Rotor Slot Direction

[tlong]

I was perusing the new Corvette Fever rag and noticed a picture of a slotted rotor that appears to be on backwards. Mine had stickers for L and R. The slots are near the hub sweeping out as the hit the caliper.

The picture had the top of the slot hitting first. Are they on wrong? Does it matter?

 

[JRMaroon]

I do not know from personal use what is correct.
The latest catalog I received from The Tire Rack yesterday shows a few installations that have the top of the slot reaching the caliper first.

 

[tnovot]

The answer might be to think about which configuration would be better in order to facilitate air movement through the slot and between pad and rotor. I'm betting JR has the answer.
Terry

 

[grapeknutz]

As I understand it the slot must sweep outwards as the wheel rotates forward....but I could be wrong!

 

[Ken]

Look closely and you will see,
The direction in which the slots should be.

​

It keeps the pads clean that way.​

 

[redc4corvette]

The drivers side of all GM cars according to them is the RIGHT SIDE.

 

[tlong]

Wha?

Right side is passenger to me, as you look ahead from the wheel seat I thought. The slots sweep away logically like the pic above. The pic in Corvette Fever was opposite, high edge leading into caliper. Still curious.:crazy

 

[c4cruiser]

The drivers side of all GM cars according to them is the RIGHT SIDE.

:confused The left side of the car is the driver's side as though you are sitting in the car. Right-hand drive cars have the driver sitting on the right side. The sides are based on being inside the car and facing the front end.

Slotted rotors should be marked as to the install side. The outside edge of the slot should be pointed in the direction or rotation. Counter-clockwise rotation (left side) should point like: \ Clockwise rotation (right side) should point like: /

 

[tlong]

I have Raybestos BruteStop rotors. Go their website and look at the pix. Left side (drivers) point /. The stickers were on mine and match these shots on their site.

The pic in the mag point / on right side. I think they are on the wrong side. It may take Hib to settle this; I match the website for Raybestos.

 

[wishuwerehere82]

When going forward, and looking at the top half of the rotor, the slot should be pointed at the rear of the car. If you look at the slot as the tire rotates the slot should radiate outward.
I talked to my parts guy and he says the drivers side is the left hand side,Unless you're in England.

This the passenger side front tire.

 

[wishuwerehere82]

OK, Now I 'm confused.

I see the picture of Ken's Vette and it looks wrong to me.
I see my picture and it looks right.

HIB!!!!! We need help!!!

 

[JRMaroon]

The attached link from BAER brakes should resolve any confusion. Ken's rotors are installed as per their directions. I'll take this as expert instruction.

http://www.baer.com/Support/TechTips.aspx?TechTipID=2

 

[wishuwerehere82]

Dang it!

I mean dang it, thanks for keeping me from trashing my new brakes. Dang it, I will be busy in the garage tomorrow.
Dang it, good thing I haven't driven the Vette since I put them on.
Dang it, I hate it when Ken is always right!:L
Dang it, I should know better.

 

[Ken]

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.

Notice the wording: "Externally modified Baer rotors, employ a reverse slot or a reverse slot & drill pattern."

Whether other manufacturers abide by that or not I'm not sure.

Now this is embarassing, but this thread caused me to take a look at mine today, and I noticed that although my Baer fronts are mounted as shown (correctly in my case), my aftermarket rears (and I forget which manufacturer it was), have the slots are facing the opposite direction. That is, they are facing the opposite of the fronts.

Trouble is, I cannot remember in which direction the coolings vanes inside the rotor are facing, although I'm sure I've got it right - I seem to recall this episode when I had the whole thing apart last year. However, to be sure, now I'm going to pull my wheels again just to satisfy my own curiosity.

 

[tlong]

It looks like they can be both ways! The vanes in my Raybestos rotors are swept correctly as installed. The new rear ones are directional vanes where the stock were not. However the slots are swept inside out, opposite from Baer.

The bad news is I can feel what is defined by Baer as 'nibble', and can't be corrected by swopping sides because of the vane direction.

I pray this doesn't head towards a poll.

 

[wishuwerehere82]

I think we need Hib,

Here's another manufacturer's rotor installations that say exactly the opposite of Brembo
http://www.nationalfleetparts.com/SP%20installation%20sheet%202004.pdf

The GM rotors that I bought have exactly the same picture for LH and RH rotors so there's no way to tell which direction the go from that info.
http://www.gmpartsdirect.com/results.cfm?singlepart=1&partnumber=88926732

http://www.gmpartsdirect.com/results.cfm?singlepart=1&partnumber=88926731

When I installed them, I took left hand to mean drivers side and right hand to mean passenger side. they were marked L and R.

 

[wishuwerehere82]

I contacted Hib, and this is what he said about this.

We are having a problem figuring out the Correct vane direction for
>drilled and slotted rotors on the CAC.

When you say "vane direction" that means to me the cooling vents or vanes

in the interior of the rotors.

If that's what *you* mean, the correct direction depends on whether or

not the vents are radial or curved.

If the vents are radial, it doesn't matter. If they are curved, rotor

direction is specific. The rotors must be installed such that, when the

car is rolling forward, via centrifugal force, they make the cooling air

flow from the center of the rotor on the inside of the wheel, though the

vents and out the circumference of the rotor. Generally, OE or

aftermarket rotors with curved venting, will either be stamped or have

labeling identifying which side of the car they go on.

Now, if you mean which way the grooves should be oriented, if the grooves

are machined in a spiral pattern, you want the inside of the slot to

sweep the pad first.

You also mentioned drilled rotors.

Caution: do not drill OE Corvette rotors. It weakens them.

Hope this helps.

If you want to repost this on CAC, feel free.





cYa

Hib Halverson

 

[Hib Halverson]

I think we need Hib,

(snip)

Nah ya don't.

In the case of grooved or drilled rotors, I'd always follow the manufacturer's instructions, even if they are the opposite of another mfg.s directions.

That said, for grooved rotors without instructions, I'd mount them so, when they turn in the direction they go when the car is moving forward, the grooves appear to spiral outwards.

Also, know that in many cases, you need to use brake pads which are compatibile with grooved rotors or you will experience high pad wear rates due to the "cheese grater" effect the grooves have on the pad material.

Lastly, with today's brake pads, most of this drilling and grooving stuff is just for looks. It offers no performance advantage. In fact, drilling OE rotors can be unsafe as it weakens the brake disc material.

Hope that helps.

 

[wishuwerehere82]

Thank you for helping solve this mystery.

Now if we could only figure out which side is left and right, we would be A-OK.:L

Pete.