Broken screws in bike frame

[Cocximus]

I tried to move a rack between two bikes and one of the screws that holds the rack broke off without much force on both bikes. Both have been carrying a lot of weight.

I got one screw drilled out, but the extractor is not budging the screw. Can I heat up an aluminum frame? Will it weaken it?

The other screw broke off at an angle. I can't punch it's center. Any tips to get a center hole punched? I was thinking to go in with a dremel first...?

[jono]

Dremel unplugged? A round burr turned back and forth by hand might help make a flat spot for the punch. (Assuming you don't have room to slot these and use a flat screwdriver.) Nice long soak with Liquid Wrench or PB Blaster helps, but maybe not so much without heads to turn.

You don't want to heat an aluminum frame up much, but it may not take much, since aluminum expands so much faster than steel. A very hot hair dryer might even help. If you know the alloy there might be data available for how hot is too hot, but absent that I'd try to stay under about 200 F. My thinking is, if 200 doesn't do it the odds of getting somewhere with heat aren't worth pushing your luck at 300.

If heat works, the next step might be the hardest. If you could get them loose you might be able to get ahold of them with a dot of superglue or quick curing epoxy on the end of another screw etc, but obviously getting glue into the threads would be a disaster.

Good luck!

[Dee Hubbs]

Left have drill bit is a miracle. Center punch, a centering drill bit to get started, then the left hand drill bit. Once the drill bit catches/cuts it will spin the bolt right out.

[detrusor]

^^^^^^

This


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[adrenalated]

You don't want to heat an aluminum frame up much, but it may not take much, since aluminum expands so much faster than steel. A very hot hair dryer might even help. If you know the alloy there might be data available for how hot is too hot, but absent that I'd try to stay under about 200 F. My thinking is, if 200 doesn't do it the odds of getting somewhere with heat aren't worth pushing your luck at 300

200F is lower than the temperatures used for any type of (permanent) heat treating of aluminum alloys and should be safe to temporarily heat the frame to. As jono noted, you really don't need much heat, as you're relying on the fact that the aluminum will expand faster than the steel. Heating the frame too much will actually work against you as the steel will start expanding too, negating the benefit of heating to begin with. You're trying to remove the bolt when the aluminum is warm but the steel isn't yet. A normal heat gun or hair dryer should work just fine.

[Cocximus]

I was thinking to use a pointy abrasive stone with the Dremel on low speed.

Great idea with the left hand drill bit. It'll either get it out or I can increase drill bit size until I can re-tap the M5. Key is to get that center punched.

Aluminum with steel oxidates and seizes like a mofo. Since aluminum conducts heat very well when I replaced the BB I had to use an oxi-acetylene torch. That was a big BB, I wasn't too worried. This small eyelet carries a lot of weight. I'll try the heat gun first.

[XXX-er]

worse case scenario you drill it out and use a nut & bolt

[cmcrawfo]

^^ truth.

Drill, re-tap threads. Forget about it.

Its not a piano or a rocket ship. Get off the keyboard and back on the tools.

[singlecross]

Tef-Gel is your friend when it comes to assembling dissimilar metals or metal to carbon. I use it everyday this time of year assembling sailboat masts and gear. Good stuff.

[grinch]

Soldering iron is good for applying heat to small screws. Reverse thread bit and a set of ez outs are useful
Screw might be too small but occasionally we'll weld/tack a nub on bolts to get purchase with vise grips

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[sfotex]

The other screw broke off at an angle. I can't punch it's center. Any tips to get a center hole punched? I was thinking to go in with a dremel first...?

Can you come at it from the backside? (I just said that. ) I assume its the standard welded on rack eyelets?

[Quadzilla]

My call is to not over think this. The screw(s) are stuck in the chain stays because the Al has oxidized around the screws essentially locking them in like glue. So, they are not coming out without luck. Thing to do is to get a metal tab about 1/2" wide, drill a hole in either end and bend the tab around the chain stay. Then simply add a small nut/bolt thru the holes and bike rack and reattach it to the bike.

[Jong Lafitte]

iffin ya wannabe
puttin a rackz on yer bike
your bestin to getz a steelie
nexta time
dan allz irrie just retap that shit.

now i'm not sure what all that means.

[XXX-er]

you are channeling skifishbum

[ill-advised strategy]

iffin ya wannabe
puttin a rackz on yer bike
your bestin to getz a steelie
nexta time
dan allz irrie just retap that shit.

now i'm not sure what all that means.

sfb!

[Cocximus]

I ended up taking one out with the extractor I had, using a small impact with a chuck adaptor. I kept the heat gun on the frame.

Now one of the screws is hard stainless steel. It will take a long time to drill it

They are blind holes., so no access from the back.

Steel is slow, aluminum is faster, carbon is fastest. Not going back.