[cdb95z28]

As you alluded to, maybe the seals and dust boots have a higher temp capability for the CCM brake package.

[h018871]

not sure what you mean by 'insert', the J57 pistons I got are one piece. Although 3 different diameters

Could be a seal difference. I used the stock ZL1 boots and I checked, they are the same boots as used on the 5th gen Z28.

[cdb95z28]

The part with the vent holes, it is an insert. It will come out of the main piston body. At least mine did. And from the looks of the yours, the one at the right, there there looks to be a tiny gap where the insert and the piston body meet, an indication of two separate pieces.

[cdb95z28]

This is a zoomed in pic of my above caliper. The center insert is on its way out of the piston, notice the larger gap, compared to the bottom piston, the insert is in the piston more.





And here is one of the seals that were original to the C& ZO6/GS calipers

[h018871]

facepalm moment

all of the ones I have are tight, HOWEVER, they are made of two different materials (how they make them hollow I guess). the vented portion is magnetic and the body of the piston is non-magnetic.

[cdb95z28]

They are a very tight fit, it's easy to miss! I just happened to notice it when I started to disassemble mine. The pistons must be aluminum, and the inserts a magnetic grade of stainless.

[h018871]

I would bet they're titanium or a non-magnetic stainless body. They're very light.
BTW the original (in my case J6H) pistons are non-magnetic also

[RUQWIKR]

Originally Posted by cdb95z28

All of these 6 piston Brembo calipers used on our late model Chevrolets/Cadillacs all have the same piston diameters, 30,34,38mm.
Whether they are the bigger calipers found on the:
-Gen6 ZL1
-Gen5 Z/28 (CCM)
-C6 ZR1 (CCM)
-C7 ZO6/GS/ZR1 (CCM)
-Gen3 CTS-V

or the smaller calipers found on the:
-Gen6 SS 1LE
-Gen5 ZL1
-C7 ZO6/GS
-Gen2 CTS-V
-ATS-V

There are however two different part #s for the vented piston kit, but it depends on whether they are iron or CCM brakes

23242510 J56 Corvette (iron rotors)
19207043 J57 Corvette/Gen5 Z/28 (CCM rotors)

What I believe is the difference is that the "smaller" 6-piston fronts like J6M SS 1LE, J56 C7Z / GS steel use 30mm pistons vs. 32mm pistons (height). The J57 is ~32.6mm height for the vented fronts and the J6H's are 32mm. Guessing, the 23242510 kit would be closer to 30mm. I'll figure it out and let you know. If you used the J57 vented pistons on the J56 calipers, I could see how they would stick out farther as pictured.

If you have a stock J56 front piston handy, or someone have a J6M SS 1LE front out and about, measure it to see if it's 30mm height. As FYI, all the big fronts (including the carbon ceramics) mentioned use the same material and same PN outer dust seal boot kit.

[cdb95z28]

Originally Posted by h018871

I would bet they're titanium or a non-magnetic stainless body. They're very light.
BTW the original (in my case J6H) pistons are non-magnetic also

Mgizzle is a GM brake engineer:

[cdb95z28]

Originally Posted by RUQWIKR

What I believe is the difference is that the "smaller" 6-piston fronts like J6M SS 1LE, J56 C7Z / GS steel use 30mm pistons vs. 32mm pistons (height). The J57 is ~32.6mm height for the vented fronts and the J6H's are 32mm. Guessing, the 23242510 kit would be closer to 30mm. I'll figure it out and let you know. If you used the J57 vented pistons on the J56 calipers, I could see how they would stick out farther as pictured.

If you have a stock J56 front piston handy, or someone have a J6M SS 1LE front out and about, measure it to see if it's 30mm height. As FYI, all the big fronts (including the carbon ceramics) mentioned use the same material and same PN outer dust seal boot kit.

Not sure if the first paragraph is referencing my pictures, but my pistons are from the J56 calipers. Once I separated all of the inserts from the pistons I cleaned everything up and used the Loctite on the inserts and installed into the pistons. The inserts all seated fully into the piston. Pic #2 pistons are the same pistons as pic #1

[RUQWIKR]

cdb95z28 - I saw where you had J56 fronts. I was saying what I thought would be the difference in the two listed front vented piston kit PN’s.

[cdb95z28]

Originally Posted by RUQWIKR

cdb95z28 - I saw where you had J56 fronts. I was saying what I thought would be the difference in the two listed front vented piston kit PN’s.

Cool, yeah, good info!

[h018871]

Thermally, I suspect aluminum makes sense. Although, for the $$$ I'd feel better if it was titanium.

[cdb95z28]

haha, yeah, I hear ya!