slotted rotor orientation (Dixcel SD) & brake fluid quantity

[SegR]

A couple of questions -

1. A while ago I had Dixcel SD slotted rotors installed on the front of the 3.0R. I note that the Dixcel web page suggests "For the 6 slot brake discs, reverse rotation (slots pointing forward) is recommended for a better brake performance.". A less than ideal shot of part of the rotor as install is here. The front of the vehicle is to the left of the image.

Have these been installed 'the wrong way around' and should I have them swapped around? Is this likely to cause any problem with pad/rotor wear? They've been installed since about January from memory.

2. How much brake fluid is needed to bleed and fill the system in the 3.0R? Will a single 500mL bottle suffice or not? (I'll be replacing my stock lines with braided ones and upgrading to Super DOT 4 fluid at the same time)

[kiahatsiu]

I installed mine (dba jobbies) the same way you did. There wasn't any dramas. I now have mine on the other way. I have been told either way is right, but mine were on backwards as per the part numbers. Probably leave them that way until you are ready to re-machine them.

[Robbks]

if you look at the grooves, you want the inner part of that groove to hit the pad first
that way the gasses and dust that builds up are "wiped" towards the outside of the rotor as it passes through the pad.

because that's what the slots are designed to do, remove the gas and dust build up from between the pad and rotor.

[SegR]

Ian - yeah I was thinking the same but then I thought with 6 months of not too heavy use, would it matter to change them around?

if you look at the grooves, you want the inner part of that groove to hit the pad first
that way the gasses and dust that builds up are "wiped" towards the outside of the rotor as it passes through the pad.

because that's what the slots are designed to do, remove the gas and dust build up from between the pad and rotor.

So to clarify what you're saying, they way I've had them installed is what you'd do and you believe it's the correct way?

Also I just did a bit of JFGI work and came across this article which indicates that installation should be dictated by the internal vane design and where the vanes are straight, then it doesn't matter (or in my opinion, follow the manufacturer's guidelines if any): http://www.zeckhausen.com/how_to_proper ... rotors.htm . Not that I'm arguing - just adding more info.

[Robbks]

hmmmmm
never knew that about the radial or angled vanes.

But I do beleive IF the slots are directional (i.e have a 100% open end) such as your dixels and the RDA's i've used then adhere to what teh manufacturer tells you
http://rdabrakes.com.au/index.php/rotors.html

RDA says they're directional
the ones pictured in your Zeckhausen link don;t look like directionally slotted rotors (both ends of the slot finish within the surface of the rotor)

[cruisn]

Ive always installed with the slots angling backward.

[SegR]

Oh well, I guess I'll leave them as they are and just ensure the rears are installed the 'right' way round. Might change the fronts round when the pads are next changed but given how long that will take I'll probably forget anyway!

So... how much brake fluid do I need if the system is bled, the lines replaced and then refilled?

[3rspecb]

2 x 500ml bottles should sort you out.

[SegR]

Thanks. No harm in having an extra bottle even if it's not needed anyway I guess.

[SegR]

Thinking I'll get the front rotors swapped round so they're facing forward when I get the new rear's installed along with braided lines and some... shiny calipers. The fronts have probably been on for a year. Unless anyone wants to tell me it's a bad idea to change them at this stage...

[BJ]

From the slot point of view you have them the wrong way around. From the vane point of view, it's hard to tell. The vanes are basically a centrifugal fan, which is designed to draw air in at the centre and expel it radially outwards. If the vanes are curved, then it depends whether it was designed as a forward curved fan or a backward curved fan. If it was me, I wouldn't worry about the vanes but would put them on so the orientation of the slots is correct, as described by Robbks.

[Rome_BRZ]

I have Dixcel Type SD rotors on the rears and they are facing forward...I now have Dixcel Type FS on the fronts and the slots are also facing forwards...both were installed by Phat who is now the Australian distributor of Dixcel so I'm assuming that is the correct way

[alessandro132]

I have Dixcel Type SD rotors on the rears and they are facing forward...I now have Dixcel Type FS on the fronts and the slots are also facing forwards...both were installed by Phat who is now the Australian distributor of Dixcel so I'm assuming that is the correct way

I'm getting my SDs fitted by the Phatman so will assume they will be the same

Dixcel reckons by facing it forward you get 10% more friction but faster disc wear.

[SegR]

Yeah Phat advised facing forward is correct but the vanes are non directional so its not a big issue. Just wondering if there's any negative effect if they are changed around at this stage.

[cynner]

When people say "facing forward" - I assume you mean the slot hitting the caliper first on the inside of the rotor... as per "forward rotation" shown in this picture?

dixcel.jpg (146.22 KiB) Viewed 6628 times

Mine were fitted the other way around, and I find the rears vibrate when braking down a steep hill... going to get them swapped to "forward rotation" today I think...