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Location:
melbourne
Registered:
June 2002
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Disc Rotor changes
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Sun, 27 October 2002 03:33
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has anyone swapped the standard disc rotors for a different one while keeping teh standard calipers? ie like dba slotted instead of standard rotors?
any benefits? thoughts?
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Location:
Melbourne Eastern Suburbs
Registered:
October 2002
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Re: Disc Rotor changes
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Sun, 27 October 2002 06:46
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any slotted and/or crossdrilled rotor keeps much cooler than a solid rotor when under intense braking. a cooler brake means it's much more responsive, to a point. when going for slotted/upgraded rotors be sure to buy the best brake pads, as cheaper pads will be pushed into the slots, and scraped.
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Location:
Brisbane
Registered:
May 2002
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Re: Disc Rotor changes
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Sun, 27 October 2002 08:18
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Cross-drilling and slotting is NOT done for cooling reasons. In fact, these methods actually decrease the mass of the disc, and in the case of cross-drilling, decrease the overall surface area as well!
The idea is to prevent the buildup of gas between the pad and the rotor under heavy braking. Obviously your brakes don't work too well when there's a cushion of air under the pads!
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Location:
Perth
Registered:
July 2002
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Re: Disc Rotor changes
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Sun, 27 October 2002 08:31
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Yeah the slots and holes remove what is called firebrand, basically vapourised brake pad and particles of bonding agent.
From tests I've done on a race car drilled discs will cool down a fair bit faster when not moving but makes no difference at all when driving.
Drilled discs also crack between the holes.
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Location:
melbourne
Registered:
June 2002
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Re: Disc Rotor changes
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Sun, 27 October 2002 09:08
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how about on the street rather than racing?
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Location:
Perth
Registered:
July 2002
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Re: Disc Rotor changes
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Sun, 27 October 2002 09:19
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Slotted or drilled discs are really only an advantage if you lean hard on your brakes all the time as you do on the track. On the road I doubt they're worth it, maybe for a heavy car like a Commodore driven hard on the road.
They look cool though, and if they don't cost more....
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Location:
Montrose, VIC
Registered:
May 2002
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Re: Disc Rotor changes
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Sun, 27 October 2002 10:20
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I'd say if you tend to give your brakes a rough time and they're nothing like adequate, its time for an upgrade to something reasonable rather than to waste money/mess around with those coin sized discs.
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: Disc Rotor changes
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Sun, 27 October 2002 11:29
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X drilling is a waste of time anyway.....the only valid reason for doing it is to reduce unsprung mass.
Slotting is worth doing, but should be performed as part of a general brake upgrade (as Mrshin said)....I think you would be hard pressed to notice the difference keeping everything else the same.
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Location:
Ipswich
Registered:
July 2002
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Re: Disc Rotor changes
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Tue, 29 October 2002 01:53
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I thought cross drilling was for releasing the gas buildup therefore increasing stopping power. Slotted was for reducing the dust buildup and ventelated was for cooling them?
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Location:
Colac, Victoria
Registered:
May 2002
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Re: Disc Rotor changes
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Tue, 29 October 2002 09:56
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Crossdrills are useless on the street for small cars - just a waste of cash - you never press youer car hard enough to get the greater effect found in racing conditions where the cooling and degassing is needed ..
AND if you are pressing your car hard to warrant it on the street - you shouldnt have a licence
I had a very lengthy discusiion with the manager of DBA australaias QLD operations not long ago - we both came to the comclusion that the DBA slotteds would be the most ideal way to go for my ya22 - considering its 90 % daily driver - 10 % harder driven fun car on the weekends ..
rotos for a pair were going to set me back about 140 for a set - straight swapover .
He also suggested the harder pads if i intended using the car for heavier fun bias.. Road test will begin of said swap to slotteds within the next 2 months
check out www.discpads.com.au for prices
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I supported Toymods
Location:
NE Melbourne
Registered:
May 2002
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Re: Disc Rotor changes
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Tue, 29 October 2002 10:26
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Norbie
"in the case of cross-drilling, decrease the overall surface area as well! "
i'm sorry but the i must correct you here... cross drilling actually increases the surface area of the disc, but not the clamping face of the disc. the internal dimentions of the "cylinder" produced by the holes is greater than the surface area lost at the ends of this "cylinder" the overall effect of this (although only very small) is to increase the ability of the steel disc to dissapate heat to the air around it because of the increased surface area.
so for those interested the addition of holes in the disc is for increased cooling degassing and weight reduction... but he main idea of degassing is taken care of by slotting. on a standard disc, drilling can lead to cracking at the edges of the holes, so for performance use slotting is most effective and often the only used means of better braking... ever noticed that many race cars now use only slotted discs???
in my opinion drilled discs carry only a "wank" factor and although drilling is a sign of increased performance, slotting only is often the best option for street use.
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Location:
Brisbane
Registered:
May 2002
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Re: Disc Rotor changes
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Tue, 29 October 2002 10:43
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I think what Norbie was saying (and he is right) is that Cross Drilling reduces the available stopping surface area (he wasn't talking about the total and hence heat dissipation surface area). 
Cheers
Wilbo
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Location:
Colac, Victoria
Registered:
May 2002
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Re: Disc Rotor changes
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Tue, 29 October 2002 10:44
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here here
they dont use em in v8 supercars - because of the crossdrills heating up so much they exploded a few times
they now use a slotted and vented harrop item ..
crossdrills are definantly a more race car application - not street
FYI the crossdrill ta22 rotors were going to set me back 260 dollars ( compared to about 140 for slotted )
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I supported Toymods
Location:
NE Melbourne
Registered:
May 2002
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Re: Disc Rotor changes
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Tue, 29 October 2002 11:01
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although drilling reduces the face are of the disc, it doesn't affect stopping power. with the same caliper and pad, the effect is less area, same force, hence higher force per unit area, and an almost unmeasurable change in the stopping potential with a drilled or undrilled disc... hence my argument that drilling aids only in cooling, degassing and weight reduction, not any change in the stopping potential of the disc itself (temperature effects aside)
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