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How to Measure Ride Height on a Semi Truck?

How to Measure Ride Height on a Semi Truck?

Here are easy methods to measure the ride height on your semi truck. You can measure the ride height of a truck at your home. It will take only 5 to 10 minutes to calculate specific ground clearance from all measurements.

How to Measure Ride Height on a Semi Truck? You can measure the ride height by taking two measurements. First, measure the distance between the vehicle frame rail where the air control valve is present and the ground. After this, measure the distance between the center of the wheel and the ground. After this, subtract the first measurement from the second measurement to calculate the ride height.

How to Measure Ride Height on a Semi Truck?

Ground clearance is another name for the ride height. It is a space between a base of a tire and the lowest point of a vehicle. In semi-truck, this point is typically the axle.

It also represents the distance between a flat ground and the lowest part of the vehicle. This part excludes all others that touch or contact the ground.

The value of a ride height for a vehicle is different; it is manufacturer specs. A 4 wheel drive vehicle should have 8.5 to 9 inches ride height.

Determine the manufacturer-specific ride height

The first step is to determine the exact ride height of the truck. You can read the truck manual to get information about the ground clearance.

It is also present on the vehicle part. You can check the manufacturer-specific value by searching it on the vehicle.

There is a height control valve that controls the airflow to vehicle suspension to maintain exact ride height.

It maintains the ride height by adding or drawing exhausting air from the suspension system. Determine the connection of the height control valve on a multi-axle vehicle.

Uplift the tires

Before taking measurements, drive the vehicle to some distance. It will release any trapped wind from the tires and other parts.

The driving distance should be up to 10 to 15 feet. It will also settle the air suspension to a resting position.

Now park the truck on clean and smooth ground. Turn off the vehicle for some time and close all the doors. Now take a choke to uplift the front tires of the vehicle. It will prevent it from rolling out. You can also choke the rear tires for safety and easy measurement of height.

Pressurize the air system

The air compressor is present at the trunk of the semi-truck. Apply a constant flow to the suspension system. The 70 to 80psig pressure of air is sufficient for a semi-truck. It should inflate all the springs of air suspension. 

Check air springs at each side to fully expand them. It is essential to maintain a perfect ride height of a truck. Then raise the suspensions of the vehicle to a proper ride height.

Measure the distance from frame rail bottom to the ground

To take the measurements, you should have a measure tape or scale. Place the measuring tape on the rail of truck frames. The rails are steep plates or beams.

Then take the take toward the ground and take the distance between the two points. Note the values on paper. Suppose it is 35 inches.

Measure the distance center of the wheel to the ground

Now measure the distance from the center of the wheel to the ground. Note down the values in the notebook. After this, you should take measurements from all the sides.

It will help in measuring both the front and rear ride height of a truck. In some cases, there is a little difference in both ride heights. Suppose it is 25 inches.

Calculate the ride height

Now you can calculate the ride height by subtracting the frame rail and bottom distance from the distance between the center of the wheel and the ground.

Our supposed values are 30 and 20 inches. When we subtract it, our ride height will be 10 inches. Match the calculated value to the manufacturer-specific ride height. It should be within +/_ 0.27 of the manufacturer value. When it is more or less, adjust the value using the height control valve.

Adjusting the ride height of a semi truck

Follow all these steps in sequence to adjust the ground clearance of a vehicle.

Disconnect the extension arm from the height control valve.

Then rotate the extension arm upward to raise the axle and downward to lower it.

Adjust the axle until the distance between the center of the axle and the suspension surface matches the recommended ride height.

Readjust the height control valve linkage to the extension arm. After 10 to 15 minutes height valve will start working. Check the following components for damage and replace them to adjust the height.

  • Link rod
  • Leveling valve
  • Air spring
  • Wear pads
  • Spring hanger frame bracket

Why it is essential to have a specified ride height of the semi truck?

It is essential to have manufacturer-specified ride height for vehicle performance. It can disturb the working of many parts when the ride height is high or low. A low value can cause damage to shocks and springs of suspension. 

It gives extension during rebound rides and increases fuel expenditure. Faulty shock absorbers will harm vehicle load.

When the ride height is high, wearing of tires will occur. The load on steering suspension is increased, leading to increased steering effort. 

Poor angulation of the U shaft delivers high vibration on drive suspension. It will also damage truck frame springs and bump stops. Uneven ride height can affect the right angle of headlights and effects safe drive during the night.

Factors to consider before measuring ride height

  • Keep all the passengers out unload all the extra weight from the truck.
  • Turn off all the electric devices of the vehicle.
  • Check the fuel level in the truck. It should be half to ¾ filled for accurate measurement of the ride height of your semi truck.

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