BigSexy181971

I bought a set of D/S rotors and put them on. My question is I have seen were the slots run forward on some cars and then backwards on others. What is correct??? Should the rotor slots take in air or expel air?

If I run the slots forward in pulls air in because of the fins, and obviously turning them around would expel air.

HWY HNTR

You need to expel the air coming through the drilled holes.

transamer79

my wilwood drilled and slotted grab the air. i had them on the wrong way at first and they felt funny so i asked wilwood and they told me to swap them. every brand is different though.

japc5

I've seen some brands stamped in the back right or left.

De_Vette

The direction of the slots or drilled holes are irrelevant. The direction of the vanes inside are what is important. That is why it appears that some have them on differently than others.

Cod

I just put them on per the instructions

AU N EGL

Look at the veins. on the sides

The veins should curve backwards on top of the rotor when installed.

GEMcLean

Last C5

FLY LOW

The vains really don't matter that's why GM stopped using the direction rotors.

The drilled and slotted rotors I put on had the R and L stamped in them.

Mike Mercury

exactly !!!

Navyvette04

Now, that is a novel idea....When all else fails, read the directions.

Camjamsdad

I don't have them on the Vette yet. I do have them on my Grand Cherokee. On the front I had them on running the low side in the direction of rotation. Hard to explain. Maybe the lower side facing forward? On the back I had them where the high side of the cut was facing the direction of travel. High side of the cut facing forward?

Anyways right after I installed them I kept throwing an ABS light. Thought it was just the nature of the beast. After a couple months I was giving it some thought and decided to swap the rears so the slot was in the direction of travel instead of against. And the ABS light doesn't come on anymore. Direction does matter in some cases.

BigSexy181971

I have them on right then.

I did not receive directions when I purchased the rotors and did not see a stamp on any of the rotors so I guess I ended up getting lucky. When I put them on I used my judgement at teh time, but was concerned after seeing so many others facing forward.

0Todd TCE

While I have to admit...it's not going to really matter for a street machine how you put them on, at higher speeds where air flow becomes more critical the only real measure of the rotor direction regardless of the surface treatment (slots, holes, dimples, whatever) will be based on the casting's internal vane design.

Another example to add to the coupe thus far:







The last one I think is a Brembo where they used to drill 4-5 holes per air channel. Porsche did this also years ago I believe. The more common wisdom today is to reverse the hole patter to the vane structure of the casting. Which is the only reason the look like the do on most apps today.

Oldvetter

Picture of mine, holes are drilled between vanes (mine were labeled LF, RF, LR, RR)