Balancing/Optimizing Wheels

In Certain Cases, It May Be Necessary To Measure Radial Force Variations. This Should Be Done Before Normal Balancing Is Performed.

The Entire Process Is Broken Down Into Several Operations:

1. Fitting The Tyre On The Rim.
2. 1. Measuring Radial Force Variations And Optimizing The Wheels If Necessary. Then Balancing The Wheels.
   2. As An Alternative To Item 2 A, If There Is No Device Available To Measure Radial Force Variations: Stationary Balancing Of The Wheel (Eliminating Static And Dynamic Imbalance) With Rolling Smoothness Optimization.
3. Fitting The Wheel On The Vehicle.

Further To 1: Fitting The Tyre On The Rim 

• Remove Rubber Residues And Dried-On Tyre Paste From The Rim, Especially From The Rim Bead And The Hump.
• Check Rim For Damage; Remove Old Balancing Weights.
• Use The Prescribed Tyre Mounting Paste (Only Tip Top Universal, Order No. 593 0601, 3.5 Kg Bucket, Or Contifix) So That The Tyre Does Not Turn On The Rim The First Time The Car Is Driven, Thereby Counteracting All Your Careful Work. If The Tyre Turns By As Little As 20 Mm With Respect To The Rim, This Can Worsen An Optimum Balancing Result.
• Fit Tyre On The Rim. When Doing So, It Is A Good Idea - And Even Necessary In Some Cases - To Fit The Tyre In A Favorable Position With Respect To The Wheel (Matching). Perform Uncontrolled And/Or Controlled Matching.

→ Use A Tyre Filling Cage.

Fig 1: Identifying Tyre Filling Cage

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

• Fill Tires To A Max. Pressure Of 4.0 Bar. By The Time The Pressure Reaches 4.0 Bar, At The Latest, The Tyre Beads Must Pop Out Of The Deep Bed And Over The Hump Of The Rim Bead In Order To Avoid Fractures Of The Bead Core. If Necessary, Interrupt The Process And Generously Coat All Necessary Surfaces With Sliding Compound (Tyre Mounting Paste). Then Repeat The Process.
• Uncontrolled Matching: Turn The Tyre On The Rim By 90° Or 180° If Necessary In Order To Achieve An Acceptable Value With Regard To Rolling Smoothness (True Running, Imbalance And Distribution Of Balance Weights).
• Controlled Matching: Using A Balancing Machine With Matching Program. In Most Cases, This Produces An Even Better Result With Regard To The Rolling Smoothness (True Running, Imbalance And Distribution Of The Balance Weights) Than Can Be Achieved With Uncontrolled Matching.
• Check The Fit Of The Tyre On The Rim Using The Bead Centering Line.
• Set The Prescribed Tyre Pressure.

Further To 2A: Measuring Radial Force Variations 

• Tension Wheel On Balancing Machine With Radial Force Variation Measurement (Vibration Monitoring System).
• Read The Operating Instructions For The Balancing Machine (Adjust The Machine From Time To Time).
• The Contact Surface Of The Wheel On The Balancing Flange (Flat Surface) And The Centering Surface Must Be Clean.
• The Display Disabling Function Must Be Switched Off.
• Adjust Tyre Pressure To 2.6 Bar (Best Test Pressure) When Balancing And Measuring Radial Force Variations.
• Particular Attention Must Be Paid To The Wheel Mounting When Measuring Radial Force Variations And When Balancing. Using The Special Pressure Pieces Provided By The Manufacturer Of The Balancing Machine Will Ensure That Wheels Are Balanced Accurately With The Highest Possible Repeat Accuracy. Read The Operating Instructions.

Maximum Deviations Permitted In Radial Force Variation Results:

If These Values Are Exceeded, The Tyre Must Be Matched On The Rim.

If These Values Are Not Reached, The Wheel Must Be Balanced.

Information 

A New Tyre Must Be Fitted If The Radial Force Variation Cannot Be Reduced To The Values Listed In The Table.

Further To 2B: Stationary Balancing With Rolling Smoothness Optimization 

• Clamp Wheel On Stationary Balancing Machine.
• Follow The Operating Instructions For The Balancing Machine; Adjust The Machine From Time To Time, If Necessary.
• The Contact Surface Of The Wheel On The Balancing Flange (Flat Surface) And The Centering Surface Must Be Clean.
• Centre (Clamp) The Wheel From The Inside Using Centering Clamping Device . This Centering Clamping Device Fits All Wheel-Balancing Machines Approved By Porsche.
• Set Required Tyre Pressure (Tyre-Pressure Plate).
• Centre (Clamp) The Wheel From The Inside Using Centering Clamping Device . This Centering Clamping Device Fits All Wheel-Balancing Machines Approved By Porsche.

Check Radial And Lateral Runout During The First Measuring Run. Values Of Less Than 1.0 Mm Are Desirable - Around 0.5 Mm Would Be Better.

Consider The Size Of The Measured Balance Weights And Their Distribution On The Inner And Outer Planes (Inner And Outer Rim Flanges) Critically.

A Uniform Distribution With Low Values (E.G. 35G/40G) Means That The Tyre Was Fitted Correctly And The Quality Of The Tyre And Rim Is Good.

A Value Of 110 G/110 G (120 G/120 G With Tyre Pressure Monitoring) Should Not Be Exceeded With Interior Balancing Behind The Wheel Centre. A Considerably Different Distribution, E.G. 40G/90G Is Not Good; This Usually Indicates Incorrect Fitting. Problem Wheels Of This Kind Often Have Pronounced Radial And Lateral Runout Values.

This Can Be Remedied By Matching (Use Correct Mounting Paste). This Can Be Improved With Uncontrolled Matching (Manual); Significant Improvement Is Possible In Almost All Cases Using The Rolling Smoothness Optimization Program (Controlled Matching).

Tyre Pressure During Balancing At Required Pressure.

Permissible Residual Imbalance Of Less Than 3G, Or Max. 3G Per Plane.

Further To 3: Fitting The Wheel On The Vehicle 

Information 

• Never Use An Impact Bolter  .
• Observe The Description On Wheel Removal And Installation (Fitting Wheel On Vehicle) →  440519 Removing And Installing Wheel   .
• Fit The Wheels With The Lowest Residual Imbalance Values On The Front Axle. Observe The Rolling Direction Of The Wheels  .

• Fit Wheel Using A Suitable Commercially Available Tool.
• Fit Wheel Bolts And Tighten Uniformly. Start At The Top When Tightening. Always Observe The Specified Tightening Torque Of 160 Nm (118 Ftlb.)
• Set Required Tyre Pressure (Tyre-Pressure Plate).