Welcome back to the My Street Car
project and Stage 2 of this build up where I will be concentrating
on the braking system upgrade. If there was ever one down fall
to our early Commodore models, it would have to be the vehicles
braking system. For years Commodore drivers were screaming out
for Bigger Brakes…!!! Yet, it
wasn't until 1998 that Holden answered the call with the release
of the all new VT model which featured an improved braking system
including a twin piston front brake caliper, improved rear brake
caliper and essentially a major overhaul as compared to previous
models. The VT Commodore was a significant step forward and finally
we had a vehicle that had stopping power and a solid foundation
for further modification.
Whether you are driving a standard domestic
vehicle or a high speed racing car, brakes are critical...!!!
When it comes to vehicle safety systems, the brake
system is at the top of the list.
I was very tempted to commence the build up
with the brake system upgrade being Stage 1 of this project, simply
as a means to strongly emphasis the extreme importance of the
braking system on modified cars. It was only my eagerness to have
a crack at the V6 engine and the fact that I knew the car would
be limited to minimal driving until I commenced the brake upgrade
that I elected to modify the engine first.
A critical element of this build up was SAFETY
SAFETY SAFETY...!!! From the beginning, it was always
my intension to improve the overall performance of My
Street Car in every aspect with strong emphasis on under
If you are modifying your engine for more power,
be sure to have a plan in place to match this power increase with
a suitable performance brake upgrade.
Most modern brake systems are more than adequate
in their performance for normal road use. However, problems start
arising when a vehicle must stop from a high speed
then do it continuously over and over again. It
is during this aggressive adverse condition that the performance
of a brake system can be truly measured.
All brake systems, being either disk or drum
use friction to stop the vehicle. Friction
is the resistance to sliding created when two surfaces are rubbed
together. With a dick brake system, there is friction between
the stationery brake pad and rotating brake disk (rotor) and with
drum brakes, the friction is between the stationary brake shoe
and rotating brake drum. Friction from the brakes creates heat.
Technically, a moving vehicle is basically now an energy source.
To slow a moving vehicle, this energy must be converted to another
form. The brake system of the motor vehicle converts the energy
from the moving vehicle to a heat energy via the friction created
from the braking system.
The heat generated from continuous brake operation
is a major concern in brake design and must be addressed with
any performance brake modification. A specific brake system and
impaticular brake friction material will have a maximum operating
temperature. Once this temperature is reached, the brake system
must have the opportunity to be cooled off to avoid dangerous
brake operation and component failure. The consequences a driver
will face with brakes that have exceeded there maximum operating
temperature range is brake fade. Brake fade
is loss of braking due to overheating. Brake fade will result
in you requiring increased brake pedal force to stop your vehicle.
If the brakes are not cooled at this point and you continue to
drive with brakes exceeding this temperature threshold, you will
eventually loose all braking power and if the brake fluid starts
to boil off you will loose your brake pedal. Brake fade usually
occurs at the worst possible time, such as braking heavily on
a descending road with a heavy load (towing) or on some vehicles
may even occur after a series of higher speed brake applications
using only moderate brake force. Driving a vehicle that is experiencing
brake fade is not a place you want to be and is a very dangerous
To further explain the results of brake fade,
I wish to share a real life experience with you. Several years
ago I was towing my ski boat down a very long hill that had several
hair pin turns that seemed to go on forever. At that time, I was
driving a VN Commodore V6 with a 5 speed manual transmission.
This particular hill was really steep and required constant braking
in a low gear just to maintain safe cornering speeds. After a
few minutes braking, I noticed excessive amounts of smoke starting
to billow out from the front wheels. Shortly after this I found
myself pushing harder and harder on the brake pedal only to find
that I was rapidly running out of braking force. Whilst I still
had a full pedal, the brakes simply no longer worked and I knew
I was in trouble as I simply could not stop...!!! I only managed
to escape from this dangerous situation by forcing the gearbox
into first gear (Thank god it was a manual) and just holding my
foot as hard as I could on the brake pedal whilst carefully applying
the handbrake. Fortunately the road did start to straighten out
and I was soon out of the danger zone. I certainly attracted plenty
of attention as the car really did look like it was on fire with
the amount of smoke these brakes were producing. This was a really
scary experience that really rammed home the importance of good
For My Street Car I feel I
have significantly enhanced the vehicles brake performance with
just a simple upgrade program. In fact the upgrade was so quick
and easy that I feel I am going to struggle to make much of a
story out of it. However, the reality is that the brakes feel
amazing and the upgrade was carried out at a very low cost.
Read on …!!!
As mentioned earlier, the VT onwards Commodore
featured a much improved braking system. Fortunately, us earlier
model Commodore drivers are blessed with the fact that these components
are interchangable onto early models with the retrofit basically
just bolt on. I was attracted to this option simply because of
the fact that these components are simple to fit, there is an
abundant supply of these brake parts in the market place, the
conversion will yield great results and the parts are very low
cost. The main advantage of this conversion is the fitment of
the twin piston front caliper. This brake caliper, its design,
appearance and just shear size makes the early single piston caliper
look sub standard by comparison. The main advantage of this brake
caliper is its capacity to fit a larger brake pad with the twin
piston feature allowing more uniform / even force being applied
to the brake pad.
A significant disadvantage of the single piston
caliper is its inability to apply uniform force across the brake
pad due to brake pad deflection under severe operating loads.
Whilst the centre section of the brake pad which is making contact
with the brake piston receives full piston pressure, the pressure
applied to the outer edges of the brake pad is greatly reduced
due to deflection of the brake pad. This situation reduces the
efficiency of the brake pad in a single piston caliper.
What a transformation...!!!
This brake set up looks amazing with all this new gear just being
a basic bolt up. The 300mm rotor is a floating type unit that
fits straight up to the wheel hub and the brake caliper bolts
directly to the existing brake caliper mounting points. The only
modification required involved the cutting and grinding of the
brake rotor dirt/dust shield. As the twin piston brake caliper
is a much larger unit, it fouls with the existing shield in its
original form. To allow fitment and prevent component fouling
the shield must be reworked. To achieve this I simply bolted the
brake caliper onto the wheel hub and then using a permanent marker
traced over the shield using the caliper as a template. Once I
had made my markings the brake caliper was removed and the dust
shield was cut back using an angle grinder with the final finish
and shaping carried out using files and a die grinder stone. This
operation was a little messy and time consuming as the modification
needs to be carried out on car as the shield is riveted onto the
wheel hub. All that is needed is a littler patience and care.
To complement this fitment, new brake hoses were also fitted.
A mandatory requirement with this brake upgrade is you must have/or
fit minium 15 inch diameter wheels to allow brake caliper running
clearance from the inside of the wheel rim.
My brake pad selection was Bendix
Heavy Duty. For some time now I have aligned myself
with Bendix products as I feel their products have provided me
with excellent quality as part of my workshop operation. Having
said this, I also believe there are several good quality brake
brands in the market place. I have always remained open minded
to the use of any products and maintain the philosophy that I
will use anything if it works well for a particular application.
The Bendix Heavy Duty brake pad is a relatively new product that
features a titanium strip that eliminates the need for brake pad
run in. (a real workshop plus when your in a hurry). I am very
impressed with the performance of this brake pad. I have recently
been fitting this brake pad to several cars that come through
the workshop, mainly targeting the more aggressive driver or customers
who are regularly towing heavy loads. So far I have had no complaints
and a real plus with this brake pad is that they work well cold.
A common problem with many performance style brake pads I have
fitted in the past relates to their poor braking performance at
cold temperatures. I believe this is a safety hazard for a road
going car and can be very dangerous for the unaware driver. There
is nothing worse than pulling out of your driveway then hitting
the brakes at the first corner only to find you have a hard pedal
with no stopping power. (This experience will kick start your
heart as you grip the steering wheel and attempt to push the brake
pedal through the firewall). The Bendix Heavy Duty brake pads
feature a maximum continous working temperature rating of 450
degrees Celsius. To conclude brake pad selection, there is no
argument that there are several good quality brake pads and options
available. Optimum brake pad selection will depend on specific
vehicle operating requirements. I feel the Bedix Heavy Duty brake
pad was suited to this application based on the intended vehicle
usage once this project is completed and also consideration was
given to value for money.
The only modification carried out to the rear
brakes included the fitment of Bendix Heavy Duty brake pads. The
brake calipers were assessed for condition with the only service
operation required being the cleaning and lubricating of the brake
caliper guide pins.
All that was left to do at this point was bleed
the brakes. As part of this operation I bleed off approximately
300-400 ml of brake fluid from each brake caliper to ensure the
brake hydraulic system was completely flushed from old brake fluid.
Do not under estimate the importance of brake
fluid. Brake fluid doesn't last for ever...!!!
More and more now vehicle manufactures are placing strong emphasis
on brake fluid changing. In fact every vehicle manufactures service
book that I know of makes clear and concise instructions for the
changing of brake fluid at intervals not exceeding 24 month's
(2 years). This fact alone confirms the importance of brake fluid
service and maintenance. The most critical property of brake fluid
is its ability to resist boiling at high temperatures. However,
the quality of brake fluid soon deteriorates due to moisture absorption.
Old brake fluid or fluid that has absorbed high moisture content
will have a considerably lower boiling point. On road, this could
result in disaster as brake fluid that has boiled creates small
gas bubbles within the brake pipes. Because these gas bubbles
are compressible, this will result in a low or spongy brake pedal.
Well, that’s it...!!! The
brake upgrade is complete. On road, the car feels great and the
brake performance strong which really does provide a greater level
of driver confidence. More importantly, My Street Car
now has the capacity to handle more punishment ensuring greater
braking power and efficiency during continuous high brake loads
and operating temperatures.
- The brake parts
for My Street Car were purchased from Hoppers
Stoppers in Melbourne. I found Hoppers Stoppers
whilst surfing the internet for brake parts and information
as part of the project research. I was very impressed with their
web site and the huge range of brake upgrades available for
many vehicles and in particular all Holden Commodore models.
This web site is truly worth a look if you are sourcing brake
information, upgrade components or complete brake kits at very
Hoppers Stoppers are at:
Address: 9 Nevada Court, Hoppers Crossing, Victoria 3029
Ph: 03 9748 6950
Stoppers do advise as part of their fitting instructions
that if a firmer brake pedal is desired then a VT 1 inch / 1
1⁄4 stepped bore master cylinder may be adapted to the
VS booster. When fitting the VT style twin piston caliper onto
earlier Commodores it is strongly recommended that a 1 inch
bore master cylinder be fitted to ensure a firm high brake pedal
is achieved. Consult Hoppers Stoppers for further information
- A personal observation
I have made during this project whilst assessing various cars
and components is a variation in the brake pipe flare where
the flexible brake caliper hose connects to the fixed steel
pipe connection on the vehicles inner guard. I have found some
steel pipes feature a double flare (Which I think is the most
common) and also other applications that feature a raised dome
type flare. The brake hoses WILL NOT interchange.
At the time of this report preparation I do not have the support
information to provide specific vehicle model to brake pipe
identification data. Just be sure to check and confirm correct
brake pipe connection relationship before fitment.
- Whilst I understand
that this brake upgrade is minor in comparison to the unlimited
brake options and components we have been blessed with in the
after market, I do feel this upgrade is credible for consideration
as it will work, provide a worthy increase in braking power
and safety and is very low cost. Considering we have the weight
saving of a V6 engine and a limited budget, this conversion
fitted the build criteria for My Street Car
perfect in every as aspect.
- My recommendation
for any persons contemplating a brake performance upgrade is
just consider your options first, do some forward planning taking
into consideration the vehicles intended usage and your desired
- Select a brake system that will provide
the greatest coefficient of friction for the intended application.
Bigger brakes and greater the braking surface area is usually
- With brake pad selection, my recommendation
is just give some thought to the intended vehicle usage and
select a brake pad type based on that information. The brake
pads and associated hard ware must have the capacity to quickly
absorb and dissipate heat energy with the friction material
(brake pad) remaining stable at expected operating temperatures.
Modifications to increase brake cooling capacity for racing
or severe operating conditions should also be considered. Eg
vented, cross drilled and slotted rotors, ducting to increase
air flow cooling capacity etc
- Use good quality and appropriate grade /
specification brake fluid. Ensure brake master cylinder caps
and seals are in good condition for the prevention of moisture
absorption and foreign particle contamination. Due to brake
fluids rapid moisture absorption characteristics it is strongly
recommended that only new brake fluid from an unopened container
be used. (The half used brake fluid bottle that has been sitting
on the garage shelf for 12months........ Get rid off it...!!!)