Nowanker

https://www.corvetteforum.com/forums...4-bbk-kit.html

Bill Dearborn

Having run the Ron Davis in my C5s for 9 years I am pretty sure you have a different problem than the radiator, I don't see 270 degrees oil temperature as too hot. I saw the oil temp go to 319 degrees on my new 2003 Z06 so 270 degrees is like a walk in the park. You aren't driving a 1960s piece of crap.

Myself and others that had the DRM setup didn't have on track cooling problems but did have problems on the street with the system cooling too much. Even when I added an thermostatic oil bypass valve along with a lot of hoses to get in place the coolant and oil temperatures only went up 30 degrees at full song. I don't know if a search would help you any but there were plenty of discussions about the cooling capacity of the RD Radiator on this forum about 18 years ago. When you have to add card board air blockers in front of your radiator to get sufficient oil temperature that might indicate the radiator is doing a great job cooling the engine. I could put my hand on the radiator tanks and feel heat on the driver's side and barely feel heat on the passenger side where the oil cooler is located. The return hose to the engine was cool to the hand.

If you don't have a thermostatically controlled oil bypass valve your coolant temps should be around 200 and oil temps around 230 after 30 minutes of hard track driving on a 90 degree day. You may have a problem that is limiting your cooling and I am pretty sure it isn't the radiator unless it has been damaged or plugged due to dirt inside or in the fins. I had to clean the fins on mine once due to running through a cloud of speedy dry that packed into the front of the radiator. We took the radiator out and dropped it about a foot face down onto a concrete floor. After dropping it 10 times we had a very nice pile of speedy dry on the floor. Following that I used an ice pick and hose to clean the crap out of the AC condenser. That was a 4 hour long job that I never want to do again. You have an old car and C5s are bottom breathers which tend to pick up a lot of crap and it gets into both the AC condenser and the radiator. The seals between the AC condenser and the radiator duct that I mentioned push outward into the engine compartment and then let a fair amount of air bypass the radiator. I found those pushed out on my 97 after 5 track days. The center air dam is another weakness as it does push back at high speed. I learned about that from a GM Engineer that used to participate in the forerunner to Corvette Forum back in the late 90s.

Bill

NoradIV

I didn't do an excellent job at putting the seals back there because they just wouldn't hold in place. I might drill holes and put a couple zip ties in there then. Also, I forgot about the condenser.

I guess that might be the problem. Thanks!

NoradIV

I am unsure what your whole post mean, however, my ultimate goal is to have a set of 18x10.5 wheels to stick the widest rubber I can get on them. This car is already seriously streching my budget with running costs, so going with a cheaper option that does 90% of the job for 20% of the price will always be my choice. The current wheels I have is this garbage (They are probably not that bad, but finding a race-friendly tire for those is not cheap, and the michelin pilot sport 4s cost 2200$ with this setup). 19x9.5 in the front, 20x10.5 on the back. I want a square setup to reduce tire cost by rotating them.

NoradIV

I do not have money before next winter, but I am going to keep an eye on the used part forum at that time. Thanks for the idea!

JRitt@essex

Lol...no worries at all! :p Even though the 325x32mm disc is the same size as the OEM, it is a far different piece of hardware! Along the lines of my previous statement, not all upgrades are created equal. The diameter and disc width only tell a part of the story. Vane shape, vane count, wall thickness, face cut, etc. all have an impact on much heat a disc can absorb, and how quickly it can cool down. Racing disc design is about efficiency. Your ideal disc is the one that can handle the amount of heat you plan to throw at it without fading, fits behind the wheels you plan to run, and will last long enough to your satisfaction. For many of our customers, our Sprint system gets the job done, and the biggest isn't always the best choice. Here are some examples of C5 Corvette owner feedback on our 325mm, four piston system:

https://www.essexparts.com/news-blog...regional-champ

https://www.essexparts.com/news-blog...n-brake-system

https://www.essexparts.com/news-blog...ake-kit-review

https://www.essexparts.com/news-blog...-brake-systems

https://www.essexparts.com/news-blog...t-buttonwillow

https://www.essexparts.com/news-blog...tion-brake-kit

https://www.essexparts.com/news-blog...-racing-brakes


As you said though, a larger disc will spread the heat out over a larger area, and may be the right choice for your car. That depends on a number of factors, as everyone's situation is different. If you answer the questions below, I will have a pretty good idea of whether or not our 325mm kit will get the job done, or whether I think you should go for a larger front disc.

Planned future horsepower?
Tire sizes and type?
Tracks being run?
Length of session (assuming 20-30 minutes, x4 per day)?
Any planned aero mods?
Planned suspension mods?

Please note, we're trying to assess your car's future state, not its current state. Your goal should be to select a system that will have you covered for the foreseeable future, so you won't be back in the same predicament anytime soon! Thanks.

Supercharged111

It really sounds to me like your issues are unique because of the short track you are running. Being in a lower gear with less airflow will tax the cooling system more. Have you tried a longer track to see if the issues remain the same there? No matter the setup you use I'd still have some spindle ducts. They made my brakes recover much quicker than without plus you can block them off if needed.

Walt G

I was waiting for someone to comment on this statement: " I know it is fluid because as soon as I bleed them, everything is back to normal. The fluid is the problem because when I go back home after the day, the pedal feel is garbage."

I agree that if bleeding fixes pedal feel then there definitely was a brake fluid problem, but in my experience, and per my understanding, simply 'boiling' fluid won't cause brakes to feel like garbage after they cool back down. When brake fluid boils, the brake fluid is going from a liquid state to a gaseous state. That makes your pedal feel terrible, or it can cause you to lose your braking force completely. I've experienced this.

But if that's all that happened, once that fluid cools back down and goes back to a liquid state, brakes are fine again.. this too I have experienced. I have boiled my brakes in the second of three track sessions, did nothing but let them cool back down, and then ran the third session with no problems at all by just taking it a little bit easier on the brakes. My drive home was fine also.

If I didn't change something they were just going to boil again, but generally speaking, once cool, they were fine.

If air has to be bled out, then that means air got in somehow, right? (<--- question for the brake experts, as I am not one).

Maybe as the boiled fluid is turning back to liquid the master cylinder isn't allowing fluid to flow back into the system to take up that space, so a partial vacuum is being created and that's sucking in air past the piston seals???

A BBK is probably a good idea, but I'd still say that the OP has got some other problem as well that needs to be addressed (as others have mentioned). Or I'd like one of the experts to explain to the rest of us how the OP can need to bleed air out of the system without some problem that is causing air to get in there in the first place.

Socko

https://www.corvetteforum.com/forums...-for-tips.html


I made this thread when i built my own brake kit a couple years ago. I think it will explain to you what i am talking about. I will go out on a limb and say i have substantial knowledge of c5z brakes. Mind you, you can build this system for 600 in parts, plus pads, plus $50 in 6061 if you know someone with a mill. If you are on a budget i don't think you can do any better. It allows you to tailor your thermal mass and rotating mass per circuit if you wanted too. It allows you to use the incredibly cheap stock blanks or any of the really great aftermarket stock replacement rotors from girodisc, dba or whoever.

96GS#007

The only time I've seen someone boil SRF on a 1 minute course in less than 10 minutes while on street tires is due to driver braking technique. Sounds an awful lot like someone dragging the brakes and being slow on/slow off entering and leaving braking zones.

What mode are you running in? Comp Mode? Nannies off or ?

mikehimself

I suggest buying temperature indicating stickers and putting them on the caliper to know what what your temperatures are. The fluid inside the caliper will be close to the temperature of the caliper body.

It sounds to me like you are over-braking. Generally faster corner speeds result in less braking effort. Try each of following techniques next time you're out and see if one works for you.

• Do a normal warmup and hot lap. Then take the entire course in a higher gear, focusing on the details of corner entry (turn in point, where you are looking, braking effort and speed).
• Let off the gas 2 seconds earlier than you used to for the hardest braking zone. Focus on doing as little braking as possible before turning in.
• A third technique is to do all of your braking in 2 seconds or less for each corner. As soon as you hit the pedal do a 1....2 count and let up.

I know that the internet doesn't like them as track brakes, but I have had very good luck with C6Z06 calipers and rotors on my C5. They are cheap and have never given me any kid of issue.

What track do you run?

NoradIV

I am actually glad you ask these questions. That show me you want to find the best product for my application.

Planned future horsepower?: I usually don't go for "planned horsepower". I spec a motor for good parts that make a great combo, and horsepower lands where it lands. The engine will be the last thing I upgrade, and when I do, I plan to swap the heads, headers and get a little more top end with a bigger cam. In the far future, I'd like to have a nascar-style high-revving bald-eagle screamer, but for the next 3-5 years, eyeball tells me 500hp at the tire at most.
Tire sizes and type?: I currently run Michelin Pilot Sport 4S at 275/30/19 in front, 295/25/20 rear, I plan to get a set of dedicated wheels for the track ending up to be 315/xx/18.
Tracks being run? : Mostly quebec tracks. For next year, I will be member of the ASE racing club, where we run at the Autodrome Saint-Eustache. I would like to add that most quebec tracks are quite small, mecaglisse is 1.2 mi, Mirabel is 1.7mi and Sanair is 1.25mi. There are other tracks (mont tremblant), but there are far and very expensive to run on. It is not where most of my events will occur.


Length of session (assuming 20-30 minutes, x4 per day)?: 2 or 3 20 minute sessions every monday, then a couple events at other tracks 4-5 weekends a year. Usually 20 minutes.
Any planned aero mods?: If I get to tracks I can use them, perhaps, but I am not knowledgeable enough to start this for now.
Planned suspension mods?: Eventually, I am not knowledgeable about this enough to answer yet, however, I plan to keep the car streetable for a while.

NoradIV

Saint-Eustache is 1.1mi long, and my best lap so far was 1:00.2 giving an average of 66mph. Top speed (100 mph) occur at turn 9, which is also the slowest turn of the track (38ish mph). This is where I kill my brakes. Perhaps that is not a fast enough track to get everything cooled down? Perhaps it is also why my RD radiator is not cooling as much as I would like to. I will run in 3rd gear almost the whole time. I will get in 2nd at the entrance of 9, and will get in 4th in the straights after 8 and after 15.

Spindle Ducts it is, then.

I also want to add that the fluid being bled is amber rhum color like. I have installed the lines myself and I will get no fluid problems on the street after 2 week of spirited driving, so I doubt leak is an issue. I also inspect my lines every week since I am there anyway (and I rotate my two front tires) and I haven't noticed any leaks. I will have it inspected by a garage next time I get the car in anyway, in case air actually get in due to improper installation.

I'll read that later. Thanks!

Competitive driving for now. Driver skill could totally be part of the problem, but I am not sure how to improve it. I have videos of me racing if you can look at them.

I have an IR thermometer, would that work? After a cooldown turn, I immidiately run after it and check the disk temp. Last time I checked I had 617 degree F.

I have done what you said, and if I run about 10 miles slower than I would normally, I do not get any fading. I have had this problem since I have decided to push it a little further because instructors said everything was very good (line, turn un points, looking, and speed). The real weakness I have is my braking, because I never know how bad my brakes will be.

I was trying not to do any hard brakes because I have noticed the problem is much worse when I do that compared to braking not as hard for a longer time.

C6Z06 brakes is something I am considering as well.

NoradIV

I would like to thank everyone for taking the time to help the little guy. I actually have a hard time answering you guys because of the amount of answers I get.

Socko

THis was my exact thought in my original post. Dragging will boil anything fast, there are weird cases where some slow tracks can be problematic, but still fresh srf boiling in 10 mins isn't a thing unless something is wrong or being used wrong, imo.

NoradIV

Alright. I'll try that next week. Short burst of hard braking.

mikehimself

To check the disks you'll need temperature paint. The IR gun will work on the caliper as long as you shoot 3-4" from the fluid filled side. Most IR guns will read the hottest point, which if you're not careful will be the disc. I recommend targeting a small patch of black tape to avoid reflection, and getting as far away from the disk while pointing. It's much easier when you have fixed caliper brakes with pistons right near the wheel.

Are you to the point of understeer on your way into the apex? Are you getting into the ABS?

It's a mental block that most of us have. If your brakes are 'troubled', you use them more, you know because of survival! At corner entry, if you're braking hard and late, it puts a lot of stress on the front tires (and brakes). The tires have a limited amount of grip, so what you'll find is that letting off the brakes will transfer some weight to the rear, allowing all of your tires to help turn the car in. I have over 500 laps at Watkins Glen, and I still play this mental game going into turn 6. I need to let off the brakes to get the grip to turn in, but high speeds + low runoff makes me overbrake. The moment I get the car pointed in, I get mad at myself and get back on the gas.

Heat generated in the disk/pad interface is transmitted through the pad, through the pistons and into the fluid. The fluid dissipates heat into the caliper. While this is happening, air is cooling the disk and the caliper (and everything else). The amount of braking energy determines the total heat load. The majority of that heat goes into the rotor because of the large swept area and the properties of the steel. The heat that is transmitted through the pad must go through the pad, the backing plate and the piston to get into the fluid. Titanium is poor at transferring heat compared to steel and aluminum, so some people put a thin titanium plate in here. It can help, and I used to run them on my Subaru. A large factor in this is the piston design, and brake pad thickness. The thicker your brake pads are, the better off you'll be. Most people recommend throwing the pads away at 20% material thickness or 1/8", due to the heat transfer.

You should post up some in-car video.

NoradIV

Yes, the car is understeering into the apex of 2,3,7,8,14 and 15.

I have practiced a lot not to get into the ABS, and I very rarely reach it unless I hit some bumps on the track. The brake fade is bad enough that at about half the track I can barely reach ABS even at the floor.

Well, that is some serious advice here. I didn't realize I was doing any of that. You make me think that the problem might be the understeer forcing me to break more than I should resulting in a brake problem.

Maybe I should try to get some more front grip?

Any other cool tips you have up your sleeve?

I'll upload a video tonight (warning, 20$ ebay action cam crap quality coming).

Bill Dearborn

I gathered the parts of the seals I could find and added some similar foam insulation, pushed it in the gap from the inside of the radiator duct and then used 2 inch wide duct tape over laid over the filled gap to hold the insulation in place and to keep the wind off it. That held very well.

Bill

MatsA