Stripped Crank Bolt Help

[bikser]

The heads on one of the pinch bolts on my Shimano crankarm has gotten stripped/ rounded while installed. No 5mm wrench that I have can get a tight enough fit to unscrew this. With the bolt being recessed it makes it trickier as well. I can't think of a good outcome if I drill it out. Thoughts on how to get this out?

[djg21]

The heads on one of the pinch bolts on my Shimano crankarm has gotten stripped/ rounded while installed. No 5mm wrench that I have can get a tight enough fit to unscrew this. With the bolt being recessed it makes it trickier as well. I can't think of a good outcome if I drill it out. Thoughts on how to get this out?

Can you tighten the other one, and then try to wedge a flathead screwdriver in the stripped one? Other than that, maybe a spriral screw extractor if you can get it in without marring the crank?

[oldpotatoe]

The heads on one of the pinch bolts on my Shimano crankarm has gotten stripped/ rounded while installed. No 5mm wrench that I have can get a tight enough fit to unscrew this. With the bolt being recessed it makes it trickier as well. I can't think of a good outcome if I drill it out. Thoughts on how to get this out?

Try a wee bit larger US sized allen..7/32 allen?..tap it in...When installing a new one..grease and follow the torque specs exactly(8-12nm??), it isn't much.

[martl]

The heads on one of the pinch bolts on my Shimano crankarm has gotten stripped/ rounded while installed. No 5mm wrench that I have can get a tight enough fit to unscrew this. With the bolt being recessed it makes it trickier as well. I can't think of a good outcome if I drill it out. Thoughts on how to get this out?

drilling it out is not such a big deal. You need a 5mm drill bit (which is exactly the size of the bolt), it will self-center because of the old allen-key hole, and the bolt will fall off the second the drill bit reaches the end of the head.

[oldpotatoe]

drilling it out is not such a big deal. You need a 5mm drill bit (which is exactly the size of the bolt), it will self-center because of the old allen-key hole, and the bolt will fall off the second the drill bit reaches the end of the head.

But how to get the remnants of the bolt out once the head is gone..'maybe' an easy out but for lots of bolts it's anything but 'easy' to get 'out'..

[martl]

But how to get the remnants of the bolt out once the head is gone..'maybe' an easy out but for lots of bolts it's anything but 'easy' to get 'out'..

Ah, we're talking the center bolt? Then its not a 5mm :) But the conceptstill works: once the crank is off, there will be enough bolt free to grab with pliers. Without the bolt head, there is nothing to create any holding force in the thread itself.

[oldpotatoe]

Ah, we're talking the center bolt? Then its not a 5mm :) But the conceptstill works: once the crank is off, there will be enough bolt free to grab with pliers. Without the bolt head, there is nothing to create any holding force in the thread itself.

No, the pinch bolt on a 2 piece shimano crank methinks. The remnant will be in the threaded portion and the 'slot' in the crank arm isn't wide enough for a needle nose.

[Clydesdale]

Can you notch the bolt and use a screwdriver?

Otherwise try superglue or epoxy on an old wrench and let it set up and then hope for the best?

[dddd]

A smaller drilled hole, following the removal of the bolt head, will allow an appropriately-sized EX out to then do it's job.

I believe there is a threadlocker coating on these bolts, so it's unlikely that the drilling would by itself rotate the bolt out of the other end.

[guyintense]

I would start with penetrating oil, Kroil is my favorite. Let it sit for a while then drill with an 1/8 inch bit but from the other side, not the head. The act of drilling should drive the screw out.

[Billybob62]

https://www.walmart.com/ip/Screw-Extractor-Drill-Bit-Combo-EX-3-5-32-Bit/22861168?wmlspartner=wlpa&selectedSellerId=0&adid=22222222227016873954&wl0=&wl1=g&wl2=c&wl3=51752135591&wl4=pla-83136654911&wl5=9005815&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=online&wl12=22861168&wl13=&veh=sem

[Cicli]

Left hand drill bits are the best. It will come right out.

[cmbicycles]

I would combine two of the above, tighten the other bolt to take some tension off the stripped bolt, then use a sae wrench as elder spud mentioned (or a torx bit, or screwdriver). These two should help you avoid needing to drill out the bolt, which works, but can be a pain in the neck. If those don't work, then you can drill off the head, use left handed drill bits, and/or use (not quite so)EZ-outs once you drill through the center of the bolt.

[Tony]

Tighten the other bolt, some penetrating oil and a torx slightly larger than the hex I bet will work.

[martl]

No, the pinch bolt on a 2 piece shimano crank methinks. The remnant will be in the threaded portion and the 'slot' in the crank arm isn't wide enough for a needle nose.

Ah merde, i'm losing contact with the modern world, it seems.
Yes i agree that may be a problem. Getting a bolt out of that cave may become a bit challenging...

[bikser]

Not going so good. Screwdriver, torx head, and extractor did not work. Trying the drilling from the reverse side. Can't tell if I'm getting the bolt or not. Keeping an eye out for a 9100 left arm just in case.

[vqdriver]

bummer, i would have suggested tapping in a torx head in there.

that's a cramped space to fit a file, but you could try an oscillating tool to cut a slot for a regular flathead

otherwise, extractors have always worked for me.

[weaponsgrade]

As last resort, slip a hacksaw blade between the slit and cut the bolt in half. Then use a needle nose plier to grab onto the cut ends and remove.

[bikser]

The Torx head didn't have enough real estate to dig into the bolt head.

The bolt is the inside pinch bolt, so with the plastic middle piece I don't think I could get a hacksaw blade in there. Or, if I did wouldn't have enough room to make a cutting stroke.

[steelbikerider]

Speedout #4 in the set works perfectly. I know through experience

https://www.youtube.com/watch?v=nfS6zQtsqQ8

[johnniecakes]

Once it loosens up you should be able to get it out relatively easily. The trick is to loosen it up. Get your self an impact driver for cheap and use the tightest fitting bit you can find and give the driver a whack with ball peen hammer. This will break it loose and then you are good to go.
1697962229

[dustyrider]

I used to work on a guy’s bike, when he got in over his head, who used round Allen keys exclusively and all of the hardware was typically rounded out. He eventually replaced all the hardware with harden steel bolts after this exact same thing happened to his shimano crank. He said he didn’t want to get another set of Allen keys...When he brought me his bike with this exact problem, scratching his head, I did all of the above in order to save the crank arm. In the end, he ordered a new crank arm and we just used a dremel cutoff wheel to slice the bolt and remove the tension. Once the arm was off, I could see maybe drilling it out from the back and pulling it with an easy out, but it is such a thin bolt you’d really want to use a drill press and plenty of patience.

[bikser]

Even if I had a drill press I don't know how I'd get my new carbon frame up into it. I'm hand drilling it. Waiting for the battery to recharge. Pretty sure the arm is toast, but won't know until I'm done. I've installed Shimano cranks 100 times never had this happen. Poo happens.

[loxx0050]

Have you tried a piece of rubber (like a wide/thick rubber band). Use that as shim to give a bit more grip inside the striped hex head (or rather cover the bolt head with the rubber band and force in the allen head through it). For low torque bolts it should be just enough grip to break loose. I can picture how to do this in my head perfectly but can't seem to eloquently explain it right now. Sorry if that is a bit confusing.

Another option is to sacrifice an old allen/hex wrench. If you have access spot weld it on the bolt to remove. Or epoxy them together.

I once stripped a headset cap bolt (stupid stock one was aluminum 2025...who spec's bolts out of aluminum?). But, I got it loose by using a ball end version of the hex (placed in normally, then basically tilted it until it was a 45 angle (ish). Basically like wedging something in there to get it to move. Replaced that sucker with a stainless bolt (and now have 24 spares as I could only find them at the time through McMaster-Carr).

[FriarQuade]

Drill the head off, once the tension is off the bolt it will make it pretty easy to get the rest of the bolt out without destroying the crank arm. You can often keep drilling with a small bit and the stud will just wind out the backside of the hole.

If it's too late for that, a helicoil or a long bolt and a nut could tide you over till you find a replacement crank arm. Perhaps Stages has a scratch and dent you could procure? They go through a lot of left side crank arms.

[steelbikerider]

I have found the pinch bolts to be pretty soft and always have spares around to replace the old ones if they even start to round out. As I stated above, the Speedout #4 made quick work of removing the old bolt when I wasn't paying attention and rounded it out. It took all of 5 minutes with just a slight rub mark on the crankarm,

[David Tollefson]

Use hex+ wrenches.

[cmbicycles]

Did you try tightening down the other pinch bolt to receive tension on the stripped one?

[bikser]

I've tried everything suggested, and a few things I saw on YouTube.

Purchased the Speedout Pro, half price at Lowes did the trick in a few seconds. There's just a small mark on the outside of the bolt hole, and the crank arm seems to be good to go too. All the drilling didn't seem to hurt the threads as the other bolt went into it just fine.

Thanks for all the suggestions Paceliners.

[cmbicycles]

It's always a good thing when the problem doesn't win. Glad you got it out.

[Black Dog]

Did you try tightening down the other pinch bolt to receive tension on the stripped one?

This. Any act of removing the striped bolt will be made easier with the other bolt tightened down.

[oliver1850]

Glad you got it out. Late to the thread but I would have gone with what Peter suggested early on. You can grind an oversized hex wrench a bit on each flat, and usually tap it into the hex far enough to break most screws loose.