The following information is based on my personal knowledge and experience installing a Western Chassis C-notch on my 1986 Silverado C10.
The reason for a C-notch is to provide increased suspension travel. Generally speaking, a 3/5” drop or more will require a C-notch to prevent bottoming-out over rough pavement. I’ll keep this essay simple by breaking it down into steps. Let’s get started!
The first step is to remove the bed. This involves removing eight bed bolts, disconnecting the wiring harness at the taillights, unbolting the filler neck assembly from the bedside(s), and the differential vent hose from the bed floor. I would also recommend removing the tailgate to save weight. Three or four people will be needed to lift the bed up and away from the frame.
Place a floor jack under the differential and raise the vehicle to a comfortable working level. Take into consideration you’ll be working under and around the vehicle. This next step is very important! You will need two pairs of solid jack stands. Place the first pair directly behind but below the cab. The next pair should be placed next to the rear spring hangers. Now, the frame is supported before and after of the C-notch location.
Remove the wheels and tires.
Getting to Work
This is where having the correct tools will make a big difference! There is several ways to remove the factory bumpstop brackets. You can use a cut-off tool, sawzall, or an air chisel. I used the latter with a cutting torch. A torch is not necessary but I would highly recommend one.
Start by removing the bumpstop with a pair of pliers. Pull down side-to-side and it will eventually remove itself. The frame mounted bracket has 4-rivets that secure it. Start heating the rivet heads located inside the frame rail one at a time. Stay 1-3” from the surface and stop when the head is “red hot”. Now, quickly place the head of the chisel against the rivet head and go for it!
As you will find out, once the rivet head is properly heated, it can be removed within seconds. Having one other person operate the torch or chisel will make this task more simple. Working in a star pattern, remove the rivet heads from both sides of the frame (Inside and bottom). Next, using a large center punch and hammer, pound the body of the rivets out. You will have to remove them from the bottom side of the frame rail, so beware of the falling bracket!
Now, repeat this procedure on the other side!
Unlike other companies, Western Chassis does not supply a template for the notch. I made my own out of cardboard easily enough. Working on a level surface, such as a bench, center the notch on a piece of cardboard. Scribe around the half moon opening using a Sharpie. Using a razor knife or quality scissors, cut on the outside of the line. TAKE NOTE: Outside of the line! The reason for this is to compensate for the inner weld inside the notch.
Raise the rear-end until it is 1-2” from the frame. Center the cardboard template directly above the axle. The bottom of the template should be flush with the bottom of the frame. Carefully, scribe around the template using a Sharpie. If the frame were painted, I would recommend sanding the paint off where you’ll be cutting. This makes the line much easier to transfer and see when working.
Now, it‘s time to start cutting! I used a cut-off tool but a sawzall will work great too. Both will deliver a precise and clean cut. Once the frame is completely cut, secure the notch to the frame using several C-clamps. A high-speed electric drill and high-quality (expensive) 1/2” drill bit will make drilling the 12 holes easy. Next, simply bolt-in the notch using the supplied Grade-8 hardware. I installed the side bolts first and tops ones last. Torque the hardware to 85lb-lt and install the polyurethane bumpstop.
Move on to the next side.
Prior to installing any C-notch kit, you must have installed the rear lowering components. For example, a flip kit pulls the rear-end back, thus changing the location.
Work on one side at a time.
Re-torque the hardware 200-300 miles after the installation.