Big Brake Track Width and MC Questions

[Neil B]

Are there any big brake setups for the '69 Camaro that maintain the stock power disc front track width or do they all add some amount of additional track width due to the separate hub and rotor? Do any kits use the factory disc spindle (instead of the drum spindle)? Do any kits allow the use of the factory 1 1/8 bore power brake master cylinder?

Thanks. --Neil

[ProdigyCustoms]

Wilwood only changes track width 1/4" per side and uses drum or dosc spindles.

[Apogee]

Neil, FWIW, KORE3 C5/C6 based big-brake kits actually narrow the front track width by .240" per side relative to the factory disc setup and widens it by .200" per side relative to the drum setup. Why the factory had such a track width discrepancy between the two versions, I can't say. Our kits are based around the Chevy drum hubs, so the track width is essentially caused by the difference in hat thickness between the C5/C6 rotor (.300") and the factory drum (~.105"). This will be true for any kit (e.g. Touring Classics) that is based around the factory drum hubs...with the only possible variable being the hat thickness of the rotor used for the kit. Kits that manufacture their hubs to some flange offset other than the factory drum hub spec can fall anywhere since they control the mounting caliper position as well.

Our kits can be installed on either of the drum spindle variants, 1/2-20 or 5/8-18 upper mounting bosses, or the disc spindles. We supply different hardware with each GM short-spindle kit so that it will match the spindle, however the brackets are the same regardless of the particular short-spindle. If you have sets of both drum and disc spindles available, we usually suggest using the drum spindles just because you can sell the disc spindles to guys who want factory discs for a much better return than you can the drum spindles.

The only aftermarket "big-brake" kit that I know of that is designed to work with a 1-1/8" bore master cylinder mounted to a vacuum booster would be the PBR SUV/truck caliper based kits offered by CPP. They manufacture their own rotors, so you're locked into using whatever they have to offer in that regard and the caliper are almost twice as heavy as a C5/C6 assembly, but they definitely fill a gap between factory type brakes and higher performance oriented big-brake kits.

Hope that helps answer your questions,
Tobin
KORE3

[Neil B]

Originally Posted by Apogee

Neil, FWIW, KORE3 C5/C6 based big-brake kits actually narrow the front track width by .240" per side relative to the factory disc setup and widens it by .200" per side relative to the drum setup. Why the factory had such a track width discrepancy between the two versions, I can't say. Our kits are based around the Chevy drum hubs, so the track width is essentially caused by the difference in hat thickness between the C5/C6 rotor (.300") and the factory drum (~.105"). This will be true for any kit (e.g. Touring Classics) that is based around the factory drum hubs...with the only possible variable being the hat thickness of the rotor used for the kit. Kits that manufacture their hubs to some flange offset other than the factory drum hub spec can fall anywhere since they control the mounting caliper position as well.

Our kits can be installed on either of the drum spindle variants, 1/2-20 or 5/8-18 upper mounting bosses, or the disc spindles. We supply different hardware with each GM short-spindle kit so that it will match the spindle, however the brackets are the same regardless of the particular short-spindle. If you have sets of both drum and disc spindles available, we usually suggest using the drum spindles just because you can sell the disc spindles to guys who want factory discs for a much better return than you can the drum spindles.

The only aftermarket "big-brake" kit that I know of that is designed to work with a 1-1/8" bore master cylinder mounted to a vacuum booster would be the PBR SUV/truck caliper based kits offered by CPP. They manufacture their own rotors, so you're locked into using whatever they have to offer in that regard and the caliper are almost twice as heavy as a C5/C6 assembly, but they definitely fill a gap between factory type brakes and higher performance oriented big-brake kits.

Hope that helps answer your questions,
Tobin
KORE3

Seems like most of the C5/C6 and aftermarket calipers have a bore area of around 4". This compares to the stock disk bore area of around 6.5". The C6 Z06 caliper bore area is larger at around 7.6". Anyone tried a C6 Z06 setup with the factory 1 1/8" master? I don't want to upgrade the master because the car is an original '69 Z28 and I want to keep it stock-appearing under the hood.

[Neil B]

I talked to CPP this morning. They say their 13-inch front big brake kit with the 52MM dual piston calipers will work on the stock disc brake spindle and has a very similar caliper bore area as the stock '69 single piston calipers. This would allow me to run the stock 1 1/8" power brake master cylinder. CPP also says they have a 'zero offset' hub and rotor option that keeps the track width stock. Sounds like a pretty good option without going crazy modding my Z28.

[Apogee]

Originally Posted by Neil B

Seems like most of the C5/C6 and aftermarket calipers have a bore area of around 4". This compares to the stock disk bore area of around 6.5". The C6 Z06 caliper bore area is larger at around 7.6". Anyone tried a C6 Z06 setup with the factory 1 1/8" master? I don't want to upgrade the master because the car is an original '69 Z28 and I want to keep it stock-appearing under the hood.

Neil, I'm not sure where you got your information regarding the C6 Z06 front calipers, but it isn't correct. The C6 Z06 6-piston caliper pistons are 33mm diameter giving them each an area of 1.326 square inches. In order to calculate the effective area of a fixed caliper, you sum the total area on one side of the caliper, so in this case it's 3*(1.326) = 3.978 square inches, virtually the same as the 2-piston C5/C6 calipers. Your factory single-piston calipers have an effective area of 6.79 square inches. The CPP kit is just below that at 6.58 square inches.

As for your master cylinder concerns, you can just run a 15/16" or 1" bore master cylinder with your vacuum booster and any C5/C6 brake kit variation you like. CPP in fact sells C3 Corvette style cast iron master cylinders in both of these bore sizes that look like a factory type unit if that's your goal. If you prefer to run one of the orignal Delco castings, you get remanufactured units at nearly any auto parts store across the country.

The only way we would suggest running a 1-1/8" bore MC with any C5, C6, C6 Z51, C6 Z06 kit would be with a hydro-boost.

Tobin
KORE3

[Neil B]

Originally Posted by Apogee

Neil, I'm not sure where you got your information regarding the C6 Z06 front calipers, but it isn't correct. The C6 Z06 6-piston caliper pistons are 33mm diameter giving them each an area of 1.326 square inches. In order to calculate the effective area of a fixed caliper, you sum the total area on one side of the caliper, so in this case it's 3*(1.326) = 3.978 square inches, virtually the same as the 2-piston C5/C6 calipers. Your factory single-piston calipers have an effective area of 6.79 square inches. The CPP kit is just below that at 6.58 square inches.

As for your master cylinder concerns, you can just run a 15/16" or 1" bore master cylinder with your vacuum booster and any C5/C6 brake kit variation you like. CPP in fact sells C3 Corvette style cast iron master cylinders in both of these bore sizes that look like a factory type unit if that's your goal. If you prefer to run one of the orignal Delco castings, you get remanufactured units at nearly any auto parts store across the country.

The only way we would suggest running a 1-1/8" bore MC with any C5, C6, C6 Z51, C6 Z06 kit would be with a hydro-boost.

Tobin
KORE3

I got the C6 Z06 specs from here (but I didn't check the calcs):

http://www.lukeskaff.com/car/brakes/...e_options.html

I'm really liking the CPP option with 13" rotors dual 52MM calipers and retaining the stock master, stock disc spindles, and stock track width. This makes it really easy to return the car to stock if I ever sell the car. Do you see any issues with this approach?

On a separate note, will the C6 Z06 front brakes bolt right on my C5 Corvette with no changes to the hydraulics?

Thanks! --Neil

[Apogee]

I checked the link you posted and be careful with any site that spells brake as "break"...it tends to indicate that there may be other typos to beware of as well. Piston area is very simple to calculate and the areas posted in that chart are way off for the front fixed caliper applications. If you check their values, they're double what they should be...so they calculated the total piston area on both sides of the caliper, not just the one side like you should. There are several other typos and misinformation with respect to rotor diameters, weights, etc, so don't assume everything written must be correct.

As for putting C6 Z06 brakes on your C5 Corvette, it's a bolt-on deal assuming you've got wheels that will clear the calipers. You must run 18's and a lot of C5 guys running the C6 Z06 brakes are running thin wheel spacers to gain a little caliper clearance, but that will depend on your wheels. Your factory 1" bore MC and dual 9" diaphragm booster is perfect for those brakes.

If you like the CPP option, go for it. You can almost as easily run kits from KORE3, Touring Classics, Wilwood, Baer, etc and return it to stock if you like, but you would just need to be aware of the track width changes and size your wheels/tires accordingly...and that's all assuming that you'd be selling the wheels & tires with the car and not returning them to something more original like the brakes.

Tobin
KORE3

[Neil B]

Originally Posted by Apogee

I checked the link you posted and be careful with any site that spells brake as "break"...it tends to indicate that there may be other typos to beware of as well. Piston area is very simple to calculate and the areas posted in that chart are way off for the front fixed caliper applications. If you check their values, they're double what they should be...so they calculated the total piston area on both sides of the caliper, not just the one side like you should. There are several other typos and misinformation with respect to rotor diameters, weights, etc, so don't assume everything written must be correct.

As for putting C6 Z06 brakes on your C5 Corvette, it's a bolt-on deal assuming you've got wheels that will clear the calipers. You must run 18's and a lot of C5 guys running the C6 Z06 brakes are running thin wheel spacers to gain a little caliper clearance, but that will depend on your wheels. Your factory 1" bore MC and dual 9" diaphragm booster is perfect for those brakes.

If you like the CPP option, go for it. You can almost as easily run kits from KORE3, Touring Classics, Wilwood, Baer, etc and return it to stock if you like, but you would just need to be aware of the track width changes and size your wheels/tires accordingly...and that's all assuming that you'd be selling the wheels & tires with the car and not returning them to something more original like the brakes.

Tobin
KORE3

The C5 Corvette has 18" CCW Classics and the '69 Z28 already has 18x8" Forgeline ZX3R's (4.75" BS which fit perfect with the stock discs).

[Apogee]

Originally Posted by Neil B

The C5 Corvette has 18" CCW Classics and the '69 Z28 already has 18x8" Forgeline ZX3R's (4.75" BS which fit perfect with the stock discs).

If you want to check whether theC6 Z06 brakes will fit inside the 18" CCW's on your C5, download the fitment templates from our website here and follow the instructions on the template.

Tobin
KORE3