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ROCK
MAGNESIUM
SERVICE MANUAL
1 9 96
For Mag 21: 1993, 1994, 1995
and 1996 model years
Mag 21SLTi: 1994 model year
Mag 10: 1993 and 1994 model years
RockShox, Inc.
I .800.6//./1/1

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INTRODUCTION
This service manual describes how to service the following RockShox suspension forks:
Mag 21: 1993, 1994, 1995 and 1996 model years
Mag 21SLTi: 1994 model year
Mag 10: 1993 and 1994 model years
The ROCK SHOX Mag suspension fork is a sophisticated system. Care and patience should be used when
servicing internal components. The damping units are oil-filled and pressurized, so a thorough understanding
of the disassembly procedure, proper tools and a clean working area must be used to achieve correct
performance and ensure that parts are not damaged. Use only genuine RockShox replacement parts.
REQUIRED
COMMON HAND TOOLS:
• Small tip external snap ring pliers
• Small tip internal snap ring pliers
• 19 & 22mm socket and ratchet or box end wrench
• Torque wrench
Metric ruler, 150mm or longer
•
Precision calipers, 6 inch (optional)
32 & 36mm headset wrenches
• #1 phillips screw driver
I-liter beaker or container for used fork oil
Safety glasses
Straight blade screwdriver
•
Bench vice
SPECIAL ROCK SHOX TOOLS:
TOOLS
Quadra bushing removal tool (PN 70106)
ROCK SHOX standard pump/air gauge
(PN 20109—Not Shown)
• RockShox needle (PN 56991)
(no hole on side to tear air valve)
MISCELLANEOUS:
• High quality bearing grease
(Judy Butter or Non-Lithium)
• Medium strength thread lock (e.g. Loc-Tite 242)
• ROCK SHOX fork oil (5wt. or 8 wt.)
1
2
3
4
5
Upper tube clamping blocks (PN 70101)
Seal/lower bushing installer (PN 70103)
Seal puller (PN 70113)
Valve body tool (PN 70105)
Drop-out vice blocks (PN 70107)
2
3
4
5
Steerer Tube
Damping Adjuster Knob
Fork Crown Bolts (2 each side)
Fork Crown
Upper Fork Tube (w/dust boot)
Fork Brace
Fork Brace Bolt
Brake Post
Lower Tube
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REMOVAL
Figure 2A
Figure 2B
1993 MAG 10
Figure 2C
1994+ MAG IO/MAG 21
Figure 2E
OF FORK TUBES FROM FORK CROWN
Note: It is not necessary to remove the crown/steerer assembly from
1.
2.
3.
the bike to service the damper units.
Disconnect front brake cable from brake lever.
Loosen fork crown bolts alternately to avoid putting too much clamping
force on one bolt and potentially stripping the bolt head (4mm hex key).
Pull both lower fork tubes out of the crown with a slight rocking
motion. (Fig. 2A)
FORK BRACE REMOVAL
1.
2.
3.
4.
Remove brakes as per manufacturer’s recommendations.
Remove both brake posts using an 8mm open end wrench. (Fig. 2B)
Remove both brace screws using a 4mm hex key.
Clean the exterior of both fork legs (use soap and water if necessary).
DEPRESSURIZE FORK
1993 MAG 21
Figure 2D
Figure 2F
1. MAG 10 (1993): Pry out upper tube dust cap from
the side. (Fig. 2C)
MAG 21 (1993): Remove air filler screw from the top
of the air cap using a #1 phillips screw driver. (fig 2D)
MAG 10 (1994) and MAG 21 (1994 and later):
Pry off rubber dustcap from top of air cap. (Fig. 2E)
2. Insert a RockShox needle (PN 56991) through the
exposed hole to depressurize the damper. (Fig. 2F)
WARNING: POINT NEEDLE AWAY FROM YOURSELF
AND OTHERS.
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FORK AIR CAP REMOVAL
1993 MAG 10
Figure 3A
Figure 3G
1993 MAG 10
figure 3B
MAG 10 (1993):
1. Push the exposed aluminum air cap down into
10mm upper tube and remove the wire clip. (fig. 3A)
NOTE: DO NOT SCRATCH THE INTERIOR WALLS
OF THE TUBE WHEN REMOVING THE WIRE CLIP.
2. Pull the air cap out of the tube with a 6mm bolt
threaded into the center hole. (Fig. 3B)
MAG 10 (1994):
1. Remove air cap by unscrewing it with an 8mm hex
key.
2. Inspect the adjuster head O-ring for signs of
wear or damage. Replace if necessary. (Fig. 3C)
MAG 21 (ALL):
1. Turn air cap counterclockwise with a 19mm (’93
MAG 21) or 22mm (’94 and later MAG 21) with
a socket or box wrench. (Fig. 3D)
NOTE: DO NOT FORCE THE DAMPING ADJUSTER KNOB
TO TURN WHEN REMOVING THE AIR CAP. THE
SOCKET OR BOX WRENCH MUST NOT GRAB THE
ADJUSTER KNOB WHEN REMOVING THE AIRCAP OR
THE ADJUSTER ROD WILL BE DAMAGED.
DRAIN OIL
1. Drain all oil by pumping unit upside down into a used oil
receptacle. (fig. 3G)
PLEASE RECYCLE!
2. For oil change only, please see the section Fluid Level Setting.
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FORK BOOT AND DUST WIPER
REMOVAL
1.
2.
3.
4.
Remove fork boots by gently pulling up on them.
Inspect boots for wear or damage. Replace as needed.
Remove dust wiper by carefully prying up with a flat, blunt screw driver. (Fig.4A)
(’93 MAG 10, ’93 MAG 21, ’94 MAG 21 and ’94 MAG 21 SLTi forks only!)
Inspect dust wiper for wear or damage. Replace as needed.
Figure 4A
Figure 4B
Figure 4C
Figure 4C
NOTE: THE FOLLOWING MAG FORKS WILL HAVE FORK BOOTS INSTALLED AND
NO DUST WIPERS: ’94 MAG 10, ’95 MAG 21, AND ’96 MAG 21.
MAIN SEAL REMOVAL
Introduction: The upper and lower tubes are held together by the main seal
1.
2.
3.
4.
5.
6.
snap ring. After removing the main seal snap ring, the main seal must be
pulled out to separate the two tubes.
Remove main seal snap-ring using internal snap ring pliers. (fg 4B)
Extend upper and lower tubes to fully topped out position.
Place seal puller over tubes (tool #70113) with the larger end over lower tube.
Clamp upper tube in a vice with the vice blocks against the small end of the
seal puller (tool#70101).
Unscrew seal puller by hand. For hard to remove main seals, refer to the
instructions below. (fig 4C)
Upper and lower tubes can now be pulled apart by hand. (fig 4D)
SPECIAL INSTRUCTIONS FOR HARD TO REMOVE MAIN SEALS:
If unable to remove seals by hand, apply heat to lower tube at location of seal
with a hot air gun or blow dryer. WARNING: DO NOT USE OPEN FLAME.
Carefully, continue to unscrew puller. If necessary, use 32mm and 36mm
headset wrenches on puller flats.
NOTE: THE SNAP RING ON THE TOP-OUT SPRING CAN FAIL IF TOO MUCH
FORCE IS USED TO REMOVE MAIN SEAL. PROCEED CAREFULLY AND
SLOWLY. APPLY HEAT TO LOWER TUBE BEFORE ATTEMPTING TO USE
32MM AND 36MM WRENCHES.
If the top-out retaining ring fails, the upper tube will separate from the lower tube
and the seal, bushings, top-out spring and top-out retaining ring will remain in the
lower tube. Grab the bushings and the main seal with one end of the Quadra
bushing removal tool (PN 70106), slide the seal puller over the bushing removal
tool shaft and attach the end of the bushing removal tool to a bench vice. Use the
seal puller to pull the bushings and main seal straight out from the lower tube. An
alternate method is to use a small, thin, flat-blade screwdriver to pry the main seal
from the lower tube—being careful not to damage the lower tube. The bushings, spacer, top-out spring
and top-out retaining ring should now slide out of the lower tube. Turn upside-down and tap the lower
tube on a bench.
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UPPER
Figure 5A
Figure 5B
TUBE PARTS EXPLAINED
1. Slide the seal, bushing washer, main seal O-ring, bushings,
bushing spacer, and top-out sleeve off the upper tube. (Fig. 5C)
NOTE: ONLY REMOVE THE VALVE BODY FROM THE UPPER TUBE
IF IT NEEDS SERVICE OR REPLACEMENT, OTHERWISE IT MAY
BE LEFT IN THE UPPER TUBE WHILE OVERHAULING THE
FORK. Skip to Upper Tube Parts Assembly.
FOR DISASSEMBLED FORKS WHERE THE TOP-OUT SPRING
2.
3.
4.
RETAINING RING FAILED, INSPECT SNAP RING GROOVE ON
VALVE BODY AND REPLACE AS NEEDED. USE ONLY GENUINE
ROCKSHOX REPLACEMENT PARTS.
Place inverted upper tube in clamping blocks (PN 70101) and
bench vice.
Insert pins, on valve body tool (PN 70105), into holes on valve body.
Turn valve body tool (PN 70105) counterclockwise with a 19mm
wrench. Apply downward force while applying torque to valve body tool
to prevent tool from pulling out and damaging valve parts. (fig. 5A)
NOTE: IF SERVICE OF THE TOP-OUT SPRING IS NOT REQUIRED, THE FOLLOWING STEP ME BE SKIPPED.
5.
•
•
Remove top-out snap ring from valve body using external snap ring pliers. The top-out spring and top-
out washer should now slide off valve body. (Fig. 5B)
1993 MAG series forks (Mag 10 and Mag 21) have identical upper and lower bushings. The bushings
may be identified by the 1.126″ (28.60mm) outside diameter.
1994 and later MAG series forks have different size upper and lower bushings. The upper bushing
outside diameter is larger than the lower bushing. Because the difference between the outside diameter
of the upper and lower bushings is very small, it is recommended that the upper bushing be marked to
avoid confusion. The lower bushing may be identified by the 1.126″ (28.60mm) outside diameter. The
upper bushing may be identified by the 1.157″ (29.39mm) outside diameter. For MAG series forks, the
1994 and later lower fork bushings are identical to the 1993 upper and lower fork bushings.
Top-out Sleeve Lower Bushing
4
Top-out Top-out
Snap Ring Spring
Upper Bushing
Top-out Valve Body
Washer
Main Seal
Dust Wiper
Bushing Spacer
Seal O-ring
Bushing Washer
Figure 5C
page 5
Main Seal
Snap Ring

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MAG
Figure 6A
Figure 6B
21
VALVE PARTS EXPLAINED
1.
2.
3.
4.
5.
6.
Screw adjuster rod all the way clockwise into valve body.
Remove E-clip from bottom end of adjuster rod using a small
straight-blade screwdriver. (fig 6A)
Unscrew adjuster rod from valve body.
Remove valve spring snap ring using snap ring pliers
Remove valve parts from adjuster rod. (fig 6B)
Inspect parts and replace as needed.
Rebound Plate
Valve Spring Washer
(plastic) Valve Spring
(aluminum)
E-clip
’93
Adjuster Rod
figure 6C
Valve Plate
Valve Spring
Snap Ring
MAG
10 VALVE PARTS EXPLAINED
figure 6D
Valve Body
1.
2.
3.
4.
Hold valve body with tool (PN 70105) and remove valve bolt with
flat blade screwdriver.
Remove E-clip from valve bolt using a straight-blade screwdriver.
(Fig. 6D)
The rebound washer, valve plate, valve spring, and spring
washer will now slide off.
Inspect parts and replace as needed.
Rebound Plate
(plastic)
E-clip
Valve Plate
Valve Spring
Figure 6E
page 6
Valve Spring Washer
(preload)
Valve Bolt

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MAG
Figure 7A
Figure 7B
Figure 7C
Figure 7D
Figure 7E
Figure 7F
COMPONENT INSPECTION
1.
All 1993 MAG series forks were assembled with stiff valve
springs (PN 44103). However, for 1994 and later MAG series
forks, the valve springs were softened (PN 44306) to improve
fork responsiveness. The valve springs are a tuning variable.
The 1993 MAG valve body had two intake port valves with a
compression bleed hole drilled 0.028″ (O. 71mm). 1994 and
later valve bodies (PN 42226) had four intake port valves with a
compression bleed hole drilled to 0.040″ (1.02mm). The intake
port valves and the compression bleed hole are tuning variables.
Another change made for the 1994 and later MAG series forks
were that the valve plate (PN 42327) was machined with a relief
step of 0.005″.
Check coating on inside of bushings and replace if scratched or
worn (brassy-colored). Replace bushings as needed. (fig 7A)
WARNING: BUSHINGS FROM 1993 REBUILD KIT WILL NOT WORK
2.
3.
4.
CORRECTLY AS UPPER BUSHINGS FOR 1994 & LATER FORKS!
Check upper tube for signs of nicks or scratches that could
damage seal or inhibit proper seal function. Replace upper tube
as needed.
Check all O-rings for evidence of tears, deformations or
scratches. Check rebound plate for deformations or scratches.
Replace as needed. (fg 7B)
Check main seal for deformations or scratches. Replace as
needed. (fig 7C)
NOTE: IT IS VERY RARE THAT A SEAL FAILS. THE PRIMARY
5.
6.
CAUSE OF SEAL LEAKAGE IS DUE TO DIRT WORKING INTO THE
LIPS OF THE SEAL OR A SCRATCHED OR DAMAGED UPPER
TUBE AND DISRUPTING THE SEAL’S FUNCTION. IN MOST
CASES, THEY MAY BE CLEANED AND REINSTALLED. PROPER
MAINTENANCE AND CLEANING OF THE UPPER TUBE AND
DUST WIPERS WILL PREVENT LEAKAGE.
Check top-out spring for correct free length. Measure spring
from end to end. Minimum length is 0.827″ (21.0mm). Replace
as needed. (fig 7 D)
Inspect fork brace at cable mount area for signs of damage
from crashes or misuse. (fig 7 E)
NOTE: IF POSSIBLE, ADJUST THE HANDLEBARS TO HIT THE TOP
7.
FRAME TUBE BEFORE THE FORK CAN SWING AROUND AND
THE CABLE MOUNT HITS THE DOWN TUBE.
Inspect lower tubes for signs of damage at the drop-out area.
(fig 7F) Replace as needed.
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VALVE ASSEMBLY
MAG 21
Rebound Plate
(plastic) Valve Spring
Valve Body
E-clip
Figure 8B
Valve Body
Adjuster Rod
Figure 8A
Valve Plate
Valve Spring
Washer
Valve Spring
Snap Ring
1. Slide the following parts onto adjuster rod in the following order:
rebound plate, valve plate, valve spring, and valve spring
washers. (fig 8A)
2. Install valve spring snap ring on the damper rod using external
snap ring pliers. Place sharp side of snap ring away from valve
spring washer. (fig 8B)
WARNING: BE CAREFUL NOT TO OVEREXTEND VALVE SPRING
SNAP RING WITH THE PLIERS.
3. Screw adjuster rod assembly completely into valve body.
4. Install E-ring on bottom of adjuster rod.
5. Slide top-out washer onto valve body, followed by top-out spring,
and install valve spring snap ring (see fig. 9C) sharp side away
from top-out spring (Fig. 8A) to retain the assembly.
MAG 10
Rebound Plate
Valve Spring Washer
Valve Body Valve Plate
Valve Bolt
Valve Spring
Figure 8C
1. Slide the following parts onto valve bolt in the following order: valve spring washer, valve spring,
valve plate, and rebound washer. (fig 8C)
2. Install E-clip with sharp side of E-ring away from rebound plate.
3. Thread valve bolt assembly into valve body using a straight-blade screwdriver. Use medium strength
threadlock and torque to 36 IN-LBS (3.3 Nm).
WARNING: OVERTIGHTENING WILL BREAK THE VALVE BOLT.
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UPPER TUBE PARTS ASSEMBLY
1.
2.
3.
4.
Hold upper leg in vice with upper tube blocks (PN 70101).
Tighten valve body into upper tube, (the valve goes into end of tube with
threads all the way to edge) apply three drops of medium strength threadlock
to valve body threads. Torque valve assembly to 35 FT-LBS (48 Nm) using
valve body tool and 19mm (3/4″) socket with torque wrench. (fig 9A) Apply
downward force while torquing to prevent tool from pulling out and damaging
valve ports.
Slide top-out sleeve onto upper tube with shoulder away from top-out
spring. (fig 9C)
Slide lower bushing onto upper tube followed by the bushing spacer, upper
bushing, main seal O-ring, and main seal washer.
Figure 9A
Figure 9B
WARNING: FOR 1994 AND LATER MAG FORKS, THE UPPER BUSHING HAS A
5.
6.
LARGER OUTSIDE DIAMETER THAN LOWER BUSHING. PLACING
BUSHINGS IN THE WRONG POSITIONS WILL DAMAGE UPPER TUBES.
FOR IDENTIFICATION OF UPPER AND LOWER BUSHINGS, SEE UPPER
TUBE PARTS EXPLAINED SECTION.
Gently press above assembly into lower tube using seal installer tool
(PN 70103). (fig. 9B)
Grease main seal inside and out. Place main seal over upper tube.
NOTE: INSTALL MAIN SEAL WITH SMALL SPRING SIDE FACING TOWARD INSIDE OF FORK. PRESS
SEAL INTO LOWER TUBE USING SEAL INSTALLER TOOL. (FIG. 9B) THE END OF TOOL WITH LARGER
BORE SHOULD FACE THE SEAL.
7. Install main seal snap ring (sharp side up, see fig. 9C) into lower leg using internal snap ring pliers.
WARNING: THE SNAP RING MUST FULLY ENGAGE GROOVE IN LOWER TUBE. IMPROPER
INSTALLATION MAY ALLOW THE TUBES TO SEPARATE DURING USE.
4
Top-out Top-out
Top-out Valve Body
Snap Ring Spring
Washer
Top-out Sleeve Lower Bushing
Upper Bushing
Main Seal
Bushing Spacer
Seal O-ring
Bushing Washer
Dust Wiper
Main Seal
Snap Ring
Figure 9C
page 9