Aug. 28, 2026
Modern SUVs increasingly use factory power liftgate systems to provide automatic opening and closing of the rear tailgate.
Under the original vehicle configuration, the liftgate weight, center of gravity, mounting geometry, electric strut force, motor torque, travel distance, and control system are designed to work together as one balanced system.
However, vehicle armoring changes this balance.
After ballistic glass, armor materials, or structural reinforcement are added to the rear tailgate, the factory power liftgate may no longer operate under the conditions for which it was originally designed.
This is one of the main reasons an OEM power liftgate can begin to struggle after an SUV is armored.
01. Armoring Adds Significant Weight to the Tailgate
Ballistic glass and armor protection are significantly heavier than standard automotive materials.
Depending on the vehicle, ballistic protection level, glass configuration, and reinforcement design, the additional weight on the rear tailgate can be substantial.
In some armored vehicle projects handled or evaluated by the engineering team, the additional tailgate weight may reach around 50 kg or more.
This does not mean every armored SUV gains the same amount of weight. The actual increase must be measured or confirmed for each project.
The important engineering point is:
The OEM power liftgate was designed for the original tailgate—not the newly armored tailgate.
02. The Tailgate Center of Gravity Also Changes
Added weight alone does not fully explain the problem.
Where the additional weight is located is equally important.
For example, adding ballistic glass to the upper section of a tailgate can change the center of gravity and increase the torque acting around the tailgate hinge.
This means two tailgates with the same total weight may still require different strut forces if their weight distribution is different.
That is why selecting a heavy-duty electric strut only according to total kilograms is not enough.
Engineers must also consider:
Tailgate center of gravity
Hinge position
Strut mounting points
Opening angle
Strut stroke
Added weight distribution
Required opening and closing behavior
03. The Original Electric Strut Force May No Longer Match
An electric power liftgate strut is not simply an electric motor attached to a rod.
Its internal spring force and mechanical structure are designed to support a specific tailgate load.
Two important parameters in custom strut engineering are often referred to as F1 and F2 force values.
After vehicle armoring, these forces may need to be recalculated and matched to the new tailgate load.
If the force is too low:
The tailgate may struggle to lift.
It may stop during opening.
It may fail to remain open.
The motor may operate under excessive load.
But simply increasing strut force as much as possible is also not a professional solution.
If the force is incorrectly matched, it can create new problems with opening behavior, closing performance, structural loads, or system control.
For an armored vehicle, the objective is therefore not:
“Use the strongest possible strut.”
The correct objective is:
“Use the correctly engineered strut force for the modified tailgate.”
04. The Drive Motor May Not Have Enough Torque
The electric motor inside a power liftgate strut must overcome the tailgate load throughout the opening and closing process.
The initial opening phase can be particularly demanding because of the mechanical geometry between the tailgate, hinge, and strut.
When armor adds significant weight, the OEM motor may operate much closer to—or beyond—its original load range.
Possible symptoms include:
Slow liftgate movement
Difficulty starting the opening movement
Intermittent stopping
Abnormal motor load
Inability to fully open
Inability to close smoothly
In some Guangzhou Tomaster Auto Parts heavy-duty electric strut designs, motors with stall torque above 10–12 N·m are used according to the specific application.
However, motor torque should not be treated as a universal specification for every armored vehicle.
It must be selected according to the complete system requirements.
05. Common Symptoms After an SUV Is Armored
When the factory power liftgate is no longer correctly matched to the modified tailgate, several symptoms may appear:
1. The tailgate opens much more slowly than before
The system requires more force to move the increased load.
2. The liftgate stops midway
The drive system may reach a load or protection limit.
3. The tailgate cannot fully open
The available spring force or motor output may be insufficient.
4. The tailgate cannot stay open securely
The supporting force may no longer match the new tailgate weight and center of gravity.
5. Opening and closing become unstable
Added load may change the entire operating balance of the original system.
These symptoms should not automatically be diagnosed as a defective motor or defective strut.
Sometimes the real problem is simply that:
The original system is being asked to operate outside its original engineering conditions.
06. Why Simply Replacing the Strut With a Stronger One May Not Work
A heavy armored tailgate is a system engineering problem.
The strut is only one part of that system.
A professional solution may require engineers to evaluate:
New tailgate weight
Added armor location
Center of gravity
F1/F2 force requirements
Motor stall torque
Strut stroke
Strut mounting geometry
Mechanical strength
Opening and closing speed
Control system behavior
Actual vehicle validation
This is why customized heavy-duty power liftgate engineering is different from simply replacing an OEM spare part.
07. How Is a Custom Electric Tailgate Strut Developed for an Armored SUV?
At Guangzhou Tomaster Auto Parts, a custom heavy-duty tailgate project can follow an engineering process such as:
Step 1: Collect Vehicle and Tailgate Data
The customer provides available project information such as:
Vehicle make, model, and year
Existing strut OE number
Strut stroke
F1/F2 force values, if available
Tailgate modification details
Added tailgate weight
Tailgate and mounting-point photos/videos
Step 2: Engineering Analysis
The engineering team evaluates:
Required spring force
Motor torque
Internal spring configuration
Mechanical structure
Strut stroke and installation geometry
Step 3: Prototype Development
Components are selected or developed according to the engineering requirements, followed by sample assembly.
Step 4: Product Inspection and Functional Testing
Depending on the project, testing may include:
F1/F2 force verification
Hall signal inspection
Working stroke inspection
Opening and closing operation
Mechanical performance
Noise inspection
Step 5: Vehicle Validation
The final prototype is tested on the actual vehicle whenever project conditions allow.
Validation may include:
Opening/closing operation
Pause/hold performance
Height-setting function
Operating stability
Only after the system is validated should the final specification be considered for the next project stage.
08. How Does Guangzhou Tomaster Auto Parts Verify Heavy-Duty Electric Struts?
For heavy-duty and specialized vehicle applications, engineering capability should be supported by testing rather than specifications alone.
Based on the test requirements used for relevant Guangzhou Tomaster Auto Parts electric tailgate struts, validation can include:
Tensile Strength Testing
Selected electric strut designs are tested to tensile loads above 6,000 N.
Radial Load Testing
A 500 N radial force can be applied around the joint area of the upper and lower strut sleeves to evaluate structural deformation and integrity.
Drop Testing
After the required drop test, the strut is inspected for:
Surface damage
Abnormal noise
Opening and closing function
Noise variation
For the relevant product test specification, noise change should remain within 5 dB(A).
Durability Testing
Relevant strut specifications include durability testing such as:
25,000 cycles at 23±2°C
5,000 cycles at 80±2°C
5,000 cycles at -40°C
These tests help evaluate whether a strut design can maintain stable operation under mechanical and environmental stress.
09. What Information Should an Armoring Company Send to Start a Custom Project?
If an armoring company, specialized vehicle builder, distributor, or engineering company is developing an armored SUV project, the first step is not immediately selecting a strut.
The first step is collecting the correct technical data.
For an initial engineering evaluation, please prepare:
Vehicle make and model
Model year
Tailgate modification photos
Approximate or measured added tailgate weight
Original electric strut information
OE number, if available
Strut stroke
F1/F2 data, if available
Required opening and closing functions
Project quantity or expected demand
This information allows the engineering team to better evaluate whether a custom electric tailgate strut or a more complete power liftgate engineering solution is required.
10. FAQ
Frequently Asked Questions About Armored SUV Power Liftgates
Q1. Can the original power liftgate still work after an SUV is armored?
Sometimes it can, depending on the amount and distribution of added weight, the original system capacity, and the vehicle design. It should be evaluated rather than assumed.
Q2. Does an armored SUV always need a stronger electric strut?
Not necessarily. The correct strut specification depends on tailgate weight, center of gravity, mounting geometry, force requirements, motor torque, and other system parameters.
Q3. Is a higher Newton force always better?
No. Excessive or incorrectly matched force can negatively affect opening, closing, mechanical loads, and overall system behavior.
Q4. Can a custom solution be developed if the vehicle has already been armored?
Yes, subject to technical evaluation. Vehicle data, existing strut parameters, added weight, photos, and installation geometry should first be collected.
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