Mazda Rotary Club

General => General Technical => Wheels & Tyres, Suspension & Brakes => Topic started by: grinder on April 03, 2012, 04:28:58 PM

Title: Grooved Discs ... which way around ??
Post by: grinder on April 03, 2012, 04:28:58 PM
Hiya ,

I have some grooved and drilled front discs for my FC

But im trying to figure out which of the front wheels it should go on

Attached is a pic of the actual disc , which i took

So is it a passenger side one , or a drivers side one

Im sure that both discs are grooved in different directions aswell

Thanks

Stu
Title: Grooved Discs ... which way around ??
Post by: Prof on April 03, 2012, 04:32:46 PM
Mine had L and R stamped on them somewhere on the disk - (could be inside the hub mounting part) - but the vents generally go in the direction of motion (like waves hitting the beach)
 
Also - just by way of addendum - the screw holes are off centre - so if you do use them, they will only fit one way around.
Title: Grooved Discs ... which way around ??
Post by: grinder on April 03, 2012, 04:45:54 PM
handy to know about the holes being offset

and with the L and R .. is that stood at the back of the car or the front ?

And with the wave theory .. the piccy on the left ( single disc ) do we assume that drivers side ( wheel will go clock wise as you move forward )

And thats a speedy response Dave :D
Title: Grooved Discs ... which way around ??
Post by: grinder on April 03, 2012, 04:54:59 PM
just so that i can find it again .. here is when i did it last time :D

http://www.mazdarotaryclub.com/forums/showthread.php?t=55775
Title: Grooved Discs ... which way around ??
Post by: lockwood77 on April 03, 2012, 05:09:59 PM
I\'ve read both way - Dixcel say mount them so that the outer-edge of the disc has the groove furthest forward, so in your first pic, that would indeed be driver side. The grooves would kind of be like your arms doing front crawl when swimming!

That said, I\'ve always mounted mine the other way, so the grooves are "swept back" as the wheel rotates (going forward). Obviously that means the single disc pic would be passenger side!
Title: Grooved Discs ... which way around ??
Post by: GrimR33per on April 03, 2012, 06:03:06 PM
The direction of rotation is dictated by the vents in the centre of the disc not the grooves you are looking at.
Title: Grooved Discs ... which way around ??
Post by: GrimR33per on April 03, 2012, 06:07:29 PM
This will help.. :)

http://www.apracing.com/drawings/cp3718-2020~1CD.pdf
Title: Grooved Discs ... which way around ??
Post by: GrimR33per on April 03, 2012, 06:12:38 PM
And a pic for inner Vane rotation.....


(http://i208.photobucket.com/albums/bb118/Tricky-Ricky13/Capture000.jpg)

(http://i208.photobucket.com/albums/bb118/Tricky-Ricky13/Capture-6.jpg)
Title: Grooved Discs ... which way around ??
Post by: grinder on April 03, 2012, 07:37:24 PM
OMG well thats more confusing !! LOL
Title: Grooved Discs ... which way around ??
Post by: wolfie1 on April 03, 2012, 09:08:42 PM
the single disc pic you put up would be a passenger side disc
Title: Grooved Discs ... which way around ??
Post by: Prof on April 03, 2012, 09:51:43 PM
I concur with wolfie - just had a look at mine in the dark (with a torch) and the single pic shows passenger, the other shows drivers and passenger side from left to right
Title: Grooved Discs ... which way around ??
Post by: GrimR33per on April 04, 2012, 05:11:09 AM
The grooves nearly always run into the pads. Check your vanes inside before you fit.  If they are straight vanes then they can go anyway you want.
Title: Grooved Discs ... which way around ??
Post by: B.Martin on April 04, 2012, 09:26:16 AM
Should sticky this, good advice for anyone with similar problems.
Title: Grooved Discs ... which way around ??
Post by: batman on April 05, 2012, 05:46:35 AM
i was told the groves go anyway forwards or back wards its the vents in side the disc that matter they should curve forwards like front crawl pulling air into the disc .
Title: Grooved Discs ... which way around ??
Post by: Bobbit on April 05, 2012, 01:54:13 PM
First pics you put up is for passengers side, 2nd pic left to right, passengers and then drivers side.
As i understand it the grooves are to help displace any trapped gasses, so the inner part of the disc would hit the pad first and any trapped gas would flow backwards away from the pad.
Title: Grooved Discs ... which way around ??
Post by: GrimR33per on April 05, 2012, 03:21:59 PM
the outer grooves are only there to stop pads from glazing plus help cool pads down under extreme condition which is why they run into rather than away..   It\'s all about the vanes inside. Check the pics I posted

Ps. I didn\'t draw those pictures myself, lol..
Title: Grooved Discs ... which way around ??
Post by: grinder on April 05, 2012, 06:33:05 PM
im sure the discs just have straight vanes

Infact , i have just looked and yes there are
Title: Grooved Discs ... which way around ??
Post by: GrimR33per on April 05, 2012, 07:40:45 PM
Quote from: grinder;818866im sure the discs just have straight vanes

Infact , i have just looked and yes there are

In that case they can go any way you desire lol.  That\'s because the outer grooves make hardly any braking difference. Either way they will work similar.  It\'s mainly into the pad though. If you think about the rotation of the disc which way do you think the grooves will collect air most efficiently?