We now have a rear rotor for C5/C6/C6Z that has an aluminum hat (with a Mil-spec coating for the parking brake), directional curved vane rotors and weighs only 14.2 pounds! This is a 5 pound saving over the C6Z rotors and a 6 pound savings over the C6 rotors (each!). It is a direct bolt on with no changes necessary for stock C6 and C6Z(with any aftermarket caliper). It can be used on C5's with a change in the caliper bracket from the original to the C6 version. As with all Hardbar products, we use nothing but the best engineering, design, materials, hardware and of course, is 100% made in USA. We did no less than 6 load cases on this, and am only showing one. Here are a couple of sneak peeks at it, (more pics to follow). Available in February, 2009.

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And yes, the parking brake does work! Unfortunately, the C6ZO6 stock PBR caliper cannot be made to fit, it hangs down too far and the clearances here are already VERY tight for the bolt heads and hat. Note how the AN (aircraft)fasteners have the bolt heads "captured" and cannot rotate. They are sized correctly to have no threads in shear and we use Nordlocks under the nuts. Also, note the rotor and hat interface area is minimized for optimum heat transfer (isolation) into the hat. Again, we focus all of our time and money on solid basic engineering principles and back it up with testing.

Here are a few more pics:
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[IMG]http://i67.photobucket.com/albums/h287/gshoffman/Brakes/Rearrotor1.jpg[/IMG]

In this pic (again, before coating) you can see how close the tolerances are, and 12 point jet nuts will be substituted on Thursday this week.
[IMG]http://i67.photobucket.com/albums/h287/gshoffman/Brakes/Insideviewofnewrearrotor.jpg[/IMG]

So is the main benefit the weight savings, or the rotor compound, or a combination of both?

Matthew

Rotor weight is a BIG deal. It not only reduces unsprung weight (mass) but for every pound (roughly) you remove off the rotating assembly, it is like aprox. 7 pounds of vehicle weight. This is relevant for both acceleration and braking. Also, the cooling is much better over the OE non directional rotors and this design also keeps the bearings cooler for longer life. All good..

Damn, if only I had one for the early C4...

Well, the C4 does not have an internal drum type parking brake so that would make it easier, and perhaps someone does make it. In the C5/C6 world, there is no aluminum hat rear rotor available, anywhere. The thing that makes this possible is new Mil-spec coatings that we have acces to that allow the drum parking brake to run on a very hard and durable surface. In addition, and I could be wrong, but I do not think the C4 market would accept the cost of it.

with you Wilwoods up front, you'd be better converting to the later style rears.

Are you talking to me? I have PFC calipers up front, the Wilwoods in the rear.

No, Central, but if you can get the new hats to fit the older cars, that would be cool

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The C5/C6 hats are much flatter (maybe thinner is a better word?) than the C4 hats. C4 hats can be made but it's all a matter of cost/benefit.

We did a design of a C4 hat back in '07 but we didn't get far with it. So far we've done pretty well with rotors from Napa and Rock Auto.

Although Gary is right on about saving weight it's hard for me to be concerned with a few pounds per corner when I look in the mirror.

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The early C4's have the internal drum type parking brakes. I don't know what yr they changed but my 85 does.

Mike

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84-87 used a internal drum parking brake. 88-96 the parking brake was integrated into the caliper.

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There's a lot more to it than that. The performance gains are the real reason to switch. You have a much wider choice of rotor compounts, thicknesses, and styles if you have a two piece, as typically you are able to use an "off the shelf" rotor instead of one specific to the car. The custom hat design allows the rotor to be generic.

Also, a two piece set up will resist distorting with heat. Ideally, you'd have a floating rotor setup for this, but you still get some advantage with a fixed rotor.

However, for the street, none of this matters except cost and looks...

Even drag racers can utilize less rotating mass, it makes a big difference. This is a "flexure floater" that accommodates the thermal expansion, without moving parts. The above prototype has been redesigned to accept any caliper. We moved the hat flange to being inboard of the rotor and using some Aerospace unique fasteners (that are basically unknown to the automotive biz, but you see them every time you board a Boeing 737 around the door) we are able to get a totally flush face on both sides. This way, it can accommodate any caliper that comes on the Corvette, slide rails included, without compromising cooling and uses standard rotors. I wish I had thought of this before the above prototypes were made, but, oh well, this is fine for the Wilwood, PFC or AP calipers that I might use.

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