Lightest Two Piece PP1 Rotors?

[DougS550]

I wanted to do a new thread on who makes the lightest rotors for 2019 PP1 GTs, weighed by actual owners.
Thanks for your help

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[2morrow]

There's a what things weigh thread in the sticky section. Just a heads up.

 

[DougS550]

There's a what things weigh thread in the sticky section. Just a heads up.

I will check. Thanks

 

[DougS550]

There's a what things weigh thread in the sticky section. Just a heads up.

I see the weight of Baer two piece listed, but not Steeda Two Piece. So maybe someone can chime in with an actual weight of Steeda PP1 Rotors.

 

[TriYellowYote]

I see the weight of Baer two piece listed, but not Steeda Two Piece. So maybe someone can chime in with an actual weight of Steeda PP1 Rotors.

Straight from Steeda's website:

"The 380 x 34mm front 15 rotors (555 6032) weigh 15.4 pounds per pair less than OE solid 1-piece front discs, while the 330 x 25mm rears (555 6033) are 4 pounds per pair less than OE."

That would make the fronts 25.7 lbs. each and the rears 15.2 lbs. each.

 

[luc]

Except if you go carbon ceramic disks, all the 2 pieces rotors are going to be, for all purpose, the same weight since they are constructed the same way with the same materials, aluminum for the hat and grey iron for the ring

 

[TeeLew]

Except if you go carbon ceramic disks, all the 2 pieces rotors are going to be, for all purpose, the same weight since they are constructed the same way with the same materials, aluminum for the hat and grey iron for the ring

This, with the noted exception of drag race brake packages which are specifically built to be as light as possible at the expense of performance.

If the OP is concerned with road race performance, then the better question is, "Which brake package is the best?", not, "Which brake package is lightest?"

 

[MRGTX]

Since brake rotors are essentially heatsinks, having less mass of a given material (without some additional means of dispersing kinetic energy that has been turned into heat) will simply mean fewer stops before they fade, start to glow, set your car on fire, etc.

 

[ihasnostang]

Since brake rotors are essentially heatsinks, having less mass of a given material (without some additional means of dispersing kinetic energy that has been turned into heat) will simply mean fewer stops before they fade, start to glow, set your car on fire, etc.

specific heat capacity is important also ( Btu/lbm.°F )

https://www.engineersedge.com/materials/specific_heat_capacity_of_metals_13259.htm

 

[TeeLew]

It's not really about having more or less mass. It's about having the appropriate mass. 450+ HP, 3800# & mediocre cooling means we have to carry reasonably big brakes. Reducing car weight & adding cooling will allow us to reduce weight to some extent, but the heat sink capacity of a cast steel brake bell is not particularly beneficial. We can make that AL without sacrificing function. The discs themselves should be full size.

Honestly, I question the necessity of 15+ inch discs. They seem overly large, even for track duty, unless you're racing. I'm curious how hot they actually get on track.

 

[Radiation Joe]

I believe there is some effect on cooling from the design of the rotor. The number and shape of cooling fins can affect the efficiency of cooling, but I don't think it's really significant. The two piece rotors help with keeping extra heat away from wheel bearings, so that is a plus in their favor.
I too feel there is not a significant practical reason for the brakes on the GTPP to be as large as they are except for marketing purposes. They WILL go farther on track with stock pads before overheating, but most people who go to the track more than once every couple of years change the pads, so they don't require the extra heat capacity and cooling the larger rotors provide.
As long as you're not melting the seals around the caliper pistons, your brakes aren't too hot.
It's generally more important to flush the fluid before a track day than anything else.

 

[NightmareMoon]

Honestly, I question the necessity of 15+ inch discs. They seem overly large, even for track duty, unless you're racing. I'm curious how hot they actually get on track.

I too feel there is not a significant practical reason for the brakes on the GTPP to be as large as they are except for marketing purposes. They WILL go farther on track with stock pads before overheating, but most people who go to the track more than once every couple of years change the pads, so they don't require the extra heat capacity and cooling the larger rotors provide.
As long as you're not melting the seals around the caliper pistons, your brakes aren't too hot.
It's generally more important to flush the fluid before a track day than anything else.

The rotors radius is sized for leverage and to support large brake pads, not just heat capacity (or else the rotors would be small and thick). Brake fluid is critical, because thats what fails first when you overheat the system, but with smaller rotors and smaller matching pads, you’re going to have a hard time slowing down a 3800 car repeatedly. The rotor size isn’t marketting, its engineering.

Just because a lot of sports car drivers see big brakes as bling appearance stuff doean’t mean thats the end of the story.

Autocross or daily driver in a flat state? Sure go get some small brakes and throw on a high temp pads and enjoy one or two hard stops every 5 minutes. Ita not just tracks tho - you can cook your brakes on downhill canyon runs too, and there’s usually a cliff on both sides of those roads.

 

[TeeLew]

My car is a little lighter and has significantly less power. We're looking at a pretty simple energy in-energy out thermo problem. I suspect the only reason 14" brakes overheat is due to the flipped hats and minimal cooling. Address both and I highly doubt a 355x34 disc is our limiting factor. Good pads will be necessary as will an adequately prepped car (I.e. Fresh brake fluid, PFC is a good option).

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