RR19: MR-02 Full Build
Part 1 - Ball Differential
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Alright Guys, everyone knows the MR-02 is king.
The AWD can be equally as fast and faster in many
instances, but it will never be as simple and
popular as the good ol' MR-02. With that in mind,
we decided to show you how we build our MR-02's;
after all we are the defending PNWC Champs in
every 2WD category, so you know that we know what
we are doing ;)
Enjoy! |
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Above is an "exploded" view of the
differential. It should help you keep reference
to see in what order the parts go. |
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The first step is always polishing your rings. Since
we are using the ultra-lightweight QteQ parts, which
are exclusive to Reflex, we will be using round, and
not D-Cut rings. We like using 600-800 grit sandpaper
to polish our rings.
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Using a little water with the sandpaper and the right
diff hub can aid you in making the polishing easier.
Use a circular pattern when polishing your rings to
ensure a smooth and even finish.
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One of the tricks to building a good differential
with round rings is to sand both sides. The side that
goes to the balls, use fine grit (600-800 sand paper)
and on the side that faces the diff hubs, use something
like 300-400 to make sure that it has a rougher texture
(see the ring on the left?) and that the CA you use
adheres better the ring.
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Next we take the shaft, our o-ring and differential
nut and prepare to install it.
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Slide the oring over the shaft and tighten the nut
slightly, just to locate it on the shaft.
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Now slide the back plate over the shaft as well.
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Put a tiny drop of CA on each of the 6 spikes from
the differential back plate.
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| Now slide the polished diff ring, rough side towards
the diff plate and hold it in place for a couple of seconds.
Once the CA sets, the ring should hold really well. |
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Grab your Reflex 53T, 64 pitch spur
gear and slide it over the shaft.
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Next we take our 3/32
ceramic balls and some Kyosho Ball diff Grease. This
stuff is really, really good... |
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Apply a generous amount
and work it in on the palm of your hand. Make sure all
the balls are fully covered with grease. |
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Install the diff balls
on the spur gear. Be patient, we are almost done! :) |
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Now, we need to glue the outside Diff
plate to the diff ring. Again, use a tiny drop on each
spike of the plate. |
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Install the diff ring
and hold it for a second, so that it bonds well. |
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Install the thrust
bearing in the outside plate, and slide the assembly
over the shaft. |
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Next install the e-clip
on the shaft. Be careful so that it does not fly out! |
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We are done! Good job. Now you can adjust your diff
to your liking.
A FEW TIPS ON DIFFS AND HOW TO TUNE THEM:
Differential tuning is something we often neglect,
but it can often be that adjustment that we have been
looking for to get our car to work to its full potential.
Below are some tips on diffs and how to tune them properly.
1.Ball diffs are effectively "traction
control" units. Use them as such. If the track
has low grip, sometimes all it takes to hook your car
up is loosening the diff a little bit. If ball diffs
were not meant to be adjustable, they wouldn't be adjustable.
;) Typically, our starting point for diff adjustment
is loosening the diff to the point where it starts to
slip slightly. Once that happens, we tighten it slightly
so that it stops slipping.
2.Higher grip tracks need tighter diff action,
conversely, lower grip tracks requier a looser diff
setting.
3.Keep your spur gears and pinions in good
shape!!! If you have worn or dirty teeth, your car will
not run well. Worn teeth affect the way a car accelerates,
slows down, its top speed and the sound it makes. Basically
if your car starts getting loud, it is time to replace
the pinion, spur or both.
4.Replace your thrust bearing often. The thrust
bearing takes all the axial load from your car. This
leads to the thrust bearing wearing hard and often.
Many times you will work your diff over and over again
and it will still be notchy and not very smooth. It
has nothing to do with your rings or diff balls; it's
your thurst bearing! Typically, you want to replace
this bearing everytime you replace your spur.
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Written by
Cristian Tabush
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