Slotted Rotors Rumble/Vibrate?

I have a 2005 Infiniti G35x. I just replaced the stock rotors with EBC slotted rotors and “green stuff” pads. The brakes work great - much better than my old worn out stock brakes. The problem I’m having is when breaking at a slow rate (say slowing from 20 to 0 at a stop sign) I feel a pulsation/vibration (it’s not a sound, I can’t hear it, just a feeling) in the front rotors. It’s not a warpped rotor feeling, and it doesn’t happen at higher speeds. The best I could describe it is the feeling you get when you ABS kick in - only much more subtle. So my question is - is this normal? One mechanic said I was feeling the slots as they went around.

The mechanic may be right. If the slots don’t have rounded edges then you may be feeling them

I’m VERY surprised that your breaking is better. Slotted rotors were designed for racing cars to keep the rotors cooler because of high temps they’ll reach while breaking at over 100mph. They should give you better breaking then the old worn out brakes…but NOT better then new OEM style brakes…

I’m with Mike (and your mechanic) on this.

Except that I’m not surprised…if I understood correctly you said the new brakes work much better than your old worn out brakes, not than new OEM brakes. I think mike interpreted the statement differently. It CAN be interpreted two different ways.

It is normal. Slotted and drilled rotors generate a perceptible buzz at low speeds. They are also more likely to crack, though cracking is rare.

My new (to me) BMW arrived with slotted rotors. They look cool and they work just fine, but I probably will replace them with conventional rotors when they wear out.

The only time I’ve ever seen slotted and/or drilled rotors work right is when they were included in a complete brake upgrade kit. I don’t recommend replacing normal rotors with slotted and/or drilled rotors without a complete brake system upgrade.

For street cars they’re just for looks, anyway. If the noise/vibration bothers you, replace them with stock rotors.

The mechanic could be quite right and on a ho-hum street car slotted or cross-drilled rotors are unnecessary anyway.

Right. They’re not highly functional like that lip spoiler I put on my trunk lid…

You mean that big rear spoiler? On your FWD car? …

Little rear spoiler, but yup. That’s the one I mean.

When I bought my Civic in 1999, a friend of mine asked me if mine had a spoiler on the back. I said, “No, I’m not going to put a spoiler on a four cylinder economy car, that would be silly.” She said, “But my Sentra has one.” I replied, “I know, and I think it looks silly.”

The one on the Chevy Cavalier looks even worse than the one they sell for the Civic. At least Honda calls the one for the Civic a “decorative” spoiler.

And what, might I ask, is wrong with useless decorations? Kids enjoy life more than we do because they’re not afraid to act silly. What could be more silly that a winged lady on the car’s hood…yet Rolls Royce has one. And it’s famous!

The OP probably knew when he installed the slotted rotors that they’re not necessary for a street car. Neither is my spoiler. But we’re both enjoying ourselves, so does it really matter?

Try adding a decoration just for the fun of it. You might like it.

If silliness is your thing, more power to you. Enjoy it. Replace your “spoiler” with a wing like ones in the attached pictures if it makes you happy.

When I add holiday lights to the interior of my car this December, I’ll be thinking of you.

Hmmmmmmmmmm…what a great idea!

The OP probably knew when he installed the slotted rotors that they’re not necessary for a street car. Neither is my spoiler. But we’re both enjoying ourselves, so does it really matter?

I put the rear spoiler and front air-scoop on my Vega…Not necessary…but fun and even looked good.

I have no problems at all with people “dressing up” their cars. The only thing I find amusing is the kid who sticks a big spoiler on the back of his FWD car (Neon’s seem to be a favorite) so it can get better traction, better performance, better grip, or whatever else. For those who understand that it merely decoration, more power to you. I’ve done my share of dressing up (my cars), but I don’t think I ever claimed it would do much to improve the ride…handling…power…whatever.

One kid (edit: young man) I knew had all these stickers down the front fender of the car (I’m sure you’ve seen the type). Hood pins, paint, the works Looked OK, I guess. I asked him how it ran. He said Great! Thinking he really might have been on to something, I asked him what the power output was, and how much he’d sunk into it. Just over $12K, and 125bhp, tested on a rolling road, with the biggest grin I’d seen in quite a while. I just smiled.

In the eagerness to harass the OP for using slotted rotors, I think some of you missed that he put upgraded pads on as well. That’s why he’s stopping better than stock. It is not at all uncommon for upgraded pads to have better stopping power than stock pads. This is why all of my cars get Porterfield R4-S pads.

You actually do get better stopping from slotted rotors as well, because of the extra friction caused by the bite of the slot against the pad, but the effect is minimal and the increased pad wear makes it very not worth it. A street car only needs the upgraded pads, not the rotors.

OP, as to whether what you’re feeling is normal, yes it is. You’re running your pad over a surface that’s been made uneven by the slots. You will feel that in the pedal. Crossdrilled rotors are better for not feeling weird when you break, but they’re also more prone to cracking (especially if they’re actually drilled rather than cast with the holes already in them). If you’re going for better breaking performance, keep putting the upgraded pads on, but next time just go with a good standard rotor. I personally like Brembo.

Mike, I did too! I could have sworn they made my Vega go faster! (:

Chaissos, I do both, a little decoration and little real improvement. it keeps life fun. Besides, all cars have a weakness here and there and I like to see if I can overcome them. My tC’s gages are silver face with orange numbers. In the shadow if the “recess” it’s almost impossible to read. I added some LEDs into the shroud to light the gages, but they’re still not great. So I just ordered new gage faces in white. Shoudl solve the problem.

Here’s a spoiler/wing I saw in China: