Brake upgrade

[axistr]

For some time I have been contemplating upgrading the brakes on the Torana. A few months ago I pulled the finger out and started working on a plan. The brakes are basically the same as on the Sandmans so it might come in handy for any forum members thinking the same.

I completed the conversion a few months ago but the site went down and didn't get around to posting it here. The Torana was still running 14" wheels 8" front and 10" rear. Unfortunately any larger than the HQ style rotors I had required larger diameter rims. Hopers stoppers kits required 15" rims as a minimum for their 287mm disc rotor kit. And of course the kit does come with a price tag of around $1,500.00 As usual I get a bigger buzz from doing it all myself.

I have a Torana K-frame in the shed so it was the perfect platform to do all my measurements. I was going to turn up some front hubs but found a pair of blank hubs on the net for $70.00 each, so wasn't worth while making them myself. I started by putting the hubs on the k-frame and take measurements for a suitable disc rotor.

Looking through my DBA brakes book I found that a BA XR8 falcon 300mm rotor suited the offset I was after. It was heaps cheaper to by a Falcon rotor than buying a blank, so just redrilled the rotor to suit the 5x108 PCD Torana stud pattern. Easy job to do on my mill. At the same time I drilled the blank front hubs and fitted the longer VT wheel studs.

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I will post up more of the conversion once I find the photos I saved somewhere, bugger I don't know where the bloody photos go sometimes. computers have a mind of their own.

[damienengland]

Hey axistr. Do you mean that you can get the bigger brakes and keep the 14 inch rims on?

[Innuendo]

I'm interested in what you come up with.
I have BA 298mm XR8 rotors using AUII calipers on custom hubs for my HQ Sandman. But I'm running 15" wheels.
Nothing installed as yet as I'm been doing 6 pot Brembos on my VY Van.

[axistr]

Hey axistr. Do you mean that you can get the bigger brakes and keep the 14 inch rims on?

No Damo, the 14" Dragways I had on the hatch had steel outer rim bands/alloy centres. Although they are reasonably large for 14" on the I.D I missed out by 3mm with 287mm rotors so I decided to go for a new set of FR17" Simmons. With 17" rims I didn't have any brake size constraints. The DBA rotors I fitted were listed as 298mm and measure 299.5mm. I rounded up to 300mm. I don't know why they measured 299.5 but that's what turned up and at $45.00 each I didn't bother to ask the question. I have set the calipers out so the pads are 1mm from the O.D of the disc rotor. On an XR8 the calipers sit 3mm less from the rotor O.D so I have picked up an extra 3mm of leverage out of the brakes, its not a lot but if I am going to the trouble then I might as well do it at is most efficient.

Innuendo here is my take on brakes, there is no need for me to go any bigger than 299mm I have. The hatch is a bit heavy due to all the mod cons I have added, its just on 1,400 kg. I was never happy with the brakes I had on it and going to 17" rims made the brakes even less efficient due to more leverage from 17" rims on the HQ style brakes I had. Putting any bigger than 300mm rotors on a Torana/Sandman and you will only achieve an over brake and unbalanced front to rear. Big brake kits bigger than 300mm are just bragging rights down at the local pub or car show. Yes 20" rims benefit from larger rotors but Company's selling bigger than you need brakes for early cars just use numbers as a selling point and can be more dangerous, its also added unsprung weight when going bigger than you need, so just can't see any benefit.

If you have ABS brakes then the benefit of larger performance brakes is less peddle pressure needed, the ABS cuts in in an over brake situation. There are a lot of misconceptions with brakes, six piston calipers are again a bit of a bragging right. The advantage of multi piston calipers is more even pad ware due to pad flex under hard braking rather than any major brake performance. Good for track work but not a major benefit on the street. There is a bit more in it than that and to lengthy to get into here.

I have some good photos of the parts I made and how I did it but still cant find them. I might have some on my phone and will transfer them soon.

[Innuendo]

Oh, I also thought you were sticking with 14" rims.

[axistr]

Sorry for any confusion on the rim size guys.

Old brakes and wheels.

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I have removed the 14" Dragways and now running FR17 Simmons. I started out by drilling the front blank hubs and drilling them to suit the 108 PCD Torana stud pattern, then fitted the longer VT commodore wheel studs due to the hat style rotors which sit over the hub and reducing the stud length by approximatly 8mm. After working out the suitable front rotors offset I purchased a pair of BA XR8 rotors as previously mentioned 299.5mm and at $45.000 each it was a quick job to multi drill them to suit the 108 PCD stud pattern. I was going to source some calipers at local wreckers and overhaul them, but at $180.00 each, again by the time I fitted new pistons and kits it just wasn't worth it.

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Now that I could place the hub and rotor on the stub axle I made a templet for the caliper mount. The original Holden stub axle caliper mount flange is 1/2" so I decided to use 12mm plate, probably a bit of an overkill but its never going to flex or twist. I made a spare set of adaptor plates so I will probably put the same brake setup on my other Torana.

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With the caliper mount plates cut out and drilled I fitted the caliper and made four spacers to place the caliper in the centre of the rotor.

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The pads sit perfectly centred and 1mm inside the O.D of the rotor.

With new bearings, seals and every thing trial fitted to my spare K-frame it was time to fit the brakes to the Hatch and take some measurements for new braked brake hoses.

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I used stainless braided hoses to reduce and hose expansion when the pressures increases. I hate spongy brake pedals and with multi piston calipers its even more reason to use good braided hoses.
I gravity bleed the brakes then got the Mrs to do a bit of pumping. (I wish). Decided to change the brake fluid in the rear brakes because its been a few years since I have flushed them. And of course its never easy in the real world and the rear calipers started playing up. The hydraulic park brake expander stuffed up and couldn't bleed them properly. I did the calipers up 14 years ago and never liked the early Girlock A9X calipers. So off with them too.

[axistr]

After have another whinge to the Mrs, I decided to get the rear brake setup off the rear of a VP commodore. They needed a bit of work so I ordered new kits and pistons, sandblasted and overhauled to like new.

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Due to engine performance a 9" diff is under the rear and of course the brakes wont fit, so I had to make some adaptor plates to mount them to. Bit of stuffing around but a day on the mill and lathe does wonders. Got rid of that horrible hydraulic park brake setup and now have the commodore inner disc shoe setup. Unless your racing your car you don't need ventilated rear disc rotors, the rear only does around 30% of the braking and doesn't generate a lot of heat.

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I decided to do a weigh in between the old and new brakes. The front weighed in at an extra 1kg per side, but the new Simmons wheels saved me 500g per side so the front unsprung weight has increased by 1kg. Even better the rear brake weight saving is an astonishing 15kg lighter.

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New wheels look awesome.


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There are a few things to consider when doing a brake upgrade.

As I have mentioned earlier its easy to get carried away with big numbers and loads of caliper pistons. I have matched front to rear and I can lock front and rear brakes almost at the same time, front locks just before the rear. My front brakes lock at close to 1,200 psi hydraulic pressure.
Consider the weight of the car. There is no real point of adding near 1,900kg VF commodore brakes to a 1,400kg early Holden. Brake master cylinder, brake boosters and brake pedal pivot points all need to work together to produce the magic number of around 1,200-1300 psi hydraulic pressure with moderate pedal pressure. By choosing all the components from a late model car of comparable weight is the best starting point. The engineers have done all the hard trial and error for you. Its interesting to see that my F80 BMW M3 which weighs in at 1,500kg only has 4 pot calipers front and 2 pot rear. You only have to breath on the pedal and your stopped, the Mrs reckons their good but in my opinion its to easy to send you through the windscreen and a savage, you need to get the feel of it quickly or its bruised forehead. So think twice before handing over that hard earned cash on brake kits that can be dangerous, expensive or just bragging rights down the pub with no extra benefit.

In the end I spent under $900 to do the front and rear brake upgrade plus rims and tyres. My first impressions from the first drive is my brakes feel 40% more efficient.

[Valencia]

You just gotta love a hatch with flares and big boots

[wbute]

Great thread Axister! Well written and obvious that you know what your doing!
Braided lines make a huge difference on dirt bike front brakes so seems logical that it’s the same on a car. Pad material must have a huge effect on brake feel on a car too?
Love the hatch back Torana, easily the best looking Holden ever!

[Kiwivan]

Excellent write up.
Good point about the comparison for weights.

Cheers Kiwi