W Stobart
Member
- Joined
- Dec 31, 2022
- Messages
- 38
- Reaction score
- 12
- Points
- 8
- Age
- 71
- Location
- Dawesville
- Members Ride
- VZ SS LS7 Ute
So I have received the engineering report confirming my diagnoses as to why my VZ Ute had a massive brake / suspension failure. Nothing to do with my hearing, or tyres, or excessive modifications, or the rest of the idiotic comments by members of this forum which should be called 'Just Commodes'. Here is the report:
PH: 9414 9555 Email: [email protected]
Condition Assessment Report
Date of Assessment: 19-02-2024
Clients Details
Name: William Stobart
Phone: -
Address: -
Background:
William Stobart requested that we examine his failed brake calliper and determine the
most probable cause of failure.
Method of Assessment:
The failed calliper and wheel have been visually examined.
Results of Assessment:
The results are presented below with the photo of the component with a description of
what is being viewed.
Picture 1 shows the effect of the failure, it is apparent that the rear bolt on the callipers
is missing, and the thread is still serviceable indicating that this bolt was at least mostly
removed before the failure event. The front bolt has however been snapped flush with
the surface of the mount indicating it has failed due to excessive shear force. The failed
bolt can still be rotated with fingers without assistance indicating no thread locker has
been used. This picture also shows the upright section of the wheel hub broken off, this
is a clean fracture and is consistent with being overloaded when the wheel and calliper
have made contact. Not shown here is the lower control arm which has been twisted
which is consistent with a failure of the upright and unlikely to be causal.
Picture 2 shows the underside of the calliper. In this photo a crack is visible in the front
of the opening consistent with it being driven forward forcefully into the disc. Bubbled
paint is also visible consistent with the calliper reaching high temperatures.
Picture 3 shows the top of the failed calliper. This photo again shows paint that has
bubbled indicating high temperatures, it also shows heavy wear marks on the back of
the calliper consistent with the rear of the calliper lifting and making contact with the
alloy rim. There is some aluminium transferred to the front portion of the calliper this
area is however built up rather than worn down indicating that it came into contact with
molten aluminium but not the solid wheel.
Picture 4 shows the inside of the damaged wheel. Again it is evident that the calliper
has made significant contact with the rim removing and simultaneously adding material
to the rims surface consistent with a high energy/high speed contact.
Vehicle Make Holden
Model Commodore
Date of manufacture -
Chassis / VIN -
PH: 9414 9555 Email: [email protected]
Picture 1 - Failed Brake Assembly
Picture 2 - Failed Calliper Bottom View
PH: 9414 9555 Email: [email protected]
Picture 3 - Failed Calliper Top View
Picture 4 – Damaged Rim
Interpretation of Result:
The examination of the failed components indicates that the rear bolt on the calliper has
come lose, likely because it wasn’t torqued correctly and has allowed the rear of the
calliper to lift up slightly under braking. The calliper has then made contact with the rim
which has a self exciting action where the friction applies a tangential force which has a
PH: 9414 9555 Email: [email protected]
radial component that further forces the calliper into the wheel which increases the
friction increasing the tangential for etc. This dramatically increases the force applied to
the calliper which then appears to have overloaded the front hub assembly allowing it to
come free and rotate forward twisting the lower control arm. As the process is self-
exciting it is likely to have happened very quickly and given very little warning.
Conclusion:
The failure is consistent with bolts not being properly torqued on the calliper. While
other explanations may be possible this is quiet a well-known failure mechanism and is
consistent with all of the evidence. It is highly likely that failure occurred due to
improperly torqued bolts.
.
Signed & Dated _______________________ ___/___/______
Jack Packard
Packard Automotive
BEng(Mech)
PH: 9414 9555 Email: [email protected]
Condition Assessment Report
Date of Assessment: 19-02-2024
Clients Details
Name: William Stobart
Phone: -
Address: -
Background:
William Stobart requested that we examine his failed brake calliper and determine the
most probable cause of failure.
Method of Assessment:
The failed calliper and wheel have been visually examined.
Results of Assessment:
The results are presented below with the photo of the component with a description of
what is being viewed.
Picture 1 shows the effect of the failure, it is apparent that the rear bolt on the callipers
is missing, and the thread is still serviceable indicating that this bolt was at least mostly
removed before the failure event. The front bolt has however been snapped flush with
the surface of the mount indicating it has failed due to excessive shear force. The failed
bolt can still be rotated with fingers without assistance indicating no thread locker has
been used. This picture also shows the upright section of the wheel hub broken off, this
is a clean fracture and is consistent with being overloaded when the wheel and calliper
have made contact. Not shown here is the lower control arm which has been twisted
which is consistent with a failure of the upright and unlikely to be causal.
Picture 2 shows the underside of the calliper. In this photo a crack is visible in the front
of the opening consistent with it being driven forward forcefully into the disc. Bubbled
paint is also visible consistent with the calliper reaching high temperatures.
Picture 3 shows the top of the failed calliper. This photo again shows paint that has
bubbled indicating high temperatures, it also shows heavy wear marks on the back of
the calliper consistent with the rear of the calliper lifting and making contact with the
alloy rim. There is some aluminium transferred to the front portion of the calliper this
area is however built up rather than worn down indicating that it came into contact with
molten aluminium but not the solid wheel.
Picture 4 shows the inside of the damaged wheel. Again it is evident that the calliper
has made significant contact with the rim removing and simultaneously adding material
to the rims surface consistent with a high energy/high speed contact.
Vehicle Make Holden
Model Commodore
Date of manufacture -
Chassis / VIN -
PH: 9414 9555 Email: [email protected]
Picture 1 - Failed Brake Assembly
Picture 2 - Failed Calliper Bottom View
PH: 9414 9555 Email: [email protected]
Picture 3 - Failed Calliper Top View
Picture 4 – Damaged Rim
Interpretation of Result:
The examination of the failed components indicates that the rear bolt on the calliper has
come lose, likely because it wasn’t torqued correctly and has allowed the rear of the
calliper to lift up slightly under braking. The calliper has then made contact with the rim
which has a self exciting action where the friction applies a tangential force which has a
PH: 9414 9555 Email: [email protected]
radial component that further forces the calliper into the wheel which increases the
friction increasing the tangential for etc. This dramatically increases the force applied to
the calliper which then appears to have overloaded the front hub assembly allowing it to
come free and rotate forward twisting the lower control arm. As the process is self-
exciting it is likely to have happened very quickly and given very little warning.
Conclusion:
The failure is consistent with bolts not being properly torqued on the calliper. While
other explanations may be possible this is quiet a well-known failure mechanism and is
consistent with all of the evidence. It is highly likely that failure occurred due to
improperly torqued bolts.
.
Signed & Dated _______________________ ___/___/______
Jack Packard
Packard Automotive
BEng(Mech)
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