Technical product information
Topic
Market
area
Brand

All New Continental GT and All New Continental GTC steering shimmy/vibration ROW
Hongkong-Macau (5HK),Russische Föderation (5RU),Australia E04 Bentley rest Asia and Australia (6E04),China 796 VW Import
Comp. Ltd (Vico), Beijing (6796),Germany E02 Bentley rest Europe (6E02),Japan E03 Bentley Japan (6E03),Russian Federation
935 Volkswagen Group RUS (6935),United Kingdom E01 Bentley UK (6E01),United States E05 Bentley USA and rest America
(6E05)
Bentley

Transaction
2045080/1
No.
Level
EH
Status
Approval
Release
date
New customer code
Object of complaint
Complaint type
Position
Running gear -> Wheels, tyres, tyre pressure monitoring -> Tyres -> Tyre tread visual appeal / surface -> bump
> not specified <
Running gear -> Steering, power-assisted steering -> Steer
Noise, vibration -> vibrate
Running gear -> Steering system
functionality
Running gear -> Steering system
Noise, vibration
Running gear -> Wheels, tyres, tyre pressure monitoring -> Tyres
component / consumables -> incorrectly built
Running gear -> Wheels, tyres, tyre pressure monitoring
Noise, vibration
New workshop code
Object of complaint
Running gear -> Wheels,
Running gear -> Wheels,
Running gear -> Wheels,
Running gear -> Wheels,
Running gear -> Wheels,

tyres,
tyres,
tyres,
tyres,
tyres,

tyre
tyre
tyre
tyre
tyre

pressure
pressure
pressure
pressure
pressure

monitoring
monitoring
monitoring
monitoring
monitoring

-> Tyres
-> Tyres
-> Tyres
-> Tyres
-> Tyres

Complaint type
component / consumables
component / consumables
component / consumables
component / consumables
component / consumables

Vehicle data
All New Continental GT and All New Continental GTC
Sales types
Type
39*
39*
39*
39*
39*

MY
2012
2013
2014
2015
2016

Brand Designation Engine code Gearbox code Final drive code
E
*
*
*
E
*
*
*
E
*
*
*
E
*
*
*
E
*
*
*

Chasssis numbers
Manufacturer
SCB
SCB
SCB
SCB
SCB
SCB

Filler
*
*
*
*
*
*

Type
ZA
3W
ZA
ZA
3W
3W

Documents
Document name
master.xml

Filler
*
*
*
*
*
*

MY
*
E
E
F
F
*

Factory
C
C
C
C
C
C

From
069713
040000
040000
040000
040000
069713

To
Prod from Prod to
999999
999999
999999
999999
999999
999999

-> unbalanced
-> unbalanced
-> unbalanced
-> unbalanced
-> incorrectly built

Position
rear right
front right
front left
rear left
> not specified <

Technical product information

Transaction No.: 2045080/1

All New Continental GT and All New Continental GTC steering shimmy/vibration ROW

Customer statement / workshop findings
This TPI is applicable to all New Continental GT and all New Continental GTC vehicles fitted with 21 Inch wheels, should 20 inch
Bentley approved wheels be fitted please raise a DISS ticket and await further instruction from TSC before commencing with any
other work.
Before carrying out any work please check that this TPI is the latest available document by searching in Elsa Pro, you must ensure that the applicable
VIN number is used when searching for any technical information.
Should a customer complain of steering wheel shimmy/vibration constantly and the condition does not improve when driven please proceed with this
TPI. Steering shimmy/vibration is most evident at 90 km/h
Before commencing with this TPI - Refer to the applicable vehicles repair history in Elsa Pro to check that the latest level parts have not already been
fitted or may not be required, please also see VIN cut off information in the Production change section of this TPI.

Technical background
Due to environmental conditions involving large changes of ambient temperature, condition can occur after a very short stationary period where flat
spots are created as the warm tyres cool down. The tread surface of the tyre forming the footprint on the road surface retains the relatively flat form
when driven and does not immediately restore to a constant radius. Hence the name of flat spotting which is generally given to this condition.
Flat spotting should not be confused with out of balance, out of round or radial force variation. It is very important that the diagnosis and correction
of these different conditions are not confused with each other. Attempting to correct flat spotting by rebalancing the assembly will not correct the
problem and worse still, when the flat spots are removed the tyres will be out of balance.
EXPLANATIONS AND DEFINITIONS
Radial force variation (RFV)
The radial force is the force with which a tyre is compressed.
Tyres have softer and stiffer areas along their circumference. In Figure 1, the softer and stiffer areas are illustrated by different size springs.
If this wheel rolls on a level road with constant wheel load (Figure 1, point 1), the centre of the wheel rises and falls by the amount (x) because of the varying
spring hardness. The change by the amount (x) can be felt in the vehicle as vibration or shaking of the steering wheel.
The change of the compression force of the tyre is the radial force variation.

Figure 1
Harmonic vibrations
The wheel force variations during the turn of the wheel can be mathematically divided into individual harmonic vibrations.
For an objective of tyre stiffness, the first harmonic (basic vibration) is used
The basic vibration or first harmonic is the share of the RFV that causes the strongest vibrations
The first harmonic (RFV) must be 85N or less
NOTE: it is imperative that the first harmonic result is used (Figure 2) please ensure your vibration balancer always shows the first harmonic result, Do
not use the Total Indicated Reading (TIR) only the first harmonic result should be used - Refer to the vibration control balancer handbook for further
details.

Figure 2

During this TPI the Workshop manual is quoted to help in carrying out various tasks, it is recommended that the procedures referenced are checked
by the operative as the process within the Workshop manual may have changed since last viewed.

Production change
IMPORTANT NOTE PLEASE READ
•

All W12 vehicles post VIN SCBFH63W6CC074020 - Check the servotronic control unit fitted is as per the ETKA parts catalogue ensuring the
applicable VIN is always used when searching, in the event the unit is not as per ETKA please replace the unit with the VIN applicable part

•

All V8 engine vehicles regardless of VIN: Please check the servotronic control unit fitted is as per the ETKA parts catalogue ensuring the applicable
VIN is always used when searching for the unit, in the event the unit is not as per ETKA please replace the unit with the applicable part

Measure
1. Check all wheels and tyres for damage/distortion. NEVER fit tyres to rims which are damaged/kerbed or distorted, tyres can be damaged/cut
during the fitment process if the rims are damaged/kerbed on the outer edge of the rim
- Check the tyres are of correct Bentley approved specification including date code otherwise this TPI does not apply
- Check that Bentley 21 inch approved wheels are fitted
- Check the front and rear suspension for any damage and wear - Refer to Workshop manual
- Check all steering components for any damage and wear - Refer to Workshop manual
- Check all wheels for distortion/buckles whilst the car is on the ramp
2. In ambient workshop temperature, ensure the engine and tyres have cooled down to ambient temperature and adjust the tyre pressure as
detailed
- Locate the tyre pressure label on the B-post (The label shown is fitted to a New Continental GTC and is for photographic purposes only)
- The tyre pressures should be the adjusted as per the tyre pressure label for speeds upto 200 km/h

The next part of this process requires the vehicle to be road tested to allow the tyres to warm up sufficiently, on return the vehicle
must be raised from the ground within two minutes, please ensure you have a wheel free ramp available on return from road test
Should the vehicle not be raised within a maximum of two minutes after returning from road test the tyres will begin to flat spot
resulting in the need to repeat the road test procedure
3.
ROAD TEST - Conduct an initial road test, the vehicle should be driven until the flat spots come out or the flat spotting condition improves,
drive the vehicle for a minimum of 30 Km at 120 km/h (where permitted) to allow the tyres to warm up to running temperature and allow the flat
spots to run out, the most sensitive speed for shimmy/vibration is 90 km/h during the road test you should also drive at this speed to validate
steering shimmy/vibration to allow the driver to make an accurate assessment.
IMPORTANT W ithin a max imum of two minutes after returning from the road test, raise the v ehicle off the ground
4. Allow the wheel assemblies to cool for 20 minutes before removal
- After 20 minutes has elapsed remove all four wheels
- The wheels should be left to cool down positioned lying flat as shown in Figure 3 ensure the rim of the wheel is protected to prevent damage when
lying on the floor WARNING Do not allow the wheels to cool down standing upright as shown in Figure 4

Figure 3

Figure 4

- Using a digital infrared thermometer check the temperature of the tyres
- The RFV process should only be conducted once the tyres are within 10% of ambient workshop temperature this is to allow and confirm the tyres
are at the correct temperature

For Example – If the Workshop temperature is 25°C the tyres should be 27.5°C before commencing with the RFV process otherwise do not
commence until the tyres have cooled to correct temperature

5. The next part of this process requires the use of the Hunter GSP9712 (VAS 6230) vibration control balancer (or similar) - Please Refer to Workshop
Manual Rep.Gr 44 Tyres - Checking Condition and Replacement - Radial force variation - Best fit practice to familiarise with the process
Key information is also detailed as follows
•

Please ensure your vibration control balancer is calibrated and is in full working order.

Self calibration (excluding service contract calibration is highly recommended every 3 days to ensure correct and accurate measurements) – please
refer to manufacturer’s instructions relating to self calibration
Please refer to the instruction manual of your particular vibration control balancer for all relevant information

•