Advantage of 2-piece rotors is that all the radial expansion that is in the rotor as it cycles from 200DegC to 700DegC and back again many times per track day lap is just that - expansion in a single plane.

When you have a 1-piece rotor, you get differential expansion in the centre of the rotor (the integral "hat" - the hump bit that fits over the hub) and the friction surface which causes stress and eventually the rotor friction surface will crack if the stress gets high enough.

I am a long-term DBA 5000-series user (because they are manufactured in Queensland - well, they were, but now in China but thats almost universal now) - I started in my first WRX Rallye Special in 1996 - and I have never had a rotor failure with them. I now get the rotors cryo-treated as they last longer.

I am also a long-term Endless pad user (TR compound originally, but now have a new one to evaluate), and occasionally use a Ferodo DS2500 for road and track (noisy and a fair bit of dust but good stopping and good temperature tolerance).

I always use a 2-piece front rotor given the extreme level of heat-stress going into them on the track.

Again - my preference has been for slotted rotors simply because they "wipe" the pad and clean any deposits that might build up on the pad surface. Remember - the pad is a sacrificial element in the system - it is designed to generate friction as the rotor abrades it away - so these bits (the "dust") need to go somewhere, and in my opinion, the slot helps "wipe" it away and this promotes braking consistency.

This thread states that F1 don;t use slotted rotors, and that is because F1 brakes are carbon/carbon and the mechanics and chemistry (there is a lot of both in a carbon/carbon braking system) are very different to an iron rotor-based braking system, so IMHO it is not really relevant.

So, to answer your question - I;d always go for a 2-piece rotor to avoid the potential for differnet rates of expansion between the hub and friction surface parts of a single-piece rotor which can only result in friction surface cracks (really big ones).

As for which one - that is up to you - you are in CONUS so you have a much wider choice than us down-under ... for my preference - I use DBA 5000-series, but my guess is that you'll have a much wider choice - so be guided by feedback from users on the forum.

As or cryo-treatment .... I do it as I've got 10+ years of emprical evidence out of my race car that it promotes rotor life - I get 1000klms+ out of my race car per set of rotors but then again - if you are only an occasional track-day user, maybe you're not so concerned at rotor life.

RB

Not sure that is necessarily true. With most 2-piece rotors you have to replace all the mounting hardware at the same time so you end up paying about the same long term. The AP rings alone cost me more than a set of solid StopTechs but they will last 12+ track days instead of 6.

The big advantage is that they can take a lot more track abuse due to the ring being able to freely expand separate of the hat. This is mainly important up front, the rears don't take as much heat (my front's get to 1100F, the rears only 750-850).

I also prefer the sweeping action of the slotted rotors. I have significant wear on my rotors yet there isn't a single gouge or irregularity on the surface, they are as flat as flat can be.

New rings and caliper seals are on the way from Stillen (thanks guys!) and I'll be all fresh for the season. I'm also switching the rear iron hats out for aluminum since I don't use the e-brake much anyway and it will save almost 20lbs of rotating mass.

So I think the bottom line is, if you track a lot then 2 piece rotors are worth the investment. If you track occasionally just get a solid or slotted rotor and get them cryo-treated.

Wow, great info.

For track use slots do provide a useful function, so do drilled rotors (but the cost out weight the benefits imo). I just won't use slots for a daily driver since they will eat through pads much quicker and have little function in daily use, the OP didn't mention track use so I assumed that wasn't a factor.

The carbon disks in F1 still do the same thing turning kinetic into thermal energy through friction which produces dust. Carbon is used because its much much lighter then steel and has much better thermal properties. But that's a discussion better left for another thread.

Um, isn't the title of this thread "Brake Rotors - Which ones are track-worthy"? :)

2-piece rotors allow for expansion and contraction of the iron ring (braking surface) without actually stressing the entire rotor. The hat is separate from the rotor-ring and bolted together with elongated holes to allow for the thermal expansion.

Sorry was already covered earlier... missed that big a$$ post above.

Although that being said, i warped the crap out of my Stoptech 2-piece rotors and had serious pad taper issues. I believe that was me just trying not to replace what amounted to another $500 for front rotors *cough.

I'm blind apparently

Dangit... Now I want the 2 piece for the front. Great info guys!:tup:

Anyone have any specifics on the cyro-treatment process like what temperature and how long? I work on heat treat furnaces and a number of the customers I deal with have cryo-processing capabilities. Just trying to figure out if I might have a way of getting cheap/free cryo-treating

Sounds like poor pad compound choice. I had the same problem in 2010 when I tried to use DS2500's in this car, left horrible pad deposits causing the "warp" effect and they tapered badly within 2 sessions. Things just got too hot for them to handle. The good news is I was able to restore the rotors and remove the deposits.

Also bleed the brakes carefully, if you develop a gas bubble on one side of the caliper you will get uneven pad pressure and horrible shudder.

two-pieces with the right hardware also help to prevent heat from transferring from the rotor to the hat to the hub to everything...

and as far as a pad 'sucking'.. its pad choice... the more aggressive the race pad, the more it will eat rotor if they are not up to their correct operating temp.. this goes to the 'squealing' on the street too.

and if youre not seriously racing there is a 'cost to longevity' factor... if one piece rotors are $200 and you get 5 track days out of them, it beats the $500 rings that make it 10 track days.

Reviving a dead thread to thank everyone for a wealth of knowledge. I'm seriously happy my G is so close to the Z as far as parts. The G community is not nearly as helpful or organized (IMO).

Anyone have experience with CZP 2-peice rotors?

Also, when will we have a 2-peice rear option available?

I believe Racing Brake makes rear two piece rotors? I remember a group buy for them a long time ago.

I believe that for the akebono's the only rear 2 piece rotors available are the Relentless Autosports rotors... I could be wrong though.