I got a question about cross drilled and slotted rotors
#58938
05/17/08 10:17 AM
05/17/08 10:17 AM
|
Joined: Feb 2005
Posts: 5,796
minnarusta
TX9H6E4CUDA
OP
master
|
OP
master
Joined: Feb 2005
Posts: 5,796
minnarusta
|
Ok i just purchased some cross drilled and slotted rotors. I figured they were a great price on the bay (cheaper then napa rotors). Well i installed them on my daily driver with some EBC green stuff pads. Well they do work great and i only have 250 miles on them, but when i hit the brakes i am getting a noise and vibration at lower speed that sounds like a wheel bearing. ITs a Vrrrrrrrrrrrrrr sound and i can feel it in the steering wheel. Are cross drilled and slotted rotors supposed to do this? Will they ever stop making this noise or will i be stuck with it forever. I was thinking of checking them out tommorrow but just wondering because this is my first set of these rotors.
Thanks moparts
For the absolute best powder coating go to J.I.T powder coating, contact infomation is in my personal profile..
|
|
|
Re: I got a question about cross drilled and slotted rotors
[Re: TX9H6E4CUDA]
#58939
05/17/08 12:06 PM
05/17/08 12:06 PM
|
Joined: Mar 2007
Posts: 532
Marion, Ohio USA
kab69440
mopar
|
mopar
Joined: Mar 2007
Posts: 532
Marion, Ohio USA
|
My guess is that until the pads and rotors "wear in" together, you'll have that noise and vibration. I've been seeking a matched pair of late-B drilled/slotted front rotors and Lincoln rears as specified for the Scarebird rear disc conversion. I can't get any one of those eBay sellers to respond to my queries regarding them.
Just because you're paranoid, it doesn't mean they are not out to get you.
WANT TO BUY- Looking for a CD by 'The Sub-Mersians' entitled "Raw Love Songs From my Garage To Your Bedroom". Also, any of the various surf-revival compilation albums this band has contributed to.
|
|
|
Re: I got a question about cross drilled and slotted rotors
[Re: kab69440]
#58940
05/17/08 01:18 PM
05/17/08 01:18 PM
|
Joined: Jun 2007
Posts: 764
Prescott Az
73 SSP
super stock
|
super stock
Joined: Jun 2007
Posts: 764
Prescott Az
|
Quote:
My guess is that until the pads and rotors "wear in" together, you'll have that noise and vibration. I've been seeking a matched pair of late-B drilled/slotted front rotors and Lincoln rears as specified for the Scarebird rear disc conversion. I can't get any one of those eBay sellers to respond to my queries regarding them.
I learned when a they don't respond their not ones to do businuss with.
|
|
|
Re: I got a question about cross drilled and slotted rotors
[Re: TX9H6E4CUDA]
#58946
05/18/08 12:04 AM
05/18/08 12:04 AM
|
Joined: Dec 2003
Posts: 22,695
Bitopia
jcc
If you can't dazzle em with diamonds..
|
If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,695
Bitopia
|
I assume the only change was the pads and rotor, and you bedded them in as per rotor pad manufacturer suggested, and you checked rotor runout, and the caliper mounting is correct, then I would say the noise is not a good sign, but a sign of what, I don't know. I would think the drilling would not be a source of your problem, and the slots if mounted wrong direction I don't know. I personally would never drive a car with drilled rotors, slots maybe. The Porsche High dollar rotors have cast holes. The little weight savings vs chance of a failed rotor does not make sense to me. And some pads do not like slots. 
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
|
|
|
Re: I got a question about cross drilled and slotted ro
[Re: TX9H6E4CUDA]
#58949
05/18/08 01:34 PM
05/18/08 01:34 PM
|
Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
Magnum
master
|
master
Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
|
I had drilled and slotted on our LHS. It was a bit louder during hard braking.
I later went back to smooth rotors because the drilled/slotted rotors wore out my front brake pads in 9 months. We typically get 3 years out of the front brakes on the LHS.
Overkill for a daily driver but they do work. I tried seriously abusing the ABS one day and the brakes would not fade or vibrate.
69 Super Bee, 93 Mustang LX, 04 Allure Super
|
|
|
Re: I got a question about cross drilled and slotted ro
[Re: Magnum]
#58950
05/18/08 01:52 PM
05/18/08 01:52 PM
|
Joined: Feb 2005
Posts: 5,796
minnarusta
TX9H6E4CUDA
OP
master
|
OP
master
Joined: Feb 2005
Posts: 5,796
minnarusta
|
so how do i know if they are on backwards? the slots and holes are heading towards front of the car when top dead to the rotor. They are mirrored looking (i guess i hit the brakes a little hard a couple of times) Im gonna hit it with some sand paper and scuff them up again
For the absolute best powder coating go to J.I.T powder coating, contact infomation is in my personal profile..
|
|
|
Re: I got a question about cross drilled and slotted ro
[Re: TX9H6E4CUDA]
#58951
05/18/08 02:03 PM
05/18/08 02:03 PM
|
Joined: Sep 2004
Posts: 1,226
Cookeville
Chilort
Will Work For Mopars
|
Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
|
Here is a drilled and slotted rotor. Granted, it is for a G-body (Daytona) but should be okay as a reference. Notice the sticker with the L and arrow. These are Baer so they are good quality. It took a while to get used to them. There is some different vibration and whatnot than a regular disc. Now that my pads are set though, it isn't as bad (it took a bit though). I really don't care if they eat pads because I love the way the car stops. This car doesn't have ABS. The action is real linear. I can go in deep and still press harder if I feel I need to. It is my daily driver in terrible ATL traffic, so stopping frequently and hard is a regular event. 
|
|
|
Re: I got a question about cross drilled and slotted rotors
[Re: TX9H6E4CUDA]
#58952
05/18/08 09:49 PM
05/18/08 09:49 PM
|
Joined: Oct 2005
Posts: 8,853
Ontario, Canada
Stanton
Don't question me!
|
Don't question me!
Joined: Oct 2005
Posts: 8,853
Ontario, Canada
|
Quote:
The little weight savings vs chance of a failed rotor does not make sense to me. And some pads do not like slots.
a) rotors are not drilled or slotted to save weight - they are drilled for cooling, they are slotted to get rid of moisture and dirt
b) pads don't know the difference whether there are slots, holes or nothing at all - as long as the rotor has been turned after the drilling or slotting process. When properly done, the holes and/or slots should both be chamfered.
c) runout would be a b*tch to check on a slotted rotor but you'd usually notice a pulsing if they weren't true as opposed to a noise.
I'd take them off and check pad wear and maybe get them turned to make sure they're true. Then chamfer all the holes and slots if they aren't already done. I'd also check the hub mounting face and make sure there's nothing like rust buildup or anything that would affect the rotor runout.
|
|
|
Re: I got a question about cross drilled and slotted rotors
[Re: Stanton]
#58953
05/19/08 06:49 AM
05/19/08 06:49 AM
|
Joined: Dec 2003
Posts: 22,695
Bitopia
jcc
If you can't dazzle em with diamonds..
|
If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,695
Bitopia
|
Quote:
Quote:
The little weight savings vs chance of a failed rotor does not make sense to me. And some pads do not like slots.
a) rotors are not drilled or slotted to save weight - they are drilled for cooling, they are slotted to get rid of moisture and dirt
b) pads don't know the difference whether there are slots, holes or nothing at all - as long as the rotor has been turned after the drilling or slotting process. When properly done, the holes and/or slots should both be chamfered.
c) runout would be a b*tch to check on a slotted rotor but you'd usually notice a pulsing if they weren't true as opposed to a noise.
I'd take them off and check pad wear and maybe get them turned to make sure they're true. Then chamfer all the holes and slots if they aren't already done. I'd also check the hub mounting face and make sure there's nothing like rust buildup or anything that would affect the rotor runout.
A. There are people who would disagree with you on why rotors are drilled. The MAIN reason seems to be it looks cool. Drilling rotors lowers their weight, that is not in dispute, which also lowers the amount of heat that can be absorbed because of less mass. We can also assume that anything solid with a hole in it, when suddenly heated drastically, has higher stress concentrations then someting without a hole in it, and therefore more prone to heat cracking.
B. by normal design a slot is almost always chamfered, a hole maybe, and some pad manufactureres care very much whether the rotors are holed or slotted 
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
|
|
|
Re: I got a question about cross drilled and slotted ro
[Re: jcc]
#58954
05/19/08 11:16 AM
05/19/08 11:16 AM
|
Joined: Jan 2003
Posts: 4,243
Canada
Kam*Kuda
master
|
master
Joined: Jan 2003
Posts: 4,243
Canada
|
Quote:
Quote:
Quote:
The little weight savings vs chance of a failed rotor does not make sense to me. And some pads do not like slots.
a) rotors are not drilled or slotted to save weight - they are drilled for cooling, they are slotted to get rid of moisture and dirt
b) pads don't know the difference whether there are slots, holes or nothing at all - as long as the rotor has been turned after the drilling or slotting process. When properly done, the holes and/or slots should both be chamfered.
c) runout would be a b*tch to check on a slotted rotor but you'd usually notice a pulsing if they weren't true as opposed to a noise.
I'd take them off and check pad wear and maybe get them turned to make sure they're true. Then chamfer all the holes and slots if they aren't already done. I'd also check the hub mounting face and make sure there's nothing like rust buildup or anything that would affect the rotor runout.
A. There are people who would disagree with you on why rotors are drilled. The MAIN reason seems to be it looks cool. Drilling rotors lowers their weight, that is not in dispute, which also lowers the amount of heat that can be absorbed because of less mass. We can also assume that anything solid with a hole in it, when suddenly heated drastically, has higher stress concentrations then someting without a hole in it, and therefore more prone to heat cracking.
B. by normal design a slot is almost always chamfered, a hole maybe, and some pad manufactureres care very much whether the rotors are holed or slotted
My understanding here.
Braking produces gasses. Cross drilling the rotors give the
gasses a way to escape. This will increase the ability to apply pressure.
1970 Barracuda Convertible
1968 Satellite Street Strip car
1654.5 Mustang
1955 Land Rover
|
|
|
Re: I got a question about cross drilled and slotted ro
[Re: Kam*Kuda]
#58955
05/19/08 11:31 AM
05/19/08 11:31 AM
|
Joined: Oct 2003
Posts: 1,249
Las Vegas
JeffC
pro stock
|
pro stock
Joined: Oct 2003
Posts: 1,249
Las Vegas
|
Quote:
Quote:
Quote:
Quote:
The little weight savings vs chance of a failed rotor does not make sense to me. And some pads do not like slots.
a) rotors are not drilled or slotted to save weight - they are drilled for cooling, they are slotted to get rid of moisture and dirt
b) pads don't know the difference whether there are slots, holes or nothing at all - as long as the rotor has been turned after the drilling or slotting process. When properly done, the holes and/or slots should both be chamfered.
c) runout would be a b*tch to check on a slotted rotor but you'd usually notice a pulsing if they weren't true as opposed to a noise.
I'd take them off and check pad wear and maybe get them turned to make sure they're true. Then chamfer all the holes and slots if they aren't already done. I'd also check the hub mounting face and make sure there's nothing like rust buildup or anything that would affect the rotor runout.
A. There are people who would disagree with you on why rotors are drilled. The MAIN reason seems to be it looks cool. Drilling rotors lowers their weight, that is not in dispute, which also lowers the amount of heat that can be absorbed because of less mass. We can also assume that anything solid with a hole in it, when suddenly heated drastically, has higher stress concentrations then someting without a hole in it, and therefore more prone to heat cracking.
B. by normal design a slot is almost always chamfered, a hole maybe, and some pad manufactureres care very much whether the rotors are holed or slotted
My understanding here.
Braking produces gasses. Cross drilling the rotors give the
gasses a way to escape. This will increase the ability to apply pressure.
Gassing out was a problem back in the day of organic brake pads. but not any more, modern brake pads don't gas out like the old ones did.
Last edited by JeffC; 05/19/08 11:32 AM.
|
|
|
Re: I got a question about cross drilled and slotted ro
[Re: jcc]
#58956
05/19/08 03:06 PM
05/19/08 03:06 PM
|
Joined: Sep 2004
Posts: 1,226
Cookeville
Chilort
Will Work For Mopars
|
Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
|
|
|
|
|
|
