1 piece rotors vs 2 piece rotors

[68vert]

Calling all you brake experts out there: what are the advantages of 2 piece rotors other than lightening up my wallet?

[JKnight]

The center of the 2 piece rotor is generally constructed out of aluminum, which makes for reduced overall weight of the rotor, which reduces unsprung weight. Lower unsprung weight will help ride quality and help the suspension to do it's job more effectively (I don't have the knowledge to expound on, or quantify this effect).

Rotational mass is also reduced, but since the rotors are near the center of rotation, I would imagine they have a negligible impact on this.

[John510]

what he said..... Plus they just look so much cooler in a 2pc.

[PhillySpeedNYC]

Not all 2 piece rotors are much lighter than steel single piece units. i work on alot of high end modern stuff which most cars have dual cast rotors with cast iron outer and a aluminum hub. When we weighed two piece rotors for direct replacements they were heavier by a good margin.

if weight is your ideal goal weigh the options literally

Most street guys who never see a track spend a good fortune for two piece rotors for cosmetic reasons as well. we see this often in the high end euro scene.

[68vert]

Originally Posted by John510

what he said..... Plus they just look so much cooler in a 2pc.

They do look sweet. An additional $$$$ sweet? Thats a lot of beer and burgers $$. I was never that cool anyways.

[JKnight]

I like to look at upgrades like the 2 pc. rotor thing this way: If the difference in cost could delay me in finishing the project and getting it back on the road, or buying another critical part, then it's not worth it. For some project budgets (or lack thereof), the cost of the upgrade won't make or break anything, so go for it.

If it had more of a functional impact, it might be a different story.

[GregWeld]

The aluminum hats are for heat dissapation. Aluminum disapates heat much faster than steel.

[chr2002ca]

Yep, what Greg said. Less heat transmits to your hub which improves bearing life in the hub. Like someone else mentioned above, I also weighed a 2-piece and 1-piece Baer rotor and didn't notice much difference in weight. One other thing to consider if your outside tire clearance is very tight: the 2-piece rotor has a thick aluminum hat which will push your tire out about 1/8"-3/16" versus the 1-piece rotor.

[GregWeld]

Forgot to add that it's also supposed to help with rotor warp.

[Apogee]

...and there are two main types of performance 2-piece rotors, floating and fixed mount designs. Most OE replacement 2-piece rotors have the same hat thickness as the OE disc it replaces. Average weight savings in my experience is 2 to 3.5 pounds per rotor, which is always a good thing, although at hundreds of dollars per pound, certainly not for every budget.

Fixed mount 2-piece rotors are just that, fixed, where the hat is directly mounted to the disc with high-temp (hopefully), high-quality stainless AN hardware. DBA5000-series rotors use this configuration (as do many Wilwood and other rotors) and are popular in a lot of rally and other relatively dirty applications, and while lighter than equivalent 1-piece rotors, these can still exhibit some issues with "coning" due to the differences in the thermal expansion of the disc and hat.

Floating discs can use a variety of mounting methods that allow the disc to thermally expand with minimal resistance from the hat to doing so. Bobbins, t-slots, radial grooves, etc...they all have their pros and cons, but they all function on basically the same in principals, some just better than others.

Tobin
KORE3