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What brake fluid?
GavR - 6/5/11 at 05:59 PM

I'm sure one of you guys will know this answer

What brake fluid does a sierra master cylinder take?

Gav

Macbeast - 6/5/11 at 06:12 PM

Dot 4 ?

" Brake fluid to Ford spec Amber SAM -1C -9103 A ( Duckhams Universal Brake and clutch fluid )

Says Haynes manual

[Edited on 6/5/11 by Macbeast]

britishtrident - 6/5/11 at 06:25 PM

Yes any Dot 4

coyoteboy - 14/5/11 at 11:38 PM

No reason not to move up to a dot 5.1, both dry and wet boiling points are better and its fully compatible with dot4. DOT 5 is NOT compatible with 3, 4 or 5.1...

Dry boiling point Wet boiling point
DOT 3 205 °C (401 °F) 140 °C (284 °F)
DOT 4 230 °C (446 °F) 155 °C (311 °F)
DOT 5 260 °C (500 °F) 180 °C (356 °F) (silicone based)
DOT 5.1 270 °C (518 °F) 190 °C (374 °F)

[Edited on 15/5/11 by coyoteboy]

britishtrident - 15/5/11 at 05:29 AM

quote:
Originally posted by coyoteboy
No reason not to move up to a dot 5.1, both dry and wet boiling points are better and its fully compatible with dot4. DOT 5 is NOT compatible with 3, 4 or 5.1...

Dry boiling point Wet boiling point
DOT 3 205 °C (401 °F) 140 °C (284 °F)
DOT 4 230 °C (446 °F) 155 °C (311 °F)
DOT 5 260 °C (500 °F) 180 °C (356 °F) (silicone based)
DOT 5.1 270 °C (518 °F) 190 °C (374 °F)

[Edited on 15/5/11 by coyoteboy]



Dot 5.1 is a lot more hygroscopic it draws in water from the environment much more quickly the intial boiling point advantage is quickly lost in the UK climate.

coyoteboy - 19/5/11 at 12:20 AM

quote:

Dot 5.1 is a lot more hygroscopic it draws in water from the environment much more quickly the intial boiling point advantage is quickly lost in the UK climate.


Interesting, never heard that before. Any data to back it up? Is there a test, other than trying to boil it, for water content? Been using DOT5.1 for about a decade now, would be nice to know some more about it.

However the last time I checked it was the same price as DOT4 so no real loss other than your suggestion about absorbtion rate.

Interestingly, Ferodo, maker of brake bits, claims that 5.1 maintains its higher boiling point better than DOT4 and that DOT4 is better than DOT3:
http://www.ferodo.co.uk/ferodo_web/car-products.aspx

No offence, but I hear stuff like this all the time on internet forums and BS gets spread viat the net like wildfire and I rarely believe it until I see hard and fast evidence. If Ferodo are lying they could be reported to the ASA, so I guess they're probably not.


[Edited on 19/5/11 by coyoteboy]

spiderman - 19/5/11 at 03:39 AM

quote:
Originally posted by coyoteboy
quote:

Dot 5.1 is a lot more hygroscopic it draws in water from the environment much more quickly the intial boiling point advantage is quickly lost in the UK climate.


Interesting, never heard that before. Any data to back it up? Is there a test, other than trying to boil it, for water content? Been using DOT5.1 for about a decade now, would be nice to know some more about it]

Absorbsion of water is what causes pistons to seize in calipers and should be replaced at least every two years. Read you Haynes manuals and check instructions on fluid tins!

coyoteboy - 20/5/11 at 12:07 AM

quote:
Absorbsion of water is what causes pistons to seize in calipers and should be replaced at least every two years. Read you Haynes manuals and check instructions on fluid tins!


I'm not THAT stupid mate, jesus. I meant I've never noticed dot5.1 absorbing water quicker than any other fluid, and that's certainly confirmed by a few links I've found now which suggest that 5.1 is better than 4 for lifespan. Found a couple of oldschool tuner types who're convinced it's all a lie though and loads of rubbish on forums across the world.