KNSBrakes

I've talked to Brett at length. He started with EBC's on his 5th gen and as expected it torches them.

I did do a torque calculation between the 5th gen and C7Z fronts and it increased the torque ratio 5%.

I did use 30/34/38 as piston sizes for the C7Z calipers.

-ken

0Todd TCE

The Z28 four pot front and rear calipers are nearly identical in area to that of the Corvette unless you take it out three decimal places. Oddly GM put a diff bore on the rear of the Camaro for some time and then appear to have cheaped out in 2017?

2015 CAMARO
40/44 fronts @ 4.2"
28/32 rears @ 2.2"

2017 CAMARO
42/42 fronts @ 4.2"
30/30 rears @ 2.2"

C7 CORVETTE
30/34/38 fronts @ 4.2"
30/30 rears @ 2.2"


* Should add that some of that is based on some data a few years ago when I was more active in the Camaro market. Things could have changed a bit more and I certainly could be off a bit on the numbers today.

Dropspeed

I ran C6Z non CC 6 pistons with vented pistons and 2 pieces rotors on my 13 1LE with Hawk DTC-60F and DTC-30R pads, Castrol SRF and had a 3" brake duct to the fronts. This set-up worked well with a stiffer sprung car (I had complete Z/28 suspension) as it mitigates the front end dive. HOWEVER the calipers will need annual attention and may be considered disposable item at $400 each as they do not like the heat over time. (ALL depend on how YOU drive).

I swapped to a Essex/AP9668 kit and it was amazing...Price of entry is higher. But the last brake set-up you will ever need for that heavy platform.

Matt

chuntington101

Just came across this in a Piston heads thread. A guy that works for a race team run a 911 and seems to have upgraded everything on it with race car inspired stuff. Anyway he is upgrading the brakes with some lovely new floating disks that just make soo much sense!

https://www.pistonheads.com/gassing/...1160#seperator

(Top of page 13 in case it doesn't work)

Anyone like to add their thoughts? So simple & solves many issues! Why isn't this standard on after market floating disks?.....

KNSBrakes

Can the hat be Aluminum in that design?

JRitt@essex

That is not really a new way of mounting a hat to a disc. Brembo does it this way in racing, and it's generally referred to as float-in-hat. The downside to this method is that the iron is pounding directly on the aluminum hat, causing it to wear out faster. The float-in-disc method (which is what we typically use at Essex/AP Racing) places the load on the iron, which is much stronger, especially at high temperatures.
Aluminum loses half of its strength at 350F, and this design places the teeth of the iron disc in hard solid contact with the aluminum hat. Yes, they use it in professional racing, but they also tend to replace hats and discs after every race. Our aftermarket customers don't want to constantly replace the aluminum hats. Our experience has shown us that our system is more wear resistant and less prone to problems, particularly at high track temps.

The weight difference is also not that much. You're probably talking about roughly 0.5 lb. per corner.

Comparing to an F1 design is not such a great comparison. F1 uses carbon/carbon discs, which require a very high number of contact points because of the weakness of the material when edge loading...a different can of worms than iron.

chuntington101

JRitt, thanks for the response. So you are saying that the conventional bobin approach is stronger / less harsh on the ally hats (bobin / iron disk take the load)? Also less heat being transferred to the hat. That makes sense.

I guess we will see what the guy in this thread reports back. He dose loads of miles in the 911 (think it's about 30k per year) so we will load test it on the road and track.

JRitt@essex

Yes. In a float-in-disc design like we use, the bobbin slides in a channel in the iron ring as the disc heats and expands. Over time the iron ring won't wear out in that area, whereas hot aluminum will. Below are some illustrations from our website. As an FYI, we have sold thousands of our Essex Designed AP Racing Competition Brake Kits over the past five years since the program inception, and under normal use I have never seen a failure on the disc flange in one of our kits (the flange part of the iron that juts out, where the disc attaches). By normal use, I mean any scenario that does not involve crashing into something at a high speed!

Over the years AP has put a lot of time and study into the design of those flanges, how much thickness is required, their shape, etc. In terms of test miles, their designs literally have millions of full race miles under their belts in a huge range of environments...F1, IMSA, DTM, Aussie V8, WRC, etc.

The float mechanism we use is simple, relatively inexpensive, doesn't contain a million pieces of hardware/attachment points, doesn't take a long time to change, allows the aluminum hats to be used over numerous iron disc changes (which for our enthusiast customers equates to years in nearly all cases), the jet nut locks the hardware down without the use of safety wire, and the AKB spring clip virtually eliminates all noise and rattling. It has proven to work exceedingly well across all environments our customers encounter.

Dirk Miller

beautiful set up Matt! Will send you a P M

fatbillybob

JRitt,

Here is my question: Lets assume new calipers or newly rebuilt new seals and floating 2 piece rotors etc. After a session on track it is easy to push the car around when in neutral by 1 person. After car and brakes cool to room temperature it takes 2 guys pushing hard to move the car around. Something causes the pistons to expand out of caliper bores and basically put the brakes on. You can drive the car no problem brake heat up and calipers don't drag. Brakes back to room temp and calipers drag. Forcing pistons back in calipers and 1 guy can push the car around again. Question is what causes the "cool down" caliper brake pad drag?

johnny c

Im not JRitt
But what calipers are you using?

johnny c

thanks for the info. i was grabbing my information from the pro touring Camaro guys that insisted on using corvette calipers and had nothing but issues.

johnny c

J Ritter,
We have guys using the FLoat in the hat or "direct drive". with all of my years at OG we haven't had one wear out yet. All components on race cars are wear items but they aren't burning as fast as you implied. at a club racing level, a hat will last you 6-7 disc changes. At a club racing amount of youse, that's easily 6+ years.
Rotational unsprung mass is 4x as important as sprung mass. so remove one pound from each corner and it will act like removing sixteen pounds from the chassis.

This is also one of those things that Jeff and I disagree on. much like stainless pistons. it's a few topics of finite braking only brake nerds will really get worked up about.

johnny c

Explain all the things.

rcroadrider

I have a c3 1970 with leaking Calipers ,do you think it is worth the extra money to get Stainless sleeved ones and o rings, or as long as SS Sleeved the o ring ones are not necessary

Bill Dearborn

I had stainless steel lined calipers on my 71 for about 5 years and never had a problem with them. However, I hear the O Ring Seal works better than the lip seal. For the slight extra cost (on some stainless steel lined caliper brands I have seen $10 extra for the O rings) it would probably be a good idea to go with the O Rings.

Bill

fatbillybob

Does not matter what calipers. I have seen it with Stoptechs, oems, and brembos, and ATE's.

That video above that talks about mechanical pad retraction but just enough to prevent long pedal is evidence that the issue I talk about with brake drag exists.

0Todd TCE

The sticking issue is a problem I remember dealing with about 20yrs ago on the new aluminum body FM (formula mazda) car calipers. The old iron parts were getting harder and harder to find so the builder had new aluminum copies made. Everyone loved them for the weight savings but in the pit they'd complain of exactly what you're talking about; excessive drag.

After some track testing with thermal couplers and such it was determined that they were not dragging on the track with normal heat cycles. But once parked for more than a bit they become heat soaked. Let them sit for 15-20 and they were back to normal.

Once the "fast kids" (dad) realized it wasn't slowing his kid down everyone just lived with it. Never seemed to have an impact on lap times.

JRitt@essex

Does the caliper in question have anti-knockback springs? If so, possibly related to anti-knockback springs behind the pistons pushing them out over time. Seals are also harder (they grab the piston a little better when warm and softer) and it is easier for the piston to slip through the seal when it is harder (cold).
Time alone is likely some of the factor as well. Have you tried the experiment you described while keeping the brakes cold? Engage the brakes, but don't get them super hot and see how it rolls? In other words, is it a matter of the heat causing the issue, or just a matter of engaging the brakes and needing some time for things to go back to steady-state?
Just trying to eliminate some variables!

I'm not saying that 'float-in-hat' systems are the devil. We actually use that attachment mechanism when packaging won't allow us to use 'float-in-disc'. We actually do so on our C7 Z51 replacement discs. We just don't view it as ideal, and we prefer the other way of doing it when we can.

realtinker

is it hard to rebuild/repair the power brake booster ?