by: Mike Ervin
Now you can use the same Lock Resistant Brake
System winning Winston Cup cars use.
Stewart Brake Development has introduced the hottest
thing in street and race car brakes since disc brakes! LBS installs easily in the
rear brake line and utilizes a unique dampening valve that acts as a shock absorber to
sense and dampen the sharp spike in line pressure when the brakes are applied
suddenly. LBS improves the brake performance on any car or light truck, even ones
with ABS. ABS was designed for panic stops, not high performance driving. LBS
will prevent the application of ABS under all but panic stops making the car much
more driver friendly. LBS works much better than a proportioning valve and
dramatically improves the brake performance of older cars and light trucks that may or may
not have one. LBS also works well with disc brake conversions on street rods and
50s-60s cars. Many people install an adjustable proportioning valve to try and
balance the brake system and find they don't do the job.
LBS was originally developed for Winston Cup cars to
prevent a loose or oversteer condition under heavy braking with lightening fuel loads and
rear tire wear. The same system will give you the same benefits on the street in a
panic stop or on a slick road. If the car is loose or oversteering, it means that
the rear tires are slipping before the fronts when cornering and/or under heavy braking
and can cause the driver to loose control or "spin out". It is preferable
to have the front tires slip first (called understeer) when braking because the driver has
more control. If you've ever had to slam on the brakes when someone pulled out in
front of you in traffic and the rear end came around, you know what we mean!
Stewart LBS assures that the front tires slip first by
dampening (not reducing) the pressure to the rear brakes. With LBS, the rear tires
will accept nearly twice as much braking force without locking up. Leading Winston
Cup teams us LBS to brake harder and drive deeper into the corners at tracks like
Martinsville and Watkins Glen and you can use the same technology to stop shorter and
safer on the street.
Why LBS works better than other brake balance systems
Passenger cars and trucks require about 70% of their
total braking force on the front wheels. This is due to weight transferring to the
front of the car under braking. Weight transfer is affected by the center of gravity
of the vehicle- a taller vehicle like a pickup has more weight transfer than a
Corvette. The rear of the Vette doesn't go as light under braking, so it can use
more rear brakes and stop harder.
The front/rear brake bias on a production car is usually
achieved by using smaller calipers or wheel cylinders on the rear. Race cars with
two master cylinders sometimes use different bore sizes to reduce rear line
pressure. Dual master cylinder setups may also use an adjustable balance bar to
change the pedal force applied to the front or rear master cylinders to achieve the proper
front/rear bias. The bar may also be driver adjustable during the race.
Each of these systems has the same problem, too much
front brake and the car doesn't utilize the stopping potential of the rear tires, too
little and the rear brakes will lock causing the car to spin.
Why proportioning valves don't work
Proportioning valves don't really prevent brake lock up
because they maintain equal front and rear line pressure up to a point called the
"knee point" which is controlled by a preset or adjustable spring. After
the knee point, rear pressure increases to only 36-57% of the front pressure, depending on
how the valve is set. Generally the knee point is higher than the pressure required
to lock the rear brakes. If the knee point is adjusted low enough to prevent rear
wheel lockup, the rear brakes will be virtually useless. If proportioning valves
worked, ABS would never have been developed.
Why LBS does work
LBS doesn't reduce rear brake pressure, it just slightly
dampens and delays it. LBS prevents rear brake lock up without degrading rear brake
performance and overloading the front brakes.
I am sure that like me, you have a story about a close
call you had while driving, where you were nearly creamed by some idiot who made a left
turn in front of you, or pulled out of a driveway, or wasn't paying attention as traffic
slowed in front of him.
Whatever the circumstances, your reaction was to go into
panic-stop mode. You slammed on the brakes, the rear tires locked up, and the back
end of your truck decided it wanted to pass the front wheels. If you were quick to
react and started counter-steering soon enough, you stood a chance of at least skidding in
a straight line, but if you were tardy, you had to hang on for a spinout.
Trucks require about 70 percent of the total braking
force to go to the front wheels. When the brakes are applied in a sudden stop,
there's a "spike" in the brake line pressure, where too much pressure is
momentarily allowed to go to the rear brakes. When that happens, because of the
weight transfer to the front of the truck, the rear brake pressure is higher than
necessary for sufficient braking.
Stewart Components of High Point, North Carolina, has
solved this dilemma by engineering a Lock Resistant Brake System that eliminates the spike
by damping and delaying the brake pressure so that excessive pressure to the rear brakes
Originally designed for Winston Cup racing, the system
has been made available to the public. It's simple to install and improves the brake
performance of any truck. I have one of these on my 85 C-10 and can testify that it
works great, and it works just as advertised.
This is a photo of the Lock Resistant Brake System (LBS)
from Stewart Components. The overall
valve is small (about 1.75 inch in diameter and 1.25 inch in length), and the ports where
the brake lines attach are 1/8 NPT. The bracket assembly is included.
1. Locate the brake line fittings where the
rear line meets with the frame line. Loosen the fittings to allow the LBS to be
mounted between the lines. Make sure that any debris on the exterior of the fittings
is cleaned prior to loosening to assure that contaminants won't enter the brake system.
2. Install the 1/2- to 1/4-inch fitting
into the valve. The valve is made of aluminum, so be careful not to cross-thread the
fitting into the valve.
3. The bracket is attached to the
valve. This gives the valve a rigid mounting platform to attach to the framerail.
4. Tighten the brake line to the
valve. Once the valve is installed, press on the brake pedal and check for any leaks
in the system. If there are on leaks, check the master cylinder to make sure the
reservoir has the proper brake fluid levels.
|Update! Stewart Components has sold the LBS part of their business to DPI Racing Products. For info on this
product you will need to contact them. They have contact information on their site.