Removing sheared bolts

[beowulf]

Kubota L3410 HST
Because I was not paying attention to keeping all bolts tightened, I found that three* bolts that attach one side of the tractor where the 'rear' section of the tractor mounts to the middle/engine area. A picture is attached to explain it a bit better. Anyway, before I learned they were sheared, I removed a bolt from the other side to determine size, thread pitch etc. and then bought replacement bolts. (14mm, 1.25). But when I went to 're-bolt' the unit I discovered the old bolts were sheared with part still in the receiving holes. The part of the bolts remaining and threaded inside and sheared off is about 1/2 to 3/4 inches. The only solution is to remove those sheared bolts and replace them with the new bolts I bought.
So, my questions: 1) If I buy whatever I need to git-er-done, (? penetrating oil, bolt extractor kit, and ?) is this a DIY task? The bolts in there are M8.8s. 2) If it a DIY task, suggestions to help with the task? 3) finally, there is a mobile tractor repair guy (or used to be) who services farm tractors in the area and likely he has experience managing this. So, would it make sense to just use him and avoid trying DIY which might fail? I know there is a cost involved by having him do it, but likely he will succeed where I may not.

And, learn from my mistakes. I guess I assumed bolts well seated would remain so forever. Not so.

As always, thanks for reading and for any suggestions.

[*There are four holes but only three of the holes ever had bolts on either side. I assume there should have been four on each side.]



Ron

 

[ptsg]

If you pull the loader mount out, it should expose a little bit of the broken bolts or at least give you a much better access to them.

Then you can pull them out using a punch and a hammer. Hitting it a way that makes it spin. If it doesn't want to play nice, weld a nut to it and should come out.

Looks like that loader mount has seen some things by all the welding done to it.

 

[beowulf]

All bolts are recessed - into the hole about half an inch. Which seemed odd to me that it would shear like that - but the first half inch or so is not threaded so had some 'play' there.

 

[beowulf]

I have now watched a few youtube videos and it seems doable if I get the right bolt removal kit and quality bits and penetrating oil - and can manage to get holes drilled in the precise centers of the sheared bolts - I think I can find some appropriately sized short shafts to help with that. I am still thinking about the DIY vs the tractor guy. I guess it would not hurt for me to try first.

 

[MossRoad]

I have now watched a few youtube videos and it seems doable if I get the right bolt removal kit and quality bits and penetrating oil - and can manage to get holes drilled in the precise centers of the sheared bolts - I think I can find some appropriately sized short shafts to help with that. I am still thinking about the DIY vs the tractor guy. I guess it would not hurt for me to try first.

So..... I bought some ez outs and left hand drill bits. Drilled a hole in the center of the bolt with the left hand bit, and the broken bolt came out with the drill bit alone. Success!

Try #2. Drilled hole with left hand drill bit and nothing happened. Used EZ out bolt extractor and bolt came out. Success!

This worked my entire life.... until... the EZ out broke off inside the bolt. EX outs are hardened metal. Drill bits won't touch them. You can't get a drill bit on it anyway since it broke off proud of the broken bolt face. I tried to make a jig with a correct sized steel rod and hole drilled in the middle. Didn't work.

Ended up getting a hole saw that was just the diameter of the bolt, drilling out the bolt and the threads, filling the whole thing in with JB weld, drilling and tapping new threads. This was just for a valve cover, nothing that had any load on it.

So make your plan of attack carefully and don't force things.

Knowing what I know, I'd try the left hand drill bit, an EZ out, heat it up and melt a bunch of candle wax in there and give it a try. Don't bugger-up the threads by drilling off-angle either.

If any of the bolt was sticking out of the hole, welding a nut to it works really well, but that's not your situation.

Good luck with your project.

 

[beowulf]

So..... I bought some ez outs and left hand drill bits. Drilled a hole in the center of the bolt with the left hand bit, and the broken bolt came out with the drill bit alone. Success!

Try #2. Drilled hole with left hand drill bit and nothing happened. Used EZ out bolt extractor and bolt came out. Success!

This worked my entire life.... until... the EZ out broke off inside the bolt. EX outs are hardened metal. Drill bits won't touch them. You can't get a drill bit on it anyway since it broke off proud of the broken bolt face. I tried to make a jig with a correct sized steel rod and hole drilled in the middle. Didn't work.

Ended up getting a hole saw that was just the diameter of the bolt, drilling out the bolt and the threads, filling the whole thing in with JB weld, drilling and tapping new threads. This was just for a valve cover, nothing that had any load on it.

So make your plan of attack carefully and don't force things.

Knowing what I know, I'd try the left hand drill bit, an EZ out, heat it up and melt a bunch of candle wax in there and give it a try. Don't bugger-up the threads by drilling off-angle either.

If any of the bolt was sticking out of the hole, welding a nut to it works really well, but that's not your situation.

Good luck with your project.

Interesting. I had not thought of the left hand drill bits but that makes sense - sort of two shots at it - the bit and then if no-go, the extractor. I am looking at kits now but will also check out the left hand drill bits. I will need to find some really good ones for the 8.8 bolts. Thank you.

 

[MossRoad]

Just remember that they are hardened, so if they break in there, they are pretty much stuck. So take your time and don't force it.

 

[ruffdog]

I have now watched a few youtube videos and it seems doable if I get the right bolt removal kit and quality bits and penetrating oil - and can manage to get holes drilled in the precise centers of the sheared bolts - I think I can find some appropriately sized short shafts to help with that. I am still thinking about the DIY vs the tractor guy. I guess it would not hurt for me to try first.

A transfer punch will help you center punch the center location.

Whoops, we couldn't find that.

 

[ultrarunner]

Heat properly applied can work wonders…

I’ve had good success with left handed drill bits… I bought mine 40 years ago from the SnapOn jobber.

You have to maximize every advantage…

At the machine shop a TIG torch would put concentrated heat in the hole… then break for lunch while it cooled and often did the trick…

 

[RayIN]

Go slow speed with the drill bit; less chance of breaking the bit and more chance of it grabbing the bolt and backing it out. Above all, drill straight, a bit will break much easier if the drill moves around.
8.8 is the class of bolt not the size.

 

[dodge man]

I agree start with left hand drill bits, then an ez out. Don’t break the ez out off. If that doesn’t work Helicoil will do it. A Helicoil you drill it out slightly over sized, tap it and then the original thread inserts go in. It comes as a complete kit and works well and is easier then it sounds.

 

[beowulf]

Go slow speed with the drill bit; less chance of breaking the bit and more chance of it grabbing the bolt and backing it out. Above all, drill straight, a bit will break much easier if the drill moves around.
8.8 is the class of bolt not the size.

Thanks - good advice. I know, or think I do, that the 8.8 is the strength rating for the bolt. The bolts on the other side read M8.8

 

[beowulf]

Go slow speed with the drill bit; less chance of breaking the bit and more chance of it grabbing the bolt and backing it out. Above all, drill straight, a bit will break much easier if the drill moves around.
8.8 is the class of bolt not the size.

Thanks for weighing in. For going in straight I am going to try to find a shaft, piece of quarter inch galvanized pipe, or whatever I can find around here, or think of, so I can slip that in the hole to hold the drill bit in straight

 

[beowulf]

I discovered another issue with the extraction. The extraction bits I have looked at are (the longest) about 3" and have a quarter inch square end to grip and turn. But I need to go through at least 3 inches of shaft to get to the bolt - plus a bit of distance drilled into the bolt. That leaves me with nothing of the extractor bit exposed to grab and turn. I am looking for a drill bit extension that will grip a square 1/4 inch shaft on the extractor bits. So far, the extenders all have the six sided shafts. I think I can reverse a small socket that will slip into the shaft - 1/4" square side first - and then fashion a way to put something into the other end of the socket in order to turn it. Some good news, though, - a 1/4 inch short piece of galvanized pipe fits perfectly into the shaft and should help me center the drill bit. We shall see.

 

[ultrarunner]

My left hand bits are very short…

 

[beowulf]

My left hand bits are very short…

good point. Likely I can use an extender for the bits IF the diameter of the connecting part of the extender fits in the shaft. Another thing to figure out.

 

[Eagle1]

Can you get to the end of the bolts from the other side?

 

[beowulf]

Unfortunately, no. But a good idea.

 

[shooterdon]

I am a chicken. I would let the mobile service guy handle it. It might cost $300-400 but it will not be his first rodeo

Doesn’t hurt to call and get a price.

 

[Gregster613]

I am a chicken. I would let the mobile service guy handle it. It might cost $300-400 but it will be his first rodeo

Doesn’t hurt to call and get a price.

Agree with shooterdon, at least get a cost estimate on the job before tackling it yourself and perhaps making it end up costing bunches more! I don't have any mobile service guys in my area (that I'm aware of anyhow) but that's the route I'd try first.