Penske 8900 series User manual

1
Table of Contents Motorcycle Shocks
Installation .................................................................................................. 2
Notes ........................................................................................................... 3
Ride Height Adjustment ............................................................................ 4
Adjustment Recommendations ................................................................ 5
8900 Series Shock
Parts List ............................................................................................... 6
Specifications ........................................................................................ 7
8100 Series Compression Adjuster
Parts List ............................................................................................... 8
Operational Guide ................................................................................. 9
8660 Series Compression Adjuster
Parts List ............................................................................................... 10
Operational Guide ................................................................................. 11
8760 Series Compression Adjuster
Parts List ............................................................................................... 12
Operational Guide ................................................................................. 13
8900 Series Rebound Adjuster ................................................................. 14
Disassembly / Assembly Instructions ..................................................... 15
Suggested Maintenance ........................................................................... 16
Trouble Shooting ....................................................................................... 16
Valving
General Valving Characteristics ............................................................. 17
A Guide To Damper Tuning ................................................................... 18
Basic Start-up Procedure ...................................................................... 19
Valve Stacks .......................................................................................... 20
VDP and Digressive Valving Information Options .................................. 21
VDP 55mm Linear Base Shim .............................................................. 21
Preload Shim Spacers ........................................................................... 21
Pistons
Flow Rate Through Multiple Bleed Holes .............................................. 22
Piston Selection .................................................................................... 23
Linear Piston ......................................................................................... 24
Digressive Piston ................................................................................... 25
Velocity Dependent Piston (VDP) ......................................................... 26
Damping Adjustments ........................................................................... 28
Dyno Graph Overview ............................................................................... 30
Notes ........................................................................................................... 34
Table of Contents Page
Technical Manual
Motorcycle Shocks
(8900 Series)
REV: 3/27/01
#7
Main Office Midwest West
150 Franklin St. 12666 US-12 2499 S. Stockton St.
P.O. Box 1056 P.O. Box 666 Unit #1
Reading, PA 19603 Brooklyn, MI 49230 Lodi, CA 95240
[phone]  [phone] Fax [phone]  [phone] Fax [phone]  [phone] Fax
www.penskeshocks.com
Authorized Penske Racing Shocks Worldwide Distributors
PRS - AUSTRALIA PRS - CANADA PRS - U.K./EUROPE PRS - SOUTH AMERICA
NTT Racing Competition Tire Canada SPA Design Saenz Hnos.
(618) 8362-2113 [phone] 44 1 827 288 328 54 114 669-0956
(618) 8362-8811 Fax [phone] Fax [phone] Fax [phone] Fax

2
Your new Penske Racing Shock comes pre-adjusted at baseline settings. However, you must check
your rear sag before you race! This is very important for optimum performance.
Setting the Sag*
STEP 1
1) Without a rider on the bike,
have an assistant lift the
rear of the motorcycle until
the rear wheel is off the
ground slightly.
2) Using a tape measure,
measure the distance
between the axle center line
and a convenient location
on the rear subframe
(Figure 1).
3) Record this measurement as "A".
STEP 2
1) This step requires the rider
and two additional people.
2) One person should hold the
front of the motorcycle, straddling
the front tire.
3) Have the rider, wearing all of their gear, sit on the bike in a tuck position.
4) The third person should then measure the distance between the axle center line and a convenient
location on the rear subframe (same locations used in Step 1).
5) Record this measurement as "B".
STEP 3
1) Subtract "B" from "A". This number is your sag.
The amount of sag required varies from rider to rider and from track to track.
The sag should be between 7/8" and 1 1/6".
If the sag is greater than 1 1/6", preload the spring by turning the adjustable spring collar.
If the sag is less than 7/8", remove preload by turning the adjustable spring collar.
Installation
* BUELL APPLICATIONS: Use Buell spring sag recommendations.

3
Notes

4
Adjusting Rear Ride Height
1. Loosen the jam nut with 1" wrench.
2. Adjust the eyelet length.
(shorter or longer)
3. Tighten the jam nut.
Ride Height Affects
Going LONGER with rear shock length "eye to eye" will:
1. Raise the rear ride height.
2. Transfer weight from the rear wheel to the front wheel.
3. Make the front turn in quicker.
4. Reduce chain torque to the rear wheel.
Going SHORTER with rear shock length "eye to eye" will:
1. Lower the rear ride height.
2. Transfer more weight to the rear wheel.
3. Make the front turn in slower.
4. Increase chain torque to the rear wheel.
CAUTION!!!
DO NOT EXCEED THIS LENGTH
Ride Height Adjustment
å
.470" (12mm)
å

5
Road Race Track Tuning: Symptoms and Suggestions
A. Change only one adjustment at a time, and send the rider out for evaluation and feedback.
B. Take notes: Keep track of rider comments, lap times, tire conditions, and current
weather conditions.
C. Be patient, go back to your original settings if you get lost.
Symptom: Tuning List:
Harsh over bumps: 1. Go softer with low speed compression, 2 to 4 clicks at a time
(counter clockwise)
2. Go softer with high speed compression, 1 to 2 clicks at a time.
3. Increase rear spring sag, -1/2 to 1 turn at a time on spring perch.
4. Change to a softer spring rate.
5. Note: Too soft on compression can bring about a harsh feeling by
allowing too much shock travel.
Excessive wheel spin
exiting corners: 1. Repeat above steps.
2. Rebound can be too fast, allowing the rear to unload and spin
the tire. Use caution when changing rebound.
Wallowing exiting corner: 1. Stiffen low speed compression (clockwise).
2. Stiffen high speed compression, 1 to 2 clicks at a time.
3. Decrease rear spring sag.
4. Slow down rebound, 1 to 2 clicks at a time (clockwise).
5. Change to a stiffer spring rate.
Slow turn-in: 1. Raise fork legs in triple clamps
2. Increase rear eyelet length, 1/2 to 1 turn at a time.
Cannot exceed 12mm of thread exposed.
3. Soften fork compression
4. Increase front fork sag
5. Speed-up rear rebound.
Mid corner push - front: 1. Stiffen rear low speed compression
2. Slow down fork rebound
Adjustment Recommendations

6
8900 Series Shock Parts List
23 BU-10DU04 Bushing, DU .625 x .250
BR-37 Bumper (Top Out Clear)
24 OR-2220-B O-Ring, 2-220, Buna 70
25 SB-89 Shaft Bearing, 8900
26 OR-2114-V O-Ring, 2-114, Viton 75
27 SL-09 Shaft Wiper, .625 Poly (Blue)
28 OR-2312-B O-Ring, 2-312, Buna 70
29 SH-_____* Shaft, Adjustable, (10.0" - 24.0")
30 NT-04J Jam Nut, 5/8" - 18
31 MR-89 Metering Rod, 8900
32 BU-04-BZ Bushing, .200 Bronze
33 SC-08 Screw, Socket Set, 8-32 x 3/8"
34 SP-14 Spring, (A109)
35 BA-125-ST Ball, Steel 1/8"
36 SM-89 Shaft Mount, 8900, Adj. Platform
37 RS-89 Rebound Screw, 8900/Slotted
38 OR-2009-B O-Ring, 2-009, Buna 70 Duro
39 NT-06J Jam Nut, 5/8" - 20
40 EY-891775 Eyelet, 8900, RHA (MO-8T20)
EY-892175A Eyelet, 8900, RHA, Aluminum (MO-8T20)
EY-892175S Eyelet, 8900, RHA, Steel (MO-8T20)
EY-893050 Eyelet, 8900, RHA (MO-8T or MO-15T)
CL--89___* Clevis
41 SR-89225 Spring Retainer, 8900, 2.25", 55mm
42 RR-06 Wire Ring, .0625 Wire Diameter x 1.900
* Incomplete Part Number
PART
NO.
1 BD-81__* Body, Aluminum Coil-over (10.0" - 24.0")
2 RH-89225 Ride Height Adjuster, 8900, 2.25"
3 OR-2221-B O-Ring, 2-221, Buna 70
4 HO-87__* Hose (4" - 36" in 1" increments)
5 FT-__* Fitting, (45oor 90o), 1/8" NPT
6 BC-81__* Body Cap, 8100, (0o, 45o, 90o, 135o)
BC-89CL Body Cap, 8900 Clearance
7 MO-8T Mono Ball, .500 ID, Teflon
MO-8T20 Mono Ball, .500 x .875 OD
MO-15T Monoball, 15mm ID x 1.00 OD
8 RR-16 Retaining Ring, 1.025 Spiroloc
RR-10 Retaining Ring, .875 Spiroloc
9 RR-05 Retaining Ring, .250 Internal
10 JT-76HAT Jet, Top Hat
11 SP-15 Spring, (FF71)
12 JT-76POP Jet, Poppet
13 JT-RDHSNG Jet, Rebound, Straight Thru
14 NE-76 Needle
15 OR-2007-B O-Ring, 2-007, Buna 70
16 MR-8100 Metering Rod
17 NT-02R Ring Nut, 1/2" - 20
18 VS-__* Valve Stack
19 PB-55 Piston Band, 55mm
20 PI-____* Piston
21 OR-2028-B O-Ring, 2-028, Buna 70
22 VW-99 Top Out Plate, 1.375 x .504
ITEM
NO. DESCRIPTION
PART
NO.
ITEM
NO. DESCRIPTION

7
8900 Series Shock Specifications
Body Cap Clocking
__ 90oFitting __ 45oFitting
__ None
180o
135o
90o
45o
0o
Extended
Length
(shortest)
Stroke
Body Length
0o
315o
270o
225o
180o
45o
90o
135o
0o
315o
270o
225o
180o
45o
90o
135o
Reservoir Clocking
â
â
â
â
â â
__ 90oFitting __ 45oFitting
__ None
Type of Adjuster ________________
Eyelet Bushing
Total Width: ________ Bolt Diameter: ________
Body Cap Bushing
Total Width: ________ Bolt Diameter: ________

8
8100 Series Compression Adjuster Parts List
12 BA-250-ST Ball, Steel - 1/4"
13 SP-10 Spring, (TA2086)
14 HO-87__* Hose (4" - 36" in 1" increments)
AS-81UD Assembly, Update 8100 CD Adj with Knob
(Includes Items 4, 9-13, 15-24)
15 SC-02 Screw, Socket Set, 8/32" x 3/8"
16 KN-81 Knob, CD 8100
17 RR-02 Retaining Ring, .250 External
18 SC-08 Screw, Socket Set, 8-32 x 1/8"
19 SP-14 Spring, (A109)
20 BA-125-ST Ball, Steel - 1/8"
21 HG-81D Housing, CD 8100 Dished
22 OR-2006-B O-Ring, 2-006, Buna 70
23 DR-81 Drum, CD 8100
24 OR-2013-B O-Ring, 2-013, Buna 70
* Incomplete Part Number
PART
NO.
1 IU-22-S Air Valve, Port O-Ring, Steel
IU-04 Valve Core, 2000 psi
IU-06 Valve Cap, High Temperature
OR-2010 O-Ring, 2-010, Buna 70
2 RR-06 Wire Ring, .0625 Wire Diameter x 1.900
3 CP-81R Cap, 8100 Reservoir
4 OR-2221-B O-Ring, 2-221, Buna 70
5 PB-55 Piston Band, 55mm
6 PI-81R Piston, Reservoir 1.72 Diameter
7 OR-2323-M O-Ring, 2-323, Moly 70
8 RB-81__* Reservoir Body, 8100, (5.50" or 7.00")
9 SC-24 Screw, SHCS, 10-24 x 3/8"
10 VW-03 Washer, Valve, .635 x .015 x .191
11 DO-04 Dowel Pin, 3/32" x 3/4"
ITEM
NO. DESCRIPTION
PART
NO.
8100 Series CD Adjuster Option
Available in 5.5" and 7" Body Lengths
ITEM
NO. DESCRIPTION

9
8100 Series Compression Adjuster
The 8100 compression adjuster is located in the remote reservoir
assembly. The remote reservoir serves as an extension of the shock
absorbers vital elements: oil and nitrogen. The remote reservoir
theory allows for the use of increased volumes of oil and nitrogen
while allowing for smaller shock packaging. Increased nitrogen
volume is essential for consistent damping forces throughout a long
race and extreme conditions.
In the compression mode of the shock absorber, fluid is forced into
the remote reservoir in direct proportion to the area of the shaft
entering the shock body. As fluid enters the reservoir, it must pass
through the compression adjuster. Inside the compression adjuster is
the CD drum. The CD drum has (6) settings, numbered (1-6), with
number one setting (the largest hole) being full soft and number six
(the smallest hole) being full firm. As fluid is forced through the CD
drum (Figure 1), it is metered through one of the preassigned orifices
in the drum; it then enters the reservoir body, moving the floating
piston. The floating piston is designed to separate the fluid and
nitrogen, eliminating any chance of aeration.
In the event of high speed shaft velocities, fluid passing through the
hole in the CD drum could pack-up, causing an increase in damping
forces, due to the fact that fluid can no longer pass through the hole.
In this event, the fluid forces open the blow-off valve (Figure 2). The
blow-off valve makes a more linear damping curve.
Note: The remote compression adjuster is a fine tuning device for the
main valving located inside the shock absorber.
Figure 1
Figure 2
Low Speed High Speed

10
8660 Series Compression Adjuster Parts List
15 SP-16 Spring, (1460)
16 OR-2222-B O-Ring, 2-222, Buna 70
17 OR-2028-B O-Ring, 2-028, Buna 70
18 HG-76____* Housing, 8760, (Side Entry or Top Entry)
19 SP-14 Spring, (A109)
20 BA-125-ST Ball, Steel - 1/8"
21 OR-2013-B O-Ring, 2-013, Buna 70
22 SC-08 Screw, Socket Set, 8/32" x 1/8"
23 OR-2010-B O-Ring, 2-010, Buna 70
24 SH-86CD Shaft, CD High Speed
25 HO-87___* Hose (4" - 36" in 1" increments)
26 RB-76___* Reservoir Body, 8760, (4.00", 5.00" or 6.00")
27 PI-76 Piston, Floating 1.75 Diameter
28 OR-4222-B Quad Ring, 4-222, Buna 70
29 SL-87 Seal, Dowty
30 SC-18 Screw, SHCS, 4 - 40 x 1/4"
31 CP-76 Cap, Reservoir Port O-Ring
32 RR-06 Wire Ring, .0625 Wire Diameter x 1.900
33 OR-2010-B O-Ring, 2-010, Buna 70
34 IU-20-A Air Valve, Port O-Ring, Aluminum
IU-04 Valve Core, 2000 psi
IU-06 Valve Cap, High Temperature
* Incomplete Part Number
PART
NO.
1 RR-12 Retaining Ring, .343 External
2 CA-92 Cage, CD Clasp .343 Diameter
3 RR-12 Retaining Ring, .343 External
4 CA-90 Cage, CD Top Hat .343 Diameter
5 VW-91 Washer, Valve, 1.475 x .010
VW-88 Washer, Valve, 1.350 x .008
VW-66 Washer, Valve, 1.200 x .006
VW-44 Washer, Valve, 1.050 x .004
VW-28 Washer, Valve, .900 x .008
VW-30 Washer, Valve, .900 x .010
VW-38 Washer, Valve, .900 x .020
6 CA-76CD Cage, Compression Adjuster
7 SC-76INS Screw, Piston Insert
8 VW-70 Washer, Valve, 1.200 x .010
9 SC-06 Screw, SHCS, 1/4" -20 x 3/4"
10 VW-01-C Crush Washer, .25 ID, Copper
11 PI-76CD Piston, Compression Adjuster
12 OR-2013-B O-Ring, 2-013, Buna 70
13 DO-06 Dowel Pin, 1/16" x 3/8"
14 BA-187-ST Ball, Steel - 3/16"
ITEM
NO. DESCRIPTION
PART
NO.
8660 Series Adjuster Option
Available in 4", 5", and 6" Body Lengths
ITEM
NO. DESCRIPTION

11
Compression Adjuster
8660 Series Compression Adjuster
COMPRESSION ADJUSTMENT
In the state of low shaft velocities (i.e. corner entry, exit, and power down), oil is displaced within the damper in
direct proportion to the volume of the shaft entering the body. The displaced fluid passes through the compres-
sion adjuster where it is metered through a fixed, low speed bleed orifice. Due to the small diameter of this
orifice and the viscosity of the damper fluid, a pressure loss occurs across the orifice. This loss of pressure is a
loss of energy in the fluid due to friction and the subsequent opposing damping force is generated.
As the shaft velocities increase, the same amount of fluid must pass through the low speed bleed orifice, but at
a much higher rate. The viscosity of the fluid causes a greater resistance to flow at the orifice entrance which in
turn produces a large internal force on the CD housing. The other major internal components, namely the piston
and shim cage, are designed to handle this extra force by allowing the shims to blow off proportionally to the
extra force generated, much like a coil spring compresses proportionally to the axial load applied. With this
arrangement, the low speed bleed orifice still meters fluid during high speed shaft movements, but the extra
forces generated are handled with the shims which have less resistance to flow at higher velocities. They are
designed to virtually bypass the low speed orifice and form a new fluid circuit. The force at which this occurs
can be varied by turning the compression adjuster in or out, which preloads the shims. Therefore, as the preload
on the shims increases, the static force required for them to activate is increased as well. The name designation
for the parts also clue one in to their purpose, with the low speed bleed orifice handling low velocity bleed flows
and the piston/shim arrangement handling high velocity flows. This principle originated in the main shaft piston/
shim arrangement and follows similar behavior.
NOTE: When making adjustments, use the full soft setting (adjuster wound all the way in against the reservoir
body) as a starting point when counting the number of clicks to the desired setting. The full soft setting should
correspond to a clicker number designation of 0. This starting datum has been proven to be most reliable and
repeatable when making compression adjustments. There are 22 +/- clicks of adjustment.
Fixed Low Speed Bleed Circuit High Speed Flow Circuit

12
8760 Series Compression Adjuster Parts List
18 HG-76____* Housing, 8760, (Side Entry or Top Entry)
19 SP-14 Spring, (A109)
20 BA-125-ST Ball, Steel - 1/8"
21 OR-2013-B O-Ring, 2-013, Buna 70
22 SC-08 Screw, Socket Set, 8/32" x 1/8"
23 OR-2010-B O-Ring, 2-010, Buna 70
24 SH-76CD12 Shaft, CD High Speed 12pt
25 DO-18 Roll Pin, 1/16" x 1/2"
26 OR-2004-B O-Ring, 2-004, Buna 70
27 SC-76CDLS Screw, CD Low Speed
28 BA-093-ST Ball, Steel - 3/32"
29 SP-12 Spring, (3648)
30 HO-87__* Hose (4" - 36", in 1" increments)
31 RB-76__* Reservoir Body, 8760, (4.00", 5.00", or 6.00")
32 PI-76 Piston, Floating 1.75 Diameter
33 OR-4222-B Quad Ring, 4-222, Buna 70
34 SL-87 Seal, Dowty
35 SC-18 Screw, SHCS, 4 - 40 x 1/4"
36 CP-76 Cap, Reservoir Port O-Ring
37 RR-06 Wire Ring, .0625 Wire Diameter x 1.900
38 OR-2010-B O-Ring, 2-010, Buna 70
39 IU-20-A Air Valve, Port O-Ring, Aluminum
IU-04 Valve Core, 2000 psi
IU-06 Valve Cap, High Temperature
* Incomplete Part Number
PART
NO.
1 JT-76CDSH Jet, High Speed Shaft
2 RR-12 Retaining Ring, .343 External
3 CA-92 Cage, CD Clasp .343 Diameter
4 CA-90 Cage, CD Top Hat .343 Diameter
5 VW-91 Washer, Valve, 1.475 x .010
VW-88 Washer, Valve, 1.350 x .008
VW-66 Washer, Valve, 1.200 x .006
VW-44 Washer, Valve, 1.050 x .004
VW-28 Washer, Valve, .900 x .008
VW-30 Washer, Valve, .900 x .010
VW-38 Washer, Valve, .900 x .020
6 CA-76CD Cage, Compression Adjuster
7 SC-76INS Screw, Piston Insert
8 VW-70 Washer, Valve, 1.200 x .010
9 SC-06 Screw, SHCS, 1/4" -20 x 3/4"
10 VW-01-C Crush Washer, .25 ID, Copper
11 PI-76CD Piston, Compression Adjuster
12 OR-2013-B O-Ring, 2-013, Buna 70
13 DO-06 Dowel Pin, 1/16" x 3/8"
14 BA-187-ST Ball, Steel - 3/16"
15 SP-16 Spring, (1460)
16 OR-2222-B O-Ring, 2-222, Buna 70
17 OR-2028-B O-Ring, 2-028, Buna 70
ITEM
NO.
PART
NO.
8760 Series Adjuster Option
Available in 4", 5", and 6" Body Lengths
ITEM
NO.
DESCRIPTIONDESCRIPTION

13
8760 Series Compression Adjuster
LOW SPEED COMPRESSION ADJUSTMENT
In the state of slow shaft movement (i.e., corner entry, exit, and
power down), oil is displaced into the reservoir in direct propor-
tion to the area of the shaft entering the shock body. The oil
passes through the compression adjuster where it is metered
through an adjustable needle and jet assembly. By shutting
down the flow of oil, the oil is restricted, causing a stiffer feel in
low speed circumstances. The low speed adjuster works in
conjunction with the high speed adjuster to delay the high speed
circuit.
The low speed compression bleed bypass adjuster has approxi-
mately 30 clicks of adjustment. Turning the adjuster knob
clockwise increases the low speed damping.
HIGH SPEED COMPRESSION ADJUSTMENT
In fast shaft movement (i.e. bumps, track inconsistencies,
etc.), oil is displaced into the reservoir, as in the low speed
state, but at a much faster velocity. The oil is forced to
bypass the low speed needle and jet due to the fact that the
small orifice in the jet causes the oil to hydraulic. In turn,
the oil is forced through another piston in which its orifices
are covered by another shim stack. This shim stack is
preloaded with force from the CD cage and preload shims.
By turning the high speed adjuster clockwise (stiffer), you
are preloading the CD cage and shims, making it tougher
for the oil to flex the shims.
The operation of the high speed adjuster assembly effect is
timed by the adjustment of the low speed needle and shaft
velocity. (i.e., if the low speed needle is full soft, at high
speed a larger volume of oil will initially pass through the
low speed jet slightly delaying the operation of the high
speed bypass mode.)
Turning the black hex adjuster clockwise increases the high
speed damping. There are 24 +/- clicks of high speed
adjustment counting from full soft.
NOTE: When making adjustments on the high speed adjuster, start at the full soft setting (adjuster wound all the way in
against the reservoir body) counting the clicks toward full firm. When adjusting low speed, start at the full firm setting
(adjuster wound all the way in against high speed adjuster) counting the clicks toward full soft. This makes your settings
more precise and less confusing for your records.

14
8760 Needle and Jet
The 8760 jet and needle combination have been designed to give the user a broader and more linear range of adjust-
ment for bleed past the piston on rebound.
The 8760 jet utilizes a spring loaded poppet valve to check the flow. This gives a better seal against the flow and a
quicker response time as the shaft changes direction.
This needle has a curved parabolic tip, which gives a very fine, linear adjustment in damping across the entire range
provided by the jet.
The 8760 needle and jet will fit any of our
adjustable shafts, but they must be used
together and cannot be interchanged with
older style needles and jets.
When installing any jet, apply a tiny drop of blue
LoctiteTM to the threads and torque to 120 inlbs.
8900 Series Rebound Adjuster
The rebound adjuster screw on the 8900 Series
shock absorber is located in the adjustable
platform at the base of the main shaft.
The rebound adjuster has 25 to 30 clicks of
adjustment. Note: the external rebound adjust-
ment is only a fine tuning device for the main
valving located inside the shock absorber.
During the rebound (extension) stage of the shaft
movement, fluid flows through two ports in the
main shaft. Inside the main shaft is a needle and
jet assembly which adjusts the amount of fluid
passing through the ports. By turning in the
rebound adjuster (clockwise), the needle is
moved into the jet, restricting the flow, causing
firmer rebound damping forces. In reverse, by
turning the adjuster out (counter clockwise), more
oil is allowed to pass through the ports causing
lighter rebound damping forces. This rebound
adjustment assembly, is in fact a timed control for
the rebound shims located on the main piston.

15
Disassembly / Assembly Instructions
Disassembly Instructions
1. Back the rebound adjuster to full soft and depressurize the remote reservoir.
2. Clamp the body cap eyelet in a vise* with the shaft pointing up. *Soft jaw vise is recommended
3. Unscrew the shaft bearing assembly and remove the shaft assembly.
4. Drain the oil. (Please dispose of properly)
5. Push the reservoir end cap up into the reservoir body. (For the 8100 Series, you must hold the hose)
6. Using a scribe, pry the wire retaining ring out of the reservoir body and remove the reservoir end cap.
7. Looking into the reservoir, you will see a threaded hole in the reservoir floating piston. Using an 8-32 (8100) or
3-8 x 24 (8760) threaded rod, remove the floating piston by holding onto the reservoir body and pulling on the
threaded rod. Drain the oil from the reservoir
8. Use solvent to clean all parts, then dry and inspect them. NOTE: Brake cleaner use is discouraged due to the
possible damaging effects on seals and wipers.
9. Inspect and replace the o-rings as needed.
10. If needed, revalving is done at this point. Clamp the adjustable platform in the vise with the piston pointing up. Remove
the 1/2" ring nut from the top of the shaft assembly to access valving or to change the seals in the shaft bearing.
Assembly Instructions
1. Reassemble the shaft and piston assembly. Before installing the ring nut, there should be no more than .150" shaft to
bottom threads exposed to avoid damaging the nut or shaft threads. Be sure to add sufficient constants to be able to
properly torque the ring nut to 25 ftlbs (300 inlbs). [Use constants on CD side for linear pistons. Digressive and VDP
can be varied.]
2. If the jet was removed, add a tiny drop of blue Loctiteäto its threads and torque to 120 inlbs (maximum).
3. Torque the jam nut on shaft to 40 ftlbs (480 inlbs).
4. With the shock returned to the vise, fill the remote reservoir half full with oil.
5. Hold the remote reservoir above the shock body and look into shock body. When the oil level is above the fitting port,
fill the reservoir to the top with oil. [ 8100 set CD on full hard, #6; 8660 set CD on full soft, turn knob counter clockwise
until it stops against CD body; 8760 high speed CD adjuster (black hex) set on full soft, turn counter clockwise until it
stops against CD body, low speed CD adjuster (silver knob) set on full hard, turn knob clockwise until it stops against
high speed hex.]
6. Before the oil lowers, insert the floating piston and 8100 piston band or 8700/8760 quad ring* into the reservoir body.
*Make sure the quad ring is not twisted.
7. Hold the remote reservoir below the level of the shock with the hose pointing up allowing any trapped air to flow up
into the shock body. Using the handle of a mallet, push the floating piston up into the reservoir body until bottomed.
[8100 CD set on full soft, #1; 8660 CD set on full soft, turn the knob counter-clockwise until it stops; 8760 high speed
CD adjuster (black hex) set on full soft, turn counter-clockwise until it stops, low speed adjuster (silver knob) set on full
soft, turn the knob counter-clockwise until it stops.]
8. Slowly pull the reservoir floating piston back, then push in 2 to 3 inches.
9. Repeat step #7 & #8 until there are no air bubbles seen coming from the reservoir. (When no air bubbles are seen go
directly from step #7 to step #10).
10. Replace the reservoir end cap and snap ring.
11. Pressurize the remote reservoir to reposition the floating piston (approx. 150 psi).
12. Fill the shock body with oil to the bottom of the threads (1/2" from the top of the body).
13. Insert the piston/shaft assembly with the teflon piston band into the shock body, pushing the piston just below the
surface of the oil, until the 2 shaft bleed hole ports are covered.
14. It is very important to remove as much air as possible from the piston assembly. To do this, start by moving the shaft
up slowly and pushing down a few times using a 1" - 2 " stroke, being sure to keep the two ports in the shaft below the
surface of the oil, or air will be sucked back into the piston assembly. Lightly tap the eyelet a few times with a mallet to
assure that all the air is released from the piston. NOTE: this step is very important; take your time, repeat as needed.
15. Slowly pull up on the shaft assembly until the two ports are just below the surface of the oil. Top off with oil to fill the
shock body.
16. Slide the shaft bearing down without moving the shaft until the o-ring contacts the body. Depressurize the remote
reservoir, tighten the shaft bearing. Do not overtighten the shaft bearing.
17. Pressurize the shock to approximately 150 psi. Please call if you have any questions on specific pressures.
NOTES
1) IMPORTANT: Reservoir floating piston must be repositioned before the shaft is inserted into the shock body (refer to
step #11).
2) Penske Suspension Fluid (Silkolene Pro RSF 5 wt.) is recommended. Use of alternate fluids may have an adverse
effect the damper's internal sealing components. (i.e., o-rings)

16
Suggested Maintenance
PRE RACE ............................................................................................. Inspect for oil leakage. Check
the nitrogen pressure.
EVERY 30 HOURS OF TRACK TIME OR YEARLY ............................. Change oil. Replace the shaft seal
o-ring, wiper, shaft bearing o-ring,
reservoir cap o-ring and piston o-ring,
floating piston quad ring, valve shims.
Trouble Shooting
LOSS OF NITROGEN PRESSURE ...................................................... Valve core is not tight or needs
replacing, o-ring on air valve
needs replacing, reservoir cap
o-ring needs replacing, leaking quad
ring, or dowty seal.
OIL LEAK AROUND SHAFT ................................................................. Shaft seal o-ring or wiper needs
replacing.
Note: minimal oil
seepage is normal.
OIL LEAK AT RESERVOIR .................................................................. Teflon tape seal on hose needs
replacing, reservoir cap or CD
housing o-ring needs replacing.
OIL LEAK BETWEEN SHAFT BEARING AND BODY ........................ Shaft bearing o-ring needs
replacing.
SHAFT WILL NOT FULLY EXTEND .................................................... Check for bent shaft, low nitrogen
pressure. Note: do not spray brake
cleaner or solvent on the shaft
wiper, it may cause it to swell
and prevent proper movement.

17
General Valving Characteristics
The damping characteristics of your shock are determined by the compression and rebound valve stacks
located on the main piston.
The valve stacks are made up of a series of high quality shims, which are made to flex under the force of oil
flowing through the piston ports and then return to their original state.
The thickness of the individual shims determines the amount of damping force the shock will produce. By
changing the thickness of the individual shims, damping forces will be altered. For example, if you are running
an A compression valving, where all the shims in the stack are .006 thick and you replace them with a B
compression valving, which consists of all .008 thick shims, the compression damping will increase.
*When the shaft is moving very slowly oil passes through the bleed hole, if there is one, before it passes to
the shims.
High Speed Low Speed* High Speed
Rebound Compression and Rebound Compression

18
A Guide To Damper Tuning
The ultimate purpose of a shock is to work together with the spring to keep the tire on the track. In
compression (bump) to help control the movement of the wheel and in rebound to help absorb the
stored energy of the compressed spring.
Usually in rain or low grip situations allowing more bleed or less low speed damping is desirable to
delay tire loading upon initial roll.
In dry high grip conditions adding damping or restricting bleed will load the tire sooner upon initial roll
increasing platform stability.
A motorcycle with too much low speed damping will usually lack grip in change of directions, cannot
put power down in slower corners (wheel spin) and lack overall grip after initial turn in.
If traction is a problem coming off slow corners, reducing low speed damping or adding more bleed
will help weight transfer at the rear thus increasing traction.
One of the most important things to know about these adjusters is their relative position to one an-
other. If for instance you have the low speed set at 25 to 30 clicks (soft), the range of high speed
adjustment will be lessened. Or in the opposite direction, if the high speed is set at 0 to 1 (off soft),
the low speed adjustment range will be lessened.
Also, when making a big adjustment in high or low speed, the change will affect the other in a small
percentage. As an example, the high speed is set at (+4) and the low speed at (-6). Now you want to
set the low speed to (-2), this will also increase a percentage of the high speed force figure. By
dropping the high speed from (+4) to (+3) would compensate for this low speed change so the overall
damper curve would remain intact. The more experience you have with these the easier it will
become to recognize what changes can occur in relation to different valvings. The tendency of these
circuits to cross talk is greatly reduced in our new digressive CD piston (part # AS-76DIGCDUP).
The rebound adjuster consists of a needle metering flow across a hole. This metered flow bypasses
the main piston/shim assembly until flow is choked off. The shims then modulate the flow.
Depending on valving, there will be an affect on adjustment range. The softer the valving (A - B), the
less force range it will have. This is due to a lower pressure required to blow the valves on the main
piston. Obviously the heavier the valving (C - E), the more effective the bleed becomes. On digres-
sive pistons, pre-load also affects the range of adjustment.
FORCE FORCE
VELOCITY (SHAFT SPEED)
LOW SPEED HIGH SPEED
VELOCITY (SHAFT SPEED)
LOW SPEED HIGH SPEED
Large Amplitude Change
Small Amplitude Change Large Amplitude Change
Small Amplitude Change
LOW SPEED ADJUSTMENT EXAMPLE HIGH SPEED ADJUSTMENT EXAMPLE

19
A Guide To Damper Tuning
The following setup procedures are basic recommendations for reaching an initial starting point using
double adjustable Penske Racing Shocks. This procedure is ideal for use on an open test schedule. A
race weekend may not allow enough time. Start by making the compression adjustments as de-
scribed below, until it feels right, then move to the rebound adjustments.
COMPRESSION
The idea is to set the compression damping forces to suit the bumps in critical areas, such as cor-
ners, corner exits and braking zones.
Increasing or lowering cannister pressure (range 150 to 300 psi) can have an influence on support
under braking, acceleration, and tire loading on turn in, and on mid-corner grip.
Step 1 - Set the rebound adjuster at full soft.
Step 2 - Starting with the compression setting at full soft, ride a lap then return to increase the
bump settings. Continue this process of adding bump control to minimize the upsets until
the bike becomes harsh, loses tire compliance and traction. At this point you know that you
have gone too far on the compression settings; back off one click.
REBOUND
The idea is to tighten up the bike, stabilize the platform and eliminate the floating "Cadillac feeling".
This will also reduce the rate of weight transfer.
Step 1 - With the rebound setting at full soft, add 5 flats (8100) or clicks (8760) of rebound
adjustment at a time, then return to continue the process until the bike becomes "skittish" or
the rear wheel hops under braking. At this point you know you have gone too far on the
rebound settings, back off one flat at a time for final balance.
Once again, this is a basic procedure for finding your initial setup for a given track. If you find that you
are at the end of your adjustment range and feel that the bike is feeling better, you will need to
revalve the shocks to allow for further adjustment in the given direction.
Basic Start-up Procedure
Also, the amount of rebound can have a great influence on weight transfer. Less front rebound allows
weight transfer to the rear under acceleration. Less rebound in the rear allows for a greater amount of
weight transfer to the front under braking and turn in.
When a motorcycle is over damped in rebound it can pack down in a series of bumps and a driver will
recognize this as too stiff and usually will think it is compression damping. Too much rebound can
cause lack of grip on cornering.
When making a large spring change keep in mind where the rebound adjuster is and do you have
enough range to compensate. Sometimes a spring change will bring a better balance to the damping
values after the spring change. If the spring/shock combination was balanced, the rule of thumb is a
stiffer spring requires lower compression and higher rebound. A softer spring requires higher com-
pression and lower rebound.

20
Part #
VS-AA AA .004 .004 .004 .004 Constant
VS-AAP AA+ .004 .004 .006 .006 Constant
VS-AM A- .006 .006 .004 .004 Constant
VS-A A .006 .006 .006 .006 Constant
VS-AP A+ .006 .006 .008 .008 Constant
VS-BM B- .008 .008 .006 .006 Constant
VS-B B .008 .008 .008 .008 Constant
VS-BP B+ .008 .008 .010 .010 Constant
VS-CM C- .010 .010 .008 .008 Constant
VS-C C .010 .010 .010 .010 Constant
VS-CP C+ .010 .010 .012 .012 Constant
VS-DM D- .012 .012 .010 .010 Constant
VS-D D .012 .012 .012 .012 Constant
VS-DP D+ .012 .012 .015 .015 Constant
VS-EM E- .015 .015 .012 .012 Constant
VS-E E .015 .015 .015 .015 Constant
VS-EP E+ .015 .015 .020 .020 Constant
VS-FM F- .020 .020 .015 .015 Constant
VS-F F .020 .020 .020 .020 Constant
1.350 O.D. 1.200 O.D. 1.050 O.D. .900 O.D. .750 X .020
Constant Compression Valve Stack Rebound Valve Stack Constant
When refering to shock valving, (example: A/B), (A) refers to the compression valve stack and (B) refers
to the rebound valve stack.
Valving
Valve Stacks
Standard
Digressive
Valve
Stack