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Fifth Wheel Hitch Installation - 2008 GMC Sierra 2500 HD

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How to Install a 5th Wheel Hitch on a 2008 GMC Sierra 2500 HD

Today on this 2008 GMC Sierra 2500 HD we will be installing Curt fifth wheel Q5 with roller part number 50064 and part number 16500. We will also be installing the fifth wheel installation kit with rails part number 50061-6008. Go ahead and lower the spare tire up out of the way. Also on some models you will find that the heat shield over here on the passenger side will interfere with the installation of your frame brackets. If that is the case you may want to go ahead and remove the heat shield out of the way as well. Okay on the models that have the factory installed electrical brake control unit will need to relocate the electrical plug mounted to the inboard side of the driver side frame rail here. Loosen those up and you can see that we can actually take the heads of the bolts, slide the bracket forward, and pop them out those larger holes there. 00:59

What we are actually going to do is to install the new bracket that is provided with our installation kit. Then this larger hole here will help us hold it on later on when we install the actual brackets to the side of the vehicle. Okay the next step is to go into the bed and we are going to go ahead and set up our front rail, the one closest to the cab. We want to check the dimensions that are listed in the in the instructions to verify the distance from the tailgate that we are going to be setting our rail onto. This is actually a short bed model, this is a 6 1/ 2 foot bed. For this model we are going to be coming from the end of the bed here to the front edge of the bracket. We want to set it up at 47 1/ 2 inches. We also just want to center the rail in between the wheel wells as well. 01:48

Go ahead and mark our holes here. On the front rail here we will be marking out the two outside most holes on each end. I am going to just simply take a Sharpe, mark those. Go ahead and move the rail out of the way and drill those holes out with 1/ 8 inch drill bit. We want to be especially careful when drilling out the driver side holes, especially the front one because the gas tank is located directly below the bed here at this attaching point. To check the alignment you want to line up this hole and this hole with the existing holes here in the frame. So you want to double check the ones on the passenger side as well. Then we can go up in the bed and enlarge those holes to 9/ 16. Next we will go back underneath the vehicle. We are going to loosely install our frame brackets to the side of the vehicle. Here from the inside of the vehicle you can see the oblong hole here at the rear attaching point for our frame bracket. You can see the hole in the frame bracket that it is aligning there. We will be attaching that with the 3/ 4 inch hex bolt here into the bracket. We are just going to rotate that. Slide it into the oblong hole in the frame and we will be attaching on the back side with the flat washer, lock washer, and nut for the U bolt that is provided with our installation kit. We have got two holes here that we can use that we will be using in the coinciding hole here at the bottom as well. Here you can see the two holes at the bottom of the frame bracket where our U bolt can align. Again you just want to take the one that is probably going to be the best clearance for you and the tightest fit. 03:36

You do want to make sure before installing the U bolt that you check to see if there are any lines that are going to be in the way when you do install it. You want to make sure that those are pulled out of the way so they do not get pinched. On this particular model that the forward set of holes are the ones that are going to provide the easiest set of force with our U bolt. We will be attaching on the back side with the flat washer, lock washer, and nut. We are just going to kind of hand tighten these for the time being until we make our final adjustments. Okay now we have got the frame brackets loosely installed on the vehicle. We can go ahead and go back in the bed and we are going to go ahead and mount our front rail. Align it back over the holes that we drilled earlier. We will be installing through those holes the 3/ 4 by two inch carriage bolts. Okay since where we drilled our holes is actually at the bottom portion of the ribs in the bed we are going to want to go ahead and put the spacers in between the rails and the bed so that we can ensure our metal to metal contact. We need to do that at all four locations. With those in what we want to do is go ahead and take the feet of our fifth wheel head and bring it up in here. What we are going to do is go ahead and test fit it inside of this rail and that will help us line up the rear rail as well. Okay with the rear rail centered we can go ahead and mark our holes. On the rear rail we are actually going to be drilling the second set of holes in from the end on both sides. You will notice that this set of holes is going to be sitting on the upper corrugation of the bed so that the spacers that are going to be put in the front rail are actually going to be under the bed on the second set of holes. I am just going to go ahead and remove the roller assembly. Move my rail again and go ahead and drill my holes out to 1/ 8 inch like we did previously. Check our alignments underneath with the frame brackets and then enlarge them to 9/ 16. Next we are going to take our 1/ 2 inch by two inch carriage bolts. Drop them through the holes that we just drilled. You need to do that at all four locations. Okay what I am actually going to do is set the slider assembly back into the rails here and then we will go underneath and tank those down. Okay and then back underneath the vehicle we are looking at the bolts that are coming through the rear mounting rail. The spacers that we used above the bed on the front rail we are actually using under the bed here. You need to do that at all four locations. We are going to attach that at the bottom using a block, lock washer, and nut. You want to repeat that set up for all of the bed rail mounting boards. Once we have got all of the fasteners in position we want to go ahead and torque our bolts down. 06:27

We are going to start with our 1/ 2 inch carriage bolts holding the bed rails to the frame brackets and then we will move on and torque the bolts holding the frame brackets to the frame of the vehicle. You will likely find that on most if not all carriage bolts that you are not going to be able to get a torque bar in there to torque them down. If that is the case just go ahead and take an open ended wrench. Get it as tight as you can with your hand and then get a breaker bar in there and give it about 1/ 4 turn and that should get you right about at your torque rating. Your torque ratings are listed in the directions. Okay with all of the bolts torqued down the installation of the fifth wheel components under the bed are completed. Coming back up inside the bed here we want to go ahead and put the hat on to our slider assembly. You can see we have got both holes here on the side of the head assembly we are going to be attaching to the slider assembly using the provided hex bolts, lock washer, and regular washer. Those are going to be going from the inside out like so and they will be threading into the existing weld nuts here on the slider assembly. Then we need to tighten down the bolts on the head assembly. We want to the pin in through the hole in the base rail and then add the clip on the back side. Then we want to torque the bolts on the head assembly. You want to check with the directions to verify the appropriate torque rating. And then when you need to use the slider assembly you simply turn the release handle and pull the vehicle forward and it will slide back into place. With the head assembly installed we just want to make sure that if you had removed your heat shield earlier that you put that back up into place and we also want to make sure we put our spare tire back up and our installation will complete. This will conclude the installation of Curt fifth wheel 50064.

Info for these parts were:

Employee Joshua S
Video by:
Joshua S
Employee Jonathan Y
Video by:
Jonathan Y
Employee Jacob T
Video Edited:
Jacob T
Employee Cole B
Installed by:
Cole B
Employee Andy C
Installed by:
Andy C
Employee Conner L
Test Fit:
Conner L
Employee Ryan G
Test Fit:
Ryan G

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