aqua

Apologies for possibly a dumb question but

What advantages are there for upgrading from the standard brake fluid in an 01 WRX and upgrading the brake hoses at the same time (I do not do track days).

I think I understand that upgraded hoses are supposed to provide more pedal feel by reducing expansion in the standard rubber hoses, but what are the advantages of DOT 5.1 (is that right?)

What suppliers should I be looking at for the above items.

Thanks in advance for any advice.

p1doc

the uprated brake fluid does contribute towards better feel but the main reason is it takes a lot more to boil it so less fade,i found a dot 4 from as performance was actually better than dot 5.1 (admittedly was from halfrauds) give as a ring and get free p+p on both mentioning you are on scoobynet
martin

DaveW

IIRC Over time brake fluid absorbs water, which reduces its effctiveness. The DOT rating just refers to how hygroscopic (water absorbing) the fluid is. So as in the case above, a better DOT4 fluid (with a higher dry boiling point) out performed a poor DOT5.1 fluid (which will just last longer before it needs changing).

Dave.

messiah

I'm looking at getting a set of goodridge brake hoses and upgrading the brake fluid. Does anyone know what fluid is used during a service at a dealer? and if I buy dot5.1 fluid - which manufacturer is recommended (silkolene?) of what quantity is needed.

cheers

mark@wrx

I use Silkolene Pro race. Get it from AS Performance. I used about 2.5 litres to fully flush the system. Never had any soft pedal issues and as Dave will acknowledge, i'm pretty hard on brakes!

ALi-B

iTrader: (1)

Dealers will no doubt use dot 4. Probably castrol, as that's who normally supplies their oil. a good brand Dot 4 is equally as good as dot5.1, just 5.1 has a higher dry boiling point (wet boiling point depend on manufacturer). Seeing that you change every 2 years as a maximum anyway I don't see the point of using 5.1 (IMO) . However....with Silicone brake fluid, it's a different story, as it does not attract water so lasts much longer, but it's pricey. And its performance (silicone is more compressible than glycol based fluid) and durabilty is questionable because it won't mix with any moisture that is present in the system.

I normally flush about 1/2 a litre out of each caliper, so you'll need about 2 to 2.5 litres.

DaveW

OK so I was wrong and the DOT rating does relate to temps.

Dry BP Wet BP
DOT 3 401°F 284°F
DOT 4 446°F 311°F
DOT 5.1 500°F 356°F

Most good DOT4's will have higher dry boiling points than normal DOT5.1. But since they degrade faster they only meet DOT4 wet boiling point specifications.

Oh and yes Mark is pretty hard on his brakes So you won't have any problems with the same fluid, I'd also change it on a yearly basis to avoid the peddle going soft.

Dave.