Mx4 Install - did I screw up?

[Bgriffin613]

Hey everyone - I tried the search function to no avail. I am trying to install the mx4 tonneau on my f150 and while reading the instructions it mentions that shims “may” be needed depending on vehicle to ensure proper angle of the side rails. The supplemental sheet doesn’t list 21’ model year either way. It looks like the tonneau rails have 4 shims on them from the factory. When I test fit the rails, it’s tough to tell if the shims should be removed or not to ensure proper rail install.

can anyone provide feedback on what is correct or what they did? Thanks!

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[Mikepa]

Hey everyone - I tried the search function to no avail. I am trying to install the mx4 tonneau on my f150 and while reading the instructions it mentions that shims “may” be needed depending on vehicle to ensure proper angle of the side rails. The supplemental sheet doesn’t list 21’ model year either way. It looks like the tonneau rails have 4 shims on them from the factory. When I test fit the rails, it’s tough to tell if the shims should be removed or not to ensure proper rail install.

can anyone provide feedback on what is correct or what they did? Thanks!

I installed mine without shims on my 5.5' bed and it appears to sit correctly.

Only problem I now have is that I was told by the online merchant that if would work with a TracRac slide rail and it does not appear to. Now the question is which product do I want more.

 

[tony72cutlass's']

Hey everyone - I tried the search function to no avail. I am trying to install the mx4 tonneau on my f150 and while reading the instructions it mentions that shims “may” be needed depending on vehicle to ensure proper angle of the side rails. The supplemental sheet doesn’t list 21’ model year either way. It looks like the tonneau rails have 4 shims on them from the factory. When I test fit the rails, it’s tough to tell if the shims should be removed or not to ensure proper rail install.

can anyone provide feedback on what is correct or what they did? Thanks!

Man I’m having the exact same problem as you! From the way the bed rail is angled, you would think it might need some more shims. But I noticed the same that 2021 was not listed in the pamphlet (glad I’m not the only one that noticed!)

I bought mine from a truck accessory dealer and I have an appointment there on Friday. The third panel from the front is very tight and it’s rubber rubs on the rails. I have to jiggle it around to make it shut properly.

 

[Bgriffin613]

Man I’m having the exact same problem as you! From the way the bed rail is angled, you would think it might need some more shims. But I noticed the same that 2021 was not listed in the pamphlet (glad I’m not the only one that noticed!)

I bought mine from a truck accessory dealer and I have an appointment there on Friday. The third panel from the front is very tight and it’s rubber rubs on the rails. I have to jiggle it around to make it shut properly.

The official verdict from Bak was that the installed shims from the factory are needed on the 21. Installed as such and seems to be working out for me now. Good luck!

 

[tony72cutlass's']

The official verdict from Bak was that the installed shims from the factory are needed on the 21. Installed as such and seems to be working out for me now. Good luck!

So there were shims already installed on your rails? I didnt really look when i installed!

 

[Bgriffin613]

Yes, there were 4 shims on each rail. When I test fit the rails it looked like it was crooked because of them but once everything was tightened down, it was clear the shims were needed. It’s 4 pieces equally spaced on each rail at the top

 

[Bgriffin613]

I installed mine without shims on my 5.5' bed and it appears to sit correctly.

Only problem I now have is that I was told by the online merchant that if would work with a TracRac slide rail and it does not appear to. Now the question is which product do I want more.

Well this is disappointing to see. I was planning on doing the same thing

 

[Mikepa]

Well this is disappointing to see. I was planning on doing the same thing

Yes. I was disappointed to say the least. One of my lumber suppliers had their F150 sales fleet (up to 2020) modified to support a similar setup by poking the rails out and redrilling them for the rubber bung. Looks ugly but seems strong enough to support the lumber stock.

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