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twinky64

Eerie Braking Sound

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I just installed drilled and slotted brake rotors and new pads. When I start braking above 45 or so mph, the brakes make a eerie "ghost" sound. ooooOOOOOoooo. When I hit 45 mph and descellerating, the ghost sound fades and disappears. Any ideas.

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its normal. slotted rotors will howl or growl, drilled will make that sound you describle. its the way the gasses and air are being cut up across the surface of the rotor. i have to REALLY be braking hard to hear it. its sort of a grrrrr sound for me, but i hear it less since i tossed some scraps of sound deadner in my fender liners to quiet rain noise (which worked pretty well)

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I didn't realize drilled rotors were noisy. How loud does it get??

Hmmm, not too terribly loud but hella noticeable. I would say somewhere around as loud as the engine or your stereo to quiet to medium noice level. Also, the music on the commerical for verizon chocolate and the nip tuck show is really good. Goldfrapp-strict machine

 

its normal. slotted rotors will howl or growl, drilled will make that sound you describle. its the way the gasses and air are being cut up across the surface of the rotor. i have to REALLY be braking hard to hear it. its sort of a grrrrr sound for me, but i hear it less since i tossed some scraps of sound deadner in my fender liners to quiet rain noise (which worked pretty well)

Thank you very much bitter

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Just keep an eye on them from time to time. Unless they are oversized rotors or two piece deals, most of the OEM dimensioned rotors start to crack around the holes and slots. Nothing you really can do about that - just the OEM sized rotors have too little heat capacity. I found out the hard way several years ago with both slotted and drilled OEM sized rotors.

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Just keep an eye on them from time to time. Unless they are oversized rotors or two piece deals, most of the OEM dimensioned rotors start to crack around the holes and slots. Nothing you really can do about that - just the OEM sized rotors have too little heat capacity. I found out the hard way several years ago with both slotted and drilled OEM sized rotors.

Do they break apart or just cause excessive wear on the brake pads?

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Just keep an eye on them from time to time. Unless they are oversized rotors or two piece deals, most of the OEM dimensioned rotors start to crack around the holes and slots. Nothing you really can do about that - just the OEM sized rotors have too little heat capacity. I found out the hard way several years ago with both slotted and drilled OEM sized rotors.

But dont they have a higher heat capacity compared to the oem sized non drilled/slotted rotors? What does "two piece deals" mean?

Edited by twinky64

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In very severe cases, they will break apart - but that doesn't happen unless you drive like you were on a road course. Most of the successful slotted and drilled rotors utilize a "two-piece" rotor - hat design. Where the rotor is generally cast iron that is bolted to an aluminum hat to save weight. Some more exotic designs use carbon fiber or ceramic compounds for the rotor and a completely floating rotor - held on with pins to the aluminum hat. These are generally designed for fixed caliper applications - our sliding caliper would have to have a lot of work done to make anything useful.

 

The drilled and slotted rotors have LESS heat capacity than the plain rotor. The only thing that slotting does, is help with "cleaning" the pad as you are braking - does not really enhance any cooling, if anything it heats it up higher than a regular rotor. The drilled ones help reduce mass (equals less material = less heat capacity) and helps in wet weather/minor out gassing of pads. The guys who rave about these say how it helps with reducing the gases coming from the face of the pads (helps make better rotor to friction material contact). That might be the case a couple decades ago - but most new pad materials do not gas as much as the old compounds.

 

Drilling and slotting is not a bad idea - just have to increase the rotor size to offset the amount of material removed - otherwise it is mostly cosmetic in design.

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the slots on my rotors arent that deep, however i think that when the brake pedal is down hard the slots do help the pad to bite into the rotor harder, but normal driving is no different, and im sure most of it is due to a better pad.

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That is true - those slots do clean off the bottom of the pad, helping keep a fresh friction surface available for braking. Generally they recommend the higher performance pads in this case, since the slots also generate extra heat in the entire system. Most track use cars see slotted vs drilled, because the slots are generally shallow (most of the brake mass is still there) and the constant cleaning of the pads keeps them soft and more consistent in braking performance. Drawback is they tend to eat pads faster - a good trade IMO, I can replace the pads pretty easily, rather have brakes that respond the same way lap after lap.

 

Site with good info on brakes:

 

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

 

Some whitepapers and more detailed FAQs

 

http://www.stoptech.com/tech_info/tech_white_papers.shtml

 

Also, don't worry about the noises too much - as they wear in, the noise will start to go away and reduce quite a bit. If the noise gets louder as you drive around - then you have a problem and need to check both the pads and the rotors for possible damage. Hopefully these are at least Brembo blanks or better that were cut afterwards and repackaged. The OEM rotors are notoriously thin and drilling/slotted them would be an invitation to disaster.

Edited by fishexpo101

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yea, i went with hawk hps pads for the slotted rotors (i got powerslots which use brembo blanks). they do dust ALOT, but i dont really notice except on the highway. after a few hours of highway driving i'll stop to get gas and notice my alloy wheels look like gun metal! i dont mind changing pads a little more often if it means i stop a couple feet shorter.

 

fish, have you ever owned a 93-97 corolla with ABS? i like to call it the afterthought abs system since it only engages AFTER a wheel has locked. if im realy quick on and off the pedal i can lock a wheel and be off before the system can react. i actually like this since it lets me threshold brake to the maximium without abs tripping early, but i find it odd that the system would be designed like this. its the delco abs 4 i think, a 3 channel system.

Edited by Bitter

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No Corolla, but a Camry around those years with ABS and the Matix with ABS - I believe that is the way they are supposed to work. If you are fast enough on the brakes - you can actually cause the ABS to swithc ON/OFF before it has a chance to do anything. That's why they tell you to just stand on it and let the system work. Might also have something to do with the ABS computer - as the Matrix is lightening fast in response compared to the almost casual way the Camry worked. Not 100% sure if this is also a function of the Matrix's Electronic Brake-force Distribution (EBD) system or not. The Camry would lock its brakes for maybe a half-second (at least it felt that way) before the system kicked in. The Matrix is something like a 1/10 of second or quicker.

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In very severe cases, they will break apart - but that doesn't happen unless you drive like you were on a road course. Most of the successful slotted and drilled rotors utilize a "two-piece" rotor - hat design. Where the rotor is generally cast iron that is bolted to an aluminum hat to save weight. Some more exotic designs use carbon fiber or ceramic compounds for the rotor and a completely floating rotor - held on with pins to the aluminum hat. These are generally designed for fixed caliper applications - our sliding caliper would have to have a lot of work done to make anything useful.

 

The drilled and slotted rotors have LESS heat capacity than the plain rotor. The only thing that slotting does, is help with "cleaning" the pad as you are braking - does not really enhance any cooling, if anything it heats it up higher than a regular rotor. The drilled ones help reduce mass (equals less material = less heat capacity) and helps in wet weather/minor out gassing of pads. The guys who rave about these say how it helps with reducing the gases coming from the face of the pads (helps make better rotor to friction material contact). That might be the case a couple decades ago - but most new pad materials do not gas as much as the old compounds.

 

Drilling and slotting is not a bad idea - just have to increase the rotor size to offset the amount of material removed - otherwise it is mostly cosmetic in design.

What are the symptoms I would experience while driving if my rotors start to crack? What is the possiblilty that as soon as the crack occurs, it will instantaneously just sunder apart?

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yea, i went with hawk hps pads for the slotted rotors (i got powerslots which use brembo blanks). they do dust ALOT, but i dont really notice except on the highway. after a few hours of highway driving i'll stop to get gas and notice my alloy wheels look like gun metal! i dont mind changing pads a little more often if it means i stop a couple feet shorter.

 

fish, have you ever owned a 93-97 corolla with ABS? i like to call it the afterthought abs system since it only engages AFTER a wheel has locked. if im realy quick on and off the pedal i can lock a wheel and be off before the system can react. i actually like this since it lets me threshold brake to the maximium without abs tripping early, but i find it odd that the system would be designed like this. its the delco abs 4 i think, a 3 channel system.

the camry sounds like my corolla. about 1/2 second sounds right. the abs does work, just slowly...but im glad to have it!

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What are the symptoms I would experience while driving if my rotors start to crack? What is the possiblilty that as soon as the crack occurs, it will instantaneously just sunder apart?

Just talked about in your other thread on drum brakes:

https://www.corolland.com/forums/index.php?...9477&st=15#

 

For the record - I have never personally gotton a rotor to blow up even under the most stress. The pulsing of the pedal and basically zero brakes will make you stop before you ever get to that point. But there was a televised one on a Corvette C5R some years ago that had its rotor blow apart at the end of a straight on the SpeedChannel network. Was not a pretty sight.

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