Installing putco bed rails?

todd308 · April 8, 2021

Has anyone ever installed bed rails on these trucks? I got a set of the putco's because I had hoped to use them for adding cross bars to. However, it doesn't seem like there's any way to install them properly.

https://accessories.gmc.com/product/bed-products/short-bed-bed-rail-new-in-black-powder-coat-by-putco-associated-accessories-19418293?year=2020&make=GMC&model=Sierra 1500&modelId=548&body=Crew Cab Pickup&bodyId=22&wheel=Short Box&wheelId=651&trim=AT4&trimId=5102&drive=4WD&driveId=8&engine=6.2L V8 GAS&engineId=5920&bodyNumDoors=5&categoryId=12010

The pictures I've seen show them mounted on top of the plastic bed rail caps but I don't see any way to do this and have them be sturdy.

The reason is the plastic bed rail cap, it's not solid under the plastic where it mates to the truck bed metal rail, there's about 1/4" of open space under the plastic cap with just a few ridges to support it so when you try and tighten down the bed rail, it just crushes the plastic bed cap down. The instructions don't mention anything about removing the plastic bed cap, but even tightening the mount bolts to 5ft/lbs (half of the final torque value) it starts to crush the plastic top caps in.

You can't remove the plastic bed cap or it leaves tons of ugly holes all down the top of the bed rails.

I'll have to try and contact Putco see what they say, but the only option I see is to A) not use them or B) to remove the plastic top cap (which it appears would damage the retention tabs as you can't get to the outermost set) and fill the area under the plastic bed cap with epoxy etc. so it's solid.

Anacortes Army Guy · April 8, 2021

I installed the Putco bed rails on my 2020 LT and they installed fine, and just as the instructions show. Mine do not crush the plastic bed cap as both the front and rear anchor points grip the metal portion of the bed sides, albeit differently in the front versus the rear, securely. The only issue I encountered was I installed them after I had installed an Undercover Ultra-Flex tri-fold hard tonneau cover. The cover's side rails intruded slightly, and I do mean slightly, into a fraction of the space where the base of the Putco bed rails anchor plates sit on the bed rail caps, but it's hardly noticeable, and doesn't affect the sturdiness of the bed rails one bit. As a side note, the bed rails I installed were from the dealership, but were a slightly different style than the ones you installed. The front anchor points use tension on a rubber block (make sure you use the correct length bolts - on this point I found the instructions to be a tad confusing - shorter bolts are used on the front anchor points), and in the back there was a bracket affixed to a bolt that goes through an access hole in the side of the bed.

Edited April 8, 2021 by AnacortesArmyGuy

todd308 · April 8, 2021

Yeah I've used the rubber block style before on my fathers 07' when we installed a slightly different Putco style that simply expanded inside the metal stake pocket. I think the attachment method is the issue, these have a metal bracket that slides down inside the stake pockets that bolt through the horizontal bed access points inside the bed, and then use a hex bolt to pull downward. As a result all the downward pressure goes onto the plastic bed cap cover itself squashing it. I wonder if they stopped using the rubber expansion block because the plastic top caps now extend into the stake pocket and it would not hold as well.

Mine use the same mounting method for their new TEC rails in this video installing into a new Denali and it also shows their installation crushing that plastic top cap.

splatmatt · April 9, 2021

I installed the same ones on my truck a few weeks ago. Send a few pictures so I can get a visual on your issue. My install was pretty straightforward and the result is a very sturdy mount. I have yakima crossbars attached to the rails for my bicycles.

todd308 · April 10, 2021

Unfortunately I already took them off, but they were just crushing the plastic bed cap down so it was curving down as it approached the bed rail mount block. 2020 AT4

The picture is horrible, and a different model, but in areas that are green is where the factory installed bed rail cap was being crushed downward by the bed rail mount, and in areas that are red due to it deforming downward in the green areas the edges were flexing away from the body. They did the same type of thing in the front, I'd say overall they were worse in the front than the back.

I actually had the same idea, I wanted to use Yakima Timberline towers with cross bars thinking it would be easy/fast to remove if I needed to and I already have yakima bike trays and skinny warrior rack to use.

Not sure what I'll do now, the plastic bed caps are actually pretty cheap only about $75, I may order a set and see if I can't use either epoxy or thermoplastic sheeting to build up the area where the bed rail mounts go so it's solid instead of hollow. I thought I could just make a spacer the same height as the plastic bed cap that the bed rail mount would sit on to support it better, but if you look at the bottom of the bed rail mount there's very little material there where the bolt is that tightens them down, so I doubt it would stand up. The only real option is to reinforce the hollow area under the factory installed plastic bed rail cover. Maybe older trucks had solid bed rail caps, or these are just very soft, you can easily flex them, but I don't think the mount tabs would survive removal.

Edited April 10, 2021 by todd308

splatmatt · April 10, 2021

I’ll take a picture of my install tomorrow. It is dark outside now.

todd308 · April 10, 2021

Here's what's happening. I tried a slightly different install method from the video above so I could better monitor the brackets and make sure they were properly positioned. Interestingly it seems to be worse on the drivers side than passenger. Also this is not even what I'd consider tight, I can still tug a bit on the bar and the two end pieces that are bolted on will shift. I'm sure it would be fine for looks or even using for the occasional tie down of cargo, but it's not solid enough I would not want to mount a yakima style bike rack to it, especially for off road use. Bikes put a lot of side to side torque on a rack when off road. A simple cargo rack would probably be fine since most of its pressure is always downward.

One thing I noticed is the seal caps that go on the bottom of the rail bar mounts are very hard and slick. I'd have expected them to be a more grippy high durometer rubber. Tried cleaning them off with acetone along with the top of the bed rail thinking that would add some grip.

All in all I think this is a pretty much total fail, unless I decide to buy a couple new bed rail caps and reinforce what's under them so they are solid and won't compress. Even if they were not compressing the plastic cap now, any amount of weight or sideways torque, especially over time off road is going to slowly compress the factory rail covers under the bed rails, and as they compress they the rails will just loosen again. It's just a horrible design to put anything that's going to carry weight on. It makes me wonder how many people that have put larger/heavier tool racks or overland setups etc. are going to have this problem over time since most of those seem to mount in the same manner.

splatmatt · April 10, 2021

It looks like you torque down on the top allen screws quite a bit. Did snug the side bolts before wrenching down on the top bolts?

Here is mine - they are very solid and the plastic caps are not warped.

todd308 · April 11, 2021

Yep I did the side bolts first and got those centered and snug, made sure the top of the brackets were fairly level then did the top allen screws. GM instructions said to do 5ft/lbs on the front, then go to 10ft/lbs on the rear making sure the spacing was tight to take any slop out of the bar, and then go back and tighten the front down to 10ft/lbs. The deformation shown is at 60in/lbs or 5 ft/lbs, I could never get the torque wrench to hit 10ft/lbs, it was just squishing the rail caps down more so I stopped. I did notice the caps are pretty soft on mine, I can deflect them just pushing down on them hard with my hand. So perhaps GM went a little too cheap on them recently, or it was just a weak batch.

splatmatt · April 11, 2021

I usually obey torque values - but in this case I did not.

I have done several projects since I installed the rails so I’m not sure if a I am mixing details. I believe I decided not to use the torque wrench because:

- I believe blue locktite was on the screws - if not then I put it on.

- The screws were long.

- I felt the engineer was giving a reference for how snug they should be and to balance the tightening off all for points. (assumption based upon experience - other people’s mileage my vary).

What I did and why:

So, I just evenly snugged all 4 corners over several steps. Torquing to specific values on a plastic surface always concerns me because plastic is can flex differently at different temperatures so you may screw more or less down the threads to achieve the same torque value based on how much the plastic flexes.

todd308 · April 11, 2021

That might be part of it too, perhaps the torque values were simply hold overs from when plastic bed caps did not exist and in the effort to obtain them it damaged the rail caps, and of course once plastic is damaged like that it's never as strong and the damage was done. GM's instructions on their parts have never been that great. I also notice that if you look at Putco's instructions for say the locker version or the Tec rail that has the same mounting brackets, the installation procedure is similar, but they never mention any torque values, or trying to achieve a specific distance from the front of the box to the "nose" of the bed rail based on vehicle model. That said as I was tightening them I never really felt they got really solid I could still easily tug on the bar and see the mounts shift/twist.

I never could find any info on Putco's site for these exact bed rails, they appear to be something made for GM specifically.

On a different note how are the Yakima Railgrab towers working out? I originally wanted to use those as I started my research since others had recommended them for bed rails, but they no longer make them and they've been replaced with the Timberline tower, which seems like it might not be as solid on a round bar. The Railgrab tower pulls the bar into the curve right, where the Timberline instructions want you to center the the bar It's basically just a strap that tightens around the bar, but doesn't seem to have any indent or shape that keeps it solidly on the bar itself so if I ever get the rail bars sorted out it will be interesting to see how solid the new Timberline style is.

Edited April 11, 2021 by todd308

splatmatt · May 4, 2021

On 4/11/2021 at 11:22 AM, todd308 said:

On a different note how are the Yakima Railgrab towers working out? I originally wanted to use those as I started my research since others had recommended them for bed rails, but they no longer make them and they've been replaced with the Timberline tower, which seems like it might not be as solid on a round bar. The Railgrab tower pulls the bar into the curve right, where the Timberline instructions want you to center the the bar It's basically just a strap that tightens around the bar, but doesn't seem to have any indent or shape that keeps it solidly on the bar itself so if I ever get the rail bars sorted out it will be interesting to see how solid the new Timberline style is.

The railgrab is what I had from a rack I used on our Subaru. So far no complaints, I am currently carrying 20 40lb beach cruiser bikes and everything stays tight. Did you ever get something working?

todd308 · May 5, 2021

Not yet, I'm actually in the process of swapping out my 2020 for a 2021 with the crazy prices Carvana/GiveMeYourVin are offering. My plan is to basically remove the bed caps reinforce them with non-compressible thermoplastic and install them over that. It's only about $75 for the plastic bed caps, so even if removing them damages them it's not bad.