The O-ring in the Banks Ram-Air Differential Cover Kit is supposed to be installed under compression. If you just lay it into the groove, you can end up with a loop of extra material near the end and think the seal is too long. It isn’t. The right move is to hold one section in place and keep pushing the O-ring into itself as you work around the cover, like an inchworm or accordion. That shortens the seal, fattens it slightly, and lets it sit fully in the groove for a proper seal. Do not cut it. If you need to start over, the cover includes a machined divot so you can pry the O-ring out and try again without damaging it.
This short video addresses a frequent customer concern about the O-ring used in Banks Ram-Air differential covers. Some installers assume the supplied O-ring is too long because extra material appears to remain as it is placed into the groove. The video makes the point immediately and clearly: the O-ring is not the wrong size, and it must not be cut. Cutting the O-ring will compromise the seal and cause a leak.
The apparent excess length is a normal part of installation, not a packaging error. As the O-ring is worked into the machined groove around the differential cover, it can seem as though a loop of extra material will remain near the end. Banks explains that this is expected if the installer simply lays the seal into the groove without managing its length. The correct approach is to compress the O-ring into itself as it is installed so the full circumference fits properly.
The demonstration begins by removing the O-ring from the cover and then reinstalling it correctly. The process is not to stretch the seal around the perimeter, but to place it into the groove gradually while controlling its shape. Banks compares the motion to an inchworm or a closing accordion: the installer shortens the O-ring by pushing material into itself rather than pulling it tight.
Installation starts by pressing one section of the O-ring into the groove and holding it in place with one finger. With the other hand, the installer pushes the O-ring into itself, effectively bunching it slightly. This makes the seal shorter and thicker as it goes into the groove. The video emphasizes that this is intentional. By fattening the O-ring and reducing its effective length during installation, the seal seats fully around the cover instead of leaving a loose loop at the end.
That same inchworm motion is repeated little by little around the entire circumference of the differential cover. One hand keeps the already seated portion from lifting out, while the other hand continues pushing the O-ring into itself and down into the groove. The installer progresses steadily around the cover until completing a full 360-degree pass. At the point where an improperly installed seal would normally leave visible excess material, the correctly installed O-ring is fully seated all the way around.
Once the O-ring has been worked completely into the groove, the final check is simple. Run a finger around the entire perimeter to confirm that the seal is uniformly seated in the groove with no lifted sections or leftover loop. In the demonstration, the result is a clean fit around the full cover, which Banks presents as the proper condition for a reliable seal.
If the O-ring does not go in perfectly on the first attempt, Banks says to remove it and try again rather than forcing the installation or trimming the seal. The cover includes a small machined divot specifically for this purpose. That feature allows the installer to insert a plastic pry tool, or another suitable tool, under the O-ring and lift it out without damaging the seal. From there, the O-ring can be peeled out and reinstalled correctly.
The closing point is that Banks intentionally supplies the correct O-ring size for the Ram-Air differential cover, even if it initially appears oversized during installation. The seal is designed to be compressed into the groove using the described method, not modified. When installed by shortening it into itself around the groove, the O-ring fits the cover properly and is positioned to provide the intended leak-free seal.
