Downtube bosses predicament

[R Olson]

Hello everyone, I've gotten myself into a bit of a predicament with one of my downtube bosses; I've sheared off the bolt flush with the brazed on boss (see pic below).  Any ideas on how to extract it?  I've tried using a drill extractor bit with my drill, but didn't work. 

Thanks!

Ryan

[Brian Forsee]

Ryan,

If you have a (very) small rotatory tool/dremel you can cut a slot in there and then use a flat head screw driver to back the bolt out. If its not quite completely flush you can try grabbing it with some vice grips too.

Good luck! If you cut a little bit of a slot into the boss itself that's probably no big deal, although depending how deep it gets it may necessitate re-tapping the threads in there.

Brian

[Will Boericke]

I hate these situations and find myself there more than I'd like.  I have never had a whole lot of success with EZouts or the like.  It looks like you have a pilot hole there; I'd be inclined to drill a bigger one and hammer a torx in, maybe with some duct tape to ensure tight fit.  Then unscrew.

Or make a slot with the dremel and use a flat head.  You probably only get to do one of these things though, as you'll run out of room.

Will

[R Olson]

Lol, glad to hear that these things happen to other people too!  Thanks so much for your ideas Brian and Will!  I like the slot idea.  I do have a dremmel tool, so I might give that a shot.

[lconley]

Use some penetrating oil on the threads (PB Blaster, etc.). Get some left handed drill bits and drill larger holes, preferably in the center of the sheared off bolt. It may be that the left handed drill bit will grab and extract the sheared off bolt all by itself. If not, the more of the sheared off bolt that you can remove with the drill, the better (the more centered you are, the more of the sheared off bolt you can remove) as it weakens the bolt. You may be able to use Dremel tool and to created a more centered starter hole before you start drilling. Stop short of removing any of the threads in the boss itself. Last resort is to use an EZ-out that is basically a left hand threaded hardened tapered tap that is designed to grab the sheared off bolt. The bigger the hole, the bigger of an EZ-out that you can use (bigger = stronger). DO NOT snap the EZ-out off in the sheared off bolt - err on the side of caution here, the EZ-out is very tough steel and hard to drill through. 

Not for the faint-of-heart, but you can also cut a slot through the threads of the boss and bolt on one of the flats of the boss. This will weaken the boss's grip on the bolt. if this works, you can repair with JB Weld, a tap, and a file.

Heat is another option, but I assume you like your paint.

If all else fails - -> Single Speed!

Laing

[Patrick Moore]

I did something similar with my 2020 Matthews: overtorqued a dry screw holding a front lowrider to the fork leg boss, and snapping the head off, leaving <1/8" of the shaft protruding. It was just barely enough to grab securely with needle-nose vise grips and with liberal applications of spray lubricant, patience, prayer, and 30 minutes of tiny back-and-forth rotation I got it out without damage to anything.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[Steve]

Ryan -    Oh yeah - been there, done that!    Here's one more trick you can try that I've had success with. Start with lube as suggested (maybe lay the frame on its side so gravity can promote penetration of the lube). Apply some "gentle heat" with something like a hair blow dryer. After the lube has had a chance to penetrate and you have it warmed it up use a punch or similar tool (small drift or even a screw driver) and wedge the tip into the dimple your drill bit formed (it looks like you may have one right on the edge of the sheared bolt) Hold the punch with a  firm grasp and begin tapping it with a small hammer. The punch should be angled as much as possible to direct the torque counterclockwise. Tap, tap tap - It will take at least a few dozen strikes. You may want to mask off the surrounding down tube with cardboard and  tape to protect it in case the tip of the punch slips. 

Let us know what works so we can all learn from your adventure. Happy wrenching!

[R Olson]

Thanks all for your suggestions!  I really appreciate it.  I did work on this over the weekend, but unfortunately could not get it out.  At first, I tried the slotting method - using a Dremel tool to cut a small slot in bolt, which I successfully did.  I also added some lube and let it sit overnight.  When I went to unscrew it, it wouldn't budge though.  I think it's just torqued in there really tight.  I don't have a blow torch, and didn't want to make the situation worse by potentially damaging the tubes or paint with this method.  It's hard to see in the picture, but there really was absolutely nothing to grab onto, it was exactly flush with the boss.  I did try hammering it a bit to try to rotate it, but it still wouldn't move.  I might just try using some adhesive to glue on the stop on that side.  I don't ever plan on putting a shift lever there, so it'll probably be ok.  The biggest takeaway for me is to grease up the bolts and rotate them in and a out a few times, and to STOP screwing it in when I feel a lot of resistance. I am going to be much more careful whenever I tighten bolts from now on for sure!

Ryan

[JohnS]

Hello Ryan,

The problem with trying to drill out a hole and using a big enough easy-out bit to be effective is getting the hole centered. Easy concept, but hard to do in reality since the drill bit wants to wander from center until it grabs. Solution, create a guide for the drill bit so that it is centered. 

Details:

1. Sack up 6 or 8 M5 washer and slide them onto a M5 bolt.

2. Using blue tape, tape the washer stack to the shifter boss and remove bolt.

3. Use a wire size #3 drill bit to drill into the bolt just slightly, about 1/32 or 1/16 of an inch.

4. Remove washers and drill a suitable hole for an easy-out to be started, but not too big that the drill hits the bosses treads, still kind of tricky.

The #3 drill bit is snug fit for the M5 washer. A 13/64 bit is loose, so I won't recommend that. I used this process recently to center a hole on a 1/2" steel rod so that I could tape it for a M5 bolt. It worked great in my situation since the rod isn't as hard as a bolt and I wasn't trying to use an easy-out. Also, I used a drill press (one of my favorite tools).

Good luck,

John

[Will Boericke]

A hair dryer might give you enough heat to make a difference. 

Thanks for the drill guide tip, John.  I'll definitely use that in the future.

Will

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[Minh]

oof tough situation.  when you cut the slot and tried to unscrew, did you use something besides a screw driver?  like a wrench with a slotted socket?  that could give you more leverage.   if you can get a small hole, a torx driver could give you more grip, and same deal with leverage.  since you are unlikely to need this boss, i'd give it a little bit more effort but at some point i'd also stop and just cover it up and leave it alone.  

[Brian Forsee]

If you think the slot you've cut gives you enough bite you can get decent torque on a screwdriver/whatever you're using, it may be worth trying the lubricant again. Put the bike on its side so the oil will drain down into the threads, and use a penetrating oil like pb blaster/boeshield/wd40 if you're not already. Flood that thing and let it sit for awhile more.

[Bill Lindsay]

You hinted at how you got here later down the thread.  Can you describe exactly how you got here?  The hint was you were screwing in a bolt into your shifter boss and you felt a lot of resistance and you just kept forcing it until the bolt broke.  

1. Seems pretty safe to guess you did not run a tap through the threads first.  Right?

2. Was there a ton of resistance from the beginning?  -OR- did it thread in easily, and then you hit the bottom of the hole and kept forcing it?

Either way, the recommendations of "penetrating oil" seem a little off-topic for this situation.  Penetrating oil is good for corrosion situations.  This is metal on metal brute forcing something.  I think the other takeaway should be that anybody who wants to pull together a build on a frameset should probably have a tap handle and the three most common taps:

1. M5x0.8mm

2. M6x1.0mm

3. M10x1.0mm

Doing those prep steps can avoid some major curse sessions...unless you break off a tap!  That's heartbreaking.  

Bill Lindsay

El Cerrito, CA

[George Schick]

1.  Bill sez, (...the recommendations of "penetrating oil" seem a little off-topic for this situation.  Penetrating oil is good for corrosion situations.  This is metal on metal brute forcing something....)  Bingo!  I've been in situations like this before, too, and have found "penetrating lubricant" to be next to useless.  You just can't work enough in between the jammed threads to make any difference.  Current case in point - I'm trying to get the drums off the rear brakes of my truck to inspect (I detect squealing from back there) and I can't budge them.  I've tried spraying PB Blast'r between the wheel studs and the outer surface of the drum - no dice.  Next step is going to be using a short piece of rebar I've filed a conical surface onto the end of, work it in between the rear edge of the drum and back plate, and bang the crap out of it with a sledge.

2.  In addition to the rest of the replies, if you do need to chase the threads be sure to use a light oil and go one turn in and back out a half turn for each inward turn to clear the tap or it may get stuck in there and break off.

[lconley]

The other possibility is that if the bolt was stainless steel, it could have galled and again, penetrating oil will be unlikely to help.

Tools: I have a set of thread cleaning tools - these are for cleaning up existing threads, they look similar to taps and dies, but will not cut into / remove the metal, thus retaining the strength of the metal. Hard to find in the smaller sizes, but the correct tool for renewing existing threads.

Laing

[Will Boericke]

Not sure what tools you have; my cordless drill has an impact-ish setting that is good for this work as well.  Keep at it!

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