I came accross this in a Race Car Enginering ad, and thought I would add it to the list since it seems to be a new product.

AP Racing PRF660 brake fluid



"Typical" New Dry Boiling Point - 320C or 608F
"Wet" E.R. (Equilibrium Reflux) Boiling Point - 199C or 390F

Not sure why they call it 660 since its boiling point is rated as 608 'Typical'. Then again their 600 fluid is rated for 590 'Typical'. Have to talk to the marketing guys!

ARRANGED BY DRY BOILING POINT:

DRY:401F -- WET:284F --- DOT3 MINIMUM (GLYCOL BASE)
DRY:446F -- WET:311F --- DOT4 MINIMUM (GLYCOL BASE)
DRY:500F -- WET:356F --- DOT5 MINIMUM (SILICONE BASE)
DRY:500F -- WET:356F --- DOT5.1 MINIMUM (GLYCOL BASE)
DRY:500F -- WET:???F --- FORD HEAVY DUTY DOT 3 PM-1C (new since 2006)
DRY:527F -- WET:302F --- AP RACING 551 ($12.95/0.5L OR 16.9 OZ)
DRY:527F -- WET:347F --- VALVOLINE SYNPOWER DOT3 & DOT4
DRY:536F -- WET:392F --- ATE SUPERBLUE/TYP200 ($9.95/1L)
DRY:550F -- WET:284F --- FORD HEAVY DUTY DOT 3 PM-1 (pre 2006) ($4/12 OZ)
DRY:570F -- WET:284F --- WILWOOD 570 ($5.65/12 OZ)
DRY:570F -- WET:284F --- PERFORMANCE Friction Z rated ($6.27/16 OZ)
DRY:590F -- WET:410F --- AP RACING 600 ($16.95/0.5L OR 16.9 OZ)
DRY:590F -- WET:518F --- CASTROL SRF ($69.00/1L 0R 33.8 OZ)
DRY:593F -- WET:420F --- MOTUL RBF600 ($12.95/0.5L OR 16.9 OZ)
DRY:601F -- WET:399F --- BREMBO LCF 600 PLUS ($26.75/0.5L OR 16.9 OZ)
DRY:608F -- WET:390F --- AP RACING 660 ($-/0.5L OR 16.9 OZ)
DRY:610F -- WET:421F --- NEO SYNTHETICS SUPER DOT 610 ($11.95/12 OZ)
DRY:610F -- WET:421F --- PROSPEED GS610 ($39.95/16 OZ)
DRY:626F -- WET:417F --- WILWOOD EXP 600 ($16.95/0.5L 16.9 OZ)

ARRANGED BY WET BOILING POINT:

DRY:500F -- WET:???F --- FORD HEAVY DUTY DOT 3 PM-1C (new since 2006)
DRY:401F -- WET:284F --- DOT3 MINIMUM
DRY:570F -- WET:284F --- WILWOOD 570
DRY:570F -- WET:284F --- PERFORMANCE Friction Z rated
DRY:550F -- WET:284F --- FORD HEAVY DUTY DOT 3
DRY:527F -- WET:302F --- AP RACING 551
DRY:446F -- WET:311F --- DOT4 MINIMUM
DRY:527F -- WET:347F --- VALVOLINE SYNPOWER DOT3 & DOT4
DRY:500F -- WET:356F --- DOT5.1 MINIMUM (GLYCOL BASE)
DRY:500F -- WET:356F --- DOT5 MINIMUM (SILICONE BASE)
DRY:608F -- WET:390F --- AP RACING 660 ($-/0.5L OR 16.9 OZ)
DRY:536F -- WET:392F --- ATE SUPERBLUE/TYP200
DRY:601F -- WET:399F --- BREMBO LCF 600 PLUS
DRY:590F -- WET:410F --- AP RACING 600
DRY:626F -- WET:417F --- WILWOOD EXP 600
DRY:593F -- WET:420F --- MOTUL RBF600
DRY:610F -- WET:421F --- NEO SYNTHETICS SUPER DOT 610
DRY:610F -- WET:421F --- PROSPEED GS610
DRY:590F -- WET:518F --- CASTROL SRF

Some fluids on the manufacturer's web site did not specify wet boiling point, so I used the relevant DOT 3 value.

Water absorption:
DOT 3: This brake fluid has a glycol base with additives. It is clear to amber in color. It is hygroscopic (meaning it absorbs moisture) and has a minimum dry boiling point of 401F (205C) minimum and a minimum wet boiling point of 284F (140C). It will absorb 1 to 2 percent of water per year depending on climate and operating conditions.

Looks like Motul 600 is still the value champ for high performance and for just $4 more per half litre you can get the Dry boiling point champ (626F), Wilwood EP 600 Plus. Castrol SRF remains as always the Wet boiling champ by a whopping 100 degrees. I don't know of any other new ones.

Edit 20060419:Updated change downward from 550F to 500F for Ford Heavy Duty PM-1 FIR No.002092 replaced by new PM-1-C FIR No 174922 fluid.


Modified by descartesfool at 1:03 PM 4/19/2006

 

Thanks for posting.

A bookmark for this topic goes straight to my favorites...

 

During a weak moment and some fatness in my wallet I bought Castrol SRF.

Barry H.

 

Keep in mind that what isn't often talked about is the entrapment of air in the fluid itself. (Especially if one uses a motive pressure bleeder which forces air into the fluid....not good)

The larger the molecules of fluid the more air will be trapped between them and more compressible the fluid will become. In fact OEMs store brake fluid in large vats under vacuum to minimize air entrapment.

Sometimes people complain about mushy brake pedal even after numerous bleedings, and entrapped air may be the cause of this, especially if one uses a pressure bleeder that forces air into the fluid....like the motive one. This gets often solved by going to a different fluid...which, most likely, has smaller molecules (and consequently less room between them to trap air)

Matt

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by descartesfool &raquo;</TD></TR><TR><TD CLASS="quote">AP Racing PRF660 brake fluid
.
.
.
Not sure why they call it 660 since its boiling point is rated as 608 'Typical'</TD></TR></TABLE>

Based on the picture in the e-mail I just received from Racer Parts Wholesale, it appears that this product is now being sold as AP Racing PRF brake fluid (without any number in the name). Even though it's still shown as PRF 660 on the AP Racing website.

They are charging $29.95 for a 500 ml bottle.

 

some one enlightem me please on difference of
wet and dry boiling point..


Thanks!

 

From Castrol SRF, the one with the highest wet boiling point:

"All conventional brake fluids used in cars and motor cycles are hygroscopic, that is, they absorb water from their surroundings. Strange though it may seem, the flexible hoses incorporated in braking systems are permeable to water and in time enough, water can find its way into the system via the hoses, and seriously affect the brake fluid's performance. This water reduces the boiling point of the fluid (ie, it lowers the temperature at which gas bubbles begin to form). When these bubbles form, they turn a virtually incompressible liquid into a mixture of gas and liquid which can be compressed quite considerably, thus severely reducing the efficiency of the brakes. In this situation, a driver finds that the brakes feel spongy. Brake-pedal travel will increase and it may be necessary to 'pump' the pedal to get the brakes to function effectively. However, when the brake fluid reaches a temperature at which the water in the fluid causes gas to be produced, which is equal to the volume swept by the piston in the rake master-cylinder, vapor-lock occurs and the brakes become inoperative. When this happens, the first indication the driver has that something is wrong is when he applies the brakes. The pedal goes down to the floor and the car carries on at undiminished - and possibly fatal speed.

The silicon ester technology in Castrol SRF addresses this problem in two ways. Firstly, Castrol SRF is less hygroscopic than conventional brake fluids - it absorbs less water in a given time. Secondly, unlike conventional glycol ether fluids, Castrol SRF reacts chemically with the absorbed water to reduce its adverse effects, thus preventing the fluid's high temperature performance and safety margins from deteriorating as rapidly as they would otherwise do.

Castrol SRF exceeds the US Federal Standards FMVSS 116 DOT 3 and DOT 4, ISO 4925, JIS K2233 and current SAE J1703 and is miscible with all conventional brake fluids conforming to these standards. However, mixing Castrol SRF and conventional brake fluids will reduce the benefits of Castrol SRF. It is strongly recommended that conventional brake fluid be drained from the system before flushing and re-filling with Castrol SRF.

The wet boiling point of Castrol SRF, 270 C, is vastly superior to the minimum requirement of 155 C demanded by the current US DOT 4 specification. The product's typical dry boiling point of 310 C is likewise outstanding. This ability to withstand temperatures in excess of 300 C, and its superior resistance to the effects of absorbed water, have established Castrol SRF as the world's premier fluid for the hydraulic brakes used in all forms of motorsport."

 

And from the old man in the sky himself: (from Stoptech's site)

"Carroll Smith's Notes on Brake Fluid

Brake fluid is possibly the single most neglected component of the automobile. Most high performance drivers check their tire pressures and change their engine oil at frequent intervals. Virtually no one (including me) ever changes the brake fluid in their street car - or even bleeds the brakes. WRONG!

The function of brake fluid is to provide an incompressible medium to transmit the driver’s foot pressure on the brake pedal through the master cylinder(s) to the calipers in order to clamp the friction material against the discs. The foot pressure is multiplied by the mechanical pedal ratio and the hydraulic ratio of the master cylinders, booster (if used) and caliper piston(s).

This is a simple concept. When fresh, all brake fluids are virtually incompressible and the system works as well as its mechanical and hydraulic design allows. There are, however significant problems. Overheated brake fluid can (and will) boil in the caliper. Boiling produces gas bubbles within any boiling fluid. Gas is compressible so boiling brake fluid leads to a “soft” brake pedal with long travel. In extreme cases overheated brake fluid necessitates “pumping the brake pedal” in order to get a pedal at all.

There are four possible solutions to the boiling fluid problem:

1. Don’t use the brakes so hard
2. Provide (copious) cooling air to the brakes
3. Install Titanium or Ceramic caliper pistons. Alternately install 2-piece pistons made from aluminum with a noise piece of Titanium or Ceramic. (Note that aluminum pistons are used as opposed to stainless steel to match the expansion rate of the piston to that of the caliper body to ensure the piston seal condition and preload is optimal through out the temperature range.)
4. Install Titanium pad backing plate if they are available for your caliper.
5. Change to a brake fluid with a higher boiling point.

The first is unacceptable. The second is expensive. The third is really expensive in its various forms. The fourth is relatively cheap. The fifth is easy and relatively cheap.

For most of us easing up on the brake usage is not an option and increasing cooling air to the system is filed under too difficult so we upgrade the fluid. Some of the reputable racing fluids include:

· AP 550
· AP 600
· ATE Super Blue Racing
· ATE TYP 200
· ELF HTX 115
· Motul 550
· Motul 600
· Neo 610
· Performance Friction Z rated

Finally, Castrol SRF is a racing brake fluid that is in a class by itself with patented chemistry and is, in my opinion, the best racing brake fluid on the market today.

This leads to a discussion of boiling points. Brake fluids are classified by both “dry boiling point” and “wet boiling point”. They are also classified by US Department of Transportation (DOT) rating, DOT 3, DOT 4, DOT 5, and DOT 5.1.

As we would expect the dry boiling point is just that - the temperature at which a given brake fluid boil when it is fresh out of the can. This is the rating by which most high performance drivers and all racers select their brake fluid – from the standard racing 550 degrees Fahrenheit to the 600+ degrees Fahrenheit offered by the extreme use fluids. As a point of interest, even though they may have the same DOT rating, racing fluids are less compressible than street fluids, especially after they have been overheated.

For high performance street car use, the wet boiling point is at least as important as the dry. DOT 3 DOT 4, and DOT 5.1 brake fluids are ether based and, as such they are hygroscopic in nature - i.e. they adsorb water at every opportunity. Since water boils at 212 degrees Fahrenheit (100 degrees Celsius) the adsorbed water dramatically lowers the boiling point of the brake fluid. A minute amount of water suspended in the fluid decreases the boiling point as much as 1/3. Damn!

The fluid in the system absorbs water through the breathers, through the caliper piston seals and by magic. Not only does this reduce the boiling point, the entrained water leads to corrosion of both ferrous and Aluminum internal parts. Double Damn!! So buy your brake fluid in small containers and don’t save the leftovers.

I use Ford C6AZ-19542 which was developed in the early 1960’s to cure the problem caused by Lincoln Continental drivers boiling the fluid by habitually resting their left feet on the brake pedal. It is inexpensive and it works just fine.

But upgrading the fluid is not the whole answer. Unfortunately the hygroscopic nature of the ether based fluids means that they should be completely replaced at scheduled time based intervals (annually would be good) and that the system should be bled to replace the fluid in the calipers every time that it is overheated to the point of generating a soft pedal. Yes, the pedal will come back as soon as the fluid cools somewhat - but the boiling point is now reduced and the pedal will go mushy at a lower temperature the next time. Triple Damn!!!

Fortunately, changing to a 550 degree Fahrenheit fluid and replacing it annually will solve the problem for all but the most heavy footed among us.

Ah ha, you say - but what about the much touted Silicone based brake fluids? They are non hygroscopic and should take care of the reduced boiling point and corrosion problems. True! That’s the good news. That is why they are specified by the U.S. Military. Unfortunately the silicone based fluids are compressible themselves so they produce a soft pedal all by themselves. For the person who doesn’t care about a spongy pedal or precise modulation silicone fluids may well be the answer - but not for anyone reading this. In fact, low compressibility is a desired characteristic in a high performance brake system – lower compressibility results in more linear force output for driver input and improved driver feedback.

So, you say, “I’ll just run my hot rod down to my dealership or mechanic and ask them to replace the fluid with AP 550.” Two problems here. First of all they won’t have it and won’t know where to get it. Second and more serious (after all you could supply it yourself) all dealerships and most independent mechanics use pressure bleeders. These devices certainly speed up the process of brake bleeding, but by forcing the fluid through tiny orifices using pressurized air, any air left in the partially filled system will be forced into the fluid solution. Quadruple Damn!!!!

If you are either racing or doing lapping days, the brake fluid should be replaced both before and after each event. A cool off lap before each stop will go a long way toward preventing fluid boil due to heat soaking after the airflow stops when the car does."

 

you are the man! descartesfool

thanks for looking up what I was too busy to find in my own...

 

I like a little air in between my brake fluid molecules. Makes it easier to modulate the brakes...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by apexinghonda &raquo;</TD></TR><TR><TD CLASS="quote">During a weak moment and some fatness in my wallet I bought Castrol SRF.
</TD></TR></TABLE>

that is still , IMO , the end all brake fluid.

and why anyone would pressure bleed a system is beyond me.

 

i'm suprised they have not found a way to make it cable driven...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Outsane &raquo;</TD></TR><TR><TD CLASS="quote">i'm suprised they have not found a way to make it cable driven...</TD></TR></TABLE>

I dont follow.

I only gravity bleed , anything else has the potential to introduce air into the system , seems pretty counter-poductive to me

 

cable driven brake system..instead of fluid...

but then again they have updated the clutch cable now to hydrolic...
i like the cables ease of adjustability


btw
i use the old pump and hold scenario..

or pump pump pump.. when goin solo

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Outsane &raquo;</TD></TR><TR><TD CLASS="quote">cable driven brake system..instead of fluid...

</TD></TR></TABLE>

they did ...in the 30's

it was nearly a disaster , plus that whole mechanical advantage thing works nicely in a hydraulic system

 

ahh.,..

 

Time to add the Endless product to the list, particularly if BAR-Honda uses it! Looks like this Endless RF-650 brkae fluid is definetly at the top of the class. Only Wilwood EXP-600 is better in the dry boiling point dept, and only Castrol SRF is better in the wet boiling point. Then again it is only just barely better than the Neo Synthetics Super DOT 610 stuff. It looks like a winner! Will have to see how much it costs.

ARRANGED BY DRY BOILING POINT:

DRY:401F -- WET:284F --- DOT3 MINIMUM (GLYCOL BASE)
DRY:446F -- WET:311F --- DOT4 MINIMUM (GLYCOL BASE)
DRY:500F -- WET:356F --- DOT5 MINIMUM (SILICONE BASE)
DRY:500F -- WET:356F --- DOT5.1 MINIMUM (GLYCOL BASE)
DRY:527F -- WET:302F --- AP RACING 551 ($12.95/0.5L OR 16.9 OZ)
DRY:527F -- WET:347F --- VALVOLINE SYNPOWER DOT3 & DOT4
DRY:536F -- WET:392F --- ATE SUPERBLUE/TYP200 ($9.95/1L)
DRY:550F -- WET:284F --- FORD HEAVY DUTY DOT 3 ($4/12 OZ)
DRY:570F -- WET:284F --- WILWOOD 570 ($5.65/12 OZ)
DRY:570F -- WET:284F --- PERFORMANCE Friction Z rated ($6.27/16 OZ)
DRY:590F -- WET:410F --- AP RACING 600 ($16.95/0.5L OR 16.9 OZ)
DRY:590F -- WET:518F --- CASTROL SRF ($69.00/1L 0R 33.8 OZ)
DRY:593F -- WET:420F --- MOTUL RBF600 ($12.95/0.5L OR 16.9 OZ)
DRY:601F -- WET:399F --- BREMBO LCF 600 PLUS ($26.75/0.5L OR 16.9 OZ)
DRY:608F -- WET:390F --- AP RACING 660 ($-/0.5L OR 16.9 OZ)
DRY:610F -- WET:421F --- NEO SYNTHETICS SUPER DOT 610 ($11.95/12 OZ)
DRY:610F -- WET:421F --- PROSPEED GS610 ($39.95/16 OZ)
DRY:613F -- WET:424F --- ENDLESS RF-650 ($??/0.5L 16.9 OZ)
DRY:626F -- WET:417F --- WILWOOD EXP 600 ($16.95/0.5L 16.9 OZ)

ARRANGED BY WET BOILING POINT:

DRY:401F -- WET:284F --- DOT3 MINIMUM
DRY:570F -- WET:284F --- WILWOOD 570
DRY:570F -- WET:284F --- PERFORMANCE Friction Z rated
DRY:550F -- WET:284F --- FORD HEAVY DUTY DOT 3
DRY:527F -- WET:302F --- AP RACING 551
DRY:446F -- WET:311F --- DOT4 MINIMUM
DRY:527F -- WET:347F --- VALVOLINE SYNPOWER DOT3 & DOT4
DRY:500F -- WET:356F --- DOT5.1 MINIMUM (GLYCOL BASE)
DRY:500F -- WET:356F --- DOT5 MINIMUM (SILICONE BASE)
DRY:608F -- WET:390F --- AP RACING 660 ($-/0.5L OR 16.9 OZ)
DRY:536F -- WET:392F --- ATE SUPERBLUE/TYP200
DRY:601F -- WET:399F --- BREMBO LCF 600 PLUS
DRY:590F -- WET:410F --- AP RACING 600
DRY:626F -- WET:417F --- WILWOOD EXP 600
DRY:593F -- WET:420F --- MOTUL RBF600
DRY:610F -- WET:421F --- NEO SYNTHETICS SUPER DOT 610
DRY:610F -- WET:421F --- PROSPEED GS610
DRY:613F -- WET:424F --- ENDLESS RF-650
DRY:590F -- WET:518F --- CASTROL SRF

Some fluids on the manufacturer's web site did not specify wet boiling point, so I used the relevant DOT 3 value.

Water absorption:
DOT 3: This brake fluid has a glycol base with additives. It is clear to amber in color. It is hygroscopic (meaning it absorbs moisture) and has a minimum dry boiling point of 401F (205C) minimum and a minimum wet boiling point of 284F (140C). It will absorb 1 to 2 percent of water per year depending on climate and operating conditions.

 

nice and useful post! thanks

 

Great write-up. Now here's a question: some websites say the fluid they sell is not recommended for street use. So which of these fluids are good for track days and driving home and forgetting about it?

Dan