Venom F14 '03 Cobra Brake Kit - Installation

[sonicmach1]

Now that they are bedded in they do really haul the car down. I haven't gotten them on the track yet, but I can tell they will work out well.

FYI, I weighed my tire/rim combos. They are definitely not track-freindly weights:

51.9lbs for the 275/18s fronts
56.4lbs for the 315/18s rear

 

[wheelhopper]

^What kind of wheels are you running. I used Saleen replicas with my 18's and while I did not weight them I go to the gym regularly and a 45lb plate feels heavier than my tire/rim combo.

 

[sonicmach1]

^What kind of wheels are you running. I used Saleen replicas with my 18's and while I did not weight them I go to the gym regularly and a 45lb plate feels heavier than my tire/rim combo.

They are 18" AFS replica wheels - 18x9" and 18x10.5" with the Pilot Sport tires. I have not yet mounted the R888 tires yet.

 

[Jimmysidecarr]

I'd love to see a test fit of a 95R R58 17 incher!
I did a test fit on a friend's Y2KR with the 14" Brembo Gran Turismo 4 piston kit.
The barrel cleared but the spokes appear to need a 1/4" spacer.
That is a different caliper than the VV F14 Brembo, I believe the rotor offset may be different too.
My friend had the 2 piece rotors, and we wondered if the hat is thicker than on the Iron GT500 rotor used on this kit?
That would effect the number of threads available on the wheel studs while using a spacer. Possibly mandating the use of extended studs.

 

[sfs32vcobra]

Looking good Brian!

Our buddy ac427cobra is now offering a nice two piece rotor setup that is a direct replacement for the GT500 14" rotors. Saves about 15 pounds total if you also use his two piece solution on the rears as well.

He also has an excellent cooling collector that fits in place of the S197 splash shields. With some ducting from the front facia, this combination of cooling / calipers / rotors yields outstanding braking performance, significantly better and more fade resistant than the cooled factory Brembo 13" setup on my '00R.

Here is the link to a thread with details regarding these rotors.

Here are a couple pictures of them as installed on my '07... I'm liking them a lot!

:beer:

 

[BlackBolt9]

That chart was generated with 18" FR500s.

I would imagine temps to increase by some % if you stuffed rotors tightly in 17" rims. I have to believe the vented benefit would suffer from lack of open air.

With proper brake cooling ducts I wouldn't be too concerned about rotor temps increasing by much at all. I would bet that the same amount of air will be forced through for the most part. If the brake system were on the edge with 18" then it may make a difference but I don't think that is the case, especially when you are running sessions as short as most open track groups run.

The thing I would be more concerned with is how much hotter the wheel will get from the hot air exiting the rotor. It may be something to keep an eye on with stick on temp sensors on the wheel near where the rotor is. Also, if you aren't already running nitrogen it would probably be a good idea to start. If you stuff brakes that large with so little clearance the internal air temperature is likely to increase and mess with you pressures more than previously.

 

[ac427cobra]

Looking good Brian!

Our buddy ac427cobra is now offering a nice two piece rotor setup that is a direct replacement for the GT500 14" rotors. Saves about 15 pounds total if you also use his two piece solution on the rears as well.

He also has an excellent cooling collector that fits in place of the S197 splash shields. With some ducting from the front facia, this combination of cooling / calipers / rotors yields outstanding braking performance, significantly better and more fade resistant than the cooled factory Brembo 13" setup on my '00R.

Here is the link to a thread with details regarding these rotors.



Here are a couple pictures of them as installed on my '07... I'm liking them a lot!

:beer:

Looks good Scott! Thanks for posting that up!

:thumbsup::coolman::beer:

 

[Jimmysidecarr]

With proper brake cooling ducts I wouldn't be too concerned about rotor temps increasing by much at all. I would bet that the same amount of air will be forced through for the most part. If the brake system were on the edge with 18" then it may make a difference but I don't think that is the case, especially when you are running sessions as short as most open track groups run.

The thing I would be more concerned with is how much hotter the wheel will get from the hot air exiting the rotor. It may be something to keep an eye on with stick on temp sensors on the wheel near where the rotor is. Also, if you aren't already running nitrogen it would probably be a good idea to start. If you stuff brakes that large with so little clearance the internal air temperature is likely to increase and mess with you pressures more than previously.

I would love to have some of those problems compared to the rapid consumption of pads and rotors I am currently experiencing.:-D

I agree that the nitrogen would be an easy fix.
Seeing how much cooler the 14s operate than the 13s I seriously doubt there will be even close to the same amount of heat accumulated in the rotors and pads. It is literally HALF!!! Tracking a car with almost the same weight as a GT500 with almost the same power creates some large demands on the brakes. Speeds at the ends of straights are pretty close, yet I have far less braking capability. When I can afford to I am going to change that, and I am going to do it with 17" wheels and tires. If it means spacers and longer studs, so be it.

 

[BlackBolt9]

I would love to have some of those problems compared to the rapid consumption of pads and rotors I am currently experiencing.:-D

I agree that the nitrogen would be an easy fix.
Seeing how much cooler the 14s operate than the 13s I seriously doubt there will be even close to the same amount of heat accumulated in the rotors and pads. It is literally HALF!!! Tracking a car with almost the same weight as a GT500 with almost the same power creates some large demands on the brakes. Speeds at the ends of straights are pretty close, yet I have far less braking capability. When I can afford to I am going to change that, and I am going to do it with 17" wheels and tires. If it means spacers and longer studs, so be it.

Jimmy,
I looked at your chart and am not sure I really have faith in it. I don’t know how they did their testing but I can tell you that our 3300# (no fuel, no driver) S197 Continental Challenge cars that run 14” front rotors and even better Brembo calipers, still have close to 1000deg rotors temps in 30 minute practices. It’s usually either the Brembo or PFC field engineers taking the temps, so I have to believe they are accurate.

Even though the rotor is larger (meaning it can hold a larger amount of heat) the actual temperature of equilibrium should still be the same since the metal is still the same (or similar) and has the same rate of heat transfer. Also, you still have the same weight car, you are trying to slow down the same amount in the same distance. This means you are shedding the same amount of kinetic energy, and that pesky law of conservation of energy then states you must change that same amount of energy into heat (in this case).

I can only assume they made this chart by going out on the first brake set-up for a couple laps, and took temps, then did a couple laps on the next set, and so on, WITHOUT letting the systems get to their equilibrium temperature.

And FWIW, I don’t think you really want your rotors to run 500deg because most (if not all) race pads are designed to work properly at the higher temperatures that are produced on a race track but that is a question for your pad supplier not someone with as little knowledge as I about that topic.

BTW, this is all just my hypothesis, there are many people out there with more knowledge and a better understanding of this, so if you can find a better explanation that either proves or disproves what I’ve said, I’m all ears to learning more.

As far as wear goes, it is what it is if you wanna go fast No one ever said racing was cheap:-D

 

[gcassidy]

Tom, I hope I'm not muddying the waters here, but your bringing up the temperature of equilibrium makes me wonder if that's what NASA's lead instructor was always talking about in classroom. He stated (and was generally agreed with by drivers faster than me), that compressing the brake zone actually cools the brakes (to a slight degree). It's almost counter-intuitive, because you think you're using the brakes harder, and that they'd get hotter. But he argued that the brakes would hit their maximum temperature regardless of going another 10 feet (or whatever) into the brake zone, and that by traveling that extra 10 feet you were getting 10 feet of extra cooling. This made sense given that the brakes were maxing out in their temperatures either way. I'm assuming this is what you're referring to in the "actual temperature of equilibrium", which lends credence to what he was saying (I always beleived him anyway because he was Dan, and you just believed in Dan).

 

[BlackBolt9]

Tom, I hope I'm not muddying the waters here, but your bringing up the temperature of equilibrium makes me wonder if that's what NASA's lead instructor was always talking about in classroom. He stated (and was generally agreed with by drivers faster than me), that compressing the brake zone actually cools the brakes (to a slight degree). It's almost counter-intuitive, because you think you're using the brakes harder, and that they'd get hotter. But he argued that the brakes would hit their maximum temperature regardless of going another 10 feet (or whatever) into the brake zone, and that by traveling that extra 10 feet you were getting 10 feet of extra cooling. This made sense given that the brakes were maxing out in their temperatures either way. I'm assuming this is what you're referring to in the "actual temperature of equilibrium", which lends credence to what he was saying (I always beleived him anyway because he was Dan, and you just believed in Dan).

That is following the conservation of energy thing more so than the temperature of equilibrium.

You are stopping the same weight, quicker but in a shorter time gives off the same amount of heat energy to the system. Therefore the total amount of energy into the system stays the same, either way you brake, therefore making no change except that you do get a longer time to cool them off so you end up with a longer period to remove heat from the system. This should in theory actually lower your average brake temperature, but I am guessing it is a rather small amount that may even be negligible.

The temperature of equilibrium is the temperature the system is at when everything stabilizes out. I do agree that this temperature could be different for the larger brakes than the smaller ones (since the larger brakes have more surface area to dissipate heat). The thing I was trying to get across was that I don’t think that chart is accurate and I DON’T THINK that there will be that large of a difference. But I also haven't done back to back comparisons or the mathematics to determine that OPINION. I'm just giving my thoughts from what I've seen working with 14" brake systems on Mustangs.

 

[gcassidy]

Thanks Tom. Wish I had taken engineering in college. Not only would I understand this better, but I could maybe afford better equipment. :loser:

 

[Jack Hidley]

Greg,

Tom is of course correct that for a given initial and final vehicle velocity and vehicle mass, the amount of work done by the brakes is a constant. However, there are some other considerations.

When you brake 10-20' later, the vehicle has been accelerating that much longer and is traveling slightly faster (higher Vi).

When you leave your braking to the last possible instant, you are going to compromise your entry line into the corner some. This is going to require you to be going slightly slower entering the cornering phase to not miss the apex, so Vf is slightly slower.

These two factors make the delta V slightly greater. You are also spending less time under braking, so more work is done by the brakes, resulting in slightly higher average temperatures.

However, the biggest difference is this. All of the thermal energy that is generated during braking occurs at the brake pad to rotor interface. The rotor has 3-5 times the thermal mass that the caliper does. So for a given amount of energy put into the system, the rotor temperature is going to rise more slowly. Bodies with large mass give you high thermal capacitance. This means they filter out the peaks and dips in the temperature as the energy input to the system goes up and down.

Since the caliper has much less thermal capacitance, its temperature goes up and down much more, following the varying energy put into the system. So when your total braking time only lasts 3 seconds instead of 3.5 seconds, the energy/time (power) goes up by the ratio of 3.5/3 (1.16). This means your caliper, brake fluid and brake pad temperature is going to go up an amount proportional to this ratio nearly instantly, while the brake rotor temperature is only going to increase in temperature a much smaller percentage. Similarly, if your total braking time is constant, but the delta V is the same, the energy/time ratio is higher and the same thing occurs.

Once the brake fluid gets too hot, no more brakes. The gas doesn't magically reform into a fluid once the temperature drops 3 seconds later. If the pads overheat during this transient, they may recover 5 seconds later if they are good track pads (while you are parked in the tire wall), but if they are organic street pads, the binding agent may overheat and they will start falling apart never to return to normal behavior.

Granted I'm ignoring a lot of things going on in the system (rotor cooling, brake pad thermal resistance, etc), but none of that changes the underlying laws that govern thermal behavior in the system.

 

[gcassidy]

Jack, honored to have you over here. I've re-read a couple times what you're saying, and think I understand the specific points about the caliper having a quicker and more varied rise and fall in temps than the rotor, as well as the effect that braking later has on your line. Am I correct in that you're saying that compressing the braking zone will have more of a detrimental effect when the brake system (pad choice, fluid type and age, presence of cooling ducts) is not at its best? I couldn't agree more. But I expect there's more there that I'm missing.

I should have pointed out the techniques of compressing the braking zone was one of the skills Dan was teaching in the HPDE classes, when you're working on developing the skill in intermediate drivers, who may still have a bit of trepidation in exploring their braking limits. The extra cooling times was mentioned as one of the by-products of braking later, the chief one being carrying terminal speed longer.

 

[BlackBolt9]

Jack, thanks for the more accurate and more in depth description of what is happening. It's always good to have someone with more knowledge of what's going on give a better understanding of what is actually happening. I have a very basic idea and was hoping someone who knew more would chime in and do a better job than what I was doing. Do you know of any accurate data between 13" & 14" braking systems?

 

[Jack Hidley]

Greg,

Yes, basically the temperature of the brake pad and fluid should vary up and down more quickly than the rotor itself, so the pad and fluid are more susceptible to overheating when you brake very late, putting more power into the brake system.

I've never seen anyone fade brakes from braking too early before the corner. I've only seen it happen when braking too late.

Tom,

I'm not sure if you know who the owner of Vintage Venom is, Rob Eaton. The link below has a short blurb on his history at Ford. I only bring this up, because I think it is good evidence that he isn't some yahoo who doesn't know how to do brake testing.

It does seem to me that his brake test temperatures are pretty low, but as long as they were running consistent lap times with similar brake points, I don't think that will affect the results in a meaningful way. I don't remember where they were placing the IR sensor or if it was even calibrated for the emissivity of the object it was pointed at.

I haven't done any instrumented testing of his 14" brake kit. I believe that Scott W did some testing of a different 13"/14" brake kits at Rehagen a couple years ago.

***I just looked at the chart that Jimmy posted in this thread***

There is a bunch more data on the temperature testing that Rob E did and posted on some other forums. I'll put a link to it below, I'm not sure if it will get censored or not.

Ford Mustang Engineer

[ame=http://forums.corral.net/forums/showthread.php?t=1228257]Brake Cooling Duct Testing - Temperature Results - Corral.net : Ford Mustang Forums[/ame]

 

[BlackBolt9]

Jack,
No I did not know who the owner was or his background. I may have met him at some point and just don’t know it or have seen him around but not been introduced. He obviously knows everything he should and his product is proof of that. I was not trying to trash him, his company, or their product. In fact, I think it is an excellent value for bigger brakes.

The only point I was really trying to make, before it spiraled into much more, was that a 14” brake kit, driven hard on track will not operate at 500deg. I do know that from my experience as limited as it is. I have no idea what that chart represents but I thought it was very misleading and wanted to point that out since it was posted here in this thread. It may be better explained some where else but it wasn’t here. I will have to do more reading and check out those links when I’m not at work. Thanks again for the additional reading and information!

P.S. I’ll have to ask Scott about the testing he did and if he has any notes leftover still.

 

[whipplecrusher]

Hey what brembo brakes can i get that are 4 piston that will fit on stock 2004 cobra rims they are 17inches?

 

[cobra-boss]

00R will fit with no problems. You will run stock 13" rotors, and the calipers are a bolt on.

Jim

 

[sonicmach1]

A few better pictures of the front brake kit.