ACR E Brake Fade

[eckeph]

I just attended my first Time Attack event. It was a pretty fast and long track and during training I experienced some alarming brake fade. It happened 4 or 5 times in the braking zones after the long straights. Suddenly when I braked I had maybe 30% less brakes. After having run straight into the run off zones for the last time I decided to call it a day.

I run Endless Brake Pads most aggressive track pads for CCD (CCD-R) Not sure if you have them in US but here in Europe they are very well renowned and come recommended by other high profile ACR-E owners. I have Motul RBF 700 Factory Line brake fluid.

I have no modifications to my brake set up other than the TKO Brake Line kit. My theory is that I need more cooling (confirmed by a Swedish National Champion in Time Attack, who also runs an ACR-E) So, my question is, has anyone who has run into these problems bought the TKO Brake Cooling kit? If so, what are your experience?

[TKO MOTORSPORTS TEAM]

We have never had any problems with the 5th gen viper ACR carbon brakes. They have impressed all of our drivers pro to amateur how well they work and how much abuse they will take. Here are a few things to take a look at that may help.
1. make sure your not dragging the brakes. Leaving your foot resting on the brake pedal even lightly; Many drivers will do this with out knowing very common problem. Use the brakes and get off them
2. Change brake fluid often, hot bleed the brakes
3. Use PFC 665 brake fluid. We tested every readily available racing brake fluid on the market. PFC 665 by far the best performance.
4. Make sure your brake fluid is fresh. Once you open the bottle and break the seal that fluid is only good for 3-6 months for racing applications depending on environment.
5. Use a sweat band around reservoir.
6. When you pull off track and stop do not keep your foot on brake to hold car. Hot carbon rotors will heat transfer and soak the calipers very quickly.

[Lawineer]

If you’re getting fade on carbon ceramics, it’s almost certainly the fluid. If not, something is dragging or it’s your driving.

[Viperawi]

I just wanted to highlight here, that I abuse my ACR-E brakes on track, and never had any brake fade issues, and it is very hot in here.
My brake system is stock from the factory, I have only changed the brake fluid to Motul 660, I also have the cooling ducts that comes with the car always attached as well.

Hope this helps.

[eckeph]

We have never had any problems with the 5th gen viper ACR carbon brakes. They have impressed all of our drivers pro to amateur how well they work and how much abuse they will take. Here are a few things to take a look at that may help.
1. make sure your not dragging the brakes. Leaving your foot resting on the brake pedal even lightly; Many drivers will do this with out knowing very common problem. Use the brakes and get off them
2. Change brake fluid often, hot bleed the brakes
3. Use PFC 665 brake fluid. We tested every readily available racing brake fluid on the market. PFC 665 by far the best performance.
4. Make sure your brake fluid is fresh. Once you open the bottle and break the seal that fluid is only good for 3-6 months for racing applications depending on environment.
5. Use a sweat band around reservoir.
6. When you pull off track and stop do not keep your foot on brake to hold car. Hot carbon rotors will heat transfer and soak the calipers very quickly.

1. I brake using my right foot so I only touch the brake when braking.
2. I emptied the system completely (even removed the calipers to get all fluid out of them) and filled it up with new, unopened, Motul RBF 700 Factory Line the day before I went to the track. "hot bleed"? Do you mean that I should bleed them while the brakes are hot?
3. Ok
4. See above.
5. Why should I do that?
6. Yes, I never do that.

Btw, is the Brake Cooling kit you sell only necessary for the ones who have steel brakes?

[TKO MOTORSPORTS TEAM]

1. I brake using my right foot so I only touch the brake when braking.
2. I emptied the system completely (even removed the calipers to get all fluid out of them) and filled it up with new, unopened, Motul RBF 700 Factory Line the day before I went to the track. "hot bleed"? Do you mean that I should bleed them while the brakes are hot?
3. Ok
4. See above.
5. Why should I do that?
6. Yes, I never do that.

Btw, is the Brake Cooling kit you sell only necessary for the ones who have steel brakes?

#1 is good then your not resting your foot on the pedal waiting to brake. You get on the brakes and off brakes quickly
#2 I would suggest not using any of the motul brake fluids or any of the European mfg brake fluids. I know its difficult to get PFC 665 brake fluid over there but I would suggest trying it.

"HOT BLEED" is the best way to bleed any brake system and its very similar to the standard "pump and bleed" procedure. Hot bleeding works much better then pump and bleed or pressure bleeding. Hot bleeding will get any trapped air in the calipers out and it also gets fresh fluid to the entire caliper. Hot bleeding is also much, much faster. You can hot bleed when car is cold or straight off the track it doesn't really matter.
Step 1 you will need 2 people. One person in car pumping brakes and one person bleeding brakes.
Step 2 fill brake fluid reservoir all the way to the top just before it spills out.
Step3 Get your self a brake bleeder can aka:" piss cup". Simple can with clear hose attached to it and a wire loop or hook to hold can while bleeding. Metal can is best
Step4 Pick a corner to bleed doesnt matter which one. We always start with left front and end with right rear that way if the car is moving out when your done you are behind it not in the way
Step 5 Wrench on caliper bleeder and piss cup hose on caliper nipple
Step 6 Have the person in the car pump the brakes 4 times calling our each pump so you can hear them, The forth pump should be very slow. 1.....2.....3......4......................... You will have the bleeder open for the first three pumps; On the forth slow pump you will close the bleeder mid stroke. When you close the bleeder you call out " CLOSED" so the person pumping the brakes can hear you and they can make sure you closed the bleeder mid stroke.
Step 7 Refill reservoir after each corner is bled. When finished with last corner check brake fluid level add fluid if you need to.

The "hot bleed" procedure may sound complicated and involved but once you do it a few times it becomes very simple and quick.

#5 sweat band around reservoir is just a safety precaution to keep any drips or sweating in control. Brake fluid is flammable and combustible and the headers are right below the brake reservoir. Brake fluid is also messy last thing you need is brake fluid in the engine compartment.


Our brake cooling kit we have run on steel rotor vipers and carbon rotor vipers. It really depends on driver skill, experience and application. If your just going out and having fun on track for 10 -20 mins you probably dont need our cooling kit. If your going out and putting down heaters for 20 mins then our brake cooling kit might be an option especially if your getting excessive caliper temps or a little brake fade. For you I would suggest first trying the better brake fluid PFC665, hot bleed the brakes, get some caliper temp stickers, and then test. If you still have problems them maybe its time to look at brake cooling.


hope this helps

[eckeph]

"HOT BLEED" is the best way to bleed any brake system and its very similar to the standard "pump and bleed" procedure. Hot bleeding works much better then pump and bleed or pressure bleeding. Hot bleeding will get any trapped air in the calipers out and it also gets fresh fluid to the entire caliper. Hot bleeding is also much, much faster. You can hot bleed when car is cold or straight off the track it doesn't really matter.

Interesting. I have never done it that way.

I used vacum bleeding (not pressure) when bleeding the brakes which, from my understanding, also gets fluid everywhere and are good at removing all the air.

[Lawineer]

Honestly, just get a powerbleeder, lol. So much easier and you only need one person.

[TKO MOTORSPORTS TEAM]

Honestly, just get a powerbleeder, lol. So much easier and you only need one person.

Power bleeders are ok to use for certain jobs but they dont have enough pressure to move some of the trapped air bubbles in the larger calipers with cross over tubes and galleys. Power bleeder aka: pressure bleeders are also much slower and add complexity. Your 100% correct hot bleed you need 2 people but who goes to the track alone? When your at the track your never alone

[TKO MOTORSPORTS TEAM]

Interesting. I have never done it that way.

I used vacum bleeding (not pressure) when bleeding the brakes which, from my understanding, also gets fluid everywhere and are good at removing all the air.

Vac bleeding can have same problem as pressure bleed ( for cars) you just cant get enough vacuum to pull all the bubbles that maybe trapped. You also cant pull enough vacuum to get all the fluid out of calipers in one shot quickly unless you have a large volume vac rig. Your also adding complexity. Complexity=lost time= less time on track= slow.

[Lawineer]

Power bleeders are ok to use for certain jobs but they dont have enough pressure to move some of the trapped air bubbles in the larger calipers with cross over tubes and galleys. Power bleeder aka: pressure bleeders are also much slower and add complexity. Your 100% correct hot bleed you need 2 people but who goes to the track alone? When your at the track your never alone

I leave my car at the track and have it serviced there. When I take my street car, I prep it in my garage by myself.
I'm not sure about the slow part. I pressurize it to 18psi (I think), and just let it bleed out. I never had a problem with air in the lines either. Goes pretty quick.

Also, I go to the track alone all the time, lol.

[TKO MOTORSPORTS TEAM]

I leave my car at the track and have it serviced there. When I take my street car, I prep it in my garage by myself.
I'm not sure about the slow part. I pressurize it to 18psi (I think), and just let it bleed out. I never had a problem with air in the lines either. Goes pretty quick.

Also, I go to the track alone all the time, lol.

I guess the slow part is relative to what your trying to accomplish. Time spent servicing rather then on track is still lost time and money for all. Many times we need to turn cars around in 3-5 mins and they have to be perfect and safe so hot bleed works best for us. Your right 18-20 psi pressure bleeder. If you hot bleed your using brake pedal pressure so your getting line pressure (900-1100 psi) and volume.

[GTS Dean]

Step4 Pick a corner to bleed doesnt matter which one. We always start with left front and end with right rear that way if the car is moving out when your done you are behind it not in the way

For you I would suggest first trying the better brake fluid PFC665, hot bleed the brakes, get some caliper temp stickers, and then test. If you still have problems them maybe its time to look at brake cooling.

hope this helps

I have always started with the most distant caliper from the MC and worked toward the nearest - RR, LR, RF, LF. That way, I'm assured of getting fresh fluid all the way out from the get-go. I always manual bleed with someone helping pump the pedal. I do not allow my helpers to let off the brake pedal until I have firmly closed the bleeder screw - and I do this 2-3 times per corner or caliper half - making sure that clean fluid is discharged before moving to the next position.

Your slow return suggestion will work, but it absolutely REQUIRES that the drain tube be submerged in fluid so as not to siphon air back to the calipers while the bleeder is open. I usually pinch the hose shut just above the bleeder before tightening.

All my experience is with iron rotors, so y'all with carbon/carbon setups are in a different league. But, there are still common considerations regardless of materials. IMO, the shorter the track, the more "brakes on" time you have. This decreases time available for cooling in between applications and brings all the system temps up. You may need temp labels on the calipers and Temipilaq on the rotors to determine just how hot the components are getting. Then you need to shop for pads that are formulated for the exact temperature range you are running. This will insure best disc/pad life and overall performance consistency.

YMMV.

[TKO MOTORSPORTS TEAM]

I have always started with the most distant caliper from the MC and worked toward the nearest - RR, LR, RF, LF. That way, I'm assured of getting fresh fluid all the way out from the get-go. I always manual bleed with someone helping pump the pedal. I do not allow my helpers to let off the brake pedal until I have firmly closed the bleeder screw - and I do this 2-3 times per corner or caliper half - making sure that clean fluid is discharged before moving to the next position.

Your slow return suggestion will work, but it absolutely REQUIRES that the drain tube be submerged in fluid so as not to siphon air back to the calipers while the bleeder is open. I usually pinch the hose shut just above the bleeder before tightening.

All my experience is with iron rotors, so y'all with carbon/carbon setups are in a different league. But, there are still common considerations regardless of materials. IMO, the shorter the track, the more "brakes on" time you have. This decreases time available for cooling in between applications and brings all the system temps up. You may need temp labels on the calipers and Temipilaq on the rotors to determine just how hot the components are getting. Then you need to shop for pads that are formulated for the exact temperature range you are running. This will insure best disc/pad life and overall performance consistency.

YMMV.

For sure pump and bleed is one way to bleed brakes and it can get the job done some times. You dont need piss cup tube submerged on hot bleed or pump and bleed because you should be closing the bleeder while you still have pressure. It doesn't really matter what corner you start with if your hot bleeding or pump and bleed. Our sequence is for safety and efficiency. We use the same sequence if we are bleeding brakes, checking tires pressures, changing tires, tire temps or adjusting shocks and springs. Start at the front done at the rear of the car and closest to pit wall when in hot pits.
Temp stickers, and rotor paint always a good idea just so you know where you are.

[Martin]

Possibly a dumb question - what ever happened to the popularity of speed bleeders? I have them on my Gen II, and had them on my Gen IV. They seemed to work great, especially if I don't have someone around to help with the job.

[TKO MOTORSPORTS TEAM]

Possibly a dumb question - what ever happened to the popularity of speed bleeders? I have them on my Gen II, and had them on my Gen IV. They seemed to work great, especially if I don't have someone around to help with the job.

Speed bleeders were always dicey at best and almost always leaked. They were outlawed in most racing series and sanctioning bodies . Speed bleeders went the same way as air bleed or bleed off tire valves. Both really cool ideas on paper only

[GTS Dean]

We use the same sequence if we are bleeding brakes, checking tires pressures, changing tires, tire temps or adjusting shocks and springs. Start at the front done at the rear of the car and closest to pit wall when in hot pits.

That makes perfect sense from a whole different perspective than the vast majority of us here.

[TKO MOTORSPORTS TEAM]

That makes perfect sense from a whole different perspective than the vast majority of us here.

Its about safety , looking out for each other and sharing a little knowledge. No matter if your just out there having fun, a grassroots competitor or a professional

[Arizona Vipers]

It's definitely the fluid. If you just put in fresh fluid correctly and still had fade, you may have got Chinese counterfeit fluid. I know there is fake Castrol SRF out there, so I'm sure there is fake Motul as well.
I have 900hp and am fast and run monster 343mm wide front slicks and have NEVER experienced fade once on stock ACR brakes and pads. Road American I'm hitting and braking from 176mph 3 times a lap. I even took the brake coolers off to save a couple pounds, still no fade. ACR brakes are amazing, I ordered another set for my turbo project.

[Pappy]

It's definitely the fluid. If you just put in fresh fluid correctly and still had fade, you may have got Chinese counterfeit fluid. I know there is fake Castrol SRF out there, so I'm sure there is fake Motul as well.
I have 900hp and am fast and run monster 343mm wide front slicks and have NEVER experienced fade once on stock ACR brakes and pads. Road American I'm hitting and braking from 176mph 3 times a lap. I even took the brake coolers off to save a couple pounds, still no fade. ACR brakes are amazing, I ordered another set for my turbo project.

Yeah, but are you sure you are using them hard enough to get any heat in them? LOL

CoolTrackPic2013 -2.jpg

[Steve-Indy]

eckeph, BEFORE you invest time, effort, and money in making any major changes to your car(other than possibly switching fluid type), I would politely suggest that you consider exploring the brake dragging situation suggested above by both TKO and Lawineer. To do this. I would employ a pedal camera both while you are driving on the street and while are taking a few hot laps on a road course

There are many variables that can lead to inadvertent unintentional, and unnoticed pressure (however light) on the brake pedal. In many cases it is related to size of one's right foot, type of shoe (small driving shoes are best while athletic shoes are the worst), driving position ( big person crammed into small space), pedal arrangement that one is used to...remembering the special cautions given/ demonstrated to the earliest Gen III pre-order folks at VOI.7 in 2002. In this case, due to the addition of the dead pedal which required moving the pedal cluster more to the right, the Skip Barber Team rode in test 2003 Vipers with each driver around a small autocross course. At the end of one's second lap, the instructor would ask the driver to stand hard on the brakes in order to test the ABS
system.. Once one was at full stop, you were asked to look at the tachometer...which invariably showed an RPM of 2500 or more since this new, closer spaced pedal arrangement caused the driver to be standing on the gas pedal as well as the brake. Lesson learned by most of us who were used to the Gen I and II pedals. Obviously this brake and gas pedal proximity could (did) cause many folks to drag the brakes unknowingly when just driving around casually. One new driver received his 2004 Viper mid afternoon one day from his out of state dealer and by 5 PM had already called his dealer to complain that all 4 rotors had turned blue. The dealer (a good friend)sent him to my house where we inspect the car on a lift...finding no problem other than the blue rotors. Once I got the guy back into his Viper, the source of the issue was obvious. As a big man wearing athletic shoes, his right foot covered half of the brake pedal when he pushed on the gas pedal.

Please take no offense as I am just sharing a little information to back up the suggestions already made.

I am sure all of us will be interested in hearing what is causing the fade issue...along with the solution.

[ViperGeorge]

It's definitely the fluid. If you just put in fresh fluid correctly and still had fade, you may have got Chinese counterfeit fluid. I know there is fake Castrol SRF out there, so I'm sure there is fake Motul as well.
I have 900hp and am fast and run monster 343mm wide front slicks and have NEVER experienced fade once on stock ACR brakes and pads. Road American I'm hitting and braking from 176mph 3 times a lap. I even took the brake coolers off to save a couple pounds, still no fade. ACR brakes are amazing, I ordered another set for my turbo project.

Cable, how would one tell if the fluid they are using is fake Chinese crap? Is there some tell tale? If you bleed the brakes and still get fade (I don't by the way) does that necessary mean you either have fake fluid or are inadvertently dragging the brakes? I use Motul 600 purchased from Amazon. My local race shop (3R Racing - they used to race Vipers) says that the Motul 660 seems to cause a soft pedal in many of their customer's cars. Switching to Motul 600 solves the problem they say. They also do not recommend the Castrol SRF stuff. They say there is no real advantage and the cost is prohibitive. They believe Motul 600 is a better fluid for the money especially since most track rats tend to bleed the brakes often.

[eckeph]

I think I need to clarify. This was my first Time Attack event, not my first track day. I have been tracking my Viper for 2 years on many different tracks. Not saying I'm the fastest guy out there but I am certainly not the slowest This was the first time I experienced brake fade. The reson behind me discussing brake cooling is because my friend, who is a national Time Attack champion (in a ACR-E) told me that I needed it. I don't know if he's right or wrong though, hence me asking in this thread.

The only change (relevant to this issue) I did before this event was changing brake fluid to Motul RBF 700 and installing the TKO Brake Line Kit.

Anyway, I have now ordered PFC 665 as per TKOs suggestion. I'm hoping that this will help! I will also try to add some cooling tubes to my front brakes to direct the air flow better. Btw, Should it be directed to the disc or the caliper?


This is a film from the last track day last year. No problems what so ever with brake fade:
https://youtu.be/bX4r37dZICM


This is from the Time Attack event where I had brake fade (not recorded in the film):
https://youtu.be/SISPjWoqMT8

[Steve-Indy]

Thanks for the clarification...and, hopefully your new fluid will eliminate the issue.

[Lawineer]

I think I need to clarify. This was my first Time Attack event, not my first track day. I have been tracking my Viper for 2 years on many different tracks. Not saying I'm the fastest guy out there but I am certainly not the slowest This was the first time I experienced brake fade. The reson behind me discussing brake cooling is because my friend, who is a national Time Attack champion (in a ACR-E) told me that I needed it. I don't know if he's right or wrong though, hence me asking in this thread.

The only change (relevant to this issue) I did before this event was changing brake fluid to Motul RBF 700 and installing the TKO Brake Line Kit.

Anyway, I have now ordered PFC 665 as per TKOs suggestion. I'm hoping that this will help! I will also try to add some cooling tubes to my front brakes to direct the air flow better. Btw, Should it be directed to the disc or the caliper?


This is a film from the last track day last year. No problems what so ever with brake fade:
https://youtu.be/bX4r37dZICM


This is from the Time Attack event where I had brake fade (not recorded in the film):
https://youtu.be/SISPjWoqMT8

I dont doubt TKO's suggestion regarding PFC over RBF, but if you're boiling either (and its fresh) something else is likely wrong. Either a the caliper or air in the lines or something.