BAKFlip MX4 side seal replacement and upgrade kit install

First project post so feel free to share any critiques.

I purchased a 2019 1794 Edition earlier this month and was excited that it came with a BAKFlip MX4 tonneau cover. It has some hail pings, paint chips, and general wear, but it has some life left in it. I noticed some significant water in the bed after the first rain so I set out to find the entry points. My right side seal had a large crack in it and many of the seals between the cover panels looked like they were cut short. They didn't fit all the way under the side seal.

I did some searching and didn't find a reference to anyone doing the side seal replacement. AZTundra mentioned he planned to replace his back in June but didn't have any updates. I verified with him and with BAK Industries that the side seal kit BAK-PARTS-326A0011 is compatible with the MX4, despite item page on RealTruck not being updated. I ordered the side seal kit and took a gamble on the MX4 upgrade kit (BAK-PARTS-MX Upgrade Kit) as well. My MX4 was the older design before they added corners and some other pieces. The upgrade kit apparently brings it up to the newer standards.

The upgrade kit came with great instructions. Sadly the side seal kit did not, so I documented the journey to share. It took about 3 hours to work through the whole project. Knowing what I'm doing I could do it again in half the time.


This is a photo of the tear in my right side seal.



This demonstrates the gap in between the cover panels.



I brought the cover indoors and let it get up to room temperature before working on it. If it were summer I would have probably done it outside.



After laying it all out it was time to rip off the old side seals. It was old enough that I was able to just pull and it separated from the adhesive and the channel portion just tore off. I then slid that out.



After pulling the old side seals off I cleaned up the old adhesive. I used razor blades, silicone kitchen scrapers, Goo gone, and a lot of elbow grease. This was by far the longest part of the project.



Once things were clean I wanted to figure out the panel seal issue. I found that my panel seals weren't centered very well. They had a large portion on the right side, well under the seal, but a half an inch missing on the left. They were all over the place. I shimmied them to center and a dry fit of the new seal showed they would be covered. But I went a step further and filled the gaps with butyl rubber tape. It's flexible and I figured it couldn't hurt. (these photos were before the final cleaning so there's still some adhesive and dirt visible)



I had two additional sets of hands help me feed the new seals into the channels. No photos of the process as all hands were in use. Careful not to tear or come out of the channel as you feed it. Don't pull the red tape yet, just feed into the channel.

The old seals had cutouts at the fold points for each panel. They varied in depth and some were so close to the edge I'm surprised they never tore. This shows two different sets of factory cuts on the old seals. The top is the original seal from mid section on the left and the bottom is the original seal from the right side near the front.



And this shows the factory cuts held up against my new seal.



I decided to duplicate the shape of the cut, but I went about half as deep. This terrible photo is the only one I have but it demonstrates what I did. And you'll see later how it looks on the fold. Hopefully this holds up!



The seal kit comes with a small 3M Primer 94 pen. This is an adhesion promoter and it needs to be applied and allowed at least 5 minutes to dry before moving on. This stuff is nasty. The warning label mentions fatality if handled improperly. Make sure you're ventilating well! My pen didn't have enough to cover all of the left and right sides. I guessed it wouldn't, so I started at all four corners and moved inward. After waiting for it to dry I then pulled back the red adhesive on the seals and set them in place. I applied spot pressure down the whole seal back and forth a few times. I then left the whole MX4 cover to sit in an open position overnight for 12 hours.

If you were replacing your seals and had existing corner caps you may have some additional work pulling those off first. As mentioned earlier I have the older model so it was time to upgrade.



I measured out the corner cap side seal cuts per the instructions and trimmed the other seals that were in the way.



I replaced my elevator bolts and top cab panel bumpers.



I added the bed rail caps.



My latch cover bumpers and prop rod clips were in good shape so I didn't see a reason to upgrade those for now.

Here is what the corner caps look like now.



And this is what the fold cuts look like fully folded.



After putting it back on the truck I folded it a few times and everything seemed to work well. I'm leaving it closed for a few more days in hopes it forms a better memory for sealing. Rain is in the forecast next week so we'll see how well it holds up. I'm hopeful! Let me know if you have any questions on the process.

 

Great write up! As you noted above, I don't believe anyone else has done this yet or at least not documented it anywhere that I could find. Now that I've dug my replacement seal out of the garage I hope to install mine very soon as well. I will definitely refer to your pictures above during the process. Glad to hear it went pretty smooth.