lsejnoha

Just wondering what you guys think. Should i go with drilled rotors, slotted and drilled or just the flat surface rotors on my 951. Right now i have the drilled rotors but they look to be a tad bit worn. I was just going to replace the pads but then i figured i might as well go ahead and do the rotors since they aren't too terribly expensive.

944Phil

Track or street or both?

I have Zimmerman drilled (cast holes?) rotors and after about 2 track days every hole on the front rotors had a crack. It's been about 8 tracks day's total now, the cracks keep growing and I have to keep and eye on it. The next set will be smooth or slotted.

Smudo

I also have Zimmerman drilled rotors already for couple of years. Have been using them with EBC Yellow stuff pads. Have done only 6 - 7 trackdays and some 5000 miles on road but have not noticed any issues with them.

jmj951

How is the car used? Can you see the rotors through the wheels, and if so, do you care how that looks?

Without any other info, I would just say flat. With any track days, I would say slotted. If appearance is important, then cross-drilled and slotted.

Willard Bridgham 3

Holy rotor's fabrication method influences the cracking problem and crack propagation; if you drill them after fabrication, they crack worse and quicker than those fabricated w/holes in, then heat treated; it relieves some stress.

Holy rotors are non-homogeneous and non-isotropic.

Materials science has lots to say about failures from stress concentrations,crack propagation and crack migration in non-homogeneous and non-isotropic metals, steel and its alloys especially. Holy track rotor failures I see could have come from a textbook.

944hal

I use Zimmerman non-drilled or slotted rotors with Hawk DTC-60 pads. Not a problem. I'm told the newer technology pads do not need slots or holes to vent hot gasses. So I'm told :-)

fasterfaster

Just replaced pads (New Mintex replacing old Textar) and noticed the surface of my drilled rotors is pretty grooved, with the high points aligning with the holes and low points between them I (radial pattern, think dropping a pebble in a pond, lest anyone think I mean warped or chattering rotors).

Doesn't seem to be a problem, but given this car only sees street use I'm pretty sure next time around I go with smooth rotors.