SFCC_DEC2021_50

BRAKES QUALITY REVIEW – 21MY UPDATE
Brakes Engineering
9th December 2021
Confidential ©2018
PTA 21MY 18'' brakes
Executive summary
Purpose
e off the
e review
w:
• Update on E-PACE, Discovery Sport and RR Evoque Brakes Refinement Performance : 21MY introduction
adversely affecting low TIS metrics.
• Review iQM Project status (Root cause, Escape point, ICA/PCA, next steps).
Expected
d outcomess :
•
Share technical direction and next steps on timeline to recover Brake Refinement as soon as possible.
Executive
e Summary:
•
•
•
Status – Brakes Refinement performance has deteriorated at 21MY for low TIS. Issues are split into two
categories:
1) Noise when braking from moderate speed (grinding – iQM P342439).
2) Noise at end of abrupt stop (graunch – iQM P343739).
• These Refinement issues do not affect the brake system primary function.
• Technical actions are in place and suppliers are involved to implement ICA and PCA asap.
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Brakes Content
21MY – E-PACE, Discovery Sport, RR Evoque
21MY
Y wass a majorr change
e pointt forr Brakess Systems,, supporting
g US
S Legislation,, vehicle
e efficiency
y and
d ADAS
S features;
• Roll-out of decoupled brakes – Integrated Power Brake (IPB)
• Improved pedal feel, Actuation NVH, decoupled system supporting ADAS implementation.
• Introduction of Lightweight disc on E-PACE (previously implemented with New Front End on Discovery
Sport and RR Evoque)
• Reduced un-sprung mass, improved ride quality.
• Low-Cu compliant front pad material
• Compliant with Jan-2021 US legislative requirement on Copper content.
• Zero-Cu compliant rear pad material
• Compliant with Jan-2025 US legislative requirement.
• New CBI/Hitachi 18” front caliper with positive pad retraction, high roll-back seals on rear calipers
• Caliper technology for low drag – improved efficiency, lower emissions, reduced pad wear.
g resultss in
n extended
d bedding-in
n period
d forr friction
n components.
• Howeverr – lowerr drag
• Auto-hold function
• This is getting very positive customer feedback (eg JD Powers).
• Friction
n couple
e related
d issuess are
e the
e outstanding
g challenges..
• Despite
e these
e modell Open
n Projects,, JLR
R overalll remainss in
n a Leadership
p position
n forr Brake
e NVH
H (2021
1 JD
D Powerss IQS
S data).
nd
• Brakess NVH
H – Noisy/Vibrate/Shudderr classed
d 2 bestt attribute
e on
n 21MY
Y Defenderr v Midsize
e Premium
m SUV.
52
34 SYSTEM BOARD REVIEW: CES_700 - BRAKES
TIMELINE
Prediction (R/1000)
Warranty Data (R/1000)
SSM
75449
21MY MP1
Zinc dust deleted
(H/W & Graz)
Zinc dust deleted
(Itatiaia)
Opposed
pad grinding
Disc roughness
(study)
Roott Cause;; Contamination of
brake pad material with zinc
dust (transit protection) on disc
rotor friction surface impacting
time for system bedding.
PCA;; Deletion of Zinc dust on
rotor rubbing path (implemented
28-Jun Halewood/Graz, 28-Aug
Itatiaia). Significant reduction in
cases following implementation.
24MY MP1
Zero Cu
GA9112 L3
21MY MP1
Opposed
pad grinding
Low Met pads
(available in
Service)
Disc roughness
(study)
Roott Cause;; Excitation due to
pad material/disc stick-slip
mechanism, as vehicle
transitions from dynamic to rest.
PCA;; Zero Cu pad material for
implementation 24MY (Sep-23).
24MY MP1
Zero Cu
GA9112 L3
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ABENTLEY COLOUR SUMMARY – REVISED GRAUNCH ASSESSMENT
• During ‘Characterisation’ section, half of stops are done at 0.25g gauge and half done at 0.5g gauge.
•captures more data in event space of graunch issue (aggressive end of stop).
• ‘Whole Vehicle Assessment’ (WVA) done across a wider deceleration range to ensure more aggressive stops are captured.
-
-
Vehicle test method developed
to characterise Graunch along
with Creep/Groan (Release)
Vehicle testing of multiple
graunch palliatives has been
conducted;
Pad materials
Grease and shim changes
Caliper modification
Optimum pad material for
graunch is zero copper
GA9112-L3, target introduction
at 24MY.
Testing has highlighted that
disc corrosion is an influencing
factor (eg - low vehicle usage
during Covid restrictions).
•
•
•
•
•
54
34 SYSTEM BOARD REVIEW: CES_700 - BRAKES
VEHICLE TESTING – GRAUNCH SUMMARY
Creep/
groan
Creep/
groan
Graunch
Graunch
Current production pad material (GA9510) performs
well for release noise (creep/groan) but exhibits end
of stop graunch.
Performance pad (AMS2) material demonstrates
improved end of stop graunch, at the expense of
increased potential for release noise. Proposed as a
Service Fix for critical customers (fix on fail).
Creep/
groan
Graunch
Optimum material for graunch is zero copper
GA9112-L3, target introduction at 24MY.
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34 SYSTEM BOARD REVIEW: CES_700 - BRAKES
PTA 21MY 18” FRONT CALIPER
Positive retraction springs pull pads clear of disc when off-brake;
Reduces mean drag from 5.25Nm (19MY) to 2.5Nm.
This have a positive effect on fuel consumption and C02 emission but impacting bedding time
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34 SYSTEM BOARD REVIEW: CES_700 - BRAKES
PTA 21MY 18” FRONT PAD FINISH GRINDING
Current pad is finish-machined with tool path that
is concentric to the machined finish on the brake
disc
Proposal from pad supplier to invert the machining
path, to accelerate friction material bedding –
successfully trialled, release in progress,
introduction Feb-2022.
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