Brake Fluid

[dan_b]

I did some web rummaging, and came across this post on a Fiat Coupe forum. Here's the link so his work is credited and sourced, this chap has done some research in to the relative wet and dry boiling points of some of the main performance brake fluids available, and draws his own conclusion on what the "Best" fluid is for his application. It's intersting reading. :

http://www.fccuk.org/ubbthreads/showthreaded.php?Cat=&Number=172500&page=0&view=&sb=5&o=&vc=1

He concludes that in value for money terms, Castrol Super Response Dot4 is the best fluid for getting best bang for buck, closely followed by Halfords Dot5.1.

He then goes on to say that the ATE Super (either blue or gold) would be his first choice on performance terms, but it is quite a lot more expensive than the above two.

He also adds that the AP Racing, and Castrol SRF fluids are more suited to "racing", due to their poorer resistance to absorbing water and their apparent lack of anti-corrosion additives: this might not be relevant if you change your brake fluid very regularly. Castrol SRF is also fearsomely expensive (and I have a hunch that it's actually a Silicone-based fluid and so therefore probably not best for the S2, either that or you must ensure a really thorough flush of your system as it won't mix with a non-silicone-based fluid.

Does anyone know a good dealer for the ATE Stuff? Perhaps a group buy could be organized here to get the cost down?

[AbsS2]

Need some advice

guys need a bit of advise. I used to get the red exclamation mark when the car was first fired up. But now its is permamnently on. I have checked the brake fluid and topped it up, but it still does it. Sometimes when stationary or flying round bends it goes away but only for a second or so. Any ideas to what could be causing this?

Cheers

[Lee]

Check da Bomb mate. Do a thread search to see the simple test you can do. Also more info on S2central website.

[dan_b]

Just to say I bought 2 litres of ATE Super off fleabay the other week for £18. Worth a look if you want this stuff.

[MidnightBlueS2]

Hi everyone,

I'll be doing my 996 brake conversion in a few days and I went to the local car parts shop and got some DOT 4 brake fluid and when getting home, I opened the bottle and it's not GREEN !!!

Can I safely mix this clear yellowish DOT 4 stuff with the green stuff that's in the car's brake and clutch system ? I remember that in Paul N.'s "Buyers Guide" he says that when checking the car over, one has to check that the brake fluid reservoir is filled with GREEN brake fluid...

Help please !

David

[Greg_S]

thats a good question, i want to change the fluid in mine to something better.

Can anyone tell me what the AP formula brake fluid is like & if it is suitable for the S2 and any others they would recommend.

Finally where I can get it from too.

ta

[dan_b]

I've done some rummaging for brake fluid specs from various manufacturers. Higher temperatures are better. Wet boiling point needs to be observed as this is how much lower the fluid will boil at once its been in your system for a while. Obviously if you change your fluid regularly (ie. once a year) this will be less of an issue. However, the "Racing" fluids tend to be more hygroscopic, so absorb water more quickly so will degrade more quickly.

If someone can find specs for Castrol SRF that would be cool.

I've got ATE Super Blue in my system at the moment - it significantly exceeds DOT4 specification - you can get it from eurocarparts.com at the moment quite easily.

ATE Super specs: Dry boiling point 280 deg C
wet boiling point 202 deg C. This fluid is NOT SILICONE and is compatible with conventional brake fluid. It also available in amber color to help when flushing the complete system. Worth noting ATE say you can use it for up to two years without changing as it's fairly non-hygroscopic.

You could also consider the Millers fluid:

Millers Racing Brake Fluid 300 Plus
Equilibrium Reflux Boiling Point - Above 300°C (310°C typical)
Wet Equilibrium Boiling Point - Above 194°C
Kinematic Viscosity at –40°C - Below 1750cSt

£20/litre from Millers, so more expensive than other Dot4s but not as expensive as Castrol SRF...

Which AP brake fluid are you thinking of, they do several:

AP551 specs: Typical New Dry Boiling Point - 275°C (527°F)
Minimum ‘Wet’ E.R. (Equilibrium Reflux) Boiling Point - 150°C (302°F)

AP DOT5.1 specs: ‘Typical’ New Dry Boiling Point - 275°C (527°F) ‘Wet’ E.R. (Equilibrium Reflux) Boiling Point - 184°C (363°F)

AP600 specs: ‘Typical’ New Dry Boiling Point in excess of - 300°C (572°F)
‘Wet’ E.R. (Equilibrium Reflux) Boiling Point - 210°C (410°F)

AP 600 Fluid has been developed for racing applications where higher than normal temperatures are being experienced, e.g. when using carbon/carbon discs and the ultimate in brake fluid performance is required. It should be noted that before using AP 600 fluid, any existing brake fluid should be drained completely from the brake system. The system should be thoroughly purged with new AP 600 brake fluid and can then be filled completely with AP 600 fluid.

IMPORTANT NOTE
DO NOT USE AP600 fluid in contact with any type of magnesium components (e.g. gearbox / clutch components) as a chemical reaction is caused resulting in gases being generated. This will then prevent the clutch hydraulics from working efficiently.

AP660 specs (worth noting AP don't recommend using 660 on road cars due to the amount of water it absorbs - you'd need to change it very regularly)

‘Typical’ New Dry Boiling Point - 320°C
‘Wet’ E.R. (Equilibrium Reflux) Boiling Point - 199°C (390°F)

AP Racing PRF660 Fluid Conforms to and exceeds U.S. FMVSS No 116 DOT 4, SAE J1703 and SAE J1704 specifications and has been developed for racing applications where higher than normal temperatures are being experienced, e.g. when using carbon/carbon discs and the ultimate in brake fluid performance is required. It should be noted that before using AP Racing PRF660 fluid, any existing brake fluid should be drained completely from the brake system. The system should be thoroughly purged with new AP Racing PRF660 brake fluid and can then be filled completely with AP Racing Racing 660 fluid.

IMPORTANT NOTE
DO NOT USE AP Racing PRF660 fluid in contact with any type of magnesium components (e.g. gearbox / clutch components) as a chemical reaction is caused resulting in gases being generated. This will then prevent the clutch hydraulics from working efficiently.

[Jas11n]

Hi everyone,

I'll be doing my 996 brake conversion in a few days and I went to the local car parts shop and got some DOT 4 brake fluid and when getting home, I opened the bottle and it's not GREEN !!!

Can I safely mix this clear yellowish DOT 4 stuff with the green stuff that's in the car's brake and clutch system ? I remember that in Paul N.'s "Buyers Guide" he says that when checking the car over, one has to check that the brake fluid reservoir is filled with GREEN brake fluid...


Help please !

David

S2central site is refering to the PAS fluid, as this powers the bomb, which in turn is what makes your brakes work (no vaccum servo assistance on our cars)
The correct PAS fluid is indeed green.
Your brake fluid is a totally seperate system all together.

And yes you can mix most decent DOT 4 fluids with other DOT 4 fluids regardless of colour.

HTH's

Check there are no serious oil or coolant leaks and check the levels are correct. Do the same for brake and hydraulic fluid.

Note that an S2 must have green fluid in the hydraulic system. The proper stuff is Audi's G002000 fluid and it isn't miscible with anything else.

[Greg_S]

Just reading Dans post. Have our cars got any magnesium components?

Any idea how much the ATE & AP fluids cost?

[Greg_S]

just found some details on s2central about brake fluids

S2 Central Brake Article

SRF is listed. as dry boiling point of 590F and 518F wet.

I have about 1.5 litres of this at home but wasnt sure of how much the S2 needed & wether it was a good idea to use the SRF

[dan_b]

@ Greg Eurocarparts now sell ATE Super blue for about £10 a litre IIRC. Don't know how much the AP stuff is. I think the Millers gook is about £20 a litre. Castrol SRF is about £50 a litre

I don't know about the Magnesium thing, but I would guess its not used in the S2 - Magnesium is usually used in racing car components to keep the weight down?

[dan_b]

From what I understand about SRF, you can use it in the S2. It does require a full flush with SRF of your old fluid first, and then you have to change the SRF for a completely new batch of SRF before using the car. SRF doesn't mix well with normal brake fluid. The S2 brake system takes I think about 750ml, so at a minimum you need 1litre, but to ensure a good full bleed to get all the old fluid out and drag out all those nasty bubbles, it's worth flowing through at least 1.5litres. That starts to make the SRF very expensive to use!

[dan_b]

just found some details on s2central about brake fluids

SRF is listed. as dry boiling point of 590F and 518F wet.

Cool - to complete the comparison then, SRF is:

Dry - 310 Celcius
Wet - 270 Celcius

[Greg_S]

well the SRF is sitting there so may be worth me using that, however I will probably need another litre....

[MidnightBlueS2]

S2central site is refering to the PAS fluid, as this powers the bomb, which in turn is what makes your brakes work (no vaccum servo assistance on our cars)
The correct PAS fluid is indeed green.
Your brake fluid is a totally seperate system all together.

And yes you can mix most decent DOT 4 fluids with other DOT 4 fluids regardless of colour.

HTH's

Great news ! Thanx !