C4 , c5, ls1, j55 ??

[rohrt]

Can someone explain the difference in the breaks between the C4, C5, LS1, J55

Is this correct

C4 = 12" 1984 to 1996
C5= 13' J55 option 1997 to 2004
LS1 breaks refers to the rear only?

PBR calipers?
Z51 front rotor?

[nullshine]

LS1 brakes refer to the brakes that came on f-bodies starting in the years they were available with the LS1, this applies to front or rear. Kind of a misnomer because LS1 is an engine, but it's just used as a reference point for f-body brakes in those years. (1998 - 2002 i believe).

I believe the Z51 RPO was a just brake rotor size upgrade to the base corvette (C6 i believe). (EDIT: and a rear caliper variation, as per Apogee's post, #4 in this thread). (EDIT #2: Z51 is apparently a handling package, which includes the J55 brake RPO).
Base: JL9 brakes
Z51: J55 brakes
Z06: J56 brakes

I think the main thing here is to not get so hung up on the RPO codes, although I know that it's hard not to when it's always referred to that way online (instead of listing rotor diameter and caliper specs, and what year/make/model of car it came from). I made a little spread sheet in excel on the corvette stuff to get my head wrapped around what all the RPOs and corvette generations (C5, C5 Z06, C6, C6 Z51, C6 Z51) meant as far as brakes. In some cases (ie. the C5 vs. C5 Z06 the only difference appears to be the colour of the powdercoating on the calipers).

Here's some of the info I have. I wish I could insert tables to keep it more organized... not sure if I can, but this should give you a basic outline.

CALIPERS:
C#, RPO, Front/Rear # and size of pistons, Mfg, Colour
C5, Base, Front x2 40.5mm pistons, P.cast PBR, black
C5, Z06, Front x2 40.5mm pistons, P.cast PBR, red
C5, Base, Rear x1 45 mm piston, P.cast PBR, black
C5, Z06, Rear x1 45 mm piston, P.cast PBR, red

C6, Base, Front x2 40.5mm pistons, P.cast PBR, black
C6, Base, Rear X1 45mm piston, P.cast PBR

C6, Z51, Rear, X1 42.5mm pistons, P.cast PBR

C6, Z06, Front x6 33mm pistons, P.cast monoblock PBR, red
C6, Z06, Rear x4 30mm pistons, P.cast monoblock PBR, red


ROTORS:
C#, RPO, Diameter, Thickness, Pilot
C5(All)/C6, Base, Front 325mm x 32mm, 70.5mm
C5(All)/C6, Base, Rear 305mm x 26mm, 70.5mm

C6, Z51, Front 340mm x 32mm, 70.5mm
C6, Z51, Rear 330mm x 26mm, 70.5mm

C6, Z06, Front 355mm x 32mm, 70.5mm
C6, Z06 Rear 340mm x 26mm, 70.5mm

As you can see I have a few holes in my information (no C4 info and some holes in the C5/6 stuff), I compiled this info from clicking around on www.kore3.com and checking out their descriptions for individual components. So if I entered anything incorrectly, I apologize if my information isn't accurate. I hate it when people spread misinformation around, so let me know if I'm being a hypocrite, and I'll edit the post! lol

Just to add fuel to the fire, I have some questions of my own:
C6 base model FRONT calipers:
Do they take up any more room than the C5 ones? They look a little different, and kore3's website says they were redesigned to be stiffer/more durable, but I'm not sure if they actually take up any more room as far as wheel fitment goes.

C6 base model REAR calipers: Same as C5 rear calipers?

Also, does anyone know the piston diameters on the 6 piston front and 4 piston rear C6 Z06 calipers? Are they also made by PBR? What do they use for abutment/mounting brackets?

Hopefully Tobin and others can chime in here.

[CarlC]

C4 front could be 12" or 13".

[Apogee]

Just to clarify a few things from the OP, the C4 Corvettes were redesigned in 1988, so that generation actually has two logical year ranges spanning 1984-1987 and 1988-1996 since they were very different cars. They initially came with 12" rotors all the way around and then with the redesign in 1988 there was a HD package that increased the front rotors to 13". In 1996, they further improved the front calipers for the "Grand Sport" model by making them pressure-cast versus gravity-cast so that they would be less prone to spreading under severe use, otherwise they still look and function the same.

As for some of Treed's questions, I'll answer as many as I can:

C6 Z06 Frt Caliper - 6x Ø33mm pistons
C6 Z06 Rr Caliper - 4x Ø30mm pistons
The C6 Z06 monoblock calipers are manufactured by PBR Australia and referred to as their "M-Series" product line. The pad-lets are the same for the front and rear calipers, other than quantity of course. These calipers are axial mount design with integral mounting ears that are sleeved with M14x2.0 threaded steel inserts, so there are no abutments required.

The C6 2-piston calipers have the same overall profile as the C5(Z06) 2-piston calipers, they just added material on the bridge of the caliper making the reinforcing ribs wider and therefore the caliper more rigid. There are 8 narrow ribs on a C5 caliper and 4 wide ribs on a C6 caliper...same wheel fitment either way.

The C6 rear single-piston calipers are slightly different than the C5's, but very similar and not more rigid like the front calipers as far as I can tell. There are several piston variations, but the base level C6 is Ø45mm and the Z51 is Ø42.5mm IIRC. There's more to it with some minor variations, but for the purposes here, that's what I'm going with.

The center hole diameters are the same for all C5 and C6 rotors and their variants at a nominal Ø70.5mm [Ø2.776"] although the ZR1 carbon/ceramic components appear to be slightly tighter tolerance fits than everything else. The cast-iron rotors typically measure .006"-.010" larger than the nominal specification.

Tobin
KORE3

[nullshine]

Wicked. Thank you very much, Tobin!

[rohrt]

Wow that a lot of data to wade through.

I want to do a 13" big break in the front and a 12" inch for the rear. I would like to Follow CarlC formula and I'm also reading up on Dave Pozzi site. Both throw around the C4/C5 names around. I was trying to get things simplified so I would know what to look for when Ebay shoping but it seems I made things worse. I have to say I'm more confused then ever whith all the different piston sizes.

It sounds like we have 12" baskets and 13" baskets for the calipers and Its my understanding that the front bracket should work for either.

This was mentioned on the Pozzi site
97+ C5 caliper, or Zo6 caliper, or 98+ Fbody caliper (all the same).

Are the Calipers the same for both 12" and 13"?

I was wanting to do a Manual break setup. Would it be better to use a bigger or smaller piston for the front calipers.



anual set up.

[Apogee]

...This was mentioned on the Pozzi site
97+ C5 caliper, or Zo6 caliper, or 98+ Fbody caliper (all the same).

Are the Calipers the same for both 12" and 13"?

I was wanting to do a Manual break setup. Would it be better to use a bigger or smaller piston for the front calipers....

The 1997-2005 C5 front calipers are the same castings whether they're from the base model or the C5 Z06, with the only difference being that the base model calipers are black and the C5 Z06 calipers are painted red. This holds true for the rear C5(Z06) calipers as well.

The 1998-2002 F-body front calipers not the same as the C5(Z06) calipers, but will interchange into the C5/C6 pad abutment brackets (PABs) since the mounting pin spacings are the same. The LS1 F-body calipers have twin-43mm pistons versus twin-40.5 for the C5/C6 and are gravity cast versus pressure cast, meaning they're less dense and more prone to spreading under use. The brake pads are slightly different as well between the F-body and Corvette applications, so the brake pads however should match the PAB, not the caliper and you'll use a combination of hardware kits with respect to the abutment shims and anti-rattle springs.

Tobin
KORE3

[rohrt]

I'm getting there.

I converted some of the measurements since I'm not Canadian

C4 = 12" 1984 to 1987 (JL9 option)
C4 = 13 HD upgrade option 1988 to 1996 (J55 option)
C5= 13' option 1997 to 2004
C6 = 2005 to present

CALIPERS:
C#, RPO, Front/Rear # and size of pistons, Mfg, Colour
C5, Base, Front x2 40.5mm pistons, P.cast PBR, black
C5, Z06, Front x2 40.5mm pistons, P.cast PBR, red
C5, Base, Rear x1 45 mm piston, P.cast PBR, black
C5, Z06, Rear x1 45 mm piston, P.cast PBR, red
98-02 LS1 Front x2 43 mm Piston Gravity.Cast
98-02 LS1 Rear????

C6, Base, Front x2 40.5mm pistons, P.cast PBR, black
C6 Z06 Frt Caliper - 6x Ø33mm pistons
C6 Z06 Rr Caliper - 4x Ø30mm pistons

ROTORS:
C#, RPO, Diameter, Thickness, Pilot
C5(All)/C6, Base, Front 325mm x 32mm, 70.5mm (12.79" x 1.26")
C5(All)/C6, Base, Rear 305mm x 26mm, 70.5mm (12" x 1")

C6, Z51, Front 340mm x 32mm, 70.5mm (13.38" x 1.26")
C6, Z51, Rear 330mm x 26mm, 70.5mm (12.99" x 1.26")
C6, Z06, Front 355mm x 32mm,70.5mm (13.97" x 1.26")
C6, Z06 Rear 330mm x 26mm, 70.5mm (12.99" x 1.26")

Notes
PBR is the Caliper Manufacture
The C6 front caliper is 20-30% more rigid then C5
C5 Red and Black Caliper are the same.
Chevy and Pontiac Hubs may have different offsets
Hubs and Axles will need to be turned down to 5.9" for the Rotors

Questions
Was the C4 13' upgrade the same as the C5 standar option?

I take it that when the C4 had the HD upgrade option that they must have redesigne the pad abutment brackets (PABs) with a different offset to accomidate the larger rotor?

If that is the case that the PAB was redesigned then the Caliper/PAB Bracket that is sold by many different vendors must be the same dimensions for both C4-12 and C4/C5 -13' option?

Last Question - WTH happened to the Geocity site. The torquer camaro site is down. Anyone know if it moved?

[E.rodz]

the c4 you are refering to can be 12" or 13" the difference is the z51 handling pkg. would come with the hd. brake option. so if you order off ebay just make sure if you order c4 rotors you order the hd. brake option they would be 13" just tell them it is for a say87 corvette with hd. brake option.the calipers for both are different the reg corvette without the z51 option will have only single piston calipers. the hd.brake option will have twin piston aluminum calipers.i thought you would be done with this project already.oh the rear on the corvette c4 are 12" and they have the ebrake built into them.

[rohrt]

i thought you would be done with this project already

I think you have me confused with someone else?

I think I have the C5 stuff down. I would like to know more about the C4 HD option at this point. I recall someone saying the hat is deeper on the C4 rotors.

Also what is the hybrid kit?

[Apogee]

The C4 HD rotors are 13" x 1.1" and significantly deeper than the C5 rotors. That combined with the thinner disc gives them more caliper clearance by effectively moving the caliper further inboard relative to a true C5/C6 kit.

Touring Classics sells a kit using the C5/C6 calipers and C4 13" HD rotor, hence the "Hybrid" designation since it's using two different generations of components.

At KORE3, we have a "Hybrid" kit that uses the 2-piston C5/C6 calipers and the 14" C6 Z06 rotor...again, two components not available from GM together and hence the designation as "Hybrid".

Happy Halloween,
Tobin
KORE3

[rohrt]

Tobin, Great information and much apprectiated.

So it sounds like the C4 setup would have less chance of wheel interferance with the deeper rotors. Now I understand the purpose of the Hybrid kits.

I know the C5 has more friction area but I would like to better understand the dimensions between the C4 and C5 calipers. With a C5 caliper on a C4 rotor does the C5 caliper sit higher or is it wider then the C4?

Also is there such a thing as a hybrid kit for the rear? Do either the c4 or c5 rear rotors have deeper hats?

[Apogee]

...So it sounds like the C4 setup would have less chance of wheel interferance with the deeper rotors. Now I understand the purpose of the Hybrid kits.

I know the C5 has more friction area but I would like to better understand the dimensions between the C4 and C5 calipers. With a C5 caliper on a C4 rotor does the C5 caliper sit higher or is it wider then the C4?

Also is there such a thing as a hybrid kit for the rear? Do either the c4 or c5 rear rotors have deeper hats?

Improved wheel fitment is the purpose of the Touring Classics Hybrid kit as it was designed to fit off-the-shelf A/R Torque Thrust II's...a historically problematic (and popular) wheel for big-brake kit fitment. The KORE3 "Hybrid" kits don't do anything to improve wheel fitment since the C6 Z06 rotors have the same overall thickness as the base level and Z51 rotors. The only drawback to a kit like this is that you're running a 28mm thick rotor with a caliper/PAB that is designed for a 32mm rotor, so you're not taking full advantage of the maximum rotor size and mass that you could be running.

As for the caliper/rotor fitment, the C4 pads are quite small relative to the size of the C4 13" HD rotor, so the C5 pads actually do a better job of utilizing the swept area of the rotor than the C4 calipers do. The C5 caliper is significantly larger than the C4 caliper as well as being significantly more rigid...plus, it's a different design being a pin-guided caliper assembly versus the pad-guided C4 design. All of these things contribute to a radially and larger package using the C5 caliper assembly. As for the axial dimensions, the C5 caliper is thicker through the face for added rigidity purposes however the pads are very similar in thickness. I don't know exactly how much thicker, but you could look at a Baer track kit template if you wanted to put a number to it.

In the rear, I don't know of anybody who offers a "hybrid" type kit for wheel fitment purposes. The LT1/C4 type kits typically don't have a lot of wheel interference issues due to the small calipers and rotors used with those kits. The C4/LT1 rotors are deeper than their C5/C6 counterparts and they're also thinner at the friction surface by about 6mm [.236"].

Tobin
KORE3

[drb930]

Subscribed!

[MJRIBEIRO]

Mostly talk about the fronts - but the 1998-2002 F-body rear calipers ARE the same as the C5 standard and Z06 calipers.

[Apogee]

Mostly talk about the fronts - but the 1998-2002 F-body rear calipers ARE the same as the C5 standard and Z06 calipers.

Right...exactly the same if you mean they're very similar to one another, but not the same. To the best of my knowledge, the C5/C6 units are pressure cast whereas the LS1 F-body calipers are not, they're gravity cast. This is why PBR has two different casting numbers for the LS1 F-body and C5 applications, #K242-113C and #K247-025C respectively.

Tobin
KORE3

[MJRIBEIRO]

Well - the pads are interchangeable and they look nearly identical. I'm running the rear C5's on my F-body brackets and abutments.
Here are pictures of them side by side:
http://www.chevelles.com/forums/show...37#post1297737

[drb930]

Right...exactly the same if you mean they're very similar to one another, but not the same. To the best of my knowledge, the C5/C6 units are pressure cast whereas the LS1 F-body calipers are not, they're gravity cast. This is why PBR has two different casting numbers for the LS1 F-body and C5 applications, #K242-113C and #K247-025C respectively.

Tobin
KORE3

Tobin,

We talked about the similarities last week regarding these 2 calipers.
I have the GN 8.5" Rear End taken apart as you requested, ready to talk to you next week on the dimensions.
From all the reading that i have done lately, on the GN 8.5" we are going to have to run the C-5 rotor-
1. it has better venting than the LS1 rotor, as you stated.
2. we need the 1/2" less in the offset of the rotor that the C-5 rotor has to move the caliper towards the outside of the axle housing to help the caliper clear the shock.

Most of the guys using the LS1 Backing plate have to do a shock relocation as the banjo bolt for the hose hits the shock.

Thanks,
Dave