Broken bolt
 

The bolt that holds my rear rack and fenders broke off flush with the frame. I picked up a bolt extractor and could not get the portion of the bolt out of the frame. So, now I have a hole drilled all the way through what is left of the bolt.

I'm afraid to keep going to a bigger drill bit, since I'll eventually be drilling and damaging the frame.

So, here are my two thoughts on where to go from here:

First option is to pick up a left-handed extraction bit. I don't have to back the remainder of bolt out of the frame. With a backward extraction bit, I would just drive the bolt on out the other side.

Second is that I get a tap/die set and just rethread the mounting hole. If I don't hit it dead center, it will rethread the frame on one side and the remainder of the broken bolt on the other. Once I have a new bolt screwed in, everything would get locked into place and I'd never have to worry about it again.

Any other thoughts on how I can get my rack back onto my bike?

The frame looks to be a steel one, is this right? I think the extractor you first tried had a left hand twist (the twist type usually are to both deepen the extractor's engagement with the bolt as well as unthread the bolt during use). So a left handed extractor might be misleading, as I wonder if you mean a right handed twist?


I would further using increasingly larger drill bits and try to remove as much of the bolt as possible. If you are able to keep the bits centered eventually you'll end up with just the threads left (from the bolt). At this point you can run a tap through and it usually will pick up on the existing threads and remove the bolt's thread remains.


If worse come to worse drill through and use a bolt long enough to use a backing nut. Either way you go I would go through ALL the hardware on the bike, ALL the threaded and clamped fittings on the bike and remove, clean and lube before more corrode in place. You have received a shot across you bow. Andy.

It is a steel Jamis Aurora.
Yes, the extractor that I used had the left-hand threads. What I meant was an extractor designed for removing left-threaded bolts. That extractor would be right-hand threaded, so it would drive the bolt out the other side.

If the other extractor doesn't work, I'll go back to drilling.

This was a case of me riding my bike through some terrain more rugged than a road bike is designed for. When I got to the other side, the bolt had snapped and my rack was sitting on my fender. The other mounting hardware I removed to get back on the road looked good, but I'll certainly give my bike a good going over.

A back nut is my last-ditch option.

Thanks.

Is there enough protruding from the back side that you can grab with a vise grip?

If the dropout eye is not a blind hole, but extends all the way through the dropout, you may be able to extract it without a dedicated bolt extractor bit. A regular drill bit is often able push the broken bolt shaft out the other side of the dropout.

Initially, there was a little shy of 1/16 of an inch sticking out the back side. My first attempt at removal was that I cut a slot into the part sticking out with a Dremel tool and tried to remove it with a small, flat-head screwdriver. Unfortunately, the grove I cut only weakened the part sticking out and it broke off. Leaving me with a bolt that was flush on both sides.

The next day, I picked up the extractor bit.

Is there enough protruding that a small, sharpish cold chisel can catch enough to collapse it inward?
Then, maybe something like a lag screw may exert enough force to spin it out.
Apply some REAL penetrating oil and let it soak for a while before and after.

If you drilled all the way through the bolt, Use the extractor on the inside and try turning it out that way. i.e. pulling it through to the inside.

I was forced to learn about bolt extraction a year ago. what worked for me:

- drilling a hole the correct diameter (for the extraction bit to get in there and grab hold)
- using a straight fluted extraction bit with the proper tap wrench

see posts #32 & #44
http://www.bikeforums.net/foo/100481...ar-body-2.html

The more I read about the straight fluted extractors, the more I'm thinking this may be my next step. I have a 1/8" hole going all the way through. If I can find a matching extractor, I can go at it from either side.

Thanks.

When drilling into the bolt or through the bolt use a carbide bit. They are hard enough to drill through a bolt and less likely to stray to the side than other bits. On the other hand, they are brittle and you have to be very careful not to break one off inside the hole. Don't push it in overly hard nor swing it to the side. Best would be to immobilize the bike relative to the drill, e.g. use a bench drill on the floor.

You can always drill it out, and tap it for a Helicoil insert.

Soak overnight in penetrating oil, and try drilling with a left handed drill bit. It will tend to back the broken piece out as you drill through. Bit size small enough not to touch the threads of the frame. Usually a well stocked old-fashioned hardware store will have them.

A couple of cheap methods to try are using a torx wrench lightly tapped in the drilled out bolt or just get the appropriately sized machine screw which will screw into the bolt and can just be used to turn it out from either side. As mentioned let soak in some penetrating oil for at least a day before trying to extract it.

Or just drill out and use a bolt and nut.
Or drill out and tap to the next larger size.

Heilcoil inserts usually want more then a few threads of overlap. Now a "T" nut... Andy.

Follow-up!
I had planned on getting a straight-fluted extractor over the weekend. The weekend got away from me and I never did. I did find my penetrating oil out in the garage and began saturating the bolt. Several times a day, I'd walk by and apply a bit more.

We had other distractions for the first part of this week, so I didn't need my bike. Yesterday, my wife's van came back from the shop and I returned the loaner car. I had to have my bike ready to get to work today. So, I decided to take another stab at extraction, last night. I again, tried the extractor that I picked up last week. I got it wedged pretty well into the bolt (sticking out the other side, even) and began applying more pressure. This lasted just a few minutes and then the extractor snapped. It had become a smooth cylinder with threads firmly wedged into the hollowed out bolt. Finding purchase to turn it in either direction was beyond difficult.

I decided that I just need to remove the extractor and take this up at a later date. So, I got my Dremel tool and created flat spots on either side of the cylinder, used a crescent wrench to turn the extractor bit and back it out.

While doing this, I realized how little material seemed to be left of the hollowed out bolt. For fear of damaging the frame's threads, I didn't want to use a fatter bit, but as suggested farther up, if I could get one side of the bolt to break and collapse in on itself, I could get it out. (Bill suggested using a chisel above.)

My cordless drill turns much slower than my AC drill and it has a more responsive trigger. I loaded up a bit that was smaller than the hole going through the bolt and put it all the way through. Then, I kept the drill at a slow pace and used it as a saw, applying pressure sideways. It was carving away tiny shavings of the bolt and I would stop very frequently to see how thin the bolt was, on that side.

Eventually, I cut entirely through to the frame. Then took a tiny flat head screwdriver, (like an eyeglass-screwdriver) and used a jeweler's hammer to gently tap it under the now exposed edge of the bolt. Once it was wedged in, I was able to pry up just a bit more of that edge of the bolt. It took two more passes with the tiny screwdriver to get the bolt folded in on itself. Driving a new bolt into the hole pushed the now hollowed and collapsed bolt out the other side.

It was after midnight, so I thought I'd wait until tonight to put my rack and fender back on. My wife then reminded me that it was supposed to rain this morning, so I stayed up and got everything back onto my bike. It did rain on my ride to work so I was glad to have the fender back in place.

As much as the ideas to get the broken bolt out were all helpful, I think the words of encouragement to stick with it were what really got me through this without giving up. Impatience would have been my undoing, if left to my own devices.
Thanks again, everyone.

Bingo!!!! I have had a lot of experience removing broken off bolts. The first thing I always did was soak the broken bolt with light oil and let it sit.

Then use a punch to "unload" the bolt, by tapping it down in the threads. Then it looks to me that at this point that an "easyout" bit will get the broke bolt out.

well done Sir!

KUDOS to your wife for reminding you of the weather and not saying"come to bed honey it'll be there in the morning"

I've had good results drilling out and tapping with the original size tap.

File or grind flush first to make it easier to center the hole,

and use increasing size bits, adjust the hole toward center after the smallest, most fragile drill sizes.

Even if the final hole is not exactly centered, and some metal is removed from the frame,

a bit of locktite will make up the difference.

Once you have a hole drilled in the problem bolt, one of the easiest things to do is to drive the square tang of a file into the hole and use an adjustable wrench to turn the file to unscrew the remaining part of the bolt. I've done this in the last year in my own garage. It's an old Italian bike mechanic's trick. No special tools, no wasted time (if you have a file the right size) and you get to post about it in places like this.

genius cuz that square tang is tapered and can be used for a spectrum of diameters. gotta remember that trick!

The tang is annealed, so it might just twist.