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Important: The shocks are
assembled at the factory
with a center-to-center
distance (between the rod
end balls) of 51mm. Any time
the shocks are removed and
disassembled, this distance
should be checked to ensure
proper operation of the
suspension.
51mm
20 • TRX-4M
TUNING ADJUSTMENTS
SUSPENSION TUNING
Springs
TRX-4M's front and rear springs (0.095 rate) have been carefully selected
to provide full suspension articulation and support for the weight of
the vehicle body. Using different bodies with lighter weight will allow
you to use lower rate springs to increase suspension articulation when
traversing difficult terrain.
SHOCK TUNING
Shock Oil
The 4 oil-filled shocks (dampers) effectively control the suspension
movement by preventing the wheels and tires from continuing to
"bounce" after rebounding from a bump. Changing the oil in the
shocks can vary the suspension damping effect. Changing the oil to
a higher viscosity oil will increase damping. Lowering the viscosity
of the oil will cause the suspension damping to be reduced.
Damping should be increased (with higher viscosity oil) when
stiffer springs are installed. Damping should be decreased (with
thinner viscosity oil) when softer springs are installed. The viscosity
of shock oil is affected by extremes in operating temperature;
an oil of certain viscosity will become less viscous at higher
temperatures and more viscous at lower temperatures. Operating
in regions with cold temperatures may require lower viscosity oil.
From the factory, the shocks are filled with SAE-20W silicone oil.
Only use 100% silicone oil in the shock.
Replacing Shock Oil
The shocks have to be removed from the
vehicle and disassembled to change the oil.
1. Remove the shock cap, bladder, and
lower spring retainer.
2. Fill the shock with new silicone shock
oil until the shock body is about 3/4 full.
3. Check the shock oil level by compressing
the shock fully until the rod end is
against the bottom of the shock body
(A). Proper oil level is 2-3 drops of oil
above the top of the shaft (B).
Note: Traxxas offers SAE-20W silicone
shock oil as part #5031 or a full silicone
shock oil set as part #5038X.
4. Move the piston up and down slowly to
remove excess air. Add oil if needed to
maintain the proper level.
5. Fully extend the shaft and reinstall the
bladder, shock cap, and lower spring
retainer.
6. Tighten the shock cap until snug.
Shock Disassembly
The shocks must be removed from the vehicle prior to disassembly.
Use the shock exploded views included with the model to aid in the
assembly process.
1. Remove the lower spring retainer and spring from the shock.
2. Remove the shock cap and empty the shock body of shock oil.
3. Use side cutters to grip the shock shaft just above the rod end.
Remove the rod end from the shock shaft.
4. Remove the lower cap from the shock body with a small flat
blade screwdriver. Slide the shock shaft with piston out of the
shock body.
5. Remove the o-rings and spacer from the bottom of the shock
body.
B
A
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