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Motorsports Technical Information - Chassis
are the “BRAINS” of
Racing has become more competitive every year! Maintaining
your shocks is crucial for consistent performance race after
“Winning Races and Championships”
You ask “Why should I spend the
money to have shocks tested?” Great Question, Here’s
• Regular maintenance on your shocks
is vital. They are the most important performance-part
of your suspension.
• Shocks are made with a cylinder,
oil, shaft, seals, and valves. Much the same as an engine.
For ultimate performance
they both need to be maintained correctly and consistently.
If not, they will wear out quickly.
• Imagine what can happen to a suspension
item that is, caked with dirt, hit with rocks, moved at
a rate of 5” to 13” per
second at different angles, and mounted by an extremely hot
brake rotor. After time, the rate will vary. Your racecars’ handling
racers never run an engine for a full season without changing
the oil and following a specific engine maintenance schedule
for the season.
should be dyno-tested when they are new, and then checked
at least every 30 racing hours. This data will give you
valuable handling information to compare.
major shock manufacturers do their best to give you a great
product, along with an affordable price. To offer an affordably
priced product, all parts need to be assembly-line manufactured.
Keeping tolerances and cost in line are very important,
however it allows for a standard deviation of a plus or
minus valve variation. Each company has tolerance variation.
This tolerance can be different on compression, or extension
(rebound), or the rate overall.
Compare these 2 shock set-ups with a 10% variation
or change in rate.
| • 4
valve shock 90#
• 5 valve shock 130#
• 6 valve Shock 170#
Rated at 5" of movement per
second for example.
5LF # 117 (-10%)
6RF # 187 (+10%)
4LR # 99 (+10%)
4RR # 81 (-10%)
5LF # 143 (+10%)
6RF # 153 (-10%)
4LR # 99 (-10%)
4RR # 81 (+10%)
LF to RF difference of 70#
LR Heavier 18#
Set up #2
LF to RF difference of 10#
LR Softer 18#
a winning racer, you need to contact us today to design a
specific maintenance schedule
for your shocks.
Shocks- What you need to know!
Timing is Everything
It’s important to understand what a shocks main purpose
is. Shocks are a controlled suspension timing devise. They control
what a spring does by dampening compression and controlling rebound,
(the different rates of valving allow shocks to control
the action happens), thus the length of time it takes for
of the movements to occur.
Understanding today’s shock technology has proved to
be the difference between winning or finishing second. Having
the right shocks on your racecar is the suspension fine-tuning
for consistently winning races and championships.
Will changing shocks solve a bad handling problem? NO!
Shocks only fine-tune your race car for improved handling
performance. Changing a shock can cover up the real handing
problem. When making a shock change, remember: What is the
best compromise? A shock change will only help after you have
removed the other variables such as, tire stagger, wheel spacers
or offset, weight ballast, and the correct spring combination.
Utilizing our track
diagram on pages 178 & 179 will help
you pinpoint what change would give you to optimum performance.
Shock Changes Affect.
Compression Rate - Front, has more affect on deceleration,
or corner entry (B,C,D of Track Diagram).
Compression Rate - Rear, has more affect on acceleration,
or corner exit (E,F,G of track diagram).
Rebound Rate - Front, has more affect on acceleration,
or corner exit (E,F,G of track diagram).
Rebound Rate - Rear, has more affect on deceleration,
or corner entry (B,C,D of Track Diagram).
Example Shock Change:
More traction is needed on corner exit (E,F,G of track diagram).
What change should you make?
Decreasing the rebound rate on the right front shock will
increase the speed of weight transfer to the left rear
Decreasing the compression rate on the left rear shock will
also increase the speed of weight transfer to the left rear
Weekly Shock Maintenance
It’s important to take the shocks off your race car
every week to check for damage. Make sure the shaft isn’t
bent. Check the shock body for dents and dings. This is extremely
important on a mono tube shock. Look for tire rub marks (very
important on a twin tube shock). Check the rod ends for any
type of bind. Push the shock in and out to make sure it doesn’t
have any slack in it. Look the shock over closely for any
oil leaks around the seal or any signs of the gas bag bursting.
If there is any signs of damage the shock needs to be rebuilt
or replaced. If the shock is a rebuildable style it needs
to be sent in for repair. If not it needs to be replaced.
If any of this occurs, or you have any questions give our
experienced technical staff a call.
Our technical staff here at JR Motorsports will recommend
the right shock package for your specific type of racing.
We will help you develop your standard shock base-line,
along with other options you’ll need for each type
of race condition. Our goal is to help you win more races
Understanding what and where a handling problem
where is actually starts is very important. In resolving
a handling problem, it is imperative to begin at the start/finish
line, follow the racecar through corner entry, mid corner apex,
corner exit, and back to the start/finish line. Not taking
the time to thoroughly diagnose the full racetrack will be a
adjustment will be made for one part of the racetrack, in turn,
creating a larger problem somewhere else. Consistent laps will
difficult to make, resulting in a slower lap time average.
Winning races and
championships are not accidental. It’s
done by making fast, but smooth consistent laps. Your racecar
will be faster, more consistent, and easier on equipment, when
the chassis set up allows the racecar to run freely through
complete corner. Constantly loading and unloading the
radically will work just the opposite and the racecar will
become very difficult to drive.
Diagram the racetrack to pin point where the handling problems
are and how large the problem. Use a highly visible mark on
your steering wheel to help the crew and driver recognize where
the front wheels are. Also marking left side tires can help
determine wheel spin and when it occurs. These are great driver
tools to help with diagnosing where a handling problem is and
exactly when it occurs.
Point to Remember, the only thing your racecar has
in common with the racetrack is the tire patch it is riding
on. You want to use the whole tire, not just three of them
or 75% of the four. Lap times will be the best with 100%
all four tires in contact with the track, keeping the car
straight, and using smooth throttle and brake applications.
This applies to both dirt and asphalt races. If a handling
problem occurs one of the four tires is being overloaded.
Tire temperatures, air pressure gains, and shock travel will
guide you in the area of a handling problem. This information
needs to be obtained as soon as possible, or it will not be
the driver and crew is very important. Understanding what
the driver’s responses are in
relationship to what the racecar actually is doing becomes
very crucial. A good driver will compensate for one handling
problem, but possibly create a different one. You adjust
the car, only in the wrong area needed for the most gain
in performance. Example: The driver says the car is very
loose off the corner, the crew say it’s tight into
the corner. They are both right. The driver is shaking
the car loose with the brakes, compensates for the tight
entry. If you tighten the car as the driver says the problem
will be worse, because you fixed the wrong problem. Answer
these questions. Is the car loose or tight when the driver applies the brakes
or the throttle? What would the car do if the car rolls
into the corner freely off the throttle and before the
are applied? This answer is key, will it push or will it
turn? Now you know where to start.
Use this track to pin point where the handling problems
are and how large the problem is.