How to Remove Rusted Bolts

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  Posted by RoadCaptain January 16, 2018 - Filed in Working on Bike - 8,349 views
  

  

   

  In browsing through many motorcycle & car repair forums, I notice a very popular question is... "What is the best way to remove a rusted-on nut or bolt?"

  There are three basic ways to remove a rusty nut or bolt... Brute Force, Heat & Solvents

  • Brute Force:  Not highly recommend. The hardware is already compromised from the rust and there is a very good chance of breaking it off.

   

  • Heat:  Again not highly recommended. The amount of heat you need to expand hardened nuts is extreme heat (i.e. oxy/acetylene torch type heat), which means other parts around the hardware are going to heat up and may get damaged (not to mention the probable presence of gasoline or fumes around a motor).  However, in extreme situations this may be the only way to go. Please do so with caution

   

  • Solvents:  This is normally the best way to remove rusted hardware because it reduces the chances of damaging the hardware or anything around it. The first thing to know about using solvents to remove a rusted nut or bolt is it takes time to break down the rust.  Remember it took years for the rust to build up and you are not going to free it by spraying penetrating oil, and coming back 2 minutes later expecting it to come right off.  Depending on how bad the rust is, and where on the bolt it is located, this could be 15 minutes to overnight... or even longer.  A really rusted bolt that goes deep into the threads could take several days of re-applying the solvent so that it can break-down the layers of rust allowing each application to move deeper in the threads.   

   

  So, which is the best solvent to use?  This article posted in Machinist Workshop Magazine several years back provides some very good data.  They performed a variety of tests with nuts and bolts that were scientifically rusted together, in a salt-water solution, to a uniform degree.  In each test, one fastener with no solution applied was removed with pure force to set a baseline. The other fasteners were treated with four popular commercially available penetrating oils/rust removers, and one home-made solution of 50/50 Automatic Transmission Fluid and Acetone.

  Here are the results of the average amount of force needed to remove each bolt...

    No Solution: 516 ft lbs

    WD-40: 238 ft lbs

    PB Blaster: 214 ft lbs

    Liquid Wrench: 127 ft lbs

    Kano Kroil: 106 ft lbs

    AFT/Acetone: 50 ft lbs

  As you can see by the results the home-made brew of 50/50 Automatic Transmission Fluid and Acetone outperformed the commercially available solutions by a long shot.

  I have personally been using this with great success since I read the article (over 10 years ago).

    

  Warning: All solutions above are extremely flammable, and may cause irritation to your eyes and skin if contacted.  Never use any of these solutions near an open flame or heat source, and always wear chemical resistant gloves and eye protection when using them.

   

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