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1. TURNBUCKLE
LENGTH
Keeping the left side of your car matched to the right side of
your car with regards to turnbuckle length is important. Instead
of trying to eyeball the center of each ball cup when measuring
with your calipers, try getting your dimensions from the base of
one ball cup to the base of the other to ensure you are
comparing your left to right turnbuckles much more accurately.
2. DROOP
Measuring droop with digital calipers is as simple as propping
your chassis up onto level blocks with your wheels removed and
measuring the axle height from the bottom up to any flat surface
such as a setup board. Unless you do some math to include the
size of your rims and tires you can only use this method to
ensure that the axle height on the left of your chassis is the
same as on the right; however, this is an amazingly accurate way
of keeping your droop levels equal from one side of your chassis
to the other.
3. SHOCK LENGTH
Shocks are the single most important tuning aid on your vehicle,
and it is super important that they are the same length from one
side of your car to the other. You can use your calipers to
compare a few dimensions when working with your shocks. Measure
from the base of the shock body to the base of the plastic ball
cup, and also compare the overall length of the shocks to be
sure they are equal in size from left to right. A quick turn or
two of the lower shock ball joint should match up any
discrepancies between the two shocks.
4. SHIM THICKNESS
Shims are a perfect place to stop with your digital calipers.
Thin shims are used in areas where proper spacing is vital to
performance, such as in the diffs on a 1/8 scale buggy, truggy,
or monster truck or to eliminate excess play out of axles,
hingepins, or clutches. It is always useful to know the
thickness of various shims so you can use the correct ones in
the correct place—not to mention the valuable dimensions you
can get regarding inner and outer diameters so you know you are
using the correct shim for the job.
5. SHOCK SPRINGS
Most manufacturers color code their shock springs so they can be
easily identified with regards to coil thickness, but if you are
unsure of how two springs are matched, you can use your calipers
to verify they are made from the same diameter of wire. It is
also a wise idea to match the overall length of springs so you
can run a matched pair from left to right on your car.
Manufacturers try their best to package shock springs in exact
pairs, but there are times when one spring can be a slightly
different in length as compared to its twin brother.
6. TIRE DIAMETER
Whether you are calculating rollout or simply wanting to match
up tire diameters from race to race, digital calipers are the
best tool to use. With tires in one hand and calipers in the
other you can also determine sidewall height, tire width, or
even wear rates from race to race. All of this information is
vital when trying to find the perfect tire setup. It will also
help you maintain consistency from race to race once you do find
the ultimate package.
7. BEARING SIZE
This one is pretty obvious, and also shows the major advantage
of a digital caliper over a dial caliper—the fact that you
have access to both metric and imperial dimensions. This is
handy when you are unsure of the origin of the bearing you are
measuring. If you're trying to match a given shaft diameter to a
bearing, calipers are the perfect tool. You may need to know
bearing dimensions so you can hit up the local hobby shop for
some replacements.
8. SHOCK PRELOAD
You can jam socket wrenches, hex keys, or any other random
objects into your shocks to try to measure spring preload, but
nothing will be as accurate as a set of digital calipers.
Assuming that your shock springs are exactly the correct length
(which they should be if you're reading this article in order),
you can easily set your preload from left to right and ensure
your vital shock dimensions are accurate and your car is sitting
flat.
9. CHASSIS CENTER
Whether you are checking droop, tweak, or balance it is always
beneficial to know the exact center of your chassis. Using your
calipers you can measure the overall width of the front and rear
of your chassis, divide the number by two, set the calipers to
that number, and scribe an accurate center point into your
carbon fiber, aluminum, or molded chassis to help you with many
other setup issues that require a reliable chassis centerline.
10. SWAY BAR THICKNESS
This one is simple yet useful. The thickness of a sway bar is
directly proportional to the stiffness of that sway bar, so use
your calipers to quickly reference what diameter of sway bar you
are running and what other options you have sitting in your
parts box. This comes in handy when you are trying to lock your
chassis to the racing surface.
11. CLUTCH SPRINGS
The thickness of a clutch spring determines its stiffness, so
being able to measure wire diameter is a very useful clutch
tuning aid. Remember that a thinner clutch spring will cause
your clutch to engage earlier, making your car easier to drive
on low traction surfaces—but at the expense of your snappy
feel. A thicker clutch spring will make your clutch engage more
into the power band of your engine, giving you explosive power
out of a turn to clear that huge set of doubles.
12. COMM DIAMETER
One of the main advantages to knowing your commutator diameter
is to determine how much life you have left in your motor. At
some point your comm becomes too small to cut any more material
away. In many handout stock motor classes, a smaller comm
diameter will produce faster motors—so there may be a buzz
around the track on what size commutator produces the highest
output. You can use your calipers to measure this. Finally, some
drivers like to use break-in tools to pre-break-in their brushes,
and since these break-in tools are available in different sizes,
it is important to know what your commutator diameter is so you
can use the correct tool diameter.
13. SCREW LENGTH
The title pretty much explains how useful digital calipers are
in this situation. You won't have to wonder if you're using the
correct size screw the next time your instructions ask you to
bolt up your bulkhead with a 4mm x 12mm flat head screw.
14. DRILL BIT DIAMETER
Most commonly used when drilling pistons, but also useful in
other drill bit dimensional instances...digital calipers will
ensure you are always boring holes with the correct sized drill
bit.
15. PILLOW BALL SETUP
Not everyone owns a fancy setup system to accurately establish
toe, camber, and width settings on their pillow ball car. Using
the center marking you made on your chassis earlier, you can
accurately match the left and right side of your chassis by
measuring and comparing key points from chassis center to hubs,
outside of wheels, or even the gap between your suspension arm
and hub. Nothing beats a setup system, but digital calipers will
definitely beat an eyeball setup any day!
16. CHASSIS TWEAK
Digital calipers aren't only useful when you wrap the jaws
around something to get a dimension. The beam of your caliper is
a reliable straight edge that you can slap against the bottom of
your chassis to determine if it is still straight after
front-siding the wall at the end of the straightaway.
17. MOTOR BRUSH LENGTH
You can get some valuable information on the wear
characteristics of different brush compounds, motor spring
rates, gearing, and timing settings by measuring the length of
your motor brush between battery packs. Be careful not to take a
chunk out of the face of your motor brush when you close the
caliper jaws around them to get your numbers. The tip of the
claws are sharp, and could easily damage the delicate motor
brush.
18. SETTING HEAD CLEARANCE
The old "slap some solder through the glow plug hole and
turn your engine over to squish the solder" trick is only
useful if you have a good set of calipers around to measure the
squished solder when you are trying to determine your head
clearance. Even after you've determined your head clearance, it
is useful to have digital calipers around so you can measure the
thickness of the head shims you want to either add or remove
from your engine.
19.DISK BRAKE SETUP
Measuring the thickness of your brake disks will give you info
about the wear patterns of your brakes. You can also use digital
calipers to set the gap between your brake pads to ensure they
are evenly spaced across the entire face of the brake disk.
20. CENTAX CLUTCH SHIMMING
The gap between your clutch shoe and bell on your Centax Clutch
is extremely important. Setting this gap too big will offer huge
amounts of bottom end power, but can cause slippage that can
melt your clutch. Digital calipers allow you to set this gap
with incredible accuracy. Calipers are also useful to measure
the diameter of the spring coil when choosing a spring rate to
install within your clutch.
CLOSING
As you can see, digital calipers are an asset to have on hand
when wrenching on your machine. The list of uses obviously goes
way beyond the 20 we just stated here, but these are the ones
you'll use on a day to day basis while at the track or at your
work bench to ensure your chassis is built straight and balanced,
and all of the vital dimensions are in check to make you faster
on the track.
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