How to Install a Peterbilt 379 Bumper Lift Kit Using 5 Steps

6th Nov 2026

Flip kits protect your expensive custom bumper from getting scraped. Simply flip a switch in your cab and the bumper lifts 8-inches in a few seconds.

If you're looking to install a Peterbilt 379 bumper flip kit for extra ground clearance and maneuverability, here's an expert-led breakdown from 12 Gauge Customs of exactly how to do it.

During an installation, you have to consider: lift arm geometry, air cylinder operation, bumper swing travel, regulator tuning, and proper blind-mount bumper integration.

How Peterbilt 379 Lift Bumpers Actually Work

The 12 Ga. Peterbilt 379 bumper lift kit isn't just an air cylinder that raises the bumper, it consists of:

Lift arm mechanisms
Pivot points mounted in the factory bumper location
Air cylinders
Cylinder ounting brackets
Blind-mount bumper plates
Lift plates that carry the bumper weight

Mechanical Sequence

Air pressure is applied to:

Open the solenoid
Air enters the cylinders
Cylinder rod extends
Lift arm rotates upward
Lift plate pushes bumper up
Entire bumper rotates away from hood path

When pressure is released: the cylinder retracts, lift arm rotates down, and bumper returns to normal driving position.

5 Step Flip Kit Installation Workflow (Simplified)

Remove the Bumper
Install the Lift Arm
Secure the Air Cylinder Mounts
Integrate the Blind-Mount Bumper Backing
Test and Adjust Lift Kit Activation Using the Cab Toggle Switch

The total installation process can take 8 hours, especially if it's a first-time DIY attempt to wire a flip kit to the pneumatic system.

#1. Remove the Factory Peterbilt Bumper

Goal: Create a clean mounting surface that replaces the factory bumper mounting structure in order to attach the lift-arm assembly.

What happens:

Remove the factory bumper from the front frame rails.
Remove the factory bumper support brackets.
Reinstall any factory 5/8" frame bolts that were removed during disassembly.

The original bumper has to be removed completely before you install the lift kit.

The lift kit has its own lift arm mechanism that replaces the original bumper supports.

When removing the bumper, you need to remove the rubber radiator shrouds located on the front side of the radiator. These will block your access during installation.

Inspect the frame rails once the bumper and brackets are removed. Make sure there are no bent surfaces, rust, corrosion, or missing hardware pieces.

Reinstall any of the factory 5/8" bolts that you removed with the bumper. They can be reinstalled into the framerails. You'll use these bolts as referential mounting points to help you later on.

What should be done by the end of the first step:

Removed the factory bumper completely
Removed (and saved) the support bracket hardware
Removed the radiator shrouds
Exposed front frame rails
Factory frame hardware (5/8" bolts) get reinstalled
Clean mounting points are now ready for the lift-arm assembly

#2. Lift Arm Assembly Installation

Goal: Square both lift arms so they move together as a single assembly.

What happens:

Bolt the lift arm mechanisms into the original bumper mounting holes using the factory hardware.
Leave all mounting bolts finger-tight initially.
Install the temporary guide plates.
Set the bumper loosely on the guide plates to ensure both lift arms are perfectly aligned.
Once alignment is verified, remove the bumper and fully tighten the lift-arm mounting bolts.

The Lift Arm Alignment

Always use guide plates to keep the lift arms parallel to the bumper.

Step 1: Install the lift arms with loose bolts for easy realignment.

Step 2: Use the bumper as an alignment tool.

Step 3: Verify that the lift plate is symmetrical and parallel.

Step 4: Remove guide plates after alignment.

Doing this ensures equidistant bumper travel distance, prevents binding when the flip kit is used, and establishes proper bumper positioning before tightening it in place.

If the lift arms are not square, the bumper can:

Rise unevenly
Twist during operation
Wear down cylinders
Touch the hood or grille

How to Square the Bumper Lift Kit Assembly

A "squared" Peterbilt 379 bumper flip kit assembly means it is geometrically aligned in these ways:

Side-to-Side: the bumper protrudes equally from both sides of the truck
Front-to-Rear: both lift arms align at the same fore/aft positions
Vertical: lift plates support the bumper at identical heights
Operational: the bumper smoothly raises and lowers without twisting

Why Guide Plates are Critical During this Phase of the Installation

New lift kit designs come with two guide plates to help align the bumper while the lift kit is being positioned for installation.

These accessories save you from costly mistakes.

For example, let's say that one arm is 1/8" ahead of the other. The bumper will then twist and contort during a lift.

If the lift kit geometry isn't aligned with the bumper, you might see:

Uneven gap between the bumper and grille
One side lifts before the other
One cylinder carries more load
Premature bushing wear
Air cylinder side-loading

#3. Air Cylinder Mounting

Goal: Connect the air-powered cylinders that will drive the lift-arm mechanism.

What happens:

Mount the cylinder brackets to the frame rails.
Install a 5/8" washer between the frame and bracket as instructed.
Attach the air cylinders using the supplied clevis pins and hardware.
Tighten the nylock nuts only enough to secure the cylinders while still allowing free pivot movement.

Cylinder Bracket Positioning

The air cylinder bracket has a unique mounting feature:

Rear hole clears an existing 5/8" frame bolt head
Front hole is used for securing bracket
Washer must be installed between frame and bracket

Incorrect spacing the cylinder brackets could cause issues like:

Cylinder misalignment
Binding
Uneven bumper lift angles

To avoid this, double check your measurements/spacing.

#4. Blind-Mount Bumper Integration

Goal: Permanently connect the blind-mount bumper to the lift-arm assembly.

What happens:

Place the bumper on the lift plates and guide plates.
Center and square the bumper on the truck.
Move Bracket "A" against the bumper's backing plate.
Mark the required drilling locations.
Remove the bumper.
Remove the inner bumper plates.
Drill:
- Two 1/2" holes
- One 3/8" hole
Remove the temporary guide plates.
Bolt the bumper plates to the lift-arm assembly.
Reinstall the bumper and make final fitment adjustments.

Blind-Mount Compatibility

Unlike standard front bumpers with exposed bolts, blind-mount bumpers have a bumper backing structure that requires some fitting and drilling in order to get the lift kit to fit.

Installation requires:

Positioning the bumper on lift plates
Moving Bracket A against the bumper backing plate
Marking the mount hole locations
Drilling two 1/2" holes and one 3/8" hole

This will createa a custom mating surface between teh lift assembly and the backing bumper structure.

Drilling Tips for the Blind Mount Bumper Flip Kit

Place bumper on truck allowing the bumper to rest on life plates and guide plates.

Bracket A is your critical reference point to:

Transfer mount hold locations
Ensure proper lift kit geometric alignment
Maintains the correct bumper orientation

After you market the location from Bracket A, identify the exact drill hole pattern locations.

You'll need to drill two 1/2" holes and one 3/8" hole.

The two small drill holes are the points that carry the bumper weight upon lift. The single 3/8" hole is the anti-rotation point that stabilizes the bumper while in operation.

Remove the inner bumper plates to drill the newly marked holes. It's important.

Drilling through the existing assembled bumper holes will misalign the plate interfaces and put stress on the fasteners.

Removing the bumper plates beforehand will ensure you have accurate drill holes and clean hardware seating.

Once you're done drilling, use the slotted mounting holes on the bumper to adjust the bumper's position until the top of the bumper is flush with the grille or at least 1/16" below the grille.

Check & Adjust the Bumper Height

Once it is installed, use the slots in the bumper plates to adjust the height (ground clearance level).

The top edge of the bumper should sit flush with the grille or 1/16" below the grille.

Verify the Hood Clearance

Before activating the air pressure that controls the lift kit, verify the hood clearance as well:

Open the hood slowly
Check the bumper clearance
Verify if the hood has enough travel room when opening and closing

If it's not spaced properly, you could see failure points when activating the lift kit:

Surface-level hood damage
Paint chipping
Chrome bumper contact to the ground surface
Excessive lift-arm travel

#5. Pneumatic & Electrical Setup and Adjustment

Goal: Fine-tune the air pressure so the bumper raises smoothly and consistently.

What happens:

Mount the electric solenoid valve in a protected location (the instructions suggest the battery box).
Run switched 12-volt power and ground from a customer-supplied dash switch.
Connect the air lines to the cylinders and solenoid.
Charge the truck's air system.
Cycle the solenoid until it operates smoothly.
Adjust the air regulator.
Slowly increase pressure until the bumper fully raises.
Add approximately one-half turn of regulator adjustment after achieving full lift.
Verify operation.

Pneumatic System Lift Kit Check

The lift kit uses:

Air regulator
Solenoid valve
Dual cylinders
T-fitting distribution

The configuration includes:

A = Normally Open

B = Normally Closed

P = Air Supply

Adjustment Procedure Explained

Start the any pneumatic/electric lift kit adjustments in this order:

Charge the air system
Increase regulator pressure
Cycle solenoid until smooth operation
Reduce pressure until supply cuts off
Slowly reintroduce pressure
Add 1/2 turn after full bumper lift

This tuning procedure is designed to minimize excess force air, cylinder shock loading, and to prevent janky bumper movement every time you use the bumper lift kit.

Step 1: Charge the Air System

Start the truck and let the air tanks reach normal operating pressure. Since the lift kit uses air to move, you won't know if the issue is an incorrect regulator adjustment or low air pressure.

Step 2: Increase Regulator Pressure

Turn the regulator adjustment knob to let more air into the bumper lift kit system.

You are gradually giving the air cylinders enough pressure to move the bumper. This lets you spot any potential issues with your installation.

Step 3: Cycle the Solenoid Until Operation is Smooth

Operate the bumper switch several times: repeatedly raise and lower it.

This helps do a few important things:

Fill the air lines
Remove trapped air
Verify the wiring connections are unhindered
Verify the solenoid is working correctly
Verify the cylinders can move freely

Step 4: Reduce Pressure Until Air Supply Stops

Turn the regulator down, lowering the air pressure, and lowering the bumper.

You'll notice the minimim air pressure point (a baseline) where the lift kit system will no longer work.

Step 5: Slowly Reintroduce Air Pressure

Start increasing the air pressure to the lift kit once more.

This is how you identify the lowest pressure level that will still raise the bumper to its full clearance height.

After each air pressure adjustment, activate the bumper, look at how it moves, and increase pressure if you need it.

Step 6: Add One-Half Turn Beyond Full Lift

Once the bumper effectively reaches full lift height, turn the regulator an additional 1/2 turn.

Doing this will add a small safety margin in case of cold weather, air pressure changes, or system wear over time.

This will give your bumper flip kit enough air to operate consistently while not over-pressurizing the cylinders.

The goal is to adjust the kit to operate at the lowest air pressure that will still efficiently lift the bumper each time you use the flip kit.

If you do it correctly, you should see:

Bumper lifts smoothly
Bumper reaches full height
No jerking or slamming
Both sides move evenly
Consistent operation every time switch is activated

Shop Peterbilt 379 Bumper Flip Kits at 4 State Trucks

Get a warranty-backed, premium bumper lift kit assembly for your 379 model year. Shop online, use the mobile app, or stop by our retail store off I44 highway in Joplin, Missouri.

6th Nov 2026