racing brake fluid

BigglesPiP · 27 Mar 2008 at 00:18

saitrix said:
From wiki

tut tut

saitrix · 27 Mar 2008 at 00:19

BigglesPiP said:
tut tut

Ahh yes of course, wiki is so different to asking on a forum. To be honest something like that will be correct on wiki.

needmorespeed · 27 Mar 2008 at 00:19

http://www.h-e-l.co.uk/HEL_Performance_Motorcycle_Brake_Lines_Brake_Doctor_FAQ.htm

BigglesPiP · 27 Mar 2008 at 00:22

saitrix said:
Ahh yes of course, wiki is so different to asking on a forum. To be honest something like that will be correct on wiki.

Fair point.

I like to use Wikki as a start if I have no idea at all on a subject, but anything i reference to later is from separate sources. Mostly because if I hand in a report which references Wikki, I fail.

Scania · 27 Mar 2008 at 04:02

Ahh, I love this forum.

Back to the OP's question, has he got a Race car? Nope, its a Mondeo.

Therefore, me thinks, he won't need race fluid......

That was hard. :rolleyes:

Best way to change it? Pay somebody else to do it for you.

>> Runs <<

Dogbreath · 27 Mar 2008 at 08:59

BigglesPiP said:
Racing fluid does not absorb water.

Well, that would depend on if the "racing" fluid is silicone or mineral based. Silicone fluid has fallen out of favour due to several drawbacks, so I was assuming we were talking about mineral. Have a look at the AP Racing website and you'll see that all their competition fluids are not silicone based, and in fact they don't recommend the use of silicone fluid.

Mattius · 27 Mar 2008 at 09:33

Racing fluid doesnt absorb water! it just has a higher boiling point than std, and is thinner in viscosity which is why you shouldnt run it in any eurobox, the chances are it will get past the seals etc.

Save your money, there is no bennefit appart from supper hard driving on the track where you can boil the fluid. Buy new pads instead then you will notice a difference, buy something decent not std and not the ebc crap.

Dogbreath · 27 Mar 2008 at 09:56

Mattius said:
Racing fluid doesnt absorb water! i

If that is the case then why do AP state a dry and a wet boiling point for their competition fluids?

Simon · 27 Mar 2008 at 10:19

Super Dot 4 has a higher boiling point than 5.1

I'd just stick anything in to be honest. Halfords own 5.1 does me.

Mattius · 27 Mar 2008 at 10:57

once boiled the fluid detereorates and hence will absorb, but you shouldnt boil your fluid in the first place. The wet figures are for when you have water in the system, it doesnt absorb the water but mixes with it, since the fluid has a higher boiling point than the water in the system lowers the boiling point.
But if you have water in your system in the first place then that is your braking problem and should sort that first.

and halfords brake fluids are not racing fluids lol.

But at the end of the day, we arent talking about a racing car, we are talking about a bloody mondeo, fit the manufacturers recomended fluid, it will tell you in the manual, otherwise you will have problems with brake seals, fitting silicon fluid if the seals are not up to it and have no brakes at all when the fluid leaks onto the pistons!!!!

As already stated race fluid will not improve your braking, end off.

Dogbreath · 27 Mar 2008 at 11:14

Mattius said:
The wet figures are for when you have water in the system, it doesnt absorb the water but mixes with it, since the fluid has a higher boiling point than the water in the system lowers the boiling point.

Any brake fluid based on polyglycol ethers (such as e.g. AP racing fluids) will be hygroscopic (i.e. attracts moisture out of the air) to some extent. Some more so than others of course.

AP web site said:
To obtain the best performance from racing brake systems, bleed the system thoroughly, immediately prior to each event using AP Racing brake fluid from a new sealed bottle. This is particularly important in wet or humid conditions or when the brakes are excessively hot. Always use fresh fluid and replace bottle cap when not in use. Never re-use brake fluid.

Mattius · 27 Mar 2008 at 11:22

yes but it doesnt absorb, if you empty brake fluid into a container from the car you will see the water floating on top of it. It mixes with the water lowering the boiling point.

Simon · 27 Mar 2008 at 11:48

Mattius said:
and halfords brake fluids are not racing fluids lol.

Who said they were? :confused:

Brake fluids are hygroscopic. They have an affinity to moisture in the atmosphere. You won't see water on top of brake fluid either, they are misible and will mix, if they did separate then, due to density, the water would be at the bottom.

This is the problem with silicone based fluids, the water goes to the lowest point of the system, the brake calipers. This also happens to be the hottest.

FYI, Wet boiling points are when the fluid has 1.5% water by mass. Hardly a huge amount.

Dogbreath · 27 Mar 2008 at 13:24

Mattius said:
yes but it doesnt absorb, if you empty brake fluid into a container from the car you will see the water floating on top of it. It mixes with the water lowering the boiling point.

I think you are confusing silicone based fluids with conventional poly glycol (including competition) based ones. Silicone doesn't absorb moisture, but hardly anyone uses these days due to it's numerous drawbacks.

Conventional brake fluids most certainly do absorb moisture, hence the recommendations for only using sealed bottles and replacing the cap after use.

Jonnycoupe · 27 Mar 2008 at 13:34

BigglesPiP said:
Fair point.

I like to use Wikki as a start if I have no idea at all on a subject, but anything i reference to later is from separate sources. Mostly because if I hand in a report which references Wikki, I fail.

Where did you get Dot 5.3 from then?

Jonnycoupe · 27 Mar 2008 at 13:35

Super dot 4 is a good road car spec, nice high wet boiling points which in the UK will be 80% of the time on something like a 2 year service anyway.

Simon · 27 Mar 2008 at 13:46

Yeah Castrol Super Dot 4 is one of the best fluids you can get for a road car.

nutcase · 27 Mar 2008 at 16:30

Dogbreath said:
Silicone doesn't absorb moisture, but hardly anyone uses these days due to it's numerous drawbacks.

Again, 20+ years in two cars, and 5 years in another (and that one has calipers all round). No hassles

It's expensive stuff to start using in the first place, but once in, it's pretty much fit and forget beyond normal checks. It's a pain to fit as you have to renew every rubber component in the system that comes in contact with the fluid as that negates the qualities of the silicone fluid. Not many people use it because of those reasons, or if they don't do it properly and then the seals start to leak quickly they complain.

It is *slightly* more compressible than standard fluid, and I wouldn't recommend it for more than the odd trackday use, but we're more than happy with it.

BigglesPiP · 27 Mar 2008 at 16:30

Jonnycoupe said:
Where did you get Dot 5.3 from then?

A mechanic.

OT: So we can reach a conclusion? Don't use silicone fluid (or anything else non-hygroscopic), try to avoid anything to thin, otherwise; it's your money.

Jonnycoupe · 27 Mar 2008 at 16:38

BigglesPiP said:
A mechanic.

OT: So we can reach a conclusion? Don't use silicone fluid (or anything else non-hygroscopic), try to avoid anything to thin, otherwise; it's your money.

With a sharpie marker pen?

Too thin? Whats that got to do with hydraulic fluids?

Infact scrap that, what you really need is some triple ester silolene Pro -B...