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Brake fluid
- Thread starter wocka
- Start date
This is the stuff I have.
Yes its DOT4, but it is rated way above the minimum requirements for DOT4.
172 Cup
Don't looking at the DOT ratings for brake fluid that's only a suitability test. You want to look at the wet boiling point of the fluid if you interested in pushing the car on a track etc.
Stolen from one of the members on Frenchcarsireland:
Ive been researching brake fluids for a bit and have been written this up as a result of my findings. Its an important consumable should not be overlooked nor neglected. I'm just sharing some of what i have learned and hope its of some interest and use.I think its fairly accurate but am open to corrections should I have errors
ok
(DOT)Department of Transportation classifies brake fluids to standard specifications. These specs relate to their boiling points and chemical make-up, both of which are important. All currently available brake fluids are covered by one of the following specs DOT3, DOT4, DOT5 and DOT5.1.
Energy from braking is turned into heat through friction. A braking system only works efficiently if the fluid remains incompressible.(liquid state) If the brake fluid boils, it turns to gas, which is compressible and the braking system becomes “spongy” or in extreme cases fails completely.might as well be using compressed air to blow the pads onto the disc. As air in a hydraulic systems fluid makes it extremely inefficient.
A brake system is not perfectly sealed and moisture can get into the system and be absorbed by the fluid.(usually through time, and through a bad seal filler cap) The effect is to reduce the boiling point of the fluid, which reduces the efficiency of the braking system,
All brake fluids with the exception of silicone based fluid are hydroscopic which means that they attract water. on a side note never use a brake fluid from an open container, or one which is years old as it could be riddled with water...
and NEVER re-use old brake fluid
The D.O.T specifies two tests for brake fluids.
The dry boiling point - the boiling point of fresh brand new uncontaminated fluid
The wet boiling point is the boiling point once the fluid has absorbed water(representing brake fluid after time spent in service)
There are two main types of brake fluids:
DOT3, 4, Super4 and Dot 5.1 which are based on poly glycol composition)
Dot5 is of Silicone composition.
Note the two types of fluid are not compatible and should never be mixed in a braking system!!! (silicone based with poly glycol)
Silicone brake fluid (DOT 5)
Silicone based Dot 5 was originally introduced to give higher temperature performance over glycol Dot 4. Silicone fluid also has other advantages, it does not damage paint and it does not absorb water.(non hydroscopic)
However, silicone fluid is a poor lubricant and does not lubricate ABS pumps as well as poly glycol fluids. It is slightly more compressible than Dot3, 4, Super4 and 5.1, which can result in a sluggish or a spongy pedal.(like the feeling that you need to bleed your brakes). It does not absorb water, any water remains as blobs, which can build up in in the braking system (eg lines, abs pump etc) and cause corrosion. The water can vaporize to gas when heated under heavy braking giving a shitty effect on braking efficiency. (most lines compose of mild steel as it is more fatigue resistant to copper (which is more flexible but can age harden and crack over time)the down side for mild steel is the corrosion aspect with regards to water ingress
DOT5 fluids are not recommended for motor sport applications, and only should be used under manufacturers recommendations
Poly glycol fluids(DOT 3, 4 AND 5.1)
Glycol based DOT 4 fluid is the basic benchmark brake fluid, and has a higher boiling point both in dry and wet conditions than its predecessor.
DOT 5.1 has higher specification still and is for fast road and occasional track day use. It has a similar spec to DOT4 for the boiling point (>260) but is a lot lower viscosity @-40C typically 900 centistoke (compared to 1500 - 1800 centistoke for DOT 4 and super DOT 4).
Listed below, are the minimum dry/wet boiling point spec for each D.O.T level.
Boiling points dry and wet:
DOT 3 - 205°degrees Centigrade (dry) and 140°Degrees Centigrade (wet)
DOT 4 - 230°C (dry) and 155°C (wet)
DOT 5 (silicone) - 260°C (dry) and 185°C (wet)
DOT 5.1 (Poly glycol) - 260°C (dry) and 185°C (wet)
Super Dot4 - 300°C (dry) and 195°C (wet)
again if i have made any mistakes..... s**t this is a long post..lol
Stolen from one of the members on Frenchcarsireland:
Ive been researching brake fluids for a bit and have been written this up as a result of my findings. Its an important consumable should not be overlooked nor neglected. I'm just sharing some of what i have learned and hope its of some interest and use.I think its fairly accurate but am open to corrections should I have errors
ok
(DOT)Department of Transportation classifies brake fluids to standard specifications. These specs relate to their boiling points and chemical make-up, both of which are important. All currently available brake fluids are covered by one of the following specs DOT3, DOT4, DOT5 and DOT5.1.
Energy from braking is turned into heat through friction. A braking system only works efficiently if the fluid remains incompressible.(liquid state) If the brake fluid boils, it turns to gas, which is compressible and the braking system becomes “spongy” or in extreme cases fails completely.might as well be using compressed air to blow the pads onto the disc. As air in a hydraulic systems fluid makes it extremely inefficient.
A brake system is not perfectly sealed and moisture can get into the system and be absorbed by the fluid.(usually through time, and through a bad seal filler cap) The effect is to reduce the boiling point of the fluid, which reduces the efficiency of the braking system,
All brake fluids with the exception of silicone based fluid are hydroscopic which means that they attract water. on a side note never use a brake fluid from an open container, or one which is years old as it could be riddled with water...
and NEVER re-use old brake fluid
The D.O.T specifies two tests for brake fluids.
The dry boiling point - the boiling point of fresh brand new uncontaminated fluid
The wet boiling point is the boiling point once the fluid has absorbed water(representing brake fluid after time spent in service)
There are two main types of brake fluids:
DOT3, 4, Super4 and Dot 5.1 which are based on poly glycol composition)
Dot5 is of Silicone composition.
Note the two types of fluid are not compatible and should never be mixed in a braking system!!! (silicone based with poly glycol)
Silicone brake fluid (DOT 5)
Silicone based Dot 5 was originally introduced to give higher temperature performance over glycol Dot 4. Silicone fluid also has other advantages, it does not damage paint and it does not absorb water.(non hydroscopic)
However, silicone fluid is a poor lubricant and does not lubricate ABS pumps as well as poly glycol fluids. It is slightly more compressible than Dot3, 4, Super4 and 5.1, which can result in a sluggish or a spongy pedal.(like the feeling that you need to bleed your brakes). It does not absorb water, any water remains as blobs, which can build up in in the braking system (eg lines, abs pump etc) and cause corrosion. The water can vaporize to gas when heated under heavy braking giving a shitty effect on braking efficiency. (most lines compose of mild steel as it is more fatigue resistant to copper (which is more flexible but can age harden and crack over time)the down side for mild steel is the corrosion aspect with regards to water ingress
DOT5 fluids are not recommended for motor sport applications, and only should be used under manufacturers recommendations
Poly glycol fluids(DOT 3, 4 AND 5.1)
Glycol based DOT 4 fluid is the basic benchmark brake fluid, and has a higher boiling point both in dry and wet conditions than its predecessor.
DOT 5.1 has higher specification still and is for fast road and occasional track day use. It has a similar spec to DOT4 for the boiling point (>260) but is a lot lower viscosity @-40C typically 900 centistoke (compared to 1500 - 1800 centistoke for DOT 4 and super DOT 4).
Listed below, are the minimum dry/wet boiling point spec for each D.O.T level.
Boiling points dry and wet:
DOT 3 - 205°degrees Centigrade (dry) and 140°Degrees Centigrade (wet)
DOT 4 - 230°C (dry) and 155°C (wet)
DOT 5 (silicone) - 260°C (dry) and 185°C (wet)
DOT 5.1 (Poly glycol) - 260°C (dry) and 185°C (wet)
Super Dot4 - 300°C (dry) and 195°C (wet)
again if i have made any mistakes..... s**t this is a long post..lol
frayz
ClioSport Club Member
Used Motul RBF600 in my impeza and its awesome. Will be using that in the Clio too. Highly recomended 
I ran ATE superblue and if you dont get it out within 12 months (and change to the Amber one) it WILL stain your lines and it will be a git to bleed through other colours later.
I moved to Mintex OEM 5.1 and its taken a beating really well, and as a bonus its about £3 per litre lol.
I moved to Mintex OEM 5.1 and its taken a beating really well, and as a bonus its about £3 per litre lol.
Thats a superb post Craig. Cheers mate.
I've just bought my 182 (about 6 months ago) and the pedal is now feeling a little spongy. Can I simply top up the existing fluid (not sure which spec it is) with 5.1 or so? Or would it be best to bleed the system first and then refill to reduce the risk of contamination?
AFAIK non-hydroscopic is hydrophobic.
cheers.
I've just bought my 182 (about 6 months ago) and the pedal is now feeling a little spongy. Can I simply top up the existing fluid (not sure which spec it is) with 5.1 or so? Or would it be best to bleed the system first and then refill to reduce the risk of contamination?
AFAIK non-hydroscopic is hydrophobic.
cheers.
I have heard this, but don't quite get how? Does it cause all other fluids to come out looking blue so its difficult to tell when the old fluid has gone and the new fluid has filled the system? What if you replace with more blue and just use 1/4 of a litre each corner?
You can do it that way... I like to be sure its changed properly though so when I dropped the ATE stuff out I ran 3Litres through and it was still streaking blue so just made do with that as I was getting bored at that point.
More blue would make life sort of easier but you cant be 100% sure youve changed the fluid, but then the same goes if using clear/Amber colour stuff
so just made do with that as I was getting bored at that point.More blue would make life sort of easier but you cant be 100% sure youve changed the fluid, but then the same goes if using clear/Amber colour stuff
172 Cup
Firstly non-hydroscopic is indeed hydrophobic, silicone race fluids are like this but will ruin you normal system if used. If your pedal is felling spongy it could be down to air in the system or the fluid is too wet. If you were going to do to the hassle of bleeding your brakes I'd just change the fluid tbh. Also you can mix fluids no problem. To do a fluid change don't empty your system just bleed the fluid and top up with the new one until you've flushed a sufficient amount through to know you've changed it all.
Astra coupe t, nova
I run ATE super blue in my clio atm. In the nova and coupe I always used to/run 5.1.
Hi stuart:rasp:
Hi stuart:rasp:
