1G Backward Brake Rotors?

[TalonJohn94]

Can Slotted (drilled) Rotors be backwards?

I recently was at HIN and other shows and I have seen that a little more than 1/2 of the cars w/slotted rotors are on in a way that looks backward. In other words, should the rotor look like its going "forward?"

Have I done any pad damage by having them in that orientation.

Also, do all slotted/drilled rotors feel like they are "warped" at 1/2 brake pressure?

Stopping distance was reduced but I have a new "shimmy" aside from my usual 55-75 mph vibration.

By the way Konig Tantrums with 215/45ZR Nitto's, D/S Rotors, Ceramic Pads.

[94 AWD Non-Abs]

 

[Defiant]

Apparently there is no "backward". I've seen manufacturers insist on both directions. I'd have said only sweeping "out" (so that the slots are slanted backward in relation to wheel rotation, with the inside end leading) makes sense, as you'd have centrifugal force tending to be assisted by the "flinging" of the rotating wheel in clearing both puck gas and water. But Brembo says to mount them the other way, and somehow I'd figure Brembo just might know more about brakes than I do, particularly their own. Your specific manufacturer should have supplied instructions or marked the rotors.

As for pulsing, you've warped one, probably by too much lug torque.

 

[jtmcinder]

But Brembo says to mount them the other way...

Oh, it gets better. When you get a set of Brembos for a WRX, the fronts pump in and the rears pump out. The key thing to look for is the vanes inside. If these are angled, then you must install them so that the air between the plates is pumped out. Which way the slots go is totally irrelevant. If the vanes are straight, then you can install them any way that you little heart desires.

- Jtoby

 

[Omega]

Here is a pic from BAER regarding the vanes that Jtoby mentioned:

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This is what they have to say about the direction of the slots/dimples:

"Externally modified Baer rotors employ a REVERSE SLOT or a REVERSE SLOT & DRILL pattern. This is current racecar practice and lowers the potential for "carbon smearing" or "transfer" from the pad material to the trailing side of the slots on the rotor. This is important because in some cases this "smearing" actually affects the rotational balance of the rotor and can cause a "shake" or "nibble" while braking."

 

[TalonJohn94]

So I have mine the BAER way and not the BREMBO way?
Keep in mind these are generic rotors.

I torqued the Gorilla Locking Lug nuts to 100 ft lbs. Too much?

If I find out I DO have them the wrong way, is it too late to switch (about 1500 miles) ?

 

[Mike1992]

As for pulsing, you've warped one, probably by too much lug torque.

Crap, I didnt know that was possible, now I understand why I have that shimmy on new rotors. Rotors have approx. 15k on them and I've had the wheels off more than 20 times i'd say and always tightened with the 4-way pretty tight for a skinny dude.

 

[Defiant]

So I have mine the BAER way and not the BREMBO way?
Keep in mind these are generic rotors.

jtmcinder has it right. The cast-in vanes are what matter most.

I torqued the Gorilla Locking Lug nuts to 100 ft lbs. Too much?

Factory spec is 90-110, but I don't know how beefy your not-really-deluxe rotors are. You can count on factory hats to have pretty solid construction. They're built to eliminate lawsuits.

If I find out I DO have them the wrong way, is it too late to switch (about 1500 miles) ?

Well... if they're already screwed-up, I don't know if you can screw them up any more.

Where the hell's Todd TCE ? He's our brake guru.

 

[ldstang50]

What I've found with slotted rotors that I've had, is I would feel, and I did feel a slight pulsation at 1/2 brake. The pads are just rubbing over the slots, which causes the pulsation feeling. But if I were to get on the brakes real hard, they wouldnt' pulsate at all. Try getting on your brakes hard one day from a decent speed, say 60mph. Just lay into them. If you feel a pulsation then you are more than likely warped, but I doubt you are. If you can't feel anything there, put the car in neutral with the ebrake on. Take off a front tire then turn the brake rotor with a lug stud. Turn in slowly, if you feel in turning smoothly all the way around, they you are good. If you feel it grab in one spot then you have a warped rotor.

 

[TalonJohn94]

Thanks, thats exactly the behavior of my brakes.

Next time I have the wheel(s) off [ probably soon- you know you it is if you used to have a DSM- very nice EVO by the way.]

 

[Todd TCE]

I'm compiling a list or pics of rotor finishes to put together soon.

I am now up to 14 different 'styles' of rotor finish.

That being said, there is no direction to any of them UNLESS the rotor is truly directional by internal venting, casting design.

Most 'properly drilled' rotors when done on DIRECTIONAL rotors are done so in order to place one hole in each of the internal slots, thus they run opposite the casting web.