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Slotted rotor 'direction'?

Lunatic Dancer
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Lunatic Dancer Collaborator

Lunatic Dancer

Posted
Posted

Hi guys...just a quick question on slotted rotors.

Does it really matter which direction the slots are pointing?

Like will there be a performance or life issue if its going round the wrong

way.

On the box there is right and left ...that is to say when you are looking

straight with the car. ie driver seat. correct?

Please see attachment if you don't understand what I'm on about :P

Btw I'm talking about the DBA 4000 ones..

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xRHETTx Mentor

xRHETTx

Posted
Posted

Yeah mine (DBA4000) go the way thats shown in the left pic.

Although i read a pbr brake kit installation manual whilst i was waiting for the discs to be put on and their slots go the other way (or their instructions are just sh!t)

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jvs007 Rising Star

jvs007

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dudes, the question hasnt been answered yet, does it affect performance or reliability if around the wrong way ????

i hav noticed different directions on slotted rotors too and would be keen on answers if anybody knows.......

thanx.

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Beer Baron Grand Master

Beer Baron

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Posted

the direction the slots face will have a marginal effect on performance. personally I think the second pic may be de-glazing the pads more effectively, but the first pic would be allowing gas to escape more effectively.

There is no right or wrong way to have the slots in general BUT, many rotors have curved vanes, this is usually why the rotos will be labled left or right. It's nothing to do with the slots. if the rotors have straight vanes it won't matter a bit, but with curved/directional vanes you ignore the direction advice at your own peril!

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  • 2 weeks later...
Roy Grand Master

Roy

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Id say that there is a right way to have the slots, and its the left pic. This is my opinion, so sorry if it disagrees with convention, could agree i dont know.

But the pic on the left will when wiping the pad face naturally tend to push the pad dust to the outside of the rotor. The pic on the right would tend to want to push the dust to the inside, but the rotor is spinning and wouldnt the centrifugal forces be wanting to push the pad dust back between the pad and the rotors? So you may end up with the situation where you have pad dust between the pad and rotor getting trapped/eroding between the two faces?!?!?!?!

Secondly the slots on the AP/Alcon/Brembo rotors that i have seen normally have the slots the way shown on the left pic. As mmmgtir says, its interesting to note as those rotors are curved vanes, and the direction of the curved vane is critical to the cooling of the rotor, so they have the curved vanes in the same direction as the slots.

Well thats how i would be looking at it?!?!?!

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Beer Baron Grand Master

Beer Baron

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Id say that there is a right way to have the slots, and its the left pic.  This is my opinion, so sorry if it disagrees with convention, could agree i dont know.  

But the pic on the left will when wiping the pad face naturally tend to push the pad dust to the outside of the rotor. The pic on the right would tend to want to push the dust to the inside, but the rotor is spinning and wouldnt the centrifugal forces be wanting to push the pad dust back between the pad and the rotors? So you may end up with the situation where you have pad dust between the pad and rotor getting trapped/eroding between the two faces?!?!?!?!

Secondly the slots on the AP/Alcon/Brembo rotors that i have seen normally have the slots the way shown on the left pic. As mmmgtir says, its interesting to note as those rotors are curved vanes, and the direction of the curved vane is critical to the cooling of the rotor, so they have the curved vanes in the same direction as the slots.

Well thats how i would be looking at it?!?!?!

most people i speak to agree with you roy on the slot direction. but I can pull up numerous pics of race cars and even factory spec cars that have slotted rotors facing the other way. from my experience it didn't make bugger all difference which way the slots faced (this was using straight vaned rotors). in any case if you have curved vane rotors it is very important that they are facing the right way. personally if you are running straight vaned, slotted rotors have the slots face which ever way makes you happy :rofl:

on another note I spent last night putting on a set of nismo brake lines and putting through some nismo brake fluid and noticed that my rotors are curved vane... noice :P

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Rexbo Apprentice

Rexbo

Posted
Posted

i dropped by Stoptech on friday and asked that exact same question and the engineer there said that performancewise, there really isnt any difference which direction they face. They DO increase performance of the rotors, but the direction they face is dependant on the orientation of the vanes inside the rotor. If you orient the slots the wrong way, you can significantly weaken the rotor by creating stress risers on the outside of the rotor that will combine with the weaker spaces on the interior of the rotor to cause flexing and eventually cracking from metal fatigue.

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blind_elk Grand Master

blind_elk

Posted
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How about - if it didn't matter, why would the manufacturers bother to specify the rotor as a "left" or a "right" ?

I think it should be set up that the slot should move towards the outer edge of the rotor when rotated in the correct direction. So in your thumbnail, the LH of the two is a LH rotor, and the RH of the two is a RH rotor (rotate it opposite to how you have marked it).

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Sydneykid Grand Master

Sydneykid

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Posted

The slot in a rotor is there to scrape off the super heated gas that comes out of the pad material and sits between the pad and the rotor, remove any loose pieces of material that might get in the way of the pad contacting the rotor and clean any small bits of materiall off the pad surface itself.

So it would be better if the slots worked the material and hot gases to the outside of the rotor, rather than to the inside where the hat would get in the way of it clearing the rotor.

;)

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Roy Grand Master

Roy

Posted
Posted

From what i can tell thats mainly pad deposits...no reason to be too worried. Or has the rotor surface now got deep grooves in it?

And notice how the inside pad wear on the inner surface isnt as bad as towards the outset. Im guessing your car is a GTST and it uses Nissan calipers?!?!?!

Its my inderstanding thats from the std Nissan calipers not being the most rigid of things and the deflection in the caliper means the pad pressure isnt consistant accross the rotor face when at high temps and high pedal pressure...anyone else confirm thats whats going on?

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Sydneykid Grand Master

Sydneykid

Posted
Posted
From what i can tell thats mainly pad deposits...no reason to be too worried.  Or has the rotor surface now got deep grooves in it?

And notice how the inside pad wear on the inner surface isnt as bad as towards the outset. Im guessing your car is a GTST and it uses Nissan calipers?!?!?!

Its my inderstanding thats from the std Nissan calipers not being the most rigid of things and the deflection in the caliper means the pad pressure isnt consistant accross the rotor face when at high temps and high pedal pressure...anyone else confirm thats whats going on?

The 4 spots are OK, the sliding single piston callipers are not as good.:rofl:

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djr81 Grand Master

djr81

Posted
Posted

Car is an R32 GT-R with standard calipers.

I wasn't worried as it is easily removed by running a small screwdriver along the slot (Tapping it with a hammer). Build up looked to be a mixture of carbon & iron (it was magnetic).

Rotors are in good shape. The surface irregularities are very shallow.

Brake rotors did get rather hot to allow this to happen, however. All three different colours of thermographic paint had flashed off. Not sure how hot the rotors have to get to be glowing, but I have some photos of the car under brakes at the end of pit atraight at Wanneroo with the rotors shining brightly....

:aroused:

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Roy Grand Master

Roy

Posted
Posted

LOL...so that was even with the Brembos? Mmm interesting, as my Nissan caliper wear the pad like that at the track, bit when you look at cars running APs etc the rotor wear appears more uniform?!?!?!?!

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Ronin 09 Grand Master

Ronin 09

Posted
Posted
Not sure how hot the rotors have to get to be glowing, but I have some photos of the car under brakes at the end of pit atraight at Wanneroo with the rotors shining brightly....

Would have liked to see a pic of my front rotors at the end of the front straight at sandown when I ran out of brakes!

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