Brake fluid

[Bounce]

Im due a brake fluid change,so thought id get some good stuff put in before the ring and spa,do you guys use castrol SRF which is on offer at the moment from Opie,athough still a lot more expensive than other race fluid,or is there another you use.

[shimmy]

AP do not recommned any silicon based fluid with AP kits (see AP details below)

SILICONE BRAKE FLUIDS – A WORD OF CAUTION
AP RACING NEITHER MARKETS SUCH FLUIDS NOR RECOMMENDS THEIR USE WITH OUR OWN OR ANY OTHER BRAKING SYSTEM
Virtually all of the problems with Silicone Brake Fluids relate to:-
Long/spongy pedal
Sudden loss of brakes
Hanging on of brakes
They reflect certain properties of silicone fluids identified by us over many years and recently ratified in SAE publications, namely:-
High ambient viscosity
High air absorption
High compressibility
Low lubricity
Immiscibility with water
Research has shown that the relationships between problems reported and properties identified may be expressed as follows:-
Long /Spongy Pedal
a) Compressibility, up to three times that of glycol based fluids
b) High viscosity, twice that of glycol based fluids, leading to slow rates of fill and retention of free air entrapped during filling, and hence bleeding difficulties.
Sudden loss of brakes
a) Air absorption. Gasification of absorbed air at relatively low temperature produces vapour lock effect.
b) Immiscibility (failure to mix) with water. Whilst the presence of dissolved water will reduce the boiling point of glycol based fluids any free water entrapped in silicone-filled systems will boil and produce vapour lock at much lower temperatures (100°C or thereabouts)
Hanging on of brakes
a) Low lubricity. In disc brake systems the sole mechanism for normalisation of system pressure upon release of pedal pressure is a designed-in tendency of seals to recover to their ‘at rest’ attitude. Low lubricity works against this tendency.
b) High viscosity exacerbates the effect of (a) above.
It should not be assumed, therefore, that the high price of silicone fluids implies higher performance in hard driving or even normal road use.
AP Racing glycol based fluids do not contain the adverse properties described above. The recently introduced Formula DOT 5.1 which exceeds the performance criteria of DOT 5 (Silicone), is suitable for all conditions likely to be encountered in modern driving conditions.

[Bounce]

What fluid do you recomend for OEM Shim,fast road and the odd track day.Apart from AP 5.1,im gonna get it from opie as there just up the road and they dont stock this.

[shimmy]

ive stuck in a couple of fluids and so have Simpsons but i guess something like the DOT5.1 from AP would be fine,


dot 5 (not 5.1) normally refers to Silicon Based fluid

[mattCSLnut]

Originally Posted by BOUNCE

Im due a brake fluid change,so thought id get some good stuff put in before the ring and spa,do you guys use castrol SRF which is on offer at the moment from Opie,athough still a lot more expensive than other race fluid,or is there another you use.

ATE Racing Blue seems to work well and readily available from ECP

[northernjim]

it seems AP do a few types of fluid now, I use motul rbf 660 myself

http://www.apracing.com/info/info.asp?section=Brake+Fluid+Details_94

[Thorney]

We use AP for all the kits including the Alcon CSL Cup kits and on the race cars.

[Mark CSL]

I like Castrol SRF Castrol SRF is an ultra high performance brake fluid specifically formulated for competitive motorsport.
Exceptionally high dry boiling point and superb anti-vapour lock properties

[shimmy]

Originally Posted by mark csl

I like Castrol SRF Castrol SRF is an ultra high performance brake fluid specifically formulated for competitive motorsport.
Exceptionally high dry boiling point and superb anti-vapour lock properties

yep but your AP calliper seals dont

[Mark CSL]

Originally Posted by shimmy

yep but your AP calliper seals dont

I did not have AP Brakes i had HiSpec 6pot with 380mm Floating Performance Friction Discs