worse situations, properly lined up and drilled right in the first place using a drill press or mill it isn't a bad thing to fix.
What you have now is a problem much harder to fix might need a helicoil or thread insert now.
The problem is keep buggering the treads and there is a good chance you will be looking for a new fly wheel.

easy outs are very evil things.

You can try using a center punch to see if you can back the bolt out that way,

I've backed out many broken bolts by using a center punch. It's my first choice to try.

I think you are to the point where you need to remove the flywheel and take it to someone who has experience in this kind of matter before you make an even bigger mess. Trying to drill a broken bolt is difficult because the bit will walk on the uneven break. And with a broken eze out in it thats harder than bits, its a difficult situation.

Aren't flywheels balanced? Bigger bolt/helicoil may put out of balance. Is it External balanced? Probably. When you are done, take it to a guy who does flywheel resurface.
They have balance knowhow.

I will try messing with it some more. If that doesnt work I will look for another fw as I dont see paying all sorts of on this. Thanks. I will keep you all posted.

Try and get the broken easy out removed with a punch. If you get it out I would use a left handed drill bit, usually the broken bolt will turn out.

I agree with that!

For years I've had great luck removing broken bolts by TIG welding a little blob on top of them, doesn't damage the threads in the least and I'd say better than 95% of the time they'll come out without drilling.

I just did a job removing some broken exhaust manifold bolts on a Cat bulldozer... the mechanics had already tried driling small holes, welding nuts on, and even broke an easy out in one of them. After giving up (not soon enough in my opinion) they removed the head so I could straighten out their mess. They expected me to set it up in the mill and drill them out, install helicoils if necessary. I figured I'd try welding on them just to see if it'd work the easy way and sure enough they all turned right out, made short work of that whole job.

I guess what I'm trying to say is broken bolts can be difficult especially for those that believe in "easy outs". It's well worth it to take the part to someone who's good at removing bolts before you make a mess of it, and even after you make a mess of it they might straighten it out for you and save the part.

Sometimes it's as quick as 2 minutes to weld on and remove a broken bolt. Same broken bolt with other methods someone could spend hours and hours drilling and who knows what else only to end up with very damaged threads.

Grigg

Check local machine shops to find out who has an EDM and take it to them. More info on the process:

http://en.wikipedia.org/wiki/Electrical_discharge_machining

Curtis suggestion X2

Welding onto the broken bolt ought to be cheaper than the hourly rate for a shop with an EDM.

Grigg

Yes welding is cheaper but if its inaccessable the edm is the way to go. 15 min tops.

CurtB, you are high tech man! but as Grigg says, watch the $$$. A new FW ain't that much at O'reilly's or Summit, etc.

Okay so after 2 hours of drilling and breaking a few drill bits I drilled through and tapped and heli coiled it. Whether it throws off the balance I will have to see. I just want to get it together and running before winter. Then by next summer I hope to have all the body parts together to paint it. After that I know I'm going to not like the lack of driveability on the highway so if I know that if the engine turns out to run good I'm going to go ahead and install a 700R4 auto in there to enhance highway speeds and fuel mileage maybe a bit. Does anyone know what these trucks run like with a 700R4 and a 230 inline 6?

I wonder if the 230 has enough power to run down the road in OD?

It might with the low geared rear? It is probably better to just upgrade the engine too. I might leave it as is if the engine turns out okay.

If possible welding a spot on the fastener as suggested by Grigg or even better welding a nut onto it should be the first choice. Drills, taps, and easy outs/extractors are generally made of high speed steel which is not as readily weldable and difficult to remove without carbide tools which is where EDM can prevent furthur damage. Another benefit of EDM is that broken fasteners are removed with no destruction of the parent material/thread and so should be a first choice in applications where a helicoil or weld repair is unacceptable.

Actually I started a long time ago by welding nuts to broken bolts and I've given up on that method unless it's really big and you need the impact to work on it.
Much better luck welding a blob on the broken bolt and using vice grips to turn it out. In my experience welded nuts shear off easier than the blob (of weld) held with vice grips.

Grigg

I've been dealing with broken bolts for over 50 years and I'm probably 75 miles from the nearest shop that has EDM. Most of the broken bolts are a result of being rusted in instead of being overtorqued. And most of them are in something that is not as portable as a flywheel. I have always used the welding method. with rusted bolts, the welding even breaks the rust loos. On large bolts that break down pretty far in the hole, drilling with a Jancy Slugger gives me the control to drill the bolt. In my opinion, small eze outs are just like glass waiting to break.

Yeah, easy outs make your life worse 85% of the time. I will think twice before using one next time. If possible it's better to drill through and use a heli coil or retap.

I ' ve always had good luck on this sort of problem by taking a nut the same ID as he OD of the bolt that was broken off and positioning it over the top of the broken bolt and then basicly welding the nut to the end of the brokenn bolt, as long as the easy out didn't get out past the OD of the bolt the heat from the welding process is usually enough to loosen the stuck bolt, and with the new nut welded to it you now have a way to turn it too!