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Great link.

News to me = low viscosity brake fluid exists. The author minimizes its importance, however it could be more useful to guys up here in Winnipeg. Not sure it's necessary, but good to know about.

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Useful for Subaru owners - I recall my clutch being stupidly stiff after a long drive in -30C. 

Also for any cars with a clutch-delay valve. 

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1 hour ago, Corey said:

Useful for Subaru owners - I recall my clutch being stupidly stiff after a long drive in -30C. 

Also for any cars with a clutch-delay valve. 

Aka: BMW, VW, Mazda (some) etc. 

Ive found my bmw slow to engage lately and this is probably why. 

I still have a new container of ate blue sitting here. Will the viu tag me if I use it? :P 

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On ‎12‎/‎28‎/‎2017 at 7:41 AM, mcorrie said:

Been doing some holiday research. Found a good bit of info on brake fluids. The chart compares every brake fluid on the market and then below the chart is some explanation that even i can understand..

https://www.lelandwest.com/brake-fluid-comparison-chart.cfm

 

 

The first time I noticed the brake pedal drop following a Time Attack session last year, I assumed it was simply some moisture boiling off from the nearly two-year-old brake fluid.

I looked for a DOT-4 brake fluid with a high dry boiling point that wasn’t overly expensive. Seemed too good to be true, but Kleen-Flo had a 509°F (265°C) boiling, was dirt cheap, and available at Piston Ring and elsewhere. I bled and flushed the system, and all was good.

But, like I said, too good to be true. Following the first Time Attack event of 2019, back to a soft pedal. This time I spared no brake fluid and made sure the system was completely bled and flushed. I assumed the previous bleeding/flushing may not have been completely thorough.

Just finished yesterday’s Time Attack and back to a soft pedal. Mind you, this time it took 10 sessions before I noticed the pedal drop.

I checked the Kleen-Flo specifications on their website and they state a dry boiling point of only 475°F (246°C). I double-checked the specifications printed on the bottle to make sure I wasn’t seeing things. Makes we wonder if there are different standards for testing brake fluid.

What is the consensus for the type of brake fluid that should be used for a 3500 lb car going 175 kph down the front straight? Do I really need a something over 600°F? and if so, would Motul RBF 660 be a good choice with a dry boiling point of 616°F (324°C)?

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Most of the road racers use the stuff from Canadian Tire. “Super dot3, 500F”.  If the pedal gets soft, we simply open the screw and let it drip for a minute while rotating tires.  Might not work on the Brembo calliper with the bleed screw straight up, but the fluid should, cheap when on sale.

https://www.canadiantire.ca/en/pdp/oem-dot-3-brake-fluid-ford-500-degrees-946ml-0381928p.html#srp

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Posted (edited)

I've used super dot 3 for 25 years,  zero brake fade. 17 bux for a liter at PS or CT.  Even after a 30 min race.   Hard pedal . I also crack my front bleeders for a couple seconds (gravity bleed) if i take wheels off just to make sure. 

 

 

Edited by Al Marcoux
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21 hours ago, Weebly said:

What is the consensus for the type of brake fluid that should be used for a 3500 lb car going 175 kph down the front straight? Do I really need a something over 600°F? and if so, would Motul RBF 660 be a good choice with a dry boiling point of 616°F (324°C)?

3500lbs and 175kmh in itself, shouldn't need anything exciting for brake fluid. The kleen-flo dot4 should be plenty for that. I use that in my RX8 which is about the same weight with driver and similar speeds.

Things to consider with managing brakes:
What pads are you using?
How would you describe your bake application while on track? Stabby? Aggressive? Progressive?
How much ducting does the Focus have? Is it blocked? Can you clean up the air-flow at all without too much effort? (remove screens, grilles etc)
And so on...

Are you by-chance using a scanner to remove all the air and old fluid from the ABS pump(s)? 
It's not uncommon to have a spongy pedal after a whole weekend of racing. Like others have mentioned, do a quick bleed process to ensure there is no air.

One of the bigger issues with DOT4, is moisture absorption. RBF600/660 are big offenders and the fluids (primarily 660) are intended for short term use before being flushed again. This is just something you need to keep in mind with DOT4 fluids.

For what it's worth, I use: 
Amsoil Dominator 600 in the Mustang (4200lbs, and requires DOT4 Fluid by Ford) 
Motul RBF600 in RaceTrix2 (2300lbs)
Kleen-Flo DOT4 in the RX8 (3200lbs)

Why the variety? It's what was available where I was shopping when I remembered I needed fluid!

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4 hours ago, Al Marcoux said:

I've used super dot 3 for 25 years,  zero brake fade. 

I will echo this.
I use whatever the car came with until i do a caliper replacement or something that requires the system to be opened. For most vehicles, it's DOT3.

Good idea or not, I raced my Civic for 2 years on whatever fluid was in the car, no idea on how old. Worked fine.

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1 hour ago, nopistons said:

3500lbs and 175kmh in itself, shouldn't need anything exciting for brake fluid. The kleen-flo dot4 should be plenty for that. I use that in my RX8 which is about the same weight with driver and similar speeds.

Things to consider with managing brakes:
What pads are you using?
How would you describe your bake application while on track? Stabby? Aggressive? Progressive?
How much ducting does the Focus have? Is it blocked? Can you clean up the air-flow at all without too much effort? (remove screens, grilles etc)
And so on...

Are you by-chance using a scanner to remove all the air and old fluid from the ABS pump(s)? 
It's not uncommon to have a spongy pedal after a whole weekend of racing. Like others have mentioned, do a quick bleed process to ensure there is no air.

One of the bigger issues with DOT4, is moisture absorption. RBF600/660 are big offenders and the fluids (primarily 660) are intended for short term use before being flushed again. This is just something you need to keep in mind with DOT4 fluids.

For what it's worth, I use: 
Amsoil Dominator 600 in the Mustang (4200lbs, and requires DOT4 Fluid by Ford) 
Motul RBF600 in RaceTrix2 (2300lbs)
Kleen-Flo DOT4 in the RX8 (3200lbs)

Why the variety? It's what was available where I was shopping when I remembered I needed fluid!

Hey @nopistons those are great recommendations ... I really appreciate you taking the time to share your experience with people like me, who are just getting into the sport.

I'll start by answering your questions:

I'm on my second set of OEM pads with 2nd set of OEM front rotors (one set of rotors worn, other set had a cracked rotor).  Hmm, not warming up the brakes during the warmup lap??

My braking application is definitely progressive (to the point of ... "geez, maybe I should be braking later and harder").

The Focus has ducting running up into the wheel well and deflectors from that point directing air toward the caliper. Ducting is open.

Good point on the ABS pump and control unit.  I've assumed all the internal passages are open when bleeding the brakes with ignition OFF.  The Focus Service Manual does not mention anything about cycling the ABS unit, but I will research further. They do, however, recommend the use of DOT 4 or better.

Moisture absorption with RBF 600/660 is not a big issue because I will flush system at least once/year.

As a last point, sometimes these problems are self-inflicted. Ford built this car knowing that it would be tracked and went so far as to say that it's performance would not fall off after 30 laps. So, I shouldn't be having these problems after only five sessions.  I guess that leaves improper bleeding/flushing technique as a possible contributor to my spongy pedal.

Here's the procedure I use:  Place a board under the brake pedal to ensure the master cylinder piston doesn't "overstroke". Next, start bleeding at longest line (RR) and work to closest (LF). I open the bleeder, then have my unwilling assistant smoothly press the pedal to the floor and hold. Bleeder screw is then closed and the pedal released. I repeat the process (5-6) times until I see enough fluid in the catch bottle to indicate no air bubbles and that the entire line has been flushed.  I never" just" bleed, because I've assumed that if the fluid has boiled, it has degraded and should be flushed.

In years past I've used the "pump the pedal several times and hold" before opening the bleeder valve.  Don't really know if there's any advantage in that method.  Anyways, if you or anyone else sees any issues in the way I'm doing the bleeding/flushing process, please let me know. 

Thanks everyone for your help!

 

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Rookie with slow Focus here:

The TA #1 event my brakes were going off after 5 hard laps.   The ceramic pads disintegrated.

Last weekend I had new OEM rotors, adjusted some undertray deflectors, EBC yellowstuff pads, Motul DOT 5.1 fluid.  I've also tried smoother braking, but still hard enough that the tires are complaining.  At one point the pedal felt hard, but was less effective (fade?).   Pedal was a bit squishy monday morning.   

I probably have one open track day of pads left.   I've flushed brake fluid again and put in Motul RBF 600.

 

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Personally I have never had luck with a gravity bleed effort. This may be just the vehicles I have tried it on.

I have used a vacuum bleeder system and a pressure bleed system. The pressure bleed system is great for a power flush if your system is extremely old and has a huge amount of junk in the really old fluid.

The vacuum bleed system is somewhat tricky getting the hose to seal on the bleeder screw but is about the cleanest method I have ever used. About the most widely used method if you have a second person handy is the "pump n' hold" method.

Most of the time for our purposes we do not have to "flush" our systems. Basic maintenance is about all we need to do. If your car is a daily driver that you occasionally track then you may wish to replace the fluid in spring but that is personal choice. 

LOOK at the fluid. does it look like it is discoloured? If so then it probably needs replacing.

If you are having a difficult time getting the air out of your system (whatever pressure method you choose) try cracking the bleeder in short bursts. Sometimes that helps to surge the air to the end of the line.

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We run motul 600 in all our cars. It's about $20 for a jug of it and you can easily bleed out a car with 2 jugs.

 

I'd never think of running anything else. The price point per value of it is amazing. 

 

Should easily last you the full year with a brake bleed every event or 2.

 

For $40 bucks you cant go wrong with it at all.

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Ps. Speed bleeders are amazing haha. We have them on both the cars. Makes bleeding brakes a 1 person job.

 

They just screw into where you stock bleed nipples. When you wanna bleed brakes just crack them half a turn and just pump away. They have a check valve built in so you never get air sucking back in.

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Brian did you bed the pads in? No/improper/botched bedding will cause irregular pedal.

motul 600/660 is $35/500ml locally now. I’ll use over 1 liter for a fluid change. I used Castrol SRF previously, it’s the best but pricing of HP brake fluid for some strange reason has gone up recently (I bought 1L of SRF for $89 CDN 2 yrs ago, now it’s $160), Motul used to be cheap as well. Not sure what’s going on there but either way - keep it simple, make decisions based on results. If you still want a fluid option not listed here, I am using Stoptech 600 this time around. Characteristics are same at Motul but price is better. I’ll let you know how it works.

There was a distinct pedal improvement with SRF - but I thought I was nuts for spending $90, I’d have to be completely crackers to buy it at $160 now. So Stoptech 600 fluid was $24/500ml...

Matt

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One thing to consider is that if your fluid is getting hot, and is wicking up into your OEM rubber lines, you might have excess balooning as the rubber warms up and your braking application gets more aggressive.

If you are getting a spongy pedals and you have good pads and fluid, maybe next thing to check is the lines.

Just a thought...

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On 7/5/2019 at 6:59 PM, mcorrie said:

Brian did you bed the pads in? No/improper/botched bedding will cause irregular pedal.

motul 600/660 is $35/500ml locally now. I’ll use over 1 liter for a fluid change. I used Castrol SRF previously, it’s the best but pricing of HP brake fluid for some strange reason has gone up recently (I bought 1L of SRF for $89 CDN 2 yrs ago, now it’s $160), Motul used to be cheap as well. Not sure what’s going on there but either way - keep it simple, make decisions based on results. If you still want a fluid option not listed here, I am using Stoptech 600 this time around. Characteristics are same at Motul but price is better. I’ll let you know how it works.

There was a distinct pedal improvement with SRF - but I thought I was nuts for spending $90, I’d have to be completely crackers to buy it at $160 now. So Stoptech 600 fluid was $24/500ml...

Matt

 

12 hours ago, nopistons said:

One thing to consider is that if your fluid is getting hot, and is wicking up into your OEM rubber lines, you might have excess balooning as the rubber warms up and your braking application gets more aggressive.

If you are getting a spongy pedals and you have good pads and fluid, maybe next thing to check is the lines.

Just a thought...

Thanks for your suggestions guys.  I'm going to try one thing at a time and see what difference it makes.  The first step I've taken is to flush out all the existing DOT 4 and replace with Motul RBF 660.  I used about 750 ml in the process, watching the volume in the catch bottle to ensure the longest line pumped through the most fluid and subsequently pushing through less and less as the lines got shorter. And Matt, you're right, that stuff is ridiculously expensive at almost $100/litre.  But, if I get a soft pedal again, I know it won't be because of brake fluid boiling.

This highly expensive, highly hygroscopic (absorbs moisture like a sponge) fluid, will therefore need to be flushed out at the end of the season and replaced with DOT 4  until the 2020 season begins.  Then repeat the flush/fill process..  I think RBF 660 is probably overkill and might look into Stoptech 600 or something more reasonably priced.

If you read through the suggestions in this thread, there seems to be a consensus that boiling shouldn't be happening with a DOT 4 fluid with a dry boiling point of 509°F.  So maybe the suggestion of rubber line swelling is the answer.  However, the one thing that supports the boiling theory is that that every time this happens (once last year, twice this year) it's never on a cool day or early in the run. It's always been at the end of the day.  In other words, it takes several heat cycles to raise the temperature to the boiling point (and it's probably happening only on the front calipers.  Front calipers also getting heat soaked by the engine.  The PTU on my car is water-cooled (for good reason), and it gets hot as heck on that side of the car when you're in the pits following a run.  Maybe I'm boiling fluid on the passenger side  inboard pistons only?

Another interesting point is that after city driving the car for three days following the event, the brake pedal becomes firm again.  Almost like the air bubbles are finding their way back to the reservoir.  Not sure how easy it would be for air bubbles to work their way back through the ABS modulator lines and eventually to the reservoir.  The other theory is that the tiny air bubbles actually get re-absorbed back into the fluid over a period of time. However, the downside is that this apparently changes the chemistry of the fluid and will lower its boiling point.  Not my theory,  just something I read on the Internet.

Anyways, I'll wait and see what happens at the next Time Attack event this month and report back before I make any further changes.

 

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