Need some advice for drilling a hardened bolt

[vertguy]

Working on the exhaust of my son's truck and ran into a snag with trying to remove the pressed in bolts that connect the muffler pipe flange to the cat output flange. The bolts are pressed into the muffler side of the flange, so we ended up removing the entire assembly to gain easy access... the first bolt was already broke (thus the reason for the repair) and the second one snapped during disassembly.

I figured this was an easy fix as we could simply drill out the pressed in bolts and replace with a normal bolt. Well, that went out the window quick as the bolts are super hard. I was able to cut the threaded side down smooth with the portaband, center punched and proceeded to try drilling them out to no avail. Started with my high speed drill bits and made little progress. Ran to HD and picked up a couple Cobalt bits thinking that was the answer... same result. Not many options today as it was Sunday afternoon and I live in a rural area.

Since the entire tailpipe and muffler is in one piece, this needs to be drilled by hand. Any advice on different bits or methods are appreciated. I am heading out of out town in the morning and hoping to have a plan to get this addressed on Friday when we get home. My plan B is to have an exhaust shop install a new flange (if that is possible), but hoping to find a way to fix it ourselves.

Thanks for any advice!!

 

[454ragtop]

Might try knocking the pressed in bolts out with a BFH, you need to have something behind the flange to support it so you don't bend the flange.
HTH, Jim

 

[bucksnort59]

torch

 

[vertguy]

Tried heat and BFH initially with no results. Never dealt with this hard of metal as even my portaband with a bi-metal blade would not fully cut off the bolt heads as it seemed to just stop cutting. And with the muffler and tailpipe attached, it really limits my options.

 

[NeuseRvrRat]

die grinder with carbide burr?

 

[ss454]

carbide burr in a die grinder

 

[bodyguy16]

Torch, heat it up cherry red and use a punch to push it out, then replace with a nut and bolt. If it doesn't come out easy heat some more.

 

[fasteddie313]

No, torch like blow your holes right through it with a torch..

Or cut both flanges off and weld in a section, I had the local muffler shop cut the leaking flanges off my subie and just quick zap in a section for $35... They can do something like that much easier than I can, and you're proving it...

 

[LXCam]

Oop's, you and others bet me to the heat idea.

 

[vertguy]

Great feedback as once again, I am over thinking this... did the same thing with my daughter's car when a joint failed as I had the shop just weld in a splice.

 

[dovco]

Cutoff wheel will cut just about anything.
HSS drill bits may dull immediately on some metals. It's SS, right? The Cobalt or Carbide should do it. Use proper speed and lubricant for best results.

 

[Hemi49]

if they are stainless steel bolts the material will work harden when machining.....Whether you are drilling, sawing or turning, do not let the tool dwell on the material.... It will get harder than you can believe.....Use sharp tools and keep them cutting....

 

[wafrederick]

Heat with a torch and a good air hammer.Heat it up red hot,put the air hammer in place hitting the trigger.Should come out.

 

[goforride57]

Plasma cutter will blow it right out.

 

[OHMS LAW]

Pb blaster and a hammer. Replace wth graded bolts and hardware

 

[xxaler]

Heat with a torch and a good air hammer.Heat it up red hot,put the air hammer in place hitting the trigger.Should come out.

This is the best method here. I use a dull tapered piece of stainless I machined to slip into my air chisel.

 

[ImportTuner]

I had the same issue; used a cutoff tool .. was done in a couple of minutes

 

[colin39]

I do these fitted, unless they are pushed and welded, heat the flange put one hammer behind just bellow the stud and whack the broken bolt and itll fly out, if its welded gas axe the back off and do the same, job done 10 mins max.

 

[St-rider]

If you use the drilling method again try a carbide drill bit.

 

[paulsomlo]

Agree with Colin39 - heat the flange, not the bolt. You want the flange to expand, rather than the fastener. And if you're unsuccessful hammering it out, once you've brought the bolt up to red heat and let it slowly cool, you may stand a good chance of annealing it, so that it's not so hard.

 

[joecon]

heat the flange red hot by the edge of the bolt hit it with a hammer and
it will come out it is just pressed in. If it dose not come out heat both
the flange and bolt red and hit it again it will come out if not, let it cool
and then heat just the bolt red and blow it out with the torch.

 

[Rookie2]

RED WRENCH to the rescue !

 

[gte718p]

Torch, heat it up cherry red and use a punch to push it out, then replace with a nut and bolt. If it doesn't come out easy heat some more.

I don't even use a torch. If you have an air hammer it will make quick work of them. Otherwise a good quality punch and a BFH and knock them out. They are pressed in. 2" stainless steel bolts and some stainless lock nuts and no issues. Nylocks don't work well in this application. The distorted thread lock nuts are key.

 

[bczygan]

Give the bolt more respect.

Then the bolt will see the error of it's ways and become more responsive.

Bolts have been neglected in our society for too long.

If you don't give the bolt it's due, which is full equality with screws, nuts and other fasteners, then the bolt will continue to be a hard-*** and refuse to do it's job for you.

Ooops......wrong forum!