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Curt Fifth Wheel Kit Installation - 2018 GMC Sierra 2500

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How to Install the Curt Fifth Wheel Kit on a 2018 GMC Sierra 2500

Speaker 1: Today on our 2018 GMC Sierra 2500, we're going to be taking a look at and I'm going to show you how to install the Curt custom fifth wheel installation kit for Chevy and GMC, part number C16411-204.This is what our rail kit looks like when it's installed. This is going to allow you to easily remove your fifth wheel base when it's not being used. Your rails are only going to take up from the top corrugation to the top of the rail, only sticks up about an inch. These rails are going to work with most industry standard fifth wheels. You can see they're going to have multiple mounting locations in each rail.One thing I really like about these rails, you can also pick up a goose neck adapter that will fit inside these mounting locations if you have a goose neck trailer that you may need to pull. You won't have to drill that large hole in the bed of your truck.

This installation is very straight forward. It's going to use existing weld nuts in the frame, so you're not going to have to drill any holes down below. The only holes that have to be drilled are for the five carriage bolts that run into each frame, down through the thread and attach to the frame brackets.Now, these rails are going to come with a carbide finish to resist any rust or corrosion. Now, that we've gone over some of the features, we'll show you how to get them installed.First thing we need to do is we need to set one of our rails in our truck bed and depending on your bed size, long bed or short bed, you're going to measure from the edge of your bed, make sure you don't go from the tailgate, from the edge of the bed up to this front edge or back edge of the rail per the distance in the instructions. Again, make sure you're using the measurement for the size of your bed.

Once we got our distance here, what I like to do is come over to the sides and measure each corner also to make sure I got the same distance from front to back or back to front and then we're going to want to go from here into this edge. We want to adjust back and forth to get that centered.Once we got it right, we're going to take a marker and we're going to mark these outside holes on this most forward rail, we're going to use the outside holes. I'm going to mark the very center out of each of these holes on the rear rail. I'm going to take a small drill bit, eighth inch drill bit works and we're going to drill out right in the center of that. Now, you're going to make sure that you this center hole that's towards the back of the truck on your rails.

Again, we'll drill our pilot hole. Then we'll open it up to the specified amount in the instructions.Next, to make it a little bit easier, we're going to remove this fender liner. You're going to have 12 T15 torch bit screws that are holding in place. We're going to go ahead remove those and pull out the liner. We'll pull our liner out, set it aside.

We're going to repeat that on the other side. Now, we're going to take one of our frame rails. We're going to loosely install it and check our hole alignment. Now, you're going to have a right and a left side, or a passenger and driver side, and how you tell is the angles on the edges. This angle right here is going to go towards the back of the truck. This rounded edge is going to go towards the front. It's going to fit just like that. So, these top holes are going to line up with these two holes and our bottom holes are going to go these existing weld nuts.We'll go ahead and use our hardware that's going to be installed just to hold our rail in place here. Then I'm going to have somebody up top, drop a screw driver or something down through the hole and see how it lines up. Now, it's going to be kind of hard to see because this top bracket goes up over top the frame but we'll do our best to show you what it looks like. Now, we'll drop our drill bit or small screw driver down through the hole. And you can have somebody just look and see if we're centered in holes in our bracket.Next, we're going to take a small set bit and we're going to open our holes to the amount specified in the instructions. We're going to do that with all remaining holes. Once you have your holes drilled, clean up all the shavings. I'm going to suggest taking some clear coat, black paint if you want and cover that bare metal. It's going to help reduce any chance of rusting in the future.Now, we'll loosely put our brackets back in place. Drop our carriage bolts, half-inch carriage bolts down through our holes and you're going to have some half-spacer blocks like this, you'll notice the corrugation drops right under the bolt What we don't want to do is we don't want to smash this where it's flat. So, we're going to take these and slide them underneath to our bolts on the ends. It should fit right around an end bolt like that.Next, we're going to take our hex bolts, we're going to use a lock washer and a flat washer and we're going to put these into place. We're going to use that same combination for both holes on both side plates. You want to make sure we're just loosely installing these right now, we don't want to tighten them down into place. Now, they're not going to tell you this in the instructions, we've gone ahead and taken the spare tire down to make it a little bit easier when we're putting in our hardware underneath the vehicle. I would suggest doing it. They also don't tell you that you're going to need to pull off this heat shield right here because the hardware for your rail is right up above your frame, which is right up on top of your heat shield. So, I mean it's not completely necessary but I would suggest doing it to make it a little bit easier, you're going to have the mounting location right here on top of this cross bar here. You're going to have one up here in the front on top of that one and then you're going to have two right on the outside on top of the frame.I went ahead and pulled this side bracket off, you can see my mounting locations right here. I always use a half-inch socket or wrench and pull out those two bolts. This one you can get to with a rail, this one is a little hard. So, we'll probably just loosen that one, take the two out from the inside, we'll take this one out just enough where we can spin this back and get our hand up in here.You can see, this allows us to move it, to be able to get up to our hardware when we mount it to the bed of the truck. This is going to be hard to see where I'm putting it in, but the two bolts that we dropped down through our rails in our bed, down through our frame rail, we're going to put on a spacer block, a square one like this and then a flange nut. I'll show you want it looks like when I get done and you're going to do that same thing on all remaining hardware that's been attached to your frame rails underneath the truck.Next, we're going to put our hardware on our center bolt that's coming down, that we dropped down through our frame rail. You can see how the corrugation raises right there from the bed of the truck. What we're going to do is we're going to put a U shaped spacer block and then our square spacer block just like that. We'll put on our flange nut like that. And then we're going to tighten all the hardware that we have installed on our front bed rails with a three-quarter inch wrench or socket. It's going to be a little bit hard to get up inside there with a socket or it may be a little bit hard. You can try. This is what our hardware is going to look like when it's installed on our frame brackets.Now, to get our measurement for our rear most rail, we're going to put our hitch into place. Again, we're going to measure from the outside here fender, or inside the fender to the edge on both sides to make sure we're square. That's going to make taking this in and out a lot easier where it's not getting snagged. Pretty close there. So, on this rear rail, we're going to be using the second holes in. We're going to do the same process we did and you can make the hole if you want. I like to mark just the center of the hole like that. We're going to be using this back hole and then we're going to drill these out the same way we did our front ones.And then we'll repeat the same process, we're going to check our hole placement with our brackets underneath and then drill out our holes to the correct size. Next, our hardware that's going to be going on the bottom is going to be the same as we did on the front one, except you're going to have a U shaped block. You can see where the corrugation goes up here, we want to slide that into place. And we'll repeat that on the front like that with our flange nut. We'll repeat that same process for our three remaining bolts on the back of our frame brackets.Next, we're going to torque all of our hardware to the specific amount in the instructions. We're going to start with the hardware that's going up to the bed. We want to repeat that for our hardware going through our frame brackets up to our bed. Now, we'll use a three-quarter inch socket to tighten everything up to the bed. We use a 15/16th socket to tighten our frame rails to our frame. We're going to torque these to the specific amount in the instructions. You're going to repeat that for the three remaining bolts going into our brackets.Now, we can reinstall the bolts for our heat shield and we'll tighten them down with our half-inch wrench. Now, we can reinstall our fender liners in reverse order from the way we took them out. Once you have everything installed, re-install your spare tire and you're ready to go.That will do it for a look at and installation on the Curt custom fifth wheel installation kit for Chevy GMC, part number C16411-204 on our 2018 GMC Sierra 2500.

Questions and Comments about this Video

Bob G.

Would be nice to see how you torqued the nuts between the bed and the frame, since you cant get a socket and ratchet in there.

Etrailer Expert
Reply from Jacob H.

Typically we will use a socket swivel to torque hardware down in the hard to reach areas. But I agree that the installer should have mentioned how he did this as it will be difficult for anyone that installs this in-bed rail kit.

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