Not sure anyone will be interested but--

Another one of those projects that takes longer at age 79-

Today I moved the F250 out of the upper garage and moved the Corvette into the F250's place, jacked up and put the Corvette on jack stands for front brake rotor and pad replacement.

I always hang the caliper from a pre installed hook in the fender well. The calipers came off easily, only two bolts, blue thread locker, at 23 foot pounds. I hang the caliper with wire from the hook in the fender well and also set it on blocks. Note the wheel angle for better access. Start the engine to turn the wheels or you may overflow the PS reservoir. Ask me how I know.

The Caliper bracket bolts require a cheater. Or bigger muscles than mine. Factory installed caliper bracket bolts are installed at 125 foot pounds + with orange thread locker and absolutely require a cheater or use of a floor jack on the breaker bar. The FSM says to replace these bolts but I have found that blue thread locker works fine. These below were installed with blue thread locker five years and eleven track days ago, still very tight but came loose with the cheater:



1/2 inch drive breaker bar plus two feet-

Originally installed caliper bracket bolts on the rear will require the car to be raised quite high for cheater or floor jack use because the rear wheels cannot be turned at an angle for better access like the fronts.

The old rotors should have been fine- but they were not. StopTech cryogenically treated slotted rotors installed five years and 11 track days ago:




They had very little wear -- but -- were starting to exhibit radial cracking -- -- And had exhibited annoying vibration on the track when braking at close to wheel lock up FROM THE DAY they were installed. I would have run them another year but the braking vibration (ONLY on track) bugs me.

I never had any need for more braking authority on track (16 track days 2011-2018) or the street with the former OEM style plain rotors but decided to try slots when the OEM style rotors became badly worn. I already knew that drilled rotors were often subject to cracking but not slotted ones.

The new rotors are PLAIN SOLID but coated PowerStops. We will see.

The PowerStop coated rotors have a ridiculous break in procedure - 30 stops from 30 to 5 mph, 30 seconds for cooling in between each. Where are you going to find a desolated road where you can do that? I got 16 in then in frustration 5 more stops from 50 to 20 and then let them cool. Again, we will see.

The pads I put on for the sixth time are Hawk HP- Plus. Never any need for more braking authority on track or street, 45,000 miles and 27 days on track. They do dust and will squeal. On the street I turn up the stereo-

New HP-Plus front pads measure about 0.570" thick including the steel backing (0.205"), so net new pad thickness is about 0.365".

Today this thinner, worn old front pad measured 0.367" total, or just 0.160" of pad remaining. NOTE TO SELF: change the pads sooner next time! The pad friction material is the heat insulator between the brake piston and brake fluid and the VERY HOT rotor on track.





Like my buddy Bill said once - "Good thing you are not hooked-"

Next on the Corvette, smaller auxiliary transmission cooler and brake flush with, as always, ATE TYP 200, before March.

Other- T-5 transmission and various parts ordered for the 1955 Mercury.

Switched vehicles back, light snow started late PM. Good thing, the Corvette tires are NOT good snow tires.

Jim



Arizona Motorsports Park late October 2023

 

Never been fans of Powerstop. I can even get them at cost and avoid them. Just my personal choice. The treated factory GM Rotors have been good for me in most applications.

While many on the road put on big brakes they generally are not needed. You never reach the level of the factory brakes on the street. But at a track time and depending on the track, the way you drive, what pad you run and how many laps you may need larger brakes.

You may want to put some temperature paint on them to check the heat limits are seeing. Odds are you are getting them over temps. They may still stop but they are going to eat the rotors up.
You have to remember the rotor is nothing but a heat sink. it removes the heat from the pads and the larger the rotor the better the heat is absorbed and transferred.

It is not so much the bigger pads but the rotors that come into play here.

I would first look into cooling ducts. Get more air in to lower the temps first. That is a much easier thing to do first. At least do the fronts. You already have air coming in now connect it to the caliper. Its are out there.

 

There is nothing wrong with stock C5 brakes on the track other than they do not last very long at all. Remember back in the day that the T1 folks ran the stock factory brake setup, just with better pads. Yes the C5 calipers will spread, yes the 12.8" rotor will heat check. I know racers that used to have spare calipers and a couple sets of spare rotors in the trailer at each event. I used to destroy C5 calipers on a custom 13" front brake setup with Hawk Blue pads back in the day, but that was on a nose heavy FWD application and a whole different story.

The main issue with the stock C5 brakes is lack of sufficient thermal mass in the fire path with the stock 12.8" rotors. But moving up to even a slightly larger diameter front brake setup requires 18" front wheels which also adds to the expense. If you are interested, the first budget upgrade for the C5 involves using the factory C6 base calipers (which are somewhat less likely to spread than the C5 calipers and use the same pads as the C5 calipers) fitted with DRM stainless steel pistons and Ti or stainless steel pad shims, both help to reduce the heat transfer into the fluid. Then mount those C6 calipers on the taller front C6 Z51 front caliper mounting brackets and use the larger C6 Z51 13.4" front rotor - just make sure to use an aftermarket non-cross drilled rotor such as say the Centric 125 Series. All of this is bolt-on to the C5 and the consumable items are easy to find and inexpensive. Better brake fluid (like what you are using) and SS braid brake hoses, as well as the above mention addition of cooling ducts or air defectors will all help in dealing with the extra heat at track events. Pads choice is personal taste, although the HP Plus is fairly aggressive, it is basically a great autocross pad. Its not the best dual purpose pad for both street and track use, but if you don't want to change pads and it works for you and as long as they doesn't fade out in the big braking zones on the track, then just be careful out there.

How are those front bearings? Track use tends to destroy them fairly quickly. The cure is SKF Tracker-X bearing, again not inexpensive but they cure the problem.

 

I raced T1 back in the day. It was not by choice but by rules that forced us to us substandard oem brakes. We fried race pads in 1 weekend and cracked front rotors on the 3rd day. It was only after we proved the OEM brakes at 3180lbs was unsafe that we were allowed big brakes. Now it is even worse because in T1 and T2 we have to run even heavier. In T2 we are 3425lb min weight!

 

My comments have little to offer for track - I have zero experience there. But I can bake a set of ceramics into fade real fast all the same.

For my Z06 I lucked into calipers which are an older design for AP but far superior to anything I have ever used. And in this hunt I also learned that I don't need to run the expensive two-piece rings, but can use in my case C6Z06 discs from KNS for just $100 per unit. I looked up a generic 2000 C5 and they sell their discs for $80 a pop. Enough track runners turn to the family over there that I figure they are worth a look.

Sad to hear of the downgrade in quality for the high carbo cryo Centrics. I swore by them myself for five years while paired with an old no longer available StopTech street/track pad. I could slap the nose of the car into the pavement at whim and control it nicely. With RBF600 in the lines it was a great combination for what I'll call spirited rips up and down the hills. What they gave me was confidence that I had access to the full range of braking power to be demanding from factory brakes provided they were not cooked. Since Centric spun StopTech mostly back into the fold it feels like the company has turned its back to performance and to quality offerings.

Link: KNS C5 Discs

 

fatbillybob - Yes I should have stated for clarity sake that back in the date the T1 racers HAD to use the OEM setup by rules and not by choice.

Tucs - The VERY expensive 2-pcs rotors are not needed when doing brake upgrades where those setup are designed to use an OE replacement rotor. The only reason I choose to go that route was for the huge weight reduction vs the 1-pcs replacement rotors. On my setup with the 14" C6 Z06 front rotor it saved 7 lbs per corner and with the 13" C6 Z51 rear rotor it saved 8 lbs per corner and while still keeping the parking brake function.
Plus they look really cool too!

 

I went 2 piece rotor and fixed caliper at the same time on my Camaro, transitioning from a C5 brake setup. The C6 calipers did absolutely nothing over the C5 calipers. When the brakes get hit the pedal gets long period. There is simply no comparison to the fixed caliper and 2 piece rotor. Brakes on track are so much more consistent, I couldn't imagine going back. Nor could I imagine running HP+ up front as a track pad.

 

Yes, the OE C5 brakes are adequate for the street. I'm not sure why they are being defended, as the OP is having issues due to track use. Several different brake limitations of the OE C5 brake system can readily be observed on the track. One of these is cracked rotors. High heat loads and uneven expansion and contraction due to these heat loads can cause cracking, especially with drilled rotors. Solid, or solid/slotted rotors can be tried and if of decent quality manufacture, they should perform better than drilled rotors. Additionally, some rotors appear to shed heat better than others, apparently due to rotor vane design. For instance, a lot of folks have good things to say about DBA rotors - both their one-piece and two-piece options. If the cracking problem persists, then two-piece rotors should be considered, as their friction surfaces are more easily able to expand and contract without the stresses experienced by sold, one-piece rotors.

But, before moving to more expensive two-piece rotors, there are a few other things worth consideration. First, removing the rotor splash shields can significantly improve heat shedding. Another thing to consider is brake cooling ducts and the fact that brake ducts, if not properly executed can actually make the problem worse. Have a look at this article for some thought starters: https://www.essexparts.com/news-blog...n-my-track-car

 

There are proper kits that can be bolted on to the existing ducts that will improve cooling if you are track timing.

Drilled rotors should be avoided.

The key to good brakes is to have a good size pad and to remove the heat from the pads. Rotors are heat sinks and they transfer the heat for the pads. This is why the brakes on the C5R are large and have cooling ducts. Track time is not much different. None of this really matters on the street but at the track it can save you an off that can do some real damage.

There are upgrades for street and there are upgrades for track. The price is much different as is the performance. Most good track brakes will put you on the belts when stopping repeatedly.

 

Keep in mind that those slash guards also act as heat shields to protect the ball joint boots. If you remove the shields, then you will need to somehow protect the ball joint boots.

 

If you feel more comfortable trimming back the sides and top of the splash shields, rather than removing them all together, you won't get an argument from me.