Brake system flush req'd when using SRF for first time?
Discussion
Ive had varying opinions on this... some people have told me that the whole brake system needs to be flushed with alcohol for SRF to actually make any difference. Others have just said drain and refil.
If you do need to flush the system is there a special alcohol based brake system cleaner that you need to buy?
Cheers
Steve
If you do need to flush the system is there a special alcohol based brake system cleaner that you need to buy?
Cheers
Steve
is this silicone fluid were talking about?
If so I know that it does not mix well with standard fluid.
I won't use it personally, although it isn't hygroscopic i am too concerned about topping up with standard fluid, and apparently it boils easier compared to fresh standard fluid, and I believe possibly affects some seals adversely.
Just have a quick read of this:
www.v8register.net/subpages/V8NOTE228.htm
If so I know that it does not mix well with standard fluid.
I won't use it personally, although it isn't hygroscopic i am too concerned about topping up with standard fluid, and apparently it boils easier compared to fresh standard fluid, and I believe possibly affects some seals adversely.
Just have a quick read of this:
www.v8register.net/subpages/V8NOTE228.htm
Edited by wildoliver on Thursday 2nd November 09:13
Hmm -
here's some more info
--
Castrol SRF Racing Brake Fluid is an ultra high performance
product formulated specifically to satisfy the ever increasing
stresses placed upon the braking systems used in international motorsport.
The silicon ester technology in Castrol SRF addresses hygroscopic
tendencies in two ways. Firstly, Castrol SRF is less hygroscopic
than conventional brake fluids - it absorbs less water in a given time.
Secondly, unlike conventional glycol ether fluids, Castrol SRF reacts
chemically with the absorbed water to reduce its adverse effects,
thus preventing the fluid's high temperature performance and safety
margins from deteriorating as rapidly as they would otherwise do.
The wet boiling point of Castrol SRF, 270 C, is vastly
superior to the minimum requirement of 155 C demanded by the
current US DOT 4 specification. The product's typical dry
boiling point of 310 C is likewise outstanding.
This ability to withstand temperatures in excess of 300 C,
and its superior resistance to the effects
of absorbed water, have established Castrol SRF as the
world's premier fluid for the hydraulic brakes
used in all forms of motorsport.
--
im not sure on the effects with seals etc..
Steve
here's some more info
--
Castrol SRF Racing Brake Fluid is an ultra high performance
product formulated specifically to satisfy the ever increasing
stresses placed upon the braking systems used in international motorsport.
The silicon ester technology in Castrol SRF addresses hygroscopic
tendencies in two ways. Firstly, Castrol SRF is less hygroscopic
than conventional brake fluids - it absorbs less water in a given time.
Secondly, unlike conventional glycol ether fluids, Castrol SRF reacts
chemically with the absorbed water to reduce its adverse effects,
thus preventing the fluid's high temperature performance and safety
margins from deteriorating as rapidly as they would otherwise do.
The wet boiling point of Castrol SRF, 270 C, is vastly
superior to the minimum requirement of 155 C demanded by the
current US DOT 4 specification. The product's typical dry
boiling point of 310 C is likewise outstanding.
This ability to withstand temperatures in excess of 300 C,
and its superior resistance to the effects
of absorbed water, have established Castrol SRF as the
world's premier fluid for the hydraulic brakes
used in all forms of motorsport.
--
im not sure on the effects with seals etc..
Steve
Hmmm. Anyone swapped over to SRF out there???
I cannot see how Castrol, with their reputation, would sell a product that could potentially kill someone?
I have 2 litres at home ready for my next fluid change from ATE Super Blue, so any info on this will obviously be useful.
There are a lot of GT3's out there running SRF although it will be interesting to hear about how the fluid was changed.
I'll bet most people pay someone to do it so wont have a clue
I cannot see how Castrol, with their reputation, would sell a product that could potentially kill someone?
I have 2 litres at home ready for my next fluid change from ATE Super Blue, so any info on this will obviously be useful.
There are a lot of GT3's out there running SRF although it will be interesting to hear about how the fluid was changed.
I'll bet most people pay someone to do it so wont have a clue
gfreeman said:
I'll bet most people pay someone to do it so wont have a clue
Well, I can tell you that some well know places don't flush the system before putting SRF in but that doesn't necessarily make it right
The way I see it - if you want the benefits of SRF, the system will surely need to be flushed otherwise its mixing with non srf / lower spec fluid left in the pipes and calipers..
Tim.. Once we have an answer, maybe we can arrange some time to do both cars together...
Steve
wildoliver said:
and apparently it boils easier compared to fresh standard fluid
Please tell me you are not being serious.
Merritt, I changed my brake fluid to SRF a couple of weeks ago and just flushed it through with a bit extra so you will probably need to buy two litres. However you should have plenty left over for future use. Performance has been excellent since.
I am being serious.
The reason standard fluid boils when it starts to get old is it absorbs moisture from the air and the water content lowers the boiling point.
However silicone has an even greater problem............It does not absorb water content at all, so if any water does find its way in to the system then you can end up with pure water and pure silicone fluid that do not mix.
And what ladies and gentlemen is the boiling point of water?
Only offering advice but I wouldn't use it, I would also put more stead in what major brake manufacturers say as opposed to the manufacturer of the product.
The reason standard fluid boils when it starts to get old is it absorbs moisture from the air and the water content lowers the boiling point.
However silicone has an even greater problem............It does not absorb water content at all, so if any water does find its way in to the system then you can end up with pure water and pure silicone fluid that do not mix.
And what ladies and gentlemen is the boiling point of water?
Only offering advice but I wouldn't use it, I would also put more stead in what major brake manufacturers say as opposed to the manufacturer of the product.
You can flush with SRF although alcohol does a better job of scavanging any water particles. If using SRF to flush, I would do the job twice, probably with a couple of days in between. The two fluids do not mix, so you would end up with blobs of squashy old fluid in the system, if you did nothing.
The reason why this is bad is in Castrol's blurb. The SRF is less hygroscopic that the old fluid. The residue of old fluid in the pipes/callipers will more readily absorb the moisture that gets into the fluid and the whole system will become as good as the saturated old fluid that remains.
Castrol recommend changing SRF at max 18 month intervals.
Personally I prefer Silkolene Pro Race 2000 and this does not need a flush as it will mix with any old fluid. The small percentage of old fluid will therefore dilute the new fluid (typically less than 1%) and the water contained in it will be too small to have any measurable effect.
The reason why this is bad is in Castrol's blurb. The SRF is less hygroscopic that the old fluid. The residue of old fluid in the pipes/callipers will more readily absorb the moisture that gets into the fluid and the whole system will become as good as the saturated old fluid that remains.
Castrol recommend changing SRF at max 18 month intervals.
Personally I prefer Silkolene Pro Race 2000 and this does not need a flush as it will mix with any old fluid. The small percentage of old fluid will therefore dilute the new fluid (typically less than 1%) and the water contained in it will be too small to have any measurable effect.
wildoliver said:
I am being serious.
The reason standard fluid boils when it starts to get old is it absorbs moisture from the air and the water content lowers the boiling point.
The reason standard fluid boils when it starts to get old is it absorbs moisture from the air and the water content lowers the boiling point.
I do think we are at crossed purposes here. I am assuming the reason Merritt is asking about racing brake fluid is because he likes to do a lot of trackdays. Now from my experience, on a circuit the reason fluid boils is because it gets too hot and boils due to the heat generated by the discs and pads, not because its been sitting in the car for two years. Once its boiled all those little air bubbles give you a nice spongey brake peddle, not much fun.
The reason some of us use SRF is becuase it has a much higher boiling point and it doesn't absorb moisture, hence your brake peddle stays nice and firm all day, which is nice.
The downside is that it doesn't last forever and you do need to replace it fairly often. However I assume most owners who do trackdays regular bleed their brakes as part of the cars prep. As a rule of thumb I replace the fluid when I change the front pads.
I alo think people may want to read up on the diffs between wet and dry boiling point. Wildoliver - I wouldn't be surprised if 99% of race teams used SRF fluid.... The concept of a *100%* flush is rarely necessary unless you've made the luid work extremely hard (unlikely on most t/days) or your current fluid is in such a bad state
Must be totally honest for the odd trackday I really cannot imagine how people are boiling fluid in a Porsche, assuming the brake system is in good condition and you are not overbraking the brakes should not get hot enough to boil, I would expect a spot of brake fade but not fluid boiling.
I suspect driver training would possibly be money better spent.............
I suspect driver training would possibly be money better spent.............
Race cars wouldn't need a flush as they will normally be built up with all new parts and only ever filled with SRF or similar. Race teams will also bleed in new fluid for every race, as part of their standard prep.
Track days can be killers on brakes and race cars probably don't suffer as much, as they ae lighter and better vented. The biggest killer for brake fluid on track days (and for warping discs) is not doing a full, very slow, cooling down lap, during which you do not use the brakes at all. Only then should you go into the pit lane and park up.
Track days can be killers on brakes and race cars probably don't suffer as much, as they ae lighter and better vented. The biggest killer for brake fluid on track days (and for warping discs) is not doing a full, very slow, cooling down lap, during which you do not use the brakes at all. Only then should you go into the pit lane and park up.
wildoliver said:
I suspect driver training would possibly be money better spent.............
As I mentioned boiling brake fluid, i'll assume that little pop is directed at me.
All drivers have different styles, some are hard on their brakes, some aren't. Some brake early, some brake late. Some like to do shorts stints on a track, others like to stay out for an hour at a time. Different situations will require a different approach.
Now if you go out and do 20 laps on the GP circuit at Donnington your brakes will get hotter than if you do 4 at Castle Combe. There is nothing wrong in either. But as you approach the chicane at Donnington for the 20th time and hit the brake pedal, I think you might be pleased you chose to use SRF and not some fluid from Halfords.
Now, I've only been racing for the last 15 years and admit I still have a lot to learn, which is why I have some coaching booked for next week.
Edited by GuyS. on Thursday 2nd November 12:22
Exactly,
motorsport car are usually stripped down, rebuilt etc.
so there is not a problem.
Your car is prolly not.
I think flushing the system will not be 100% some residue will be left on the seals and this is where they could fail.
only SAFE way is to replace all seals which may be effected flush it out properly then replace seals. make a note that anyone in future knows this.
Also to go back to non-srf., you'd need to do the same.
I'd stick with flushing and bleeding with new brake fuild and do te pads, every session if its that bad
motorsport car are usually stripped down, rebuilt etc.
so there is not a problem.
Your car is prolly not.
I think flushing the system will not be 100% some residue will be left on the seals and this is where they could fail.
only SAFE way is to replace all seals which may be effected flush it out properly then replace seals. make a note that anyone in future knows this.
Also to go back to non-srf., you'd need to do the same.
I'd stick with flushing and bleeding with new brake fuild and do te pads, every session if its that bad
Raven Flyer said:
Race cars wouldn't need a flush as they will normally be built up with all new parts and only ever filled with SRF or similar. Race teams will also bleed in new fluid for every race, as part of their standard prep.
Track days can be killers on brakes and race cars probably don't suffer as much, as they ae lighter and better vented. The biggest killer for brake fluid on track days (and for warping discs) is not doing a full, very slow, cooling down lap, during which you do not use the brakes at all. Only then should you go into the pit lane and park up.
Track days can be killers on brakes and race cars probably don't suffer as much, as they ae lighter and better vented. The biggest killer for brake fluid on track days (and for warping discs) is not doing a full, very slow, cooling down lap, during which you do not use the brakes at all. Only then should you go into the pit lane and park up.
bite-me said:
Exactly,
motorsport car are usually stripped down, rebuilt etc.
so there is not a problem.
Your car is prolly not.
I think flushing the system will not be 100% some residue will be left on the seals and this is where they could fail.
only SAFE way is to replace all seals which may be effected flush it out properly then replace seals. make a note that anyone in future knows this.
Also to go back to non-srf., you'd need to do the same.
I'd stick with flushing and bleeding with new brake fuild and do te pads, every session if its that bad
motorsport car are usually stripped down, rebuilt etc.
so there is not a problem.
Your car is prolly not.
I think flushing the system will not be 100% some residue will be left on the seals and this is where they could fail.
only SAFE way is to replace all seals which may be effected flush it out properly then replace seals. make a note that anyone in future knows this.
Also to go back to non-srf., you'd need to do the same.
I'd stick with flushing and bleeding with new brake fuild and do te pads, every session if its that bad
At last a sensible comment.
If you want ot stick Silicone brake fluid in your brakes go and do it, at least you have been warned, I'm quite sure you know more about brakes than AP lockheed etc.
This is actually a very good description of the problems associated with silicone (sorry about the parent website but its easier than scanning technical atricles in to computer)
www.womanmotorist.com/index.php/news/main/5668/event=view
Basically Silicone is great on a fresh build car that will never have its fluid changed through neglect, but is a negative on a well looked after car, the combination of lack of water absorbtion, tendency to hold air bubbles, damage to rubber seals and incompatibility with all other brake fluids make it a P.I.T.A.
Edited by wildoliver on Thursday 2nd November 13:39
I think you need to read up on the differences between silicone (i.e. DOT 5) fluid and silcone ester (e.g. SRF, DOT 4) fluids before you post any more comments. SRF is NOT A PURE SILICONE FLUID.
www.stoptech.com/tech_info/wp_brakefluid_1a.shtml
www.stoptech.com/tech_info/wp_brakefluid_1a.shtml
Edited by fergus on Thursday 2nd November 14:36
Only pointing out the obvious to WildOliver, who was banging on about the dangers of silicone fluid.....
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