What Is Line-Lock, And How Does It Work?

10 min read

What Is Line-Lock, And How Does It Work?

10 min read

What Is A Line-Lock, And What Does It Do?

Put simply, Line-Lock is a solenoid that you activate from inside your car. A solenoid is a simple device made up of only a few pieces: a coil of tightly wound copper wire, a housing, and a plunger made of magnetic material. When electrical current is applied to the coil, a magnetic field forms, which draws the plunger in and converts the electrical energy into mechanical work. A solenoid is an electromagnet, which means it can be turned on and off by application or removal of electric current, unlike permanent magnets.

One of the essential components to a successful pass down the dragstrip is starting-line grip, which is best achieved after performing a burnout on a rear (or front) tire, depending on your vehicle's drive configuration. The activated line-lock closes off the brake circuit and locks the wheels at the vehicle's non-drive-end. The locked wheels hold the vehicle stationary in the burnout box so that the drive wheels can achieve the perfect burnout, warm, the tires, and not burn up the brakes on the driven wheels.

When And How Do I Use It?

The perfect burnout at the dragstrip is something of an art: it requires adequate — but not excessive — throttle pedal application to build the right amount of wheelspeed. An automatic-transmission car typically requires the driver to complete a shift to maintain wheelspeed without hitting the rev limiter. Once the tires are warmed up properly, the driver must power out of the burnout without losing control of the vehicle.

A line-lock makes the burnout process simpler and removes one of the variables from the process. By holding the pressure in the non-driven-wheel brake circuit, the driver can concentrate on the rest of the process without stomping on the brakes and adding that additional variable. Not to mention that using one prolongs brake life for that end of the vehicle since the brakes are not applied during the burnout process.

Using it is simple but depends on a couple of steps to be completed in sequence to work correctly. We'll describe how to use it when installing the parts supplied in this kit.

• Drive the car into the burnout box, and stop with the drive wheels just out of the water

• Turn the line-lock solenoid on with the power on/off switch

• Set the brake pressure by holding the brakes down firmly

• Activate the line-lock by holding the momentary switch down which uses brake fluid pressure to lock the non-driven wheels

• Apply the throttle to get the drive wheels spinning and perform your burnout.

• The proper RPM level and length of time for this part of the process will depend on your specific tire. Contact your tire manufacturer for a recommendation on appropriate after-burnout tire temperature. This recommendation will help you to determine the length of time you need to heat your tires properly. If necessary, you can shift in the middle of the burnout (automatic transmission only) to keep the wheel speed in the correct range to achieve the proper temperature. Manual transmission vehicles typically drop the clutch in the gear that will provide the correct wheel speed.

• Let go of the line-lock button and drive out of the burnout, releasing the throttle and applying the brakes with your foot to stop the vehicle properly.

• Switch off the line-lock

• Stage the vehicle normally


Where Do I Install Line-Lock?

The line-lock solenoid gets installed in-line into the front brake hydraulic circuit or rear-brake circuit if you're racing a front-wheel-drive car.

The direct-fit Hurst line-lock system we installed into our test-subject 2011 Mustang comes with the pieces required for a clean installation into the vehicle: the line-lock solenoid, pre-bent, direct-fit brake lines, all required electrical connectors, and even the switch and button. This specific installation differed slightly from the instructions in the form of a different activation button, but the rest of the process remains the same. Follow along with our captions to see the essential highlights.

Line lock thread tape

Use thread sealer tape on the plugs for the solenoid body to prevent leaks under pressure.

line lock long line

The long pre-formed brake line routes from the front of the solenoid around the master cylinder and into the port that was left empty in the previous step.

Line lock clockspring connector

Chuck made this installation super-trick by digging into the wiring schematic for the 2011 Mustang and wiring the activation button into the clockspring connector. There are open channels in this connector, and we used one for the line-lock switch.

line lock wiring

He wired in a relay to ensure everything worked properly when the line-lock is active.

line lock finished wheel

The finished installation. We also wired in a trans-brake button on the opposite side of the wheel for later use.


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