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Phil, you're paying attention! GM bean-counter engineering at it's best. I've tried many times to get a "straight" answer, and nothing comes back making any sense.

When the Z51 package for the C6 was introduced (2005, I recall), I looked at an early production unit, noting the drilled rotors--I think it was before the parts information had fully updated at dealers--but I couldn't, for the life of me, figure out what the heck was going on. I kept looking at the car because something "wasn't right" and it then hit me that the rotors were reversed--of course I assumed it was an early model, and they had to finish the car, and had not received the correct RH rotors yet. Wrong answer.....

Best I've ever been able to find out is that someone "decided" that testing showed no significant difference in rotor temps side-to-side, so the parts book shows only 2 PN's....1 for front & 1 for rear, used on both sides--and that is the case with each of the brake systems that were offered before ZR1 came along. The previous model (C5) had 4 individual PN's, specific to each corner.

C5
F 325mm directional vane (left & right - separate PN's)
R 305mm directional vane (left & right - separate PN's)

C6 base
same as C5 above, but pillar vane (non-directional)
F (left & right same PN's)
R (left & right same PN's)

C6 Z51 (thru 2009) (drill pattern reversed on RH side)
F 340mm directional vane, drilled (left & right same PN's)
R 330mm directional vane, drilled (left & right same PN's)

C6 Z06 (drill patter reversed on RH side) and 2010 Grand Sport with Z51 package
F 355mm, pillar vane, drilled (left & right same PN's)
R 340mm, pillar vane, drilled (left & right same PN's)

As noted, there is a difference--the Z51 rotors are actually directional vane venting, which should be a worst-case situation, trying to flow air out from the rotor center with the vanes acting as a dam, basically.

Turns out that C6 went to pillar-vane style rotors for the standard and Z06 models (rear only, I recall), which don't care about direction of rotation--like a DBA "Kangaroo Paw", so any external pattern (slotting and/or drilling) isn't really going to matter as much--for whatever reason the Z51 spec rotors remained directional-vane--front & rear.

Bottom line--the Z51 rotor on the rear is probably large enough that the temp differences won't be a factor unless Scott decides to do some SERIOUS track time with the car.
 

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I love this mod, so how much are we looking at here???
 

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My part of it runs $765 (12" rotor) or $775 (13" rotor) with standard pads and standard finish calipers. "Reds" are now an extra cost option, $35/pr. All new parts.

Rotors come from KORE3, separate purchase--depends on what rotors you choose. Standard 12" OE/ACDelco run $143/pr plus shipping, Z51's (13") run about $120 each plus shipping.

Scott used new hard lines and caliper hoses that aren't part of the base kit, so I don't know how much more he might add to these numbers.
 

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Those are some big-ass brakes on there!
 

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Funny. I was going to point that out also. (not wishing to appear be picking on Bill's work however I did not)

What he's saying it true and common knowledge to those in the BBK biz or on the Corvette forums. A buddy's C6 Z06 still has the one way casting on both sides of his car. Noted it when I fit some other parts for testing and got a chuckle out of it.

Truth is; for a DD car there's nothing lost here. Maybe the most balls out track car can see some real value but nobody else.
 

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Bill & Todd thanks for your informative answers.
Excellent research there Bill :cheers:
 

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OEM OTC Parts vs. Pre-Packaged Kit???

If I were to go to AutoZone to buy rotors, pads, & calipers for a C5 Corvette, what else would I need? I believe I need a special bracket that adapts the Corvette brakes to the Impala rear axle, but I thought the other parts were OEM Corvette? I also understand that the rear discs have to be modified for the 5” bolt circle and the hole on the middle of the rotor had to be enlarged. Does anyone sell an AutoZone filler kit that has the parts that AZ does not have? Why is it necessary to buy the same OEM C5 parts that are available over the counter in a prepackaged kit? Or is there something I am missing? Is it possible to buy the rotors, pads, & calipers for a C5 Corvette and then order the custom bracket, put it all together and you have C5 rear brakes? I need to do something quick, my Impala is sitting with NO rear brakes on it and I going to have to buy new stock SS calipers, pads, & rotors and I would rather buy the Corvette stuff for about the same price...
 

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Questions Answered...

Mr. Bill Harper was kind enough to answer all my questions and to explain why you can not go to AutoZone and get C5/6 parts over the counter and bolt them on to your B-Body. It also explains why the cost of the kit is more than the parts cost at your local supplier. Lastly, it convinced me that I should not try to modify the Corvette parts myself simply because of safety risks involved with modifying such a critical part - the brakes.

Thank you, Mr. Harper, for providing the following information...

”If I were to go to AutoZone to buy rotors, pads, & calipers for a C5 Corvette, what else would I need?”

The kit includes new OE backing plates that are modified specifically to work with the adapter setup I've created. This involves installing threaded inserts to allow the 4 flange mounting bolts to be installed "blind", with no separate nut to retain the parts, due to inadequate access to the area behind the axle shaft flange in the C5 brake installation, since the backing plates are moved outboard 0.450" per side.

”I believe I need a special bracket that adapts the Corvette brakes to the Impala rear axle, but I thought the other parts were OEM Corvette?”

The C5/C6 caliper abutment bracket is modified for clearance in 12" rotor installations, and a different adapter bracket is used for 13" rotor installations. Either way, it does require both a caliper adapter AND a unique split spacer to properly locate and secure the stock B-body backing plates in the correct position for Corvette rotors, which have a lower hat height compared to the B-body rotor. Without the spacer setup, the backing plate(s) would be about half-way engaged in the rotors, meaning the park brake is nowhere properly positioned, and the caliper bracket(s) would not fit down over the rotors properly.

”I also understand that the rear discs have to be modified for the 5” bolt circle and the hole on the middle of the rotor had to be enlarged. Does anyone sell an AutoZone filler kit that has the parts that AZ does not have?”

I used to try to do the rotor machining locally, but with the relationship I've got with KORE3 (in Oregon), it is a lot easier and better (excellent machine work & consistency) to have them supply the rotors modified to proper specs--wheel stud pattern, center bore re-sizing, and other minor modifications on the inside of the hat/drum area. $143 plus shipping for a pair of 12" ACDelco C5 rear rotors that are modified and ready to use is going to be hard to beat unless you're a machinist or have access to someone who is going to do the job for free. The C6 13" rotors are probably not something you will find at AutoZone, but I have not checked, to be honest.

”Why is it necessary to buy the same OEM C5 parts that are available over the counter in a prepackaged kit? Or is there something I am missing?”

As I've indicated, there are modifications necessary to the backing plates (new, with all-new park brake hardware) and the Corvette caliper abutments, as well as the rotors. Special adapters and spacers complete the "must have" parts. The only things NOT modified are the calipers & pads themselves.

”Is it possible to buy the rotors, pads, & calipers for a C5 Corvette and then order the custom bracket, put it all together and you have C5 rear brakes?”

I don't sell the rotors--you get them from KORE3, as I've mentioned. My package price for everything else is going to be hard to beat as a complete box of parts ready to bolt on with no further modification--even buying calipers yourself (new vs. remanufactured from AZ) will probably cost about as much as having them included as part of the kit.
 
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