Trackday Brake Fluid

[pettsy]

The time has come to fill up the re-piped brake system, was just wondering what brake fluid everyone is using out on track? Tried searching the forum but couldn't find anything

Pettsy

[UweM3]

if you are on a budget Halfords DOT 5.1

if you want to spend a little bit more ATE Super Blue, Motul RBF 600

if you want the best CASTROL SRF (£40ish the liter!)

from my experience you either stay with Halfords 5.1 or you go for SRF, there is not much difference otherwise.

[billgatese30]

I tend to go for Motul RBF 600/660 as I order it a few litres at a time from Opie Oils

[AlpineAde]

I've used both AP Racing and Motul brake fluids. I've been very happy with both.

[pettsy]

i did have a look at the motul stuff on the opieoils site (got to order some diff oil too) but wasn't sure what the difference between the R600 and R660 is?

[billgatese30]

not sure tbh, i tried to look but they are both DOT 4 with the same boiling points. I usually get whatever they have in stock.

[AlpineAde]

From the Motul Australia site:

RBF600

"100% synthetic, RBF 600 FACTORY LINE is a polyglycol-based brake fluid exclusively designed for races. Developed to resist high temperatures and wet-weather conditions, RBF 600 has a high dry boiling point of 312°C and a wet boiling point of 216°C. This ensures effective braking under extreme racing or rainy conditions. Couple this with its outstanding anti-vapor lock performance, RBF 600 has become a well-trusted brake fluid in many races."

RBF660

"100% Synthetic Racing Fluid ”“ DOT4
Very high boiling point: 325℃/617°F
Very high wet boiling point: 204℃/400°F.

All types of hydraulic brake and clutch actuators requiring non-silicone synthetic fluid. Specially designed to resist to extreme temperature generated by racing carbon and ceramic brakes allowing to minimize air entrance for brake cooling"

And here is a very good page on brake fluid:

http://www.stoptech.com/tech_info/wp_br ... d_1a.shtml

Well worth the read.

[Simon13]

ATE super blue is very good but its wet boiling point is a bit lower than the motul 600 which is slightly higher spec. Depends on how hard you are on brakes a little

[pettsy]

think i'll go for the Rbf600. Will 2 litres be enough to fill an empty system?

[billgatese30]

depends on how much bleeding it takes, I have sometimes used nearly a litre just to bleed brakes before, some of the time I have needed less than 250ml.

I think I may go between super blue and motul from now on as it is easier to see when the new stuff is through.

Wet boiling points are only relevant when the fluid is old, if they are fresh before a trackday then you should have no problems (unless you start boiling it, which with good fresh stuff you shouldn't have too much to worry about).

[Jon_Bmw]

Some might disagree with you there Bill. Some argue that performance fluids absorb water very quickly and you should pay more attention to the wet boiling point. We change every session or every other and have had no problems with doing this. It also means I don't have to investigate which to pay more attention to (wet or dry)!!

[billgatese30]

I change more often than that Jon, even with the MR2 (because it was even easier than the e30) I did it about 3 or 4 times a year.

I've been trying to get my hands on a good brake fluid metre for a while now, but for a decent one they are all expensive.

[BadDave]

I think I may go between super blue and motul from now on as it is easier to see when the new stuff is through.

Chris
No need to swap between brands
ATE Super Blue(Blue in colour) and ATE TYP 200(Gold in colour) are the same fluid, just a different colour to make it easier to see when you've flushed all the old stuff out of the system.

Both should cost the same

[billgatese30]

I've always been a motul man untill now, I have only used super blue as that is what was supplied in the S50 and its seems to work well, I have just finished ordering the last of my high tech 'mad scientist' brake fluid tester kit too.

[UweM3]

Some might disagree with you there Bill. Some argue that performance fluids absorb water very quickly and you should pay more attention to the wet boiling point. We change every session or every other and have had no problems with doing this. It also means I don't have to investigate which to pay more attention to (wet or dry)!!

Use SRF and you can forget about changing the fluid every session.
I know it's expensive but even for a tight a**e like me it's worth the money. More free time at the track and not running around with the bleeder.

[djs325]

Except for Castrol SRF, nearly all the other "racing' brake fluids are made by the same company, and just get different dyes and bottle colours/designs. Motul, Penrite, AP Racing etc (as far as I know) are all the same, they have a 600F (~315C) and 660F (~325C) fluid. These are 'better' than Castrol SRF's dry ~310C boiling point. But they all have a poor wet boiling point (~200-220C) compared to SRF (~280C). Which is why nearly every racing team that I have seen working on brakes, where performance was absolutely critical, uses SRF.

Personally, I have an arrangement with Motul for RBF660. It works fine, so long as you flush it through regularly. One advantage over SRF is the amber dye, which makes it easier to spot the fill levels and any leaks.

For street and occasional use I would highly recommend a good DOT 5.1 Fluid. Avoid DOT 5, as this is a silicon fluid that is not compatible with most of the rubber seals used in BMW braking systems.

For track day, any of the racing (600/660) fluids are good, provided that you take good care of the system and bleed before every day. Better yet, make good use of the down time between track sessions and double-check the system by doing a quick pressure bleed with a mate helping you. Never know when you'll be generating bubbles.

For the professional, I always observe that Castrol SRF is the choice of champions. Maybe they know what they're doing...

[RPM]

I run the ATE racing fluid on the race car, and probably change it 4 times a year, more for peace of mind than anything.

Never had any problems with it, touchwood

[billgatese30]

I'm going to start checking my fluid rather than just changing it for peace of mind, it'll be interesting to see how long it takes (or not as the case may be) before the boiling point drops.

[ShakeyC]

I run the ATE racing fluid on the race car, and probably change it 4 times a year, more for peace of mind than anything.

Never had any problems with it, touchwood

Spot on the problem is the fluid may have a 2yr shelf life and people think its ok to not change it for 2yrs+

Some of the dot3 out perform dot5.1 with way higher wet and dry points infact some big names are basically rebranded to 5.1 but technically its a dot3 fluid.... but i wont go there not to confuse everyone but its certainly cheap high quality stuff

[Splondike]

I use ATE superblue in the M535i and it has not given me any problems, I just refresh it after each track day normally.