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One piece brake rotor vs. two piece?

 
Old 07-12-2019, 09:48 AM
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gmarcucio
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Default One piece brake rotor vs. two piece?

I went from a 2019 Stingray to a 2019 Grand Sport. The Grand Sport has two piece brake rotors. Whats the benefit of a two piece rotor? I know it's for performance but what benefit does the two piece have?
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Old 07-12-2019, 09:49 AM
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Tool Hoarder
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1. 2-part rotor can handle a wider range of thermal expansion cycles w/o cracking like a 1 part.

2. The 2-part rotor transmits less heat to the wheel hub/bearing which extends service life.
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Old 07-12-2019, 09:56 AM
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What he said.... and ....

Two part rotor also is made of different materials to save on unsprung weight.

https://www.brembo.com/en/company/ne...-brembo-brakes

"On a floating disc, the braking band and the housing are made with different materials. Since they are made in lightweight aluminum alloy, a floating disc housing is lighter than a traditional housing: therefore, by reducing the unsprung weight, the performance, comfort and handling of the vehicle increase.

The separation between the two parts also prevents the heat generated by the friction from being transmitted from the braking band, which can dilate both in the radial and axial direction, to the housing."
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Old 07-12-2019, 11:52 AM
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And to add to that in a racing scenario the friction ring can be replaced instead of the entire rotor which is supposed to keep cost down.
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Old 07-12-2019, 12:51 PM
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Understood! Makes perfect sense! Thank you for all of your responses !!!
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Old 07-12-2019, 01:16 PM
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Originally Posted by Tool Hoarder View Post
1. 2-part rotor can handle a wider range of thermal expansion cycles w/o cracking like a 1 part.

2. The 2-part rotor transmits less heat to the wheel hub/bearing which extends service life.
And for racing one cast rotor ring can be adapted to any number of center hats which are machined rather than cast so production is easier/faster etc.
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Old 07-12-2019, 04:23 PM
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Originally Posted by subieworx View Post
And to add to that in a racing scenario the friction ring can be replaced instead of the entire rotor which is supposed to keep cost down.
And yet replacement 2 piece rings are more expensive then 1 piece blanks so it appears to be a racing part tax.
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Old 07-12-2019, 04:27 PM
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As was said earlier, the two piece rotor with the aluminum hat section is lighter for les unsprung weight, it also has less rotating inertia so there is less mass to slow down. Also, it allows a floating rotor setup to reduce pad kick back or a pulsating brake pedal.
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Old 07-12-2019, 09:32 PM
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Wow, Didn't realize that many benefits of the floating rotor which translates into better performance. So I would imagine just replacing the rotor section when it needs replacement and leaving the hub section in place eliminates having to cut new rotors on the car to compensate for hub run-out also?
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Old 07-12-2019, 10:39 PM
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Originally Posted by JMII View Post
And yet replacement 2 piece rings are more expensive then 1 piece blanks so it appears to be a racing part tax.
No - just a volume game. The first casting is in the $50k range. The second one is $25.

Even a low production C6Z front rotor is 15000+ units per year for several years. Big brake kits are no where near that volume.

2 piece rotors on production cars are I would assume driven by the machined AL hat, hardware, and assembly cost.
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Old 07-13-2019, 08:57 AM
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Two piece floating rotors like the Brembo are used as the calipers are in a fixed position on the Corvette. This allows the rotors to center between the pucks when the brakes are applied. The floating caliper style with fixed rotors would sometimes get a wear pattern on the studs the calipers rested upon and cause a slight binding to occur during braking. I saw this on motorcycle brakes in the past. The ridge worn on the studs that supported the caliper would cause more of the wear to be on one of the two brake pads. Pistons being on both sides of the caliper versus the older design with only pistons on one side and allowing the caliper to float on the studs also caused tipping and uneven wear on the pads.
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Old 07-15-2019, 01:10 PM
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Originally Posted by KNSBrakes View Post
No - just a volume game. The first casting is in the $50k range. The second one is $25.
Understood, its a niche product.

How much do replacement rings go for? For example - the DBA T3 ClubSpec 5000 rotors you sell? (Z51 fronts). I assume the hat is the cheaper part, thus by reusing it you only save 20-30% of the total cost.

In a racing scenario 2 piece units makes sense both in terms of cost and performance, but on a street driven car it seems like overkill.
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Old 07-15-2019, 01:20 PM
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Originally Posted by JMII View Post
Understood, its a niche product.

How much do replacement rings go for? For example - the DBA T3 ClubSpec 5000 rotors you sell? (Z51 fronts). I assume the hat is the cheaper part, thus by reusing it you only save 20-30% of the total cost.

In a racing scenario 2 piece units makes sense both in terms of cost and performance, but on a street driven car it seems like overkill.
The iron rings vary from $200 up to probably as must as $1000 or more for certain ones.

Rotor hats are roughly $200/each to make in smaller #'s and it can go up if the raw stock diameter is larger. I'm not certain on break points for price on size/volume but they are there. If you were making say 5000 hats you would create tooling and processes to streamline etc.
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