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Disc Discussion

Steve Borg - DBA's Technical Support Manager - talks to us about the company's range of high performance brake rotors.

By Michael Knowling

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AutoSpeed: What does DBA offers in the way of high performance brake rotors?

Steve Borg: Before we get into it, I'd have to say that our rotors are performance discs, but they're not racing discs. I think we have to clarify the difference between performance and racing. And, although a lot of people do use them on the racetrack, they are not sold or marketed as such. Our two performance rotors work very, very well in terms of dissipating heat, deglazing and degassing. In fact, our cross-drilled and slotted (DBA Longlife Gold) and Longlife slotted rotors (which are designed for police cars and taxis etc) stop vehicles up to 2.2 metres shorter than a normal disc rotor - as proven on a VT Commodore from 100 km/h.

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AutoSpeed: Given that DBA doesn't manufacture brake pads, which pads were used to achieve your quoted 2.2 metre braking improvement? And what pads do you generally recommend?

Steve Borg: We used the Bendix Ultimates. The Ultimates are my preferred pad - but they're just my preference. They work very well when they're cold, and at 600 degrees C they still have excellent braking performance. I do a lot of highway driving one day and city driving on the next, and they work very well. However, I'd say that any quality disc pad would suffice. Note though, if you use a cheap imported pad, you won't get the performance out of the disc because the pad will let you down.

AutoSpeed: To what recognised standard are DBA discs manufactured?

Steve Borg: World standards IS0 9002 and QS 9000 - for new car manufacturers. Our product consistency is also very, very good because we don't make engine blocks or anything else - all we manufacture is rotors. We pour them one at a time to ensure accuracy, while some other manufacturers - I can't mention names - pour their rotors in lots of six or eight. And, if a temperature difference occurs in this process, they get inconsistencies that can later create shuddering and distorting. The rotors also come with a 12 months/20,000km warranty - for street use only.

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AutoSpeed: What materials are DBA discs made from?

Steve Borg: They are all made from T220 grade graphite cast iron. And, usually, our discs weight about the same as an OE part. (According to Steve's tech literature, iron has a high co-efficient of friction, is cheap, strong and has good heat dissipation. However, it's also quite heavy.) The Gold rotors are finally coated in either zinc chromite or sprayed gold (depending on if they're hat or hub types). The Longlife slotteds aren't plated - which helps keep them low-cost.

AutoSpeed: How much does a pair of DBA performance discs typically cost?

Steve Borg: Well, we've only got six customers nationally and we only sell wholesale. However, if you're gonna buy DBA rotors, shop around because the prices do vary from shop to shop. They are generally similar in price to most OE stuff.

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AutoSpeed: Give us a background to the two DBA high performance discs - the drilled Golds and the slotted.

Steve Borg: When we introduced the cross drilled and slotted rotors into the market place in '97, people were coming up to us at shows and saying, "that's great, I want some cross drilled rotors for my HQ Holden" or whatever, but they didn't really like their premium price. These people didn't care about how they looked, they just wanted the performance value. So we got thinking and said, "okay, we need another product between the cross drilled and our standard". One that will perform, but not carry the marketing of our premium grade product. Hence the slotted came into the market. It only costs 15-20 percent more than a normal disc rotor - and it performs just as good as the drilled rotor.

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AutoSpeed: What are the advantages of drilled discs?

Steve Borg: They dissipate water and dirt, degas the pads (giving better braking distance) and also stay moderately cooler. But that's not an issue - I don't think - for street use. We guarantee our drilled discs to up to 700 degrees C - and they will withstand more than that - but you'd never exceed 450 degrees on the street. On the racetrack you'd probably get up to 600-700 degrees. Again, though, our rotors aren't sold as racing discs. And, of course, our drilled discs look the part - especially behind mag wheels. The slotted discs perform exactly the same and do exactly the same job - getting rid of the water, dust, gasses, deglazing the pads.

AutoSpeed: What are the disadvantages of drilled discs?

They are a little bit noisy - you do get a whirring noise. And, with our drilled and slotted rotors, you do lose about 10% pad life. In saying that, you gain in rotor life because the pad won't bite hard into the disc. If you let the pads glaze up, their material becomes harder than the cast iron of the rotor, and it then starts to bite in and create grooves. But, with slotted and drilled discs, that doesn't happen because you've always got a nice fresh pad surface running over the disc.

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AutoSpeed: We have seen several sets of cracked drilled discs - how do you explain this?

Steve Borg: Look, I keep myself fairly fit, but I'd be crazy to jump out of bed and do a sprint without warming up. It's just like you don't take an engine and go racing without warming it up. It's the same for rotors. They're cast iron, they expand when they get hot, and you really need to warm them up before working them. Abuse them when they're cold and they'll crack. You don't have to warm them 'till they're red hot, so long as the heat sink is right through the rotor and it's not just the outside surfaces getting hot, it's fine.

AutoSpeed: Other than building up brake heat before you go racing, what can you do to look after your discs?

Steve Borg: Brakes get very hot - about 420-450 degrees C during everyday trips. People that drive around the city and then decide to give their car a wash, often hit their rotors with cold water. This will obviously distort them. Rotors are cast iron - they will distort, you know. And, in racing conditions, you'll notice that if a driver pulls into the pits after a stint, one of the things the mechanics do is roll the car backwards and forwards so the pads aren't sitting in the one spot. That's because if they sit in one spot for a certain amount of time, it'll generate a lot of heat in that area and the rotor may crack. The same goes for when any brake disc and pad get extra hot.

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AutoSpeed: Getting back to pads, are harsh pads - such as metallic pads - appropriate for use on DBA performance discs?

Steve Borg: Yes. Look, something like the Bendix Ultimate is very hard on the rotor. It will wear it out. When you generate friction to give braking performance, something's gotta wear. You can't have a pad that gives high mileage and great braking - it just doesn't go. One of the things that we've found with the cross drilled and slotted discs is that even although you've got an aggressive pad, they don't bite into the face of the disc. Even though it's wearing, it's wearing evenly across the face of the disc and you've always got 100% braking all the time.

AutoSpeed: Do you recommend using exotic, race pad materials?

Steve Borg: Racing pads - especially carbon fibre pads - work very, very well when they get hot. But if you use them for street use, you won't reach the temperature where you get maximum performance out of them. Here, two things come into play - you've paid $1000 for pads and you're not getting their maximum effect and, two, if you do get them to that temperature, you may have a problem with the carbon fibre working too good. We put a note with our cross drilled rotors not to use carbon fibre pads. That's because we're frightened that if you use them with our rotors and you have a sticky right caliper, obviously, that right side will be working more efficiently. So - on the street - you might find yourself applying the brakes and straightaway veering right into oncoming traffic...

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AutoSpeed: We've noticed DBA's recent release for the VT Commodore, tell us about this and any new products on the horizon.

Steve Borg: The VT has had a problem with distortion and shudder - pedal pulsation. We've now got new Diamond Teardrop design vanes that are found in our now 040 DBAs. These help dissipate heat a lot quicker, strengthen the face of the disc (over a straight vane) and, we believe, eliminate a lot of the problems the VT has with pedal pulsation.

We've also got some 2-piece rotors coming in, that will even allow you to fit 330mm discs to a WRX. These are being used in America at the moment.

AutoSpeed: The average person might fit aftermarket pads and, perhaps, cooling ducts to their car for improved braking - what are your views on this?

Steve Borg: If you really want a braking upgrade, the easiest way to explain it is this: the bigger the diameter of the disc rotor, the better the braking ability. Look at a bicycle. Their brakes are very, very efficient - yet they've only got a one inch pad. It's all because the disc rotor spans the entire diameter of the wheel. I guess it depends how serious you want to get. Just by fitting cross drilled or slotted discs - for an extra 40 dollars or whatever - you can get 15-20% more efficiency. But if you seriously want a major braking upgrade, you should go to a bigger diameter rotor with slotted discs. We don't do brake upgrades or brake modifications, we are an aftermarket rotor manufacturer. We make to OE specifications, and I do believe - in most cases - that we make rotors as good as or better than OE.

Contact:

DBA (Disc Brakes Australia)
+61 2 9748 0211

http://www.dba.com.au/

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