The proper direction for slotted rotors

**jad628** · 07-02-2008, 07:13 AM

This has puzzled me for quite some time. Does anyone know if there is a CORRECT direction for slotted rotors to rotate on a car? I've seen them done different ways and have no idea which is correct.

Here is a photo of mine (left front wheel).

They work fine and are slotted/drilled.

Just curious if anyone can confirm if it even matters, or if - since they can't be turned - if anyone has ever toy'd with rotating sides with them to increase wear time or if that is a mistake like trying to do it with a directional tire.

**SSTODD** · 07-02-2008, 07:29 AM

I also have wondered, but it would depend on the manufacturer of your rotors. My rotor company told me that mine are NOT directional because that has to do with the vanes between the rotor and if those are directional then the rotor needs to be mounted a certain way. I put mine so looking at the upper half of the rotor on the driver side my slots / slant up and toward the back like an airplane tail. I see them every which way but I like my airplane tail slanting toward the back theory.

**jad628** · 07-02-2008, 07:33 AM

Originally Posted by SSTODD

I also have wondered, but it would depend on the manufacturer of your rotors. My rotor company told me that mine are NOT directional because that has to do with the vanes between the rotor and if those are directional then the rotor needs to be mounted a certain way. I put mine so looking at the upper half of the rotor on the driver side my slots / slant up and toward the back like an airplane tail. I see them every which way but I like my airplane tail slanting toward the back theory.

Sounds like we have them the same way. I figured they are more aerodynamic that wya and would make less wind noise, although I never thought it would be significant either way.

**Silver Streak** · 07-02-2008, 08:06 AM

Yeah, there are different ways that they are manufactured. Some are directional.. some arn't... the ones I got came with a pic on which direction they should be.

**One_Bad_TA** · 07-02-2008, 10:33 PM

When i bought my car the slots in the front rotors went in an opposit direction then the rear. So i moved my front driver side rotor to the passenger side. So they match. But i did not notice any difference from before/after

**jad628** · 07-03-2008, 03:29 AM

Originally Posted by One_Bad_TA

When i bought my car the slots in the front rotors went in an opposit direction then the rear. So i moved my front driver side rotor to the passenger side. So they match. But i did not notice any difference from before/after

Yeah, I figured how many times has someone turned a plain set of rotors and then forgotten which was on each side? Seems like it wouldn't be an issue, but I honestly don't know for sure becasue it's never been something I've looked into.

**stephen02ws6** · 07-03-2008, 05:38 AM

when i got mine, they had what side they go on

**muteki** · 07-04-2008, 02:21 PM

I never even thought about it until now. I will be sure to ask when I buy some.

**Z28er** · 07-07-2008, 09:44 AM

Mine had sides on them too, but even though I did what the manuf said, a guy at a shop told me mine are backwards....I will see which way the the slots are facing....I have slot/drilled as well, but I can not remb who made them? They were cheap, but look nice, prob better than stock, and I had a friend running them with no probs, so I went for it a few years ago and have never had any probs.

Though, they do make a strange screech once in awhile on the passg side?

**gnomee** · 07-07-2008, 06:34 PM

I'm not sure what the "correct" way is either. I bought some rotors from rotorsonline.com (Sorry if they are not a sponsor) and they did not come with any directions as far as which way they mount. The slots on mine are not curved like yours in the pic and more of a straight slot. I ended up putting them on opposite of what you have there based on a tech TV show I saw

.

I've had a buddy tell me they are on wrong but they work just fine. They are on my 96 T/A which ate rotors like it eats Mustangs. I've had these on for over a year now and they are not warped and I have not ate any pads so I'm voting they are on right

.

I agree with above though maybe depending on how they are made it may or may not matter.

**jad628** · 07-10-2008, 03:06 AM

Being this is a car site with some pretty schooled folks as members, I have to assume this situation is basically a personal preference if the maker doesn't specify a certain direction.

I just looked at it like honing a knife blade on a wetstone.

**SSTODD** · 07-10-2008, 03:13 AM

I did mine for the zinc coating and the looks thru the wheels. The performance or cracking worries are not an issue because I only have 18k original owner miles and I don't beat on it. They seem like they will last and look good forever with my use.

**Eugenio_SS** · 07-10-2008, 06:34 PM

it's not the slot that decides the direction... They can be either way.
What decides the direction of the rotor is the vents inside the rotor... id they are straight, the rotor can go either way... if they are curved vane, they should be as in this image.
This rotor should be on the right side, so that air goes from the center to the outside... ie clockwise, on this case

As a comparison, this is a straight vane, meaning the rotor can be placed on both sides of the vehicle.

**SSTODD** · 07-11-2008, 02:18 AM

Perfect, a picture is worth a thousand words. I mentioned the vanes but had no cut-away photos. Thanks

**jad628** · 07-11-2008, 07:07 AM

Originally Posted by Eugenio_SS

it's not the slot that decides the direction... They can be either way.
What decides the direction of the rotor is the vents inside the rotor... id they are straight, the rotor can go either way... if they are curved vane, they should be as in this image.
This rotor should be on the right side, so that air goes from the center to the outside... ie clockwise, on this case

As a comparison, this is a straight vane, meaning the rotor can be placed on both sides of the vehicle.

Great info!! Very definitive. Thanks for the input!

**Z28er** · 07-11-2008, 10:12 AM

The question is...How can you tell how they look on the inside?

I agree, this is awesome, but how can I tell how mine were built?

**jad628** · 07-11-2008, 10:20 AM

Originally Posted by Z28er

The question is...How can you tell how they look on the inside?

I agree, this is awesome, but how can I tell how mine were built?

Look down between the two pad wear surfaces. If the vanes are curved or angled, it should be noticeable. Obviously if the rotors are installed and the wheel are on, this becomes a little more difficult.