Broken Sprocket Attachment Bolt - REMOVAL?

[cooperxs650]

Hello,

I've just started tearing down a 79 Special. I have removed the rear wheel (mag), and, upon inspection, noticed one of the sprocket attachment bolts had broken in the hole. A PO had tried to drill it out and stopped. I had a go at it, but, quit when the drill started to walk away from the hole centre.

I'm thinking a Helicoil (10mm bolt?) could be put in the hole, and, I could use the sprocket as a drill guide to drill out the bolt if I get a full size drill.

Anyone had this problem? Can it be fixed, or, is the wheel done. Can it be done with a hand drill or should this go to a machine shop?


Here's a pic of what I'm up against. You can see, it's been drilled a bit off centre.
Thanks

Cooperxs650

 

[marp68]

You could try using a left driving drill bit. At the same time as it is drilling, it will also force the bolt to unbolt and hopefully come out the whole way. I did it myself and it worked. When the bolt head is off, there is no torque on the threads, so it comes out easier.

There are also left driven "bolts" (don't know the English word for it) that kan be used to drive the old bolt out. You first drill a smaller hole in the broken bolt and then use this smaller left threaded piece to drive the bolt out.

Good luck!

 

[3Deuces]

E-Z Out

http://www.amazon.com/Easy-Out-Screw-Extractor-Set/dp/B0002SDAIY

 

[Tim H]

Start soaking it with penetrating oil now, and give it some time before attempting.

Center punch and drill a small hole through the center using a left hand drill bit.
Step it up in drill sizes couple of times until you are close to hitting the threads.
(the closer to the center you are the larger the hole you will be able to drill)
Use an easy out to get the bolt out if it hasn't already with the left handed bits.

I've done this with rusted broken chassis bolts in my car, and sometimes with a little heat I have rarely had one best me.

If you get frustrated hose it down with more penetrating oil and walk away. I use PB blaster.

 

[xjwmx]

Knock the bearings out. There's an easy way to do that you can search.

The bolts stick out the inside of the hub. Grab it inside with a mini vicegrip and just turn it. If it's still stubborn use heat or dry ice on it to break the threads loose.

 

[cooperxs650]

Well, I got the thing drilled out. The threads are shot, but, I'm pretty sure the hole isn't oversized beyond a helicoil requirement. I've also concluded the chips fell into the hub, and, some of them might be caught up in a bearing, so, it looks like bearing replacement too (they were questionable to begin with).

Does anyone know the exact sizes of the bolt threads? I'm guessing they are M10x1.5. Need to know before I stick a coil in!

Thanks

 

[Brother]

ya beat me to it...

 

[XSLeo]

Do you have one of the other bolts? If so measure it. Or take a bolt with you to the store and get the right size that way.
Leo

 

[cooperxs650]

I broke the bank and splurged $6.00 on a set of thread gauges at Princess Auto. It's M10x1.25. Thanks!