suspension setup seminar

8/8/2019 Suspension Setup Seminar

http://slidepdf.com/reader/full/suspension-setup-seminar 1/12

Page- 1 -

PREPARED BY: GARY JAEHNE (AFM #13)

DVANCED

SUSPENSION

SETUP

SEMINAR

DVANCED

SUSPENSION

SETUP

SEMINAR

DVANCED

SUSPENSION

SETUP

SEMINAR



Page- 2 -

PRESENATION OUTLINE

Main Topics

1. Suspension Basics: Review

2. SPRINGS: "The Whole Story"

• Coil (Fork) Springs: "All The Flavors"

• Straight-Rate

• Progressive Rate

• Dual-Rate

• Customizing Fork Springs: "Stiffening Spring-Rates"

3. FREE (Static) vs. RIDER Sag: "Evaluating Proper Spring-Rates"

• Rear shock

• Front Forks

4. Diagnosing Handling Problems: "Cause & Effect"

• Running wide in corners• Bottoming under hard braking

• Wallowy and unstable in corners

• Loss of traction under acceleration

• Lack of stability, nervousness

• Front-end instability under acceleration off corners (headshake)

• Ground clearance (touching down hard-parts)

5. Questions & Answers



Page- 3 -

Ø SUSPENSION BASICS: REVIEW

Rake

BASIC CHASSIS GEOMETRY

Wheelbase

Trail

SwingarmAngle

RemoteReservoir

"REBOUND"

Adjuster Wheel

Location

"PRELOAD"

Adjuster Ring

Location

"COMPRESSION"

(low speed)

Adjuster Knob

Location

"RIDE HEIGHT"

Adjustment

Location

Piston with

Shimstack Gas

Separator

Bladder

GasFill Valve

(Schraeder)

Rear Shock Components

Typical

"REBOUND"

Adjuster Screw

Location

Typical

"PRELOAD"

Adjuster

Location

Typical

"COMPRESSION"

(low speed)

Adjuster Screw

Location

CARTRIDGE FORKCOMPONENTS

CartridgeTube

Damping

Rod

Piston

Fork

Spring

Damping

ControlValve &

Shimstack

Bottom-Out

Piston



Page- 5 -

Ø Customizing fork springs: (stiffening spring-rate):

In some instances it’s possible to utilize the process of shortening of the existing fork springs, for the

purpose of achieving a target stiffer spring rate. The characteristics of the existing springs (straight rate vs

progressive, length), and the total travel requirements of the bike, will determine whether this is possible(or not) on a particular motorcycle. Calculating all of these parameters PRIOR to attempting such a

change, is critical!

Calculation formula for determining the number of coils to be removed:

Parameter definitions:

C : Current spring-rate

D : Desired spring-rate

E : Existing spring coil count

F : Final spring coil count

-----------------------------------------------------------------------------------------------------------------------------

Example:

Current spring-rate.................. .50Kg/mm

Desired spring-rate.................. .75Kg/mmExisting spring coil count....... 32 coils

------------------------------------------------------------Final spring coil count ............ 21 coils

Number of coils to cut off ...... 11 coils

-----------------------------------------------------------------------------------------------------------------------------

STRAIGHT-RATE(Before/After)

Original Spring

Spring Rate: .50 Kg/mm

ShortenedSpring

Spring Rate: .75Kg/mm

11 Coils removed

C

Dx E = F

.50

.75x 32 = 21



Page- 6 -

Ø "Free" (“Static”) vs. "Rider" Sag: Evaluating Proper Spring-Rates:

"Rider Sag” adjustment is done to achieve a target amount of suspension travel, with the weight of the rider

on the bike, with the existing spring stiffness (“spring rate”). Despite the fact that you’re able to achieve

the target "rider sag" numbers on your bike, using the preload adjusters, does not insure that the springs inyour forks, and on your rear shock, are the ideal spring-rate for the combined weight of you and your bike.

Overly soft, or overly hard (spring rates) springs can often be made to provide the target "rider sag"

numbers, despite them still not being “right”. This can occur in cases where the adjustment consisted ofremoving nearly all spring preload (in the case of springs being too stiff ), or compressing the installed

height of the springs an extreme amount (in the case of too soft springs).

The following section will discuss the process of measuring "free sag" and "rider sag" numbers on yourbike, and comparing those numbers to determine if the spring rates (spring stiffness) of your fork and shock

springs are in the ballpark for providing optimum performance.

Rear Suspension: Measuring "Rider-Sag" and "Free (Static)-Sag" (Illustration)

StaticSag

Dimension

Piece

of tape

REAR SUSPENSION:

UnlaidenDimension

Rider

SagDimension

90

Preload

Adjustment

Sprung

Weight

Fully Lifted

R S

U



Page- 7 -

PROCEDURE: Rear Shock: Measuring - Adjusting "RIDER-SAG"

1. Measure distance between fixed reference point (tape on tailsection) and the center of the rear axle,with the rider sitting with their full weight on the bike, in riding gear.

1. Measure distance between fixed reference point and the center of the rear axle, with the rider OFF thebike, and the bike's sprung weight fully lifted off the suspension (lifting the bike by the

tailsection/subframe).

2. Subtract Step 1 measurement (R), from Step 2 measurement (U), to determine "Rider-Sag".

U - R = "RIDER SAG"

3. Adjust the preload adjuster on the rear shock, in the proper direction, until the recommended targetdimensions for "Rider-Sag for your bike is achieved. (Approximately 25-30% of total travel: about 25-

32mm on most sportbikes)

StaticSag

Dimension

Piece

of tape

REAR SUSPENSION:

UnlaidenDimension

RiderSag

Dimension

90

PreloadAdjustment

Sprung

Weight

Fully Lifted

R S

U

• PROCEDURE: Rear Shock: Measuring "FREE (Static)-SAG"

1. Allow the natural sprung weight of the bike to again rest on the rear suspension.

2. Measure the distance between the same fixed reference point (tape on the tailsection) and the center of the rear axle. This dimension will be called (S), which is the dimension that will be used for calculating

"Static-Sag"

3. Subtract the static sag dimension (S) from the original unlaiden measurement (U), to determine the

"Staic-Sag"

U - S = "STATIC SAG"



Page- 8 -

• DETERMINING SHOCK SPRING COMPATIBILITY:

Note 1: Static-Sag value AFTER "Rider-Sag" has been properly adjusted by springpreload

Note 2: The following numbers are ONLY intended as basic “ballpark” guidelines, and

may vary by bike, suspension components installed, and rider/suspension tunerpreferences

STATIC-SAG Shock Spring Compatibility

• 0 - 2mm: Spring rate TOO SOFT for this rider/bike application

• 3 - 8mm Spring rate CORRECT for this rider/bike application

• 9mm - > Spring rate TOO STIFF for this rider/bike application



Page- 9 -

Front Suspension: Measuring "RIDER-SAG" & "FREE (Static)-SAG" (Illustration)

Unlaiden

RS

Zip-tie

FRONT SUSPENSION:

Lift

fully

Preload

Adjust

• PROCEDURE: Front Fork: Measuring "RIDER-SAG"

1. Install a flexible zip-tie around the inner fork tube, on one fork leg.

2. Once the rider sitting on the bike in full gear, with their full weight on the bike (feet on the pegs) slidethe zip-tie against the black rubber dust seal on the fork, to mark the travel point.

3. With the rider then off the bike, lift the front of the bike fully, until the front tire is just off the ground,

and then measure the distance from the zip-tie to the black rubber dust seal on the fork. This distance

(R) is the "Rider Sag"

4. If the "Rider Sag" measurement is more or less than the basic ballpark settings for the bike (usually

about 32-38mm, for most sportbikes), adjust the spring preload adjusters, at the top of the fork tubes,until the target measurement is achieved.

• PROCEDURE: Front Fork: Measuring "FREE (Static)-SAG"

1. With the Rider OFF the bike, allow the natural sprung weight of the bike to rest on the front suspension

2. Slide the zip-tie against the black rubber dust seal on the fork, to mark the travel point.

3. Lift the front of the bike fully, until the front tire is just off the ground, and then measure the distancefrom the zip-tie to the black rubber dust seal on the fork. This distance (S) is the "Static Sag" "



Page- 10 -

• DETERMINING FORK SPRING COMPATIBILITY:

Note 1: Static-Sag value AFTER "Rider-Sag" has been properly adjusted by springpreload

Note 2: The following numbers are ONLY intended as basic “ballpark” guidelines, and

may vary by bike, suspension components installed, and rider/suspension tunerpreferences

STATIC-SAG Fork Spring Compatibility

• 0 - 9mm: Spring rate TOO SOFT for this rider/bike application

• 10 - 20mm Spring rate CORRECT for this rider/bike application

• 21mm - > Spring rate TOO STIFF for this rider/bike application



Page- 11 -

DIAGNOSING HANDLING PROBLEMS:

“SUSPENSION FIXES”

SYMPTOM POTENTIAL FIXES

Running wide in corners, slow

turn-in

• Increase shock spring preload (if sag incorrect)

• Increase rear “ride height”

• Decrease fork spring preload (if sag incorrect)

• Move fork tubes up in triple-clamps (lower front)

• Increase shock low-speed compression damping

• Decrease front fork compression damping

Bottoming under hard braking • Increase front fork compression damping

• Raise fork oil level in 5mm increments

• Verify fork spring preload (rider sag)

• Replace fork springs (w/stiffer units)

• Increase shock rebound damping

Lack of stability, nervousness • Increase front fork rebound damping

• Increase fork spring preload (if sag incorrect)• Increase shock rebound damping

• Decrease shock spring preload (if sag incorrect)

• Adjust rear ride height

• Move fork tubes slightly in triple clamps

Loss of traction under acceleration • Increase rear ride height

• Decrease shock compression damping

• Decrease shock preload (if sag incorrect)

Front-end instability under

acceleration off corners

(headshake)

• Increase front fork rebound damping


•

Check fork and shock preload (rider sag)• Increase rear ride height

• Move fork tubes slightly in triple clamps

Scraping footpegs, muffler,

bodywork in turns (ground

clearance)

• Increase shock spring preload (if sag incorrect)

• Increase fork spring preload (if sag incorrect)

• Increase rear ride height


• Increase front fork compression damping

• Move fork tubes down in triple-clamps (raise

front, in conjunction with rear ride height)



Page- 12 -

STUDENT NOTE-TAKING WORKSHEET

suspension setup seminar

Documents