In The Shop: Broken Exhaust Stud

A very common owner mistake that can usually be avoided: The dreaded, broken exhaust stud.

This is more likely to be an issue on bikes that are stored in sheds or left outside for long periods of time where rust develops on the raw steel exhaust studs & flare nuts. The exhaust may need to be removed for a repair or replacement and the exhaust flare nut is completely frozen on the stud.

What should you do??? Well, what we typically see is; the owner grabs for a longer handle ratchet and inevitably snaps the stud. Not cool!!!

What most riders may not realize is that, nine out of ten times, the cylinder head will need to be removed in order to extract the broken stud and install a new one. To make matters worse, we often see the motorcycle after somebody tries making a feeble attempt at drilling out the stud with the head still bolted to the motorcycle. The early outcome is usually a crooked hole or half of the stud removed with a half hole adjacent to the half stud! Again, Not cool!!

We had a similar job roll into our shop this week. In this case, the bike had only 5,800 miles. It was like new and in pristine condition. No rust at all.

The owner may have been a little over ambitious installing a new exhaust system. In this instance, over-tightening caused the stud to snap. Then, in haste, there was an attempt to drill & extract even though a frame down tube would make it impossible to drill straight.

The best way to avoid this issue:

When installing or tightening an exhaust, always tighten evenly. Reference factory torque specs & torque sequences. If exhaust studs or hardware is rusted or seized, try soaking with a premium rust penetrating fluid like PB Blaster or Spectro Penetrating Lube. Let the hardware soak overnight if possible.

Use a propane torch to help free up frozen hardware if it is safe to do so. Whenever dealing with frozen hardware, practice patience. Take your time. Work the nut or bolt back and forth and, most importantly, try to get a good feel through your tool.

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4 Responses to “In The Shop: Broken Exhaust Stud”
  1. W. Rundgren
    W. Rundgren

    When possible on a new machine that I have purchased I apply anti seize compound on all hardware that I think I will have to remove at a later date. This mostly eliminate any rust from forming on the hardware. Seems to work for me.

    • Rory Corneille
      Rory Corneille

      You have to be carful when using an anti seize compound on a torqued bolt that only a small amount is used. Great copious amounts can effect a torque setting.

  2. Dave

    I always enjoy reading items that talk about removal of broken bolts or in this case a stud. Being a journeyman machine repairman having served a 4 year apprenticeship then working for 30 years, I have much I could say about the topic. My 1st comment is “don’t break anything especially threaded fasteners in hard to access locations. Break away torque should not exceed applied torque by much especially on small fasteners. Heat being applied to the surrounding area can work wonders. The suggestion of applying PB Blaster is good. A little known trick from my tool bag is to apply bees wax to the heated fastener at the thread area. Once you get the slightest movement, work the fastener back and forth. Take your time. There should be no rush. The wax may not be a common item in most tool boxes but its worth the effort of locating some. Dave from Ford Motor Company. A pound Harley rider for 50+ years

  3. Steve Fortino
    Steve Fortino

    When I was a teen I busted an exhaust stud in the head of my Honda 125 the head was aluminum and the stud was steel. A buddy’s dad worked as a fabricator at a rocket company. He was able to get a hold of an acid that would dissolve steel and not aluminum. We propped the bike up right applies the acid and let it sit over night… turned out perfect.