BMI Racing Copperhead 10 - Manual (Page 9)

Step 22
Assemble the IRS Nickel-Teflon Macro Shock as per
the included instructions with 40wt silicon shock oil.
Trim 1/8” (3mm) from the ball cup that threads onto the
shock cap. Thread the ball cups on the ends of the
shock so the over all shock length is 3.312” . This
length will give you the standard setting of 1.5mm of
rear pod droop.
Diff Assembly:
1. Put a small dab of diff grease on the axle flange
so the diff will stick to it. Place a diff ring on the
flange so its flat keys onto the flat on the diff
flange.
2. Place a flanged 3/8 x ¼” bearing in the center
of the spur gear. Slide the spur gear and
bearing unit on to the axle until it stops against
the diff ring.
3. With a small flat screw driver remove the diff
balls from the diff grease and snap them into
the outer row of holes in the spur gear.
4. Place a flanged 3/8 x ¼” bearing into the inside
face of the right side diff hub. Put a small dab of
diff grease on the hub flange so the diff will
stick to it. Place a diff ring on the flange so its
flat keys onto the flat on the hub flange. Slide
this unit on to axle.
5. Slide a flanged 3/8 x ¼” bearing over the axle
into the outside face of the right side diff hub.
Slide the stepped thrust cone onto the axles so
the smaller diameter part is against the right
hub bearing.
Locate the rear axle parts bag. There are a couple
of steps that can make your diff last longer that should be
done at this time.
Use the right alloy diff hub as a holder and sand
both sides of each diff ring on 600 grit sand paper using
electric motor cleaner spray as a lubricant. Sand until you
see an even scoring pattern across the face of each diff
ring. Clean them with motor spray and set them aside.
The diff balls may have a protective oil coating on
them. Place them on a clean paper towel and carefully
clean them with motor spray. When dry drop them into
your cup of diff grease and stir them to coat them with diff
grease.
Step 23
Step 23 Continued
1. Thread the black nylon lock nut onto the
threaded stud on the axles until it makes
contact with the thrust cone.
2. Tighten the black lock nut gradually with an
11/32” nut driver until you notice you cannot slip
the spur gear when holding the axle and right
hub in a fixed position.
Six 4-40 x ¼” cap head screws are supplied to mount
your rear wheels.
Notes:
Keep you fingers clean with motor spray. Diff
assembly is like surgery. You do not want dirt
or oil where it does not belong.
The grease on the diff balls when you pluck them out
of the cup of diff grease is all you need.
Smearing diff grease on the rings will make
your diff get dirty faster and make a mess.
The ultimate goal in building a diff is one which is
extremely free and glass smooth but requires a
lot of force to slip the spur gear.