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Drilled-Slotted Rotors & differential bore calipers

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j-c-c
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Drilled-Slotted Rotors & differential bore calipers

Post by j-c-c »

Does using slotted and/or drilled rotors eliminate or mitigate the need for differential piston bore calipers? My question disregards in this discussion weight or cooling issues, in the thinking slots are best at "wiping" pads and holes are useful for removing pad gases/debris. And is the reverse then somewhat true, using same size caliper pistons in a 4 or more piston caliper with slotted and/or rotor holes, has few downsides?
lefty o
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Re: Drilled-Slotted Rotors & differential bore calipers

Post by lefty o »

still need the same size calipers/pads regardless of slotting or drilling. drilling rotors is generally not a great idea as they tend to be where rotors crack when they get hot. slotting doesnt have the same issue.
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Rick!
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Re: Drilled-Slotted Rotors & differential bore calipers

Post by Rick! »

Maybe look up essexparts.com and talk to Mike O’Neil.
He hangs out on an SAE forum now and then and seems to be well versed in performance braking.
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Re: Drilled-Slotted Rotors & differential bore calipers

Post by BOOT »

From my research Slots are safe and the rotor may last longer, holes are best for weight reduction but crack. Either help with gases or wiping the pad(staggered holes).

Differential piston bore calipers never herd of em BUT I'm into acceleration more than de-acceleration. Anyways w/o knowing how they work and just giving it a bit of thought in relation to your points in your post. The rear piston would see a hotter rotor than the front, so is a larger piston used in the rear?
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j-c-c
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Re: Drilled-Slotted Rotors & differential bore calipers

Post by j-c-c »

Yes, if "rear" here is defined as the trailing piston in regards to rotation. Not sure how much "heat" directly plays in this solution so much as pad "debris/gas"?
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Re: Drilled-Slotted Rotors & differential bore calipers

Post by David Redszus »

Slots are used on solid rotors to "wipe" them clean of debris and hot gases.

Drilled holes are used on vented rotors to improve the air flow through the rotor vents.
Very often, holes are drilled randomly (or incorrectly) which does not produce proper
heat distribution and then leads to cracking. With a correct hole pattern and chamfered
edges, cracking can be reduced; also by reducing rotor temperature.

Early single piston calipers used a stepped edge on the piston/pad contact interface.
This would provide a tapered force from leading edge to trailing pad surface.
With multi-piston calipers the differentiated diameter pistons now serve the same purpose.
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BigBlockMopar
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Re: Drilled-Slotted Rotors & differential bore calipers

Post by BigBlockMopar »

IMO I would think a hole chamfer would also need to be deep enough to be still present after the rotor has worn down a bit, otherwise it would develop sharp edges and promote cracking again.
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Re: Drilled-Slotted Rotors & differential bore calipers

Post by RossDM »

David Redszus wrote: Mon May 10, 2021 11:48 am Slots are used on solid rotors to "wipe" them clean of debris and hot gases.

Drilled holes are used on vented rotors to improve the air flow through the rotor vents.
Very often, holes are drilled randomly (or incorrectly) which does not produce proper
heat distribution and then leads to cracking. With a correct hole pattern and chamfered
edges, cracking can be reduced; also by reducing rotor temperature.

Early single piston calipers used a stepped edge on the piston/pad contact interface.
This would provide a tapered force from leading edge to trailing pad surface.
With multi-piston calipers the differentiated diameter pistons now serve the same purpose.
It seems somebody drilled holes randomly on buddy's new Mustang project. There's no pattern and showing some signs of cracks. We'll see what else need to address after we finished installing the bumper and winch on the truck and clear the garage.
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