Line Lock Kits: What They Do and How to Pick One

What a line lock actually does

Your brake system is hydraulic. Press the pedal and fluid pressure goes to all four corners at once. A line lock is an electric solenoid valve plumbed into the front brake line, and when you energise it, it traps the pressure that is already in there.

So the sequence at the startline is this. You press the pedal. You hit the switch. You let the pedal up — and the fronts stay locked, because the fluid has nowhere to go. Now you can bring the revs up and spin the rears against stationary fronts. Release the switch and the trapped pressure drops, the fronts let go, and you drive forward into the beams.

That is the whole idea. Heat in the rear tires before you launch, without the car creeping down the track while you do it.

Why you would want one

A cold tire does not grip. On a prepared surface the difference between a warm rear tire and a cold one is the difference between hooking up and going up in smoke, and a burnout is how you get the heat in.

You can do a burnout by standing on the brake pedal with your left foot. Plenty of people do. But holding the pedal means holding all four corners, so you are fighting the rears as well as the fronts, and you are doing it with one foot while managing throttle with the other. A line lock takes the fronts out of your hands and gives them to a switch. It is more controlled, it is repeatable, and it is considerably easier to do the same thing twice.

Two-port or four-port

This is the first thing to settle, and it is about how your brake lines are run rather than how much money you want to spend.

A two-port valve has one line in and one line out. It goes inline on a single circuit. The Granatelli 760300 Tire Fryer solenoid is the two-port, and it is sold as a valve only — no switch, no fittings. That is deliberate: it is for people building a custom brake-control setup who already know what else they need.

A four-port valve handles a split front circuit, one in and one out for each side. Most modern cars are plumbed this way, which is why the four-port is the one most people end up with. The 760500 universal kit, the 760512 for the Camaro and the 760515 for the Mustang are all four-port.

If you are not certain which your car has, look at how many hard lines leave the master cylinder and the proportioning valve for the front brakes. Or call us and describe the car.

Universal or built for your car

Universal means the valve, the switch and the supporting hardware, and you work out the plumbing and the mounting yourself. The 760500 is the universal four-port kit. It fits anything, which is another way of saying it fits nothing in particular — you will be making lines and finding a home for the solenoid.

Vehicle-specific means the design already accounts for where your lines run. The 760512 is built for the 2010–2015 Chevrolet Camaro and the 760515 for the Ford Mustang GT, Shelby GT500 and V6. Both do the same job as the universal kit; both save you the custom plumbing.

If we make one for your car, buy that one. The extra outlay is less than an afternoon of making brake lines, and a line you did not have to fabricate is a line that cannot be fabricated badly.

Kit or valve — what is actually in the box

Worth being blunt about, because it is the thing people get wrong when they order.

The 760300 is the valve on its own. Rebuildable, nickel-plated, 12 to 24 volts, quick to release. If you order it expecting a complete kit, you will open the box and find a solenoid.

The 760500, 760512 and 760515 are kits — the solenoid plus the activation switch and the supporting installation components.

Switches are also sold on their own, so a failed one does not mean replacing the lot. The 760508 is the line lock switch and the 760506 is the replacement activation switch, both in the braking system range alongside the kits.

Where we would tell you not to buy one

A line lock is a racing part. Here is the honest version of what that means.

It is not a parking brake and it will not hold a car indefinitely. It traps hydraulic pressure, and trapped pressure bleeds off. Engage it, do your burnout, release it. It is not for leaving the car on a slope.

It does nothing for a street car. If you are not doing burnouts on a prepared surface, there is no job here for it to do.

It goes on the front circuit, not the rear. Locking the rears and spinning the fronts is not a burnout; on a rear-wheel-drive car it is a way to go somewhere you did not intend.

Where and when you can use one is governed by law and by your sanctioning body, and both vary. Some tracks require a particular installation. Some states take a dim view of modified brake systems on a road-registered car. We build the part; we cannot tell you the rules where you are, and anybody who tells you there are none is guessing. Check before you fit it.

Brakes are brakes. This is plumbed into the system that stops your car. If you are not confident making and bleeding brake lines, this is the job to hand to somebody who is.

Fitting it

The valve goes inline on the front circuit, after the master cylinder. The switch goes where your hand falls at the startline — most people put it on the shifter or the wheel, because you will be using it with the revs up and you want it without looking.

Wiring is 12 to 24 volts on the Granatelli valves. Bleed the brakes properly afterwards and test the release on a closed surface before you trust it anywhere near a startline. The first thing to confirm is not that it holds. It is that it lets go.

What to do next

Work out whether your front circuit is two-port or four-port, then check whether we build a kit for your car. If we do, that is the one to have. If we do not, the universal four-port kit covers everything else. The parts themselves are made in Oxnard, California, and the guides are written by JoJo Granatelli, who races what we build.

Not sure, or describing your car is easier than measuring it? Call the shop on 1-805-486-6644, Monday to Friday, 8am to 5pm Pacific. The people answering are in the building in Oxnard where these are made, and they would rather talk you out of the wrong part than sell it to you.