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There are a number of factors that affect an off-road cars handling. an off-road car will never turn as tight and nice or
be nearly as smooth as an on-road car, but an on-road car can't go 120 mph over the whoops, or jump 80 feet! The reason for
all of this is in long travel suspension designs. In the off-road world, there are a few variables that do not exist in on-road
driving; 1) roads may exist, but are generally not groomed and can have large rocks, whoops, jumps, or any other of a number
of obstacles that do not exist on streets and highways. But, since these obstacles are what make our sport fun, we have designed
suspensions capable of handling them without breaking (or not as often). 2) At any given point all four tires could leave
the ground, on purpose or not, and you could be twenty feet in the air. When you return to the earth, the car needs to soak
up the hit without giving you back and neck problems, and since you'll want to do it again, it needs to soak these hits up
repeatedly, and smoothly.
There are many variations of front and rear end designs, so I'll just talk about ours, and why we decided this was
the best way to go. I'll discuss the limitations and positive points, and give you a base of knowledge on how and why it works.
Long Travel J Over A Arm Front Suspension
Long travel in the front of a car is almost synonymous with "A-Arm Suspension." Anything over 15" is usually
considered "Long-travel," and as you travel goes up, so are the problems with achieving and maintaining affective
travel. Too little travel will limit the speed at which you can drive over the roughest terrain, but too much travel without
good engineering will give the car painful and sometimes dangerous handling characteristics.
We use an equal length A arm setup (which is misleading as the rear bar of the arm is slightly longer in order to
move the tire center forward) with the upper control arm being a J arm type. Both arms are made of thicker steel than the
frame, all parts are chromoly for rigidity and strength, and they are plated for additional strength and a firm feel at the
wheel. The more rigid the front end is the more solid the handling will feel due to reduced vibration at the wheel. The A-arm
is very long and extends from the center of the car out to the spindle upright; or around 30"! Remember, the wider the
better. This allows for massive travel numbers while keeping shock travel numbers small. But we still use longer shocks and
here's why...
We have a design that obtains 28" of front end travel, among the top numbers in the entire recreational off-road
industry. Few manufacturers can claim this number and include superior handling in the description, but we have done it through
extensive research and development. There are two big problems most people run into with this much travel: Bump-steer and
body-roll. Bump steer happens as the tire moves in its arc and the front track width narrows at full bump and full droop,
and is widened at its center point. This affects handling because as you hit a bump on one side of the car, the track width
of the front of the tire is narrowing which turns the car slightly. The affect is increased with the size of the bump as the
turn is more drastic. As you drive over bumps the car will feel like it is steering itself. We have minimized this affect
through the placement of our steering box and adding a little play into the steering wheel. The placement off the rack determines
how much bump steer you will have, and as you can never have NO bump steer, we have gotten down to ALMOST no bump steer. Do
not worry, a little play in our steering wheel does not make it feel loose. Our cars handle so tight that you will never miss
that 1/4".
And now the big one, Body roll. The problem with center mounted A arms like ours is that you've placed a pivot right
at the center of the car, right where it wants to roll! Many companies neglect this problem and take advantage of the travel
while running a small shock that costs less, straight from the arm to the frame right above it. We run the shock from the
outside of the arm, to the CENTER of the car. It counters the movement totally from the movement of the arms. Now, the shock
must be longer, and valved much heavier to run this way because of the drastic angle; in fact, we run the exact same shock
length with the exact same valving on the front as on the rear, with lighter spring rates to make up for chassis weight. Our
suspension design counters itself during a turn and thus feels less body roll. And with this much travel, feel free to hit
the whoops at 120mph, or fling the car 30' in the air or 100' long, our suspension will soak it up every time!
The J arms are only there to hold the tire upright, and control the camber & caster of the tire. We use a J arm
specifically because it allows us to run a larger diameter shock and lean it back a little towards the rear of the car in
order to achieve the desired compression affect. Otherwise it is just a small a arm where both attachments are on one side
of the shock.
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Dual-pivot Trailing Arms
Trailing arm designs are generally based off of the old VW design, where a tube running across the car carried a torsion or
"Twist" bar, and two arms bolted onto it going backwards towards where the tire mounts. The torsion bar supports
the cars weight and gives the suspension its rebound, and shocks could then be added to smooth the ride out. with the advent
of coil-over shocks, the torsion bar became obsolete, but the design is so structurally sound and the suspension behavior
so efficient, the trailing arms were retained and mounted to a strong tube that replaced the torsion bar housing.
The same stock dimensions of VW arms are still used as a reference for length and width of the arms, represented as
a number by a number or 3 x 3, 5 x 6, etc. A 3 x 3 being 3" longer, and 3" wider than a stock VW trailing arm. The
reason for the extra length and width is that you stabilize the car by making it wider, and you also increase the axle length
which decreases CV joint angle which increases travel potential...if you don't understand that then just know that longer
and wider arms give our cars the 25" of travel they need to soak up the huge whoops and jumps you like to drive over.
Our cars are capable of 25" but are limited to 23" so as to preserve the components. One of the problems with more
travel is body roll. An off-road car is higher for clearing obstacles, and it has a plush absorbent suspension for soaking
up hits, so when you corner the car will lean out of the turn more than an on-road car. The way to counter this is with driving
style. Drifting hard turns forces the rear end around while keeping engine RPMs up for acceleration after the turn. Learning
this technique is fun, but with high horsepower cars it can cause you to lose control so be careful. The extra width of our
track also minimizes the affects of body roll. Cutting brakes make a huge difference in turn radius and minimize body roll
as well. By forcing brake on the inside tire, the tranny automatically sends the excess power to the outside tire which needs
to move faster to turn harder. The lack of power to the inside and excess of power to the outside make the car feel as if
it is turning in place without even moving forward. This will scare the bejebus out of your unsuspecting passengers, but be
careful how fast you are moving so as not to roll the car or break a tire bead!
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