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Vibration Diagnostics. Vibration Diagnostics. Vibration Diagnostics. Vibration Diagnostics. Why Wheel Balancing?. What is . Vibration?. Vibration?. Vibration?. Vibration?. In order to Diagnose a Vibration we must understand some... . Basic Principles. 1st cycle. 2nd cycle.

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slide1

Vibration Diagnostics

Vibration Diagnostics

Vibration Diagnostics

Vibration Diagnostics

Why Wheel Balancing?

slide2

What is

Vibration?

Vibration?

Vibration?

Vibration?

slide4

1st cycle

2nd cycle

What is a cycle?

1 second in time

2 cycles per second or 2 Hz

slide5

Frequency

1 second in time

1st cycle

2nd cycle

Frequency is 2 CPS or 2 Hz

slide6

1 second

Tire Imbalance

With a Frequency of 4 Hz

Imbalance

4 Revolutions = Frequency of 4 CPS/Hz

slide7

Amplitude of Force

1 second

6 Hz

Tire Imbalance

If the Frequency increases...

so does the amplitude of force

Imbalance

slide8

Reed Tachometer

can identify Frequency

500 250 100 25

Hz

slide9

"Steering Wheel Shake"

Wobble

Shimmy

Waddle

slide11

What is Static Balance?

Static Balance is when the weight of the wheel and tire assembly is distributed equally around the axis of the wheel rotation.

If static Balance exists the wheel will have no tendency to rotate.

If rotated it rotates with Equal Force

slide12

How do we Balance this Wheel?

Heavy Area Rotates to Bottom

.25 oz Imbalance

slide13

Is this wheel in static balance?

.25 oz imbalance

.25 oz weight added

slide14

If this wheel is in perfect balance at a

speed of 40 mph,

will it remain in balance at all speeds?

.25 oz imbalance

.25 oz weight added

slide15

Yes,

the

is the word

“Perfectly”

slide16

.86 lbs

.86 lbs

At 20 MPH

.25 ounces of imbalance generates

.86 pounds of force

Imbalance in Tire

Balance Weight Applied

slide17

10.5 lbs.

10.5 lbs.

At 70 MPH

.25 ounces of imbalance generates

10.5 pounds of force

slide18

At 70 mph the force is 10.53 pounds

It\'s still in perfect balance!

10.53 lbs.

NOTE: Speed rated Tires Utilize a Nylon Over-lay to prevent tire distortion at high speeds.

10.53 lbs.

slide19

Common Problems:

  • Round Off vs. Fine Mode
  • Mounting
  • Clean Mounting Surface
  • Excessive Runout
  • Tolerance stack up
slide20

Consider this...

Most Computer Wheel Balancers Round off to the nearest .25 oz.

1 oz. Balance Weight

1.12 oz. Imbalance

Is this a Problem?

slide21

1.12 ounces Imbalance

.25 Round Off = .12 Error

1 oz. Balance Weight

1.12 oz. Imbalance

Is this a Problem?

slide22

On most cars,

this Slight Imbalance would not be felt, however

"My Car Vibrates at 55 MPH"

slide23

Why Does it Vibrate at

One Speed?

RESONANCE

slide24

To Understand Resonance,

you must understand an objects

Natural Frequency

Mechanical Objects have there own

Natural Frequency

slide25

1 second

Tire Imbalance

With a Frequency of 4 Hz

Imbalance

4 Revolutions = Frequency of 4 CPS/HZ

slide26

Amplitude of Force

1 second

6 Hz

Tire and Wheel Frequency increases...

with Speed

Imbalance

slide27

Suspension Natural Frequency

Range from 10 - 15 Hz/CPS

14 Hz

12 Hz

slide28

Suspension Frequency

Tire & Wheel Frequency

Sum of Tire & Wheel

Beating - & - Phasing

slide29

Vibration at One Speed

1st order harmonic

15

10

5

0 10 20 30 40 50 60

slide30

"...But I balanced the tires in

the fine mode and...

... it still vibrates at 55 MPH"

slide31

If a Tire and Wheel assembly is square,

can it be balanced to Zero?

Yes, balance only refers to force

slide32

Are Tires and Wheels

Perfectly Round?

slide33

Center Hole

-or-

Lug Circle...

can be off-center as much as .010”

slide34

95% of O.E.M wheels are Hub-centric

& *100% through 1 Ton

*(as of 1/1/00)

Mounting Error

Duplicate O.E.M. Mounting

Hub-centric

Are wheels centered by the center hole?

Are wheels centered by the lug nuts?

Lug-centric

slide35

Mounting Error

Corvette Wheel

Hub-centric

slide36

Tire High Spot

Wheel High Spot

Max assembly radial and lateral runout is .050” measured off the vehicle and .060” on the vehicle

Note: Rule of thumb for passenger cars and light trucks

Would this tire and wheel mismatch

cause a problem?

slide37

One Revolution

Radial Runout

slide38

15

10

5

0 10 20 30 40 50 60

Runout Problem

1st order harmonics

slide39

Match Mounting

Mis-Matched Matched

slide41

Lateral Runout .045” Steel Wheel*

.030” Aluminum*

Radial Runout .040” Steel Wheel*

.030” Aluminum*

Wheel Runout Lateral and Radial

* Reference GM

slide42

Radial Runout .040” Steel Wheel*

.030” Aluminum*

Wheel Runout Lateral and Radial

Measure runout at bead seat area

* Reference GM

slide43

Lateral Runout .045” Steel Wheel*

.030” Aluminum*

Wheel Runout Lateral and Radial

Measure lateral runout at inside rim lip

* Reference GM

slide44

Lateral Runout

.050” Off Vehicle*

.060” On Vehicle*

Radial Runout .050” Off Vehicle*

.060” On Vehicle*

Assembly Runout Lateral and Radial

* Reference GM

slide45

Radial Runout .050” Off Vehicle*

.060” On Vehicle*

Assembly Runout Lateral and Radial

Tape

* Reference GM

slide46

Lateral Runout

.050” Off Vehicle*

.060” On Vehicle*

Assembly Runout Lateral and Radial

* Reference GM

slide48

Dynamic Imbalance

1 oz. Imbalance

slide51

Dynamic Imbalance

Is normally not a problem

under 30MPH

slide52

Dynamic Imbalance

Under 30MPH Excessive

Lateral Runout of Tire/Wheel

can cause

Low Speed “Waddle”

slide53

Look for Bulges

Bulges indicate weak areas and indention\'s are strong areas

slide54

Sidewall Stiffness

“Radial Force Variations”

slide55

Sidewall Stiffness

“Radial Force Variations”

Manufacturers Test for Radial Force Variations at the Factory

…and it is not a common problem

slide56

Mounting Errors

.011” Can Results in 1oz. Dynamic Imbalance Error

slide57

Mounting Errors

.011” Can Results in 1oz. Dynamic Imbalance Error

slide58

Mounting Errors

Duplicate O.E.M. Mounting

Back Cone

-or-

Front Cone

Hub Centric

-or-

Lug Centric

slide59

Mounting Errors

Check Cones for Damage or Wear

2.000”

2.001”

slide60

Mounting Errors

On a 36 lb. Tire and Wheel, .006” cone wear can result in 1/2 ounce imbalance

2.000”

2.006”

Off center .006” creates more mass on one side

slide61

...and don\'t forget about

Calibration

Eliminates Weight Chasing

slide62

On Behalf of

Thank You

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