Brake fluid capacity/recommended upgrade fluid?
06 August 2002, 07:57 AM
#1
Just had a look at the SIDC FAQ and it had capacities for everything apart from the brake system (unless i'm going blind 
). Does anybody know the capacity and also recommend a good fluid. Im putting braided lines in and some 4 pots so it's a good time to get some good fluid in too.
Cheers,
Tony.
). Does anybody know the capacity and also recommend a good fluid. Im putting braided lines in and some 4 pots so it's a good time to get some good fluid in too.Cheers,
Tony.
06 August 2002, 12:09 PM
#2
Scooby Regular
Capacity is about 0.5 litres (though if you changing fliud you'll need another 0.5l to flush the system).
Fliud wise, take your pick! (just make sure it's DOT 5.1) I used AP/Lockhead but there are loads of others
Fliud wise, take your pick! (just make sure it's DOT 5.1) I used AP/Lockhead but there are loads of others
.
06 August 2002, 01:15 PM
#4
Scooby Regular
That's what I mean. Take your pick!! All the brands have their followers.
They all do the same job and I doubt you'll notice any difference in the fliuds for what we're using it for
It comes down to where you can get it from and what they supply.
If can source AP stuff locally use that if it's Silkolene, use that!!!
They all do the same job and I doubt you'll notice any difference in the fliuds for what we're using it for
It comes down to where you can get it from and what they supply.
If can source AP stuff locally use that if it's Silkolene, use that!!!
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07 August 2002, 01:49 AM
#8
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The DOT rating is a measure of water absorbancy. Which basically boils down to lower DOTs need changing more often and are used by race teams who change them every five minutes, or you get a soft pedal. But in a fast car like a Scoob, you should be changing the fluid one a year regardless.
The Silkolene DOT 4 stuff is top (ScoobySport) as is the AP Lockheed Ultra 5.1 (ScoobyMania).
Regards,
Richard.
The Silkolene DOT 4 stuff is top (ScoobySport) as is the AP Lockheed Ultra 5.1 (ScoobyMania).
Regards,
Richard.
07 August 2002, 10:14 AM
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Taken from the MLR:-
The DOT rating affects moisture take up and is not a guide to the fluid's performance.
The DOT number refers to the rate at which the fluid absorbs water. The higher the better for long service life. It is not a heat rating. Racing fluids are usually DOT 3 and have superior properties, but must be changed frequently.
Use a glycol-ether based brake fluid but it is worth noting that these fluids are hygroscopic (absorb moisture). Water absorbing into the fluid leads to a drop in the fluid boiling point and therefore brake fade can occur, it can also lead to corrosion of the caliper pistons if not changed regularly. It has been found that moisture absorption is mainly by diffusion through the brake hoses, the fluid at the Master Cylinder may be fine but it can be a different story at the calipers! That is why it is recommended for general road use the brake fluid should be changed at a very minimum of once a year.
DOT 5 fluids are Silicone based and are not recommended for high performance use. Although Silicone fluids are not hygroscopic they are highly compressible and offer inferior lubrication. Any water that does get in the system is not absorbed in the fluid but sits in little pockets boiling and forming vapour bubbles at over 100°C and freezing into ice crystals below 0°C leading to poor braking performance compared to glycol-ether based fluids. The trapped water can also cause bad pockets of corrosion.
DOT 5.1 is a different story though and these are non-silicone fluids that pass the DOT 5 specification. ‘Super’ DOT 4 and DOT 5.1 fluids are generally superior to the standard DOT 4 fluids as they are treated with Boric acid which partially esterifies the free OH (hydroxyl) groups making them capable of reacting with water to help nullify it’s effects. These fluids should last longer than similar specified DOT 4 fluids.
Silicone-ester based fluids are a completely different story to normal Silicone fluids. Patented by Castrol they are virtually the perfect fluids offering brilliant performance and an excellent viscosity however, they are quite hygroscopic and expensive to buy.
General notes on Brake Fluid
Hygroscopic brake fluids can absorb moisture through plastic containers, that’s why the better fluids come in metal containers. It’s not a problem having a plastic container but remember to only buy enough fluid for what you need and only use fluid from freshly opened containers.
Never use Mineral based fluids, they require braking systems specifically designed for their use.
When working out the quality of brake fluids you generally need to know two things:
Dry boiling point
This is the temperature at which vapour bubbles may start to form in the fluid.
Wet Boiling point
This is the temperature at which vapour bubbles may start to form in the fluid subsequent to moisture absorption under specified conditions (approx. 3.5%).
The higher the two figures the better, pay attention to the wet boiling point. Low figures mean you may need to change the fluid fairly regularly or performance will drop.
Although not generally stated, it is also worth noting the Cold Viscosity rating especially for use with ABS systems. The thinner the viscosity of the fluid the better the flow rate through the ABS micro valves.
Info from 2 examples:-
Silkolene Pro Race 2000
A racing brake fluid designed for high performance, racing cars and motorcycles both on and off road. Meets or Exceeds DOT 4 performance requirements. Very high boiling point of 300C, 572F. Suitable for almost all modern vehicles but must not be used in certain Citroen and other cars requiring mineral oil. Conforms to current FMVSS 116 DOT 4, SAE J1703 specifications.
Motul 600 Synthetic Racing Brake Fluid - the ultimate high performance brake fluid which maximises hydraulic pressure to the calliper, Motul Synthetic 600 exceeds DOT 4 brake fluid specs. It has a dry boiling point of 593ºF and a wet boiling point of 421ºF. This is a pure synthetic (NOT silicone) brake fluid that is designed to racing standards for racing or everyday use
EXTREME THERMAL RESISTANCE AND STABILITY: the elevated boiling point of RBF 600 FACTORY LINE (312°c / 585°F) enables effective braking even under the extreme conditions of competition.
VERY EFFICIENT IN WET CONDITIONS: the very high wet boiling point (216°c / 420°F), is superior to conventional brake fluids and provides a particularly efficient braking system in rain and retards the apparition of vapour lock.
Conforms to current FMVSS 116 DOT 4 / SAE J 1703 / ISO 4925 specifications.
The DOT rating affects moisture take up and is not a guide to the fluid's performance.
The DOT number refers to the rate at which the fluid absorbs water. The higher the better for long service life. It is not a heat rating. Racing fluids are usually DOT 3 and have superior properties, but must be changed frequently.
Use a glycol-ether based brake fluid but it is worth noting that these fluids are hygroscopic (absorb moisture). Water absorbing into the fluid leads to a drop in the fluid boiling point and therefore brake fade can occur, it can also lead to corrosion of the caliper pistons if not changed regularly. It has been found that moisture absorption is mainly by diffusion through the brake hoses, the fluid at the Master Cylinder may be fine but it can be a different story at the calipers! That is why it is recommended for general road use the brake fluid should be changed at a very minimum of once a year.
DOT 5 fluids are Silicone based and are not recommended for high performance use. Although Silicone fluids are not hygroscopic they are highly compressible and offer inferior lubrication. Any water that does get in the system is not absorbed in the fluid but sits in little pockets boiling and forming vapour bubbles at over 100°C and freezing into ice crystals below 0°C leading to poor braking performance compared to glycol-ether based fluids. The trapped water can also cause bad pockets of corrosion.
DOT 5.1 is a different story though and these are non-silicone fluids that pass the DOT 5 specification. ‘Super’ DOT 4 and DOT 5.1 fluids are generally superior to the standard DOT 4 fluids as they are treated with Boric acid which partially esterifies the free OH (hydroxyl) groups making them capable of reacting with water to help nullify it’s effects. These fluids should last longer than similar specified DOT 4 fluids.
Silicone-ester based fluids are a completely different story to normal Silicone fluids. Patented by Castrol they are virtually the perfect fluids offering brilliant performance and an excellent viscosity however, they are quite hygroscopic and expensive to buy.
General notes on Brake Fluid
Hygroscopic brake fluids can absorb moisture through plastic containers, that’s why the better fluids come in metal containers. It’s not a problem having a plastic container but remember to only buy enough fluid for what you need and only use fluid from freshly opened containers.
Never use Mineral based fluids, they require braking systems specifically designed for their use.
When working out the quality of brake fluids you generally need to know two things:
Dry boiling point
This is the temperature at which vapour bubbles may start to form in the fluid.
Wet Boiling point
This is the temperature at which vapour bubbles may start to form in the fluid subsequent to moisture absorption under specified conditions (approx. 3.5%).
The higher the two figures the better, pay attention to the wet boiling point. Low figures mean you may need to change the fluid fairly regularly or performance will drop.
Although not generally stated, it is also worth noting the Cold Viscosity rating especially for use with ABS systems. The thinner the viscosity of the fluid the better the flow rate through the ABS micro valves.
Info from 2 examples:-
Silkolene Pro Race 2000
A racing brake fluid designed for high performance, racing cars and motorcycles both on and off road. Meets or Exceeds DOT 4 performance requirements. Very high boiling point of 300C, 572F. Suitable for almost all modern vehicles but must not be used in certain Citroen and other cars requiring mineral oil. Conforms to current FMVSS 116 DOT 4, SAE J1703 specifications.
Motul 600 Synthetic Racing Brake Fluid - the ultimate high performance brake fluid which maximises hydraulic pressure to the calliper, Motul Synthetic 600 exceeds DOT 4 brake fluid specs. It has a dry boiling point of 593ºF and a wet boiling point of 421ºF. This is a pure synthetic (NOT silicone) brake fluid that is designed to racing standards for racing or everyday use
EXTREME THERMAL RESISTANCE AND STABILITY: the elevated boiling point of RBF 600 FACTORY LINE (312°c / 585°F) enables effective braking even under the extreme conditions of competition.
VERY EFFICIENT IN WET CONDITIONS: the very high wet boiling point (216°c / 420°F), is superior to conventional brake fluids and provides a particularly efficient braking system in rain and retards the apparition of vapour lock.
Conforms to current FMVSS 116 DOT 4 / SAE J 1703 / ISO 4925 specifications.
07 August 2002, 10:39 AM
#10
Hmmmm, still unsure what to go for. I beleive that the SWRT use Motul oils (as advertised on the cars) so maybe i'll go with that. Seems to have a slightly higher boiling point too and i get hold of it easily.
Probably change my mind in five mins tho .
Tony.
Probably change my mind in five mins tho
.Tony.
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