racing brake fluid

DannyW · 24 Mar 2008 at 22:36

will i notice a difference on a mondeo? or should i just buy good old comma?

also guys, whats the best way to CHANGE brake fluid, i already know how to bleed it.

thanks.

jon.bda · 24 Mar 2008 at 22:38

Save a good wedge, stick the normal stuff in, its all you'll need...and bleed it until the new stuff comes through...thats how to change it...

DannyW · 24 Mar 2008 at 22:40

would 500 ml be enough to do all 4 corners?

Bradley8988 · 24 Mar 2008 at 22:43

i used to run silicon stuff but i it was really hard to get a good feel outa em so went back to using normal stuff.

helpimcrap · 24 Mar 2008 at 22:45

halfords super dot 4 works for me.

use it on my race bikes - no problems.

DannyW · 24 Mar 2008 at 22:46

will i even benefit from a brake fluid change?

saitrix · 24 Mar 2008 at 22:47

I just use Comma dot 4, no problems with it at all. All you need for a normal car.

If you have an easy bleed put it on with the bleed nipple open but with no fluid in the bottle. It will force out all of the old fluid.

helpimcrap · 24 Mar 2008 at 22:48

DannyW said:
will i even benefit from a brake fluid change?

for normal use not really, but if your fluid had water in you will notice a better pedal feel.

Oakesy2001uk · 25 Mar 2008 at 07:55

Basicly fluid picks water up as it is used. race stuff doesn't pick water up as fast, more water means fluid gets hotter. Also works in a higher temperature range that you will never see on the road. don't worry about it.

I use Castrol SRF in my race bike purely because I can change that once every 4-5 td's, 2-3 races instead of one for normal fluid. its cost effective this way. but i didn't worry about it until started doing semi-decent times. just use decent halfords stuff once a year for road cars/bikes.

lordrobs · 25 Mar 2008 at 09:28

Oakesy2001uk said:
race stuff doesn't pick water up as fast,

I thought it was the other way around and hence why the race stuff wasn't any good for a road car where the intervals for changing brake fluid are much longer?

kirbrot · 25 Mar 2008 at 09:40

lordrobs said:
I thought it was the other way around and hence why the race stuff wasn't any good for a road car where the intervals for changing brake fluid are much longer?

I agree. the silicon race stuff should (according to the manufacturers) be changed after every meeting for this very reason. I used it for while but didn't really see any difference over the AP dot5.1 fluid whilst using standard calipers and discs.

I certainly wouldn't bother with it in the car.

Dogbreath · 25 Mar 2008 at 09:45

DannyW said:
will i even benefit from a brake fluid change?

If it hasn't been changed according to the service schedule then yes. Brake fluid absorbs moisture, lowering it's boiling point and causing corrosion within the hydraulic system.

"Racing" brake fluid will be designed to have a higher "dry" boiling point than standard fluid, but usually the boiling point degrades more quickly as it absorbs moisture. Absolutely no point on a standard road car unless you have a problem with boiling brake fluid regularly...

BigglesPiP · 25 Mar 2008 at 16:18

DannyW said:
will i notice a difference on a mondeo?

Racing fluid? You mean dot 5? YES you will notice a HUGE difference. About 1 week after you filled it, you will completely loose your brakes on the 2nd press of the pedal.

Dot 4 mixes with moisture, which reduces the boiling point of the fluid.

Dot 5 does not mix with any moisture in the system, instead the water forms a separate layer, which the brake fluid then floats on top of. So you have water in the lowest part of the system, the callipers.

When you 1st brake, the water will be heated, when you release pressure the water will rapidly boil, and fill your callipers and a lot of the brake lines with steam, which is lousy as brake fluid.

Dot 5 needs work before every racing weekend. The best stuff for your road car is fresh Dot 4 which hasn't had time to fill with much moisture.

BigglesPiP · 25 Mar 2008 at 16:19

Dogbreath said:
"Racing" brake fluid will be designed to have a higher "dry" boiling point than standard fluid, but usually the boiling point degrades more quickly as it absorbs moisture.

Racing fluid does not absorb water.

needmorespeed · 25 Mar 2008 at 16:41

dot 5 is silcone which doesn't absorb water and is useless for high performance driving you want dot 5.1 which is a normal fluid but has a higher boiling point then dot 4. I'm using halfords dot 5.1 in my car and i haven't boiled it yet but i did managed to boil dot 4fluid

nutcase · 25 Mar 2008 at 19:09

We've had silicone (DOT 5) fluid in two cars for over 20 years without any need for bleeding out water. It's not suitable for ABS systems though as it can foam.

On 99% of cars, no point going for anything but standard DOT 4.

BigglesPiP · 26 Mar 2008 at 22:18

OK guys, I ****** up.

DOT 5 is not silicone fluid.

DOT 5 will absorb water, it's silicone racing fluid which is the dangerous stuff.

DOT 5 is simply DOT 4 with a higher boiling point, you can get DOT 5.3 too.

needmorespeed · 27 Mar 2008 at 00:14

BigglesPiP said:
OK guys, I ****** up.

DOT 5 is not silicone fluid.

DOT 5 will absorb water, it's silicone racing fluid which is the dangerous stuff.

DOT 5 is simply DOT 4 with a higher boiling point, you can get DOT 5.3 too.

wrong DOT 5 is silicone based dot 5.1 is like dot 4 but with higher boiling points

BigglesPiP · 27 Mar 2008 at 00:15

Balls, so I was right the 1st time.

saitrix · 27 Mar 2008 at 00:16

From wiki,

"DOT 2 is essentially castor oil; DOT 3, DOT 4, and DOT 5.1 are composed of various mineral oils, glycol esters, and ethers; some are synthetic oil based, and DOT 5 is silicone-based."