Brake Fluid Suggestion?

[rraghvani]

During this weekend I’m planning on flushing the old brake fluid with new fluid as I’ve seem to have boiled the fluid again – it feels quite spongy. I’m looking for a high temp brake fluid but I don’t know what to go for and was wondering whether you guys could recommend anything? I have Black Diamond (combi range) disc with EBC Red Stuff (and it’s not a good combination!) on a standard S3 (225bhp)

 

[AwesomeSarah]

Hi Mate
Usually just a good dot4 brake fluid is good
You can get a dot5.1 but IIRC it needs flushing before you can use it
Sarah

 

[rraghvani]

What about Motul DOT 4 Racing Fluid? or is that just the same as any other DOT 4 fluid but with a fancy name?

 

[AwesomeSarah]

That is true
Sarah

 

[Dave_Bayern]

Dot 5.1 does NOT need flushing before use, DOT5 does, as DOT5 is a different type of brake fluid using different chemicals.

However you can happily mix DOT5.1 and DOT4, and they will mix and make a fluid in the middle of the two composition wise.

I have DOT5.1 AP racing fluid, and I also use DOT4 VW fluid, even considering track days, there is not an awful lot of difference between the two, It seems like the qualities of DOT5.1 are only displayed in harsher use and hotter atmospheric conditions than the UK temperate climate and road driving/track days.

I found the biggest difference to be slinging EBC red and green and replacing with Ferrodo DS2500.

 

[scib4]

I asked a similar question on anther forum,

"The DOT standard includes boiling point, but also includes other factors, hence some of the best fluids don't meet DOT5.1 standard despite being much better brake fluids... And just to confuse everyone, DOT5 is completely different again for silicone based fluids

The most important factors are dry (i.e. when the fluid is brand new) and wet (when the fluid is older and has absorbed moisture) boiling points - Castrol SRF is much better, but Motul isn't too bad either - with smaller brakes on a heavier car, your fluid temperature is going to be pretty high on track...

All brake fluids are hugely hygroscopic (absorb water), but you could add milk and two sugars to SRF and it would still out perform all the others:

Fluid ............................DRY....... WET
Castrol LMA DOT 3/4......446 .......311
Ford Heavy Duty DOT 3..550....... 290
ATE Super Blue Racing...536........392
ATE TYP 200 .................536........392
Motul Racing 600 ...........585........421
Castrol SRF ...................590........518
Performance Friction .......550...... 284 "

The Castrol SRF is the best as you can see from the table, but is also about twice the price of Motul Racing 600!

I use MBF 600, and never had any problems, and that includes track days!

Mike

 

[AwesomeSarah]

Dot 5.1 does NOT need flushing before use, DOT5 does, as DOT5 is a different type of brake fluid using different chemicals.

However you can happily mix DOT5.1 and DOT4, and they will mix and make a fluid in the middle of the two composition wise.

I have DOT5.1 AP racing fluid, and I also use DOT4 VW fluid, even considering track days, there is not an awful lot of difference between the two, It seems like the qualities of DOT5.1 are only displayed in harsher use and hotter atmospheric conditions than the UK temperate climate and road driving/track days.

I found the biggest difference to be slinging EBC red and green and replacing with Ferrodo DS2500.

Hi
Thank you for that
I did a bit of research on this a while back , but with my old age I have forgotten which way round it was
I must admit , I have never really liked the EBC pads
Sarah

 

[rraghvani]

Castrol SRF, I’ll look into that, thanks – I take it that’s DOT 4?

As with the brake pads, there crap, although they do work great in the wet! Even the oem brakes were better!!

 

[Paul-RS6]

ATE Dot 5.1 in mine

have run Dot 5.1 since the Porsche brakes.

 

[dultanur]

ATE racing blue 5.1 here also...

 

[rraghvani]

Finally replaced the brake fluid with DOT 5.1, i had quite a lot of air in the system as I saw bubbles appearing while bleeding. Got one slight issue now, in order to stop the car I have to push the brake pedal all the way down. How can I adjust this, so that I can tap the brakes and the car will stop? I had replaced the brake fluid while the engine was running.

 

[dultanur]

i've also had this problem. i bled the brakes with the engine running, starting with the corner farthest from me working in. although its a lot better now, it's a lot softer then it was.

i don't think i've left any air in the system as the brakes work properly without bottoming out, maybe 5.1 fluids give this softer feeling? or maybe its because of the new pads? i dont know.

 

[rraghvani]

I'm quite sure all the air has been removed from all four corners, I'll try it again with the engine off this time.

 

[dultanur]

someone here also suggested that the master cylinder may need to be bled, but i'm not sure how.

 

[rraghvani]

I did bleed the master cylinder as well, bit of a tight squeeze to get to though!
I'm going to attempt bleeding the brakes via following StopTech instructions, and then see how it goes from there.

 

[Paul-RS6]

there is also a procedure with vag-com iirc to put the abs pump in the correct state for bleeding.

For this reason, i dont mess about with brake fluid. I pay vag specialists to do it.

 

[dultanur]

thats very wise, but over here i'm sure even the specialist won't know how to do it

if i were in the UK, seeing how much trouble this is, and the importance of brakes (!) i would have gotten a specialist to do it.

 

[Mo-S3]

you shouldnt ever let the system run dry which can create air pockets in the abs system.
Suck out the old fluid from reservoir and then fill with new stuff until you have enough in and bleed it through whilst constantly adding new fluid.
Pumping the brake pedal is crap. Best to use a vacuum system.
Looks like you have air in your system somewhere which needs to be removed asap. Have you bled the valve on the clutch cylinder?

 

[Mo-S3]

Oh and your not meant to mix mineral and synthetic (IIRC) fluids as it can eat through the seals.

 

[rraghvani]

I'm quite sure all air has been removed from the system, old fluid has been replaced with DOT 5.1

 

[rraghvani]

Finally got some feel to the brakes now , I used Eezibleed Kit that i purchased from Halfords. Spent bleeding each corner about 5 times, didn't have to pump the brakes or require any assistance. It's worth buying a compression tool to do the brake bleeding :thumbsup: