What performance brake fluid and how much?
Discussion
Press the brake pedal and hold it down before disconnecting brake hoses, this will close the filling side of the master cylinder, and stop the fluid draining through the system completely, preventing air getting in the system. Then once everything is reconnected, syringe out as much of the fluid from the reservoir as possible, refill with new fluid before going through the bleeding process - with this, start furthest away from the master cylinder, then work towards it.
ATE super blue fluid is apparently very good, and being blue, is easy to identify when it bleeds through. I just used Halfords DOT 5.1 on the BMW I just rebuilt, it's a small amount extra and works well. Don't use 'racing' fluids on the road, as they are usually much more hygroscopic and need changing more often (which they are on race cars), making them unsuitable for being left for a couple of years in a road car brake system.
Use DIS to do a ABS/DSC bleed procedure.
ATE super blue fluid is apparently very good, and being blue, is easy to identify when it bleeds through. I just used Halfords DOT 5.1 on the BMW I just rebuilt, it's a small amount extra and works well. Don't use 'racing' fluids on the road, as they are usually much more hygroscopic and need changing more often (which they are on race cars), making them unsuitable for being left for a couple of years in a road car brake system.
Use DIS to do a ABS/DSC bleed procedure.
bgunn said:
ATE super blue fluid is apparently very good, and being blue, is easy to identify when it bleeds through.
This is cheap from Eurocarparts and has a very high boiling point for the money. Not too far off RBF600.Fluid choice depends on how hot you get the brakes, and how often you plan on changing the fluid.
DOT 5.1 doesn't necessarily mean better than DOT4, the best fluids are generally DOT4. The base chemical composition defines what category it falls into, most DOT4 way exceed the DOT5.1 boiling point standards these days as well.
Castrol SRF is without doubt the best fluid you can use, and to use it will cost you less than a tank of fuel - if you truly want "performance" I wouldn't consider anything else.
Castrol SRF is without doubt the best fluid you can use, and to use it will cost you less than a tank of fuel - if you truly want "performance" I wouldn't consider anything else.
SRF is not the best and has not been for some time. Brembo, AP Racing and Motul all have better performing racing fluids.
Best all round road fluid is probably TRW 5.1/ESP. There are some racing DOT 4 fluids with better boiling point, but they will not be as good at the low temperature viscosity. If your car has a modern ABS system you're best to go for 5.1.
Best all round road fluid is probably TRW 5.1/ESP. There are some racing DOT 4 fluids with better boiling point, but they will not be as good at the low temperature viscosity. If your car has a modern ABS system you're best to go for 5.1.
Yeah, just standard common all garden brake fluid is fine, the higher performance ones tend to not last as long and are overkill on a road car, the braided hoses are good, you do notice the difference, especially when coming from older rubber ones, I did the fronts on my 944 (not got to the rears yet) and gave the calipers a good clean and it was a pleasing improvement. I invested in a Gunson "Easi Bleed" from Amazon and it makes bleeding the brakes afterwards a breeze, it uses the pressure from a tyre, a lot easier than enlisting the wife or one of the kids to sit there pumping the brakes.
Dont tend to find cars are under braked these days so usually, well maintained standard, with some decent pads, clean fluid and the hoses means you have as much brakign as you ever need, years since I boiled any brakes, or set fire to them.
Dont tend to find cars are under braked these days so usually, well maintained standard, with some decent pads, clean fluid and the hoses means you have as much brakign as you ever need, years since I boiled any brakes, or set fire to them.
Hudges said:
SRF is not the best and has not been for some time. Brembo, AP Racing and Motul all have better performing racing fluids.
Best all round road fluid is probably TRW 5.1/ESP. There are some racing DOT 4 fluids with better boiling point, but they will not be as good at the low temperature viscosity. If your car has a modern ABS system you're best to go for 5.1.
Sorry to disagree, but none of the fluids you mention has a wet boiling point which can come close to SRF, and IME wet boiling point is what matters unless you either live in a desert or are changing fluid before each use. As for a modern ABS system needing 5.1 - sorry, just not true.Best all round road fluid is probably TRW 5.1/ESP. There are some racing DOT 4 fluids with better boiling point, but they will not be as good at the low temperature viscosity. If your car has a modern ABS system you're best to go for 5.1.
Braided hoses? I declare cosmetic. High performance car manufacturers don't usually fit braided. If your rubber hoses are knackered, fit new OEM rubber ones. It's the new fluid which changes the feel of the brakes, not the hose.
New fluid? Regular changes make good sense. Most manufacturers specify every 2 years but unfortunately a lot of owners don't bother. Fluid absorbs water over time. "One of the most significant changes that increased moisture brings is a decrease in the fluid boiling temperature. 2% water content can result in a 90° C drop in its boiling point. Brake fluid can commonly see 150 – 200° C at the brake callipers. This combination of lower boiling point along with high temperatures can introduce vapour lock under adverse braking conditions, with potentially fatal results."
High performance fluid? Brake fluid is brake fluid (use correct type) unless you're running mahoosive brake temperatures - for instance carbon brakes. Which is unlikely.
New fluid? Regular changes make good sense. Most manufacturers specify every 2 years but unfortunately a lot of owners don't bother. Fluid absorbs water over time. "One of the most significant changes that increased moisture brings is a decrease in the fluid boiling temperature. 2% water content can result in a 90° C drop in its boiling point. Brake fluid can commonly see 150 – 200° C at the brake callipers. This combination of lower boiling point along with high temperatures can introduce vapour lock under adverse braking conditions, with potentially fatal results."
High performance fluid? Brake fluid is brake fluid (use correct type) unless you're running mahoosive brake temperatures - for instance carbon brakes. Which is unlikely.
alistair1234 said:
Should have said this is for track use.
That's the only reason why I'm doing this, 30 min's last time (which was my first ever time on track in my own car) and they were gone.
If you 'lost' the brakes, you need to identify whether the problem was with the disks, pads or fluid. Different types of failure, different solutions.That's the only reason why I'm doing this, 30 min's last time (which was my first ever time on track in my own car) and they were gone.
Dry boiling point
Wet boiling point
Viscosity limit
Primary constituent
DOT 2 190 °C (374 °F) 140 °C (284 °F) ? Castor oil/alcohol
DOT 3 205 °C (401 °F) 140 °C (284 °F) 1500 mm2/s Glycol Ether
DOT 4 230 °C (446 °F) 155 °C (311 °F) 1800 mm2/s Glycol Ether/Borate Ester
DOT 5 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s Silicone
DOT 5.1 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s Glycol Ether/Borate Ester
Not easy to see, but Dot 5.1 dry boiling point 260 deg C and wet boil point of 180 deg C exceeds Dot 4. (Don't use Dot 5 in most systems as silicon and glycol are not compatible.
Simple answer - use Dot 5.1 for everything.
bearman68 said:
Dry boiling point
Wet boiling point
Viscosity limit
Primary constituent
DOT 2 190 °C (374 °F) 140 °C (284 °F) ? Castor oil/alcohol
DOT 3 205 °C (401 °F) 140 °C (284 °F) 1500 mm2/s Glycol Ether
DOT 4 230 °C (446 °F) 155 °C (311 °F) 1800 mm2/s Glycol Ether/Borate Ester
DOT 5 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s Silicone
DOT 5.1 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s Glycol Ether/Borate Ester
Not easy to see, but Dot 5.1 dry boiling point 260 deg C and wet boil point of 180 deg C exceeds Dot 4. (Don't use Dot 5 in most systems as silicon and glycol are not compatible.
Simple answer - use Dot 5.1 for everything.
Those are the minimum specifications to meet the DOT requirements. There are numerous DOT4 fluids that exceed the DOT5.1 specifications for boiling points. It's all a bit academic unless you are actually boiling the fluid however, which is very rare with fresh fluid.Wet boiling point
Viscosity limit
Primary constituent
DOT 2 190 °C (374 °F) 140 °C (284 °F) ? Castor oil/alcohol
DOT 3 205 °C (401 °F) 140 °C (284 °F) 1500 mm2/s Glycol Ether
DOT 4 230 °C (446 °F) 155 °C (311 °F) 1800 mm2/s Glycol Ether/Borate Ester
DOT 5 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s Silicone
DOT 5.1 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s Glycol Ether/Borate Ester
Not easy to see, but Dot 5.1 dry boiling point 260 deg C and wet boil point of 180 deg C exceeds Dot 4. (Don't use Dot 5 in most systems as silicon and glycol are not compatible.
Simple answer - use Dot 5.1 for everything.
Ozzie Osmond said:
Braided hoses? I declare cosmetic. High performance car manufacturers don't usually fit braided. If your rubber hoses are knackered, fit new OEM rubber ones. It's the new fluid which changes the feel of the brakes, not the hose.
I agree. Besides, OEM lines are not rubber, they are just rubber coated (hence the lack of prettyness) but more often than not braided Kevlar underneath (which is very stiff and doesn't deform particularly more than braided metallic lines).I usually get insulted for daring to say that HEL or Goodridge lines are only good at placebo...
Gassing Station | General Gassing | Top of Page | What's New | My Stuff