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Old 29-04-18, 00:35   #1
Drugsy's Avatar
Join Date: 08-03-08
Location: SA, Riverland
Car: VL 1987
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Upgrade Front brakes to 32mm X 320mm discs

A quick guide on how to upgrade from standard 22mm x 271mm discs and single piston calipers to larger 32mm x 320mm discs with twin piston calipers.
I recommend only doing this upgrade if you have already upgraded the brake master and booster.
I used parts from a 2006 Pontiac GTO (same as SSZ/VZ Monaro/06 SS) but the process is similar (easier) for the popular VT upgrade.
These are not the biggest or best brakes in the world but they work much better than the standard setup and they use standard off the shelf disks and pads unlike some of the eBay kits.
Brakes are an important part of any car so if you're not sure what your doing or donít understand, please ask someone in the know or take your car to a mechanic.
Iím also NOT a mechanic so please correct me if you think any of the following information is wrong or misleading.

Parts required

Pads 7599 / FDSE1553
Discs 42020S
Calipers C6 92175207 / 92175206
Shims/sleeves (only required for C6 calipers)
Hub adapters
Wheel bearings/seals
Brake fluid

Step 1.
Jack up car and support with stands.
Remove wheels then unbolt the calipers. Leave the old calipers attached to the brake lines for now so brake fluid doesnít leak out everywhere. Just hang em off the front spring with some wire.

Step 2.
Remove the Hub/Disk and old bearings/seal.

Step 3.
Dismantle and clean up the new calipers and paint if required, use a rebuild kit if pistons or seals are rusted/broken.

Step 4.
The C6 callipers I used had 14mm bolt holes so I made some shims to adapt to 12mm bolts. You can buy specific sleeves but I made some using dynabolts I had. DON'T use copper pipe as it will squash under pressure causing the brake mounts to be loose.

Step 5.
I also had to grind a small bit off one side of the caliper mount so it would bolt up flush to the strut knuckle.

Step 6.
Clean the stub axle and install the new dust seal, then grease up the wheel bearings and install on the axle along with the hub adapter.
Put the new disk on with a couple of wheel nuts.

Step 7.
Bolt the caliper bracket to the knuckle with some locktite and install pads, then attach the caliper checking everthing lines up ok. Test fit the wheel to make sure it clears everything.

Step 8.
Take the wheel back off and install new flexible brake lines. The old nuts can be really tough to loosen, donít even bother with a normal open ended spanner as it will more than likely just round the edges off the nut. Try a 10mm flare nut spanner first then maybe multi grips or other tools that clamp the nut.

Step 9.
Bleed the brake lines then chuck the wheels back on and lower the car.
Carefully drive the car making sure you have brake pressure before bedding in the new brakes.
These brakes easily fit under my 17inch rims and might fit some 16s but I can't be certain.

Here is some info I came across while I was researching brakes.

Common brake sizes
Sliding Calipers , Discs , Pads , Piston diameter
VL Standard , 22mm x 271mm , 136 x 61 x 14 mm , 53.9mm x 1
VL Turbo/v8 , 22mm x 290mm , 136 x 61 x 14 mm , 53.9mm x 1
VT Standard , 28mm x 296mm , 184 x 63 x 15 mm , 42.0mm x 2
VE Standard , 30mm x 298mm , 153 x 53 x 17 mm , 41.9mm x 2
C4 VN SV5000 , 28mm x 327mm , 171 x 52 x 16 mm , 38.1mm x 2
C5 HSV VT-VZ , 32mm x 330mm , 184 x 63 x 14 mm , 40.4mm x 2
C6 GTO/Monaro , 32mm x 320mm , 184 x 63 x 14 mm , 40.4mm x 2
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Old 29-04-18, 13:19   #2
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Nice writeup and good info.
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Old 30-04-18, 07:46   #3
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Join Date: 20-07-14
Location: WA, SoR
Car: -86 VL Turbo
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Nice one!
Have the same brake kit sitting in a box in the garage waiting to go on, need to do booster and master first, and get some new lines made up for the calipers.
Keen to get it happening soon though.
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Old 01-05-18, 19:59   #4
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Is it easier to lock up the brakes with bigger brakes when you slam them on? I recently locked my stock turbo brakes (was cut off by a truck) and was completely surprised how easy it did it
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Old 05-05-18, 11:18   #5
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Join Date: 08-03-08
Location: SA, Riverland
Car: VL 1987
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Originally Posted by battery View Post
Is it easier to lock up the brakes with bigger brakes when you slam them on? I recently locked my stock turbo brakes (was cut off by a truck) and was completely surprised how easy it did it
Its not so much how easy it is to lock up the wheels but how easy it is to control the pedal to the point of not locking.
Thicker and larger diameter discs and bigger pads also absorb and dissipate more heat which reduces brake fade in repeated heavy braking situations.

See here for more information
Brake pressure vs deceleration

The graph below explains the science behind threshold braking in a little more depth. The process of locking a wheel does not occur all in one go, and varying amounts of wheel slip can occur until the wheel rotation stops (100% wheel slip). Maximum braking performance occurs at about 20% wheel slip, but as you can see from the graph this only drops about 30% when the wheels are fully locked. So the main points are that the best braking performance in any vehicle occurs before the point of wheel lock, however locked wheel braking is a lot better than nothing.

Tyre slip versus braking efficiency

So, unless youíre a professional racing driver, the best strategy to adopt is to best to brake hard, and if you find some wheels are locking, slightly releasing the brakes and then reapplying with a bit less pressure. As you learn how your car behaves in these conditions youíll get better at judging the pressure needed for maximum deceleration.
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Old 14-05-18, 07:56   #6
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Great article man! Keep em coming
R.I.P Mum 16/08/1958 - 10/07/2006
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