Big Brakes

[EricM]

Why the recommendation for slotted rotors?

I've had them on one car and know they generate more pulsations in the pedal than non-slotted rotors on the same car. You also have less thermal mass whcih is not a benefit.

What's the advantage? Outgassing? That's not really a thing with pads anymore.

Cleaning mud from the interface in an off-road setting? Maybe?

 

[TomDirt]

Get solid rotors.

Offroad is all about reliability. Not weight savings, not designing for specific conditions like wet, dry, dusty, etc. You want the "rode hard, put away wet", version.

 

[Johnny@Apollo-Optics]

Anyone have the Brembos?

Ive done a few Brembos for customer builds. Watcha wondering?

 

[EricM]

Why the recommendation for slotted rotors?

They look cool. Also, the retailers can sell them for more money.

Oh, OK. That's what I thought.

I figured someone might have a actual reason for using them aside from looks and profit though.

 

[The Car Stereo Company]

They look cool. Also, the retailers can sell them for more money.

Oh, OK. That's what I thought.

I figured someone might have a actual reason for using them aside from looks and profit though.

my understanding is the cooldown factor. a chunck of metal that has slots and holes cools down faster than that same chunk of metal in a solid form

 

[EricM]

It's all about looks and profit nowdays.

You aren't getting any extra cooling from slotted rotors.

Cross drilled rotors were originally used to give out-gassing from crappy pads back in the 50s and 60s somewhere to go, so you could still stop if the pads overheated and outgassed. Drilled rotors crack like crazy, so they tried slotting them instead- which gave the same ability to relieve outgassing, but would not crack like the drilled discs.

Outgassing of pads is not a concern anymore with modern brake sizes and pad compounds, so there is no need for cross drilling or slots.

So why are cross drilled rotors on some cars as OEM equipment? It's not for cooling. It is because you don't need all of the mass in the huge rotors they use. They are only after the additional moment arm of the larger rotors, not the addtional thermal heatsink or weight/rotational inertia. If they crack in 3000 miles- so what. The guys buying GT3 cars and racing them are pissing away money on everything they own at ungodly rates. $5000 every season of racing to replace cracked rotors is not a big deal to them.

 

[TomDirt]

You aren't getting any extra cooling from slotted rotors.

Because Ford already slotted them.

 

[EricM]

My SHO has OEM rotors with a vented hat. I'd guess very few have seen that feature before.

Tight fin spacing too. This is a max effort OEM disc.

The original 2009 SHO brakes were a joke. This was their second attempt. If drilling/slotting the swept area would have helped, Ford would have done it.

 

[Nick@Apollo-Optics]

Why the recommendation for slotted rotors?

I've had them on one car and know they generate more pulsations in the pedal than non-slotted rotors on the same car. You also have less thermal mass whcih is not a benefit.

What's the advantage? Outgassing? That's not really a thing with pads anymore.

Cleaning mud from the interface in an off-road setting? Maybe?

Slotted rotors clear debris from the rotor surface.

Offroad is all about reliability. Not weight savings, not designing for specific conditions like wet, dry, dusty, etc. You want the "rode hard, put away wet", version.

Slotted rotors help clear debris, so there's a clear use case for off-road. Drilled, not so much.

my understanding is the cooldown factor. a chunck of metal that has slots and holes cools down faster than that same chunk of metal in a solid form

Slotted rotors doesn't help with cooling, oddly enough. The benefit is clearing debris from the rotor face. As for drilled rotors, it helps with outgassing and cuts weight. Not really needed for this application. But some people like the way they look. I run drilled and slotted on my F-250.

Because Ford already slotted them.

Those are not slots. Those are vents.