Weight saving on Rotors
 

Need some help with choosing rotors.

I'm currently running 04 STi rotors (5x100) on my WRX that is fitted with brembos. What would be a good alternative to save few kgs? Will I get some improvement by dropping 2-3kgs from unsprung weight? Some claim that each kilo of unsprung weight = 30kg in kerb weight. Sounds fishy.

2 piece rotors are lighter by appx less than a kg ea, not much but will make a slight difference.

2 piece rotors probably cost fair bit of coin. So, what about normal DBA rotors, are they any lighter?

[QUOTE=Kai;839923]2 piece rotors probably cost fair bit of coin. So, what about normal DBA rotors, are they any lighter?[/QUOTE]
I wouldn't be surprised if they are heavier..

There is alot metal in the ventilation slots....

1 dba T3-4000 single piece rotor front 326 x 30 114pcd approx 9.5kg

1 dba t3-5000 two piece rotor same size approx 9kg

1 standard brembo rotor in same size approx 10kg

I have wilwood 2 piece rotors front and biot 3 piece rotors rear. In my opinion it does make a difference. But its not a big difference.

But the claim of 1kg [i]unspung[/i] mass = 30kg regular mass is bullshit.
Id say that 1kg [I]rotating[/I] mass is equal to maybe 3-4kg regular mass. At a rough guess.

sounds interesting..

[QUOTE=nick73;839925]1 dba T3-4000 single piece rotor front 326 x 30 114pcd approx 9.5kg

1 dba t3-5000 two piece rotor same size approx 9kg

1 standard brembo rotor in same size approx 10kg[/QUOTE]

This was my 13" wilwood rotor when new. At 332x32 It is a few mm LARGER diameter than brembo, and also a couple of mm THICKER than brembo. And it wieghs 6.670kg, which is very light. The light wieght was great, but the down side is less thermal handling. And i actually upgraded to a 14" rotor because i was overheating the brakes at RAC once my driving skills improved.
[IMG]http://rs292.pbsrc.com/albums/mm27/im_lunch_box/20131010_165416_zps999ebb05.jpg?w=480&h=480&fit=clip[/IMG]

The Biot rear rotors (brembo 2 pot fitment) were also lighter than standard brembo rotors, but the dufference was not as impressive.

Thats very light indeed. Do these come in 5x100 to fit Brembos? Did you buy them locally?

[QUOTE=Kai;839945]Thats very light indeed. Do these come in 5x100 to fit Brembos? Did you buy them locally?[/QUOTE]

No. They are designed specifically to suit Wilwood 6 piston forged narraw superlites. FNSL6R. I bought them from USA. When i bought them, they came in 5x100 which i then had re-drilled for 5x4.5" by Russ Kapp. But i believe they now come on dual PCD from Wilwood.

The lightness was great for responsiveness. But as i said earlier, because being light, the brakes overheat while racing. So i went up to a 14" Wilwood rotor. (355mm.) Being radial mount calipers, changing disc size is easy. Simply put spacers on the dog bones and swap out the disc rotor ring to bigger diameter

What hubs are you running? Reason I ask is the pre 05 WRX hubs are prone to destroying wheel bearings. Post 05 went 30% larger and handle track heat significantly better without "pad knock off". If you have the smaller bearings a lower thermal transfer into the wheel bearing is extremely desirable.

Moving from standard to DBA 5000 two piece I noticed a good gain in acceleration response, braking and handling. This was with ultra light light 16x8 SSR Type C rims that were 5.48 kg each+R Spec tyres on a race track... Implying that some may not notice any gains due to already having overweight rims, poor rubber or simply obeying the road rules. Unsprung weight reduction is all win.

[QUOTE=maddog;840274]What hubs are you running? Reason I ask is the pre 05 WRX hubs are prone to destroying wheel bearings. Post 05 went 30% larger and handle track heat significantly better without "pad knock off". If you have the smaller bearings a lower thermal transfer into the wheel bearing is extremely desirable.

Moving from standard to DBA 5000 two piece I noticed a good gain in acceleration response, braking and handling. This was with ultra light light 16x8 SSR Type C rims that were 5.48 kg each+R Spec tyres on a race track... Implying that some may not notice any gains due to already having overweight rims, poor rubber or simply obeying the road rules. Unsprung weight reduction is all win.[/QUOTE]

If you are talking to me. My hubs are all swapped the sti 5x4.5". This is because of the stronger front bearings. And also the better stud pattern for rim selection.

Wheels are rays volk ze40, good for wieght being forged, but are 18x10.5 so i can run 295 yoko a050 tyres. The 18x10.5 / 295 combo wiegh less than my old 17x8 with 235 hankook z221s.

I also have a carbon fibre 1piece tailshaft. Which wieghs less than 1/2 of the STi 6spd tail shaft. And i have also got a Exedy Carbon D clutch which is also very light, both on the flywheel/pressure plate side aswell as the friction discs/drive hub is also light. So it makes shifting very fast aswell as being very responsive on the engine side.

All that coupled with stripping the interior etc for vehicle wieght savings makes the car incredibly nimble and agile.

Sorry Bram, my reply was to Kai.

Just weighed a few old rotors for reference only:
290mm DBA5000 5.1kg each, two piece.
290mm DBA Gold Drilled and Slotted 6.5kg each

[IMG]http://i31.photobucket.com/albums/c379/my99maddog/image_zps39pwxzs3.jpeg~original[/IMG]

Girodisc 2 piece rotors. Cheaper than DBA 5000's and much better. Vision R stock them locally

[QUOTE=Spektre;840299]Girodisc 2 piece rotors. Cheaper than DBA 5000's and much better. Vision R stock them locally[/QUOTE]

Besides being cheaper why are they much better?

they dont crack after 2 race meets. they are a proper floating hat.

[QUOTE=Spektre;840310]they dont crack after 2 race meets. they are a proper floating hat.[/QUOTE]

Wow that's average. I only asked because I was advised not to use a full floating rotor on standard brembo calipers because they don't have self aligning pad springs and can cause knock off at the track.

brake check before every corner as habit. Does get some knock off but only around quite full on corners.