Page 18
ChASSIS TUNING GUIDE
The Rail features front, centre and rear bevel gear differentials that feature O-Ring seals and cup-style housings. All three differentials
are packed with differential grease that works well for most driving conditions. You can make fine-tuned adjustments to each differential
by removing them from the chassis, opening them up and replacing the grease with different weights of silicone oil.
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Front and Rear Differentials:
Adding heavier silicone oil will tighten the differentials and adding lighter silicone oil will loosen the
differentials. If your Rail feels loose (uncontrollable) during turns, you can tighten the front differential or loosen the rear differential. If
your Rail is pushing (understeer) during turns, you can loosen the front differential or tighten the rear differential.
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Centre Differential:
Using a lighter weight oil will cause the differential to unload easier. Generally, this is good for loose tracks with
little traction. Using a heavier weight oil will provide a more even amount of power to the front and rear. On loose tracks, this can
cause the Rail to be too 'squirrely' (uncontrollable) or cause the rear end to slide out. For this reason, we only suggest using heavier
oil if you're driving on a high-traction surface.
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Adjusting the Differentials - Front, Centre, and Rear
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Remove the upper hinge pins, then remove the screws that hold the upper suspension
plate in place.
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Remove the upper and lower suspension plates, then firmly pull the front half of the
differential case straight out.
We detail below the removal of the front differential. Removing the centre and rear differentials is similar. If necessary, refer to the
Exploded View Assembly Drawings beginning on page 28 for more detailed information.
recommended Initial settings
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Unless you're racing, we recommend initially using the grease that already fills each differential. For general dirt track racing, we
recommend using the following weights of differential oils: 3K in the Front, 10K in the Centre, and 2K in the Rear. For use in the sand,
we recommend using 30K in the Front, 70K in the Centre and 10K in the Rear.
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Remove the hinge pins, drop the lower suspension arms, then firmly pull the
differential assembly straight out.
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Remove the four 2 x 10mm self-tapping screws that hold the differential housing
together. Pull the differential housing apart, then pull the differential assembly out of
the differential housing.
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You can now disassemble the differential, remove the grease, then reassemble and
refill the differential with the silicone oil of your choice.
For detailed information about disassembling, then re-assembling the differentials,
see the 'STEP 1: FRONT, REAR, AND CENTRE DIFFERENTIALS' section on page 28.
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Remove the two 4 x 12mm self-tapping screws and the two 4 x 16mm self-tapping
screws from the bottom of the chassis that hold the front bumper and front half of
the gearbox in place, then remove the front bumper.
When reinstalling the front bumper after filling the differential, make sure to install
the two longer 4 x 16mm self-tapping screws in the front half of the gearbox and
the two shorter 4 x 12mm self-tapping screws in the front bumper.
