Installation of OEM running boards/step bars for Chevrolet Tahoe/GMC Yukon (GMT 400)

Discussion in 'Technical write ups & Installation Guides' started by JsnChristianson, Mar 13, 2008.

  1. JsnChristianson

    JsnChristianson Full Access Member

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    This is a simple write up showing how to install OEM running boards/step bars for the 1995-2000 Chevrolet Tahoe and GMC Yukon (GMT 400) vehicles that did not come from the factory equipped with the running board option.

    I recently purchased and installed a set of GM factory side assist step bars from a 1999 Chevrolet Tahoe Z71 on my 1997 Chevrolet Tahoe LT. My vehicle did not come from the factory with the running board/side step option, and therefore installation of these were slightly more difficult than initially anticipated, although this was overall still a managable modification.

    Vehicles that came from the factory with the running board option were also equipped with 10 mounting brackets that are welded to the inner rocker panel of the vehicle and allow running boards to bolt to the vehicle. If the vehicle that you desire to mount the running boards to did not come from the factory with this option, these brackets will need to be purchased in order to install the running boards.

    Below is are two pictures of the passenger side rocker panel of my 1997 Chevrolet Tahoe LT. The first picture shows where the front brackets are to be welded, the second picture shows where the rear brackets are to be welded. Notice the difference in the shape of the rocker panel at the rear of the vehicle.
    [​IMG]

    [​IMG]

    The brackets that are needed and quantities are;
    1. Front brackets, GM part number 15978912, quantity 8
    2. Rear brackets, GM part number 15978913, quantity 2

    In addition to the brackets, you have the option to purchase GM nuts and bolts that will go with teh brackets as well, but I found it much more simple and inexpensive to simply visit a local hardware store after the brackets are shipped to find the correct bolts.

    After shopping around at the local dealership and a few online websites, I found the best prices for these parts shipped to my address at GM Parts Direct.

    Below are images of the brackets that will be needed.
    [​IMG]

    The OEM running boards/step bars have five mounting points that bolt to the brackets.

    Below is a picture of the passenger side step bar as I purchased them without the mounting brackets attached.
    [​IMG]

    In order for the brackets to bolt to the running boards without measuring, I found it easier to loosely bolt the mounting brackets to the step bars and then weld the whole assembly to the vehicle, as opposed to measuring and welding the brackets to the vehicle first and then hoping the measurements were correct so that the running boards will bolt up correctly.

    Below is a picture of the passenger side step bar with the mounting brackets loosely attached.
    [​IMG]

    Next comes the most difficult part when installing the running boards; welding them to the thin metal on the rocker panel of the vehicle without burning a hole through the vehicle.

    When determining the location of the running board on the vehicle, use the rear bracket on the rocker panel of the vehicle dictate the correct position. The rear bracket must be behind the last plastic plug on the rocker panel, and before the wheel well starts to curve upwards. There is only centimeters of room for it to move forward or backward, so it is fairly easy to get in to mount in the correct place, and in turn mount the entire assembly in the correct place.

    I did not personally weld the brackets on, but I am told that this was successfully accomplished by directing the majority of the heat at the thick metal of the brackets rather than the thin metal of the vehicle. This allowed for the brackets to be securely welded to the vehicle without burning a hole through the rocker panel.

    Additionally, be sure to remove the plastic vehicle caps that are located next to the bracket mounting points to prevent them from destruction due to the heat. They pop out easily with a screwdriver and pop back in to place easily after the welding is completed. Finally, remember to firmly tighten the bolts that secure the mounting brackets to the running boards after welding is complete.

    Below are pictures of the rocker panel of the vehicle after the brackets have been welded to the vehicle. The first picture shows the passenger side front brackets, while the second picture shows the passenger side rear bracket.
    [​IMG]

    [​IMG]

    After all five mounting brackets are firmly welded to the rocker panel of the vehicle, installation of OEM running boards/step bars will be complete.

    Below are pictures of the passenger side step bars securely mounted to the vehicle.
    [​IMG]

    [​IMG]

    So this is everything that is needed to successfully install OEM running boards to the GMT 400 Chevrolet Tahoe/GMC Yukon. Hopefully this write up is helpful for other Tahoe/Yukon owners who are considering this modification for their vehicles. If you have any other questions or I failed to mention anything, just let me know. Thank you and take care.
     
  2. NoEcm

    NoEcm New Member

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    Excellent post, excellent documentation and a well done on the mounting of your factory step bars.

    I'm considering doing the same project with a set of the factory running boards.

    One question, instead of welding the brackets to the inner rocker panels I'm thinking about bolting them on. I would drill a hole in the bracket and a corresponding hole in the inner rocker panel.

    Are each one of the body plugs close enough to the brackets so that one could reach behind with a nut to secure the brackets to the body?




    Thanks again for your excellent post!!!
     
  3. JsnChristianson

    JsnChristianson Full Access Member

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    In response to your question, I measured the distance from the plastic plugs to the brackets. The plugs are all located just adjacent to the mounting brackets, with the exception of the 2nd bracket and the 4th bracket. There is a plastic plug located approximately 4 inches to the front of the 2nd bracket, and another plug is approximately 6 inches to the front of the 4th bracket.

    So yes, the plastic plugs are all relatively close to where the brackets are located, with the most distant being located 6 inches from respective bracket.

    Let me know if this helps and how bolting the brackets on works for you. Take care.
     
    Last edited: Mar 14, 2008
  4. treepete

    treepete Full Access Member

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    Jason,
    Nice work. Very professional documentation. If I needed to install running boards or step bars, I would definately prefer this over any OEM installation guide.

    Pete
     
  5. mudman2007

    mudman2007 New Member

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    I have also just completed this process for a set of factory running boards. I did not however, purchase the factory brackets as I was told they were NLA. I got a set of LUND universal brackets for the universal steps from a local truck accessory supplier, the price of the kit for the brackets was $109 plus shipping. These are 2 sets of three brackets that clamp and bolt to the rocker panels and the body seam under the doors. There are three brackets per side. I centered them up trying to put one in the center of the wheel well, and one each in the center of the doors. I then used a grinder with a cut off wheel and removed the factory brackets from the factory boards, and set the boards on the Lund Brackets. then with some patients, I removed everything from the factory board down to the steel substraight and bolted them to the Lund brackets, then replaced the the plastic covers. The installation is very firm, and looks very good!
     
  6. treepete

    treepete Full Access Member

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    Mudman, welcome to the forum.
    Had the original brackes failed then?

    The other day I saw a guy on the side of the road jacking his car up and was using the ground effects trim for his load point. duh... it was ruined.

    anyway, welcome to the forum. post a pic of your ride.

    Pete
     
  7. spero

    spero New Member

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    A sign hit by a County Plow Truck hit my running board on my 99 Chevy Tahoe. It broke off some of the running board but most of the endcap extension at the rear driver's side passenger door. How do you just replace the running board extension?
     
  8. JsnChristianson

    JsnChristianson Full Access Member

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    I am trying to visualize what you described. Check the image I attached to this post, are you talking about the part labeled "4?"

    If this is the part you are referring to, you can purchase it at GMPartsDirect for $18.10 (excluding shipping) at the following link;

    GMPartsDirect.com - Find a Item

    Hopefully this helps! If not, let me know and I will do what I can to help you. Take care!
     

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  9. Colabella7077

    Colabella7077 Full Access Member

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    It's hard to look for just the end peice but depending on the set-up of the step bars, because there are so many stock chevy/GM step-bars to aftermarket step bars, you might have to replace the whole peice. Check out you're local scrap auto yards, it will turn up.
     
  10. Jason L

    Jason L New Member

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    Why are the pictures not loading?