Hi All,
I'm about to change my brake fluid ready for a track day & wondering which one to go for. I need one which will reduce the likelihood of brake fade regardless of cost. Iv been looking at Performance Friction or Motul RBF600 Dot 4, but need some advice before I buy.
Thanks, Ruchard.

 

castrol rsf

 

Brake fade is caused by the over heating of the friction materials within the system... You can tell when you have fade as the pedal starts to, and eventually will go rock solid with virtually no braking efficiency available whatsoever, no matter how hard you press that pedal she just wont stop!... It feels like someone has put a block of wood under the pedal...

If you are unlucky enough to suffer from the fluid boiling, then this will have the effect of the pedal starting to get very long as it reaches that boiling point & eventually going straight to the floor when you try and press it... And again you won't stop (unless you hit something)

Having had a lot of experience in this field (and having tried other so called "racing Fluids", you can not go wrong with Castrol SRF Racing Brake Fluid... It costs the earth at about £40 - £45 a litre, but we have used this over the years in various guises of rally & race cars & its been the one component of the braking system that has been very consistent & never failed the drivers... I have seen the brake discs literally glowing cherry red for extended periods of time during the race/rally stage and the fluid has not boiled or deteriorated... If anything it's been the discs or pads that have succumb to the intense heat build up & started to drop off in performance.

This stuff has a dry boiling point of over 300 deg c & has a very high vapour lock point (the most important bit).

The last time I checked, both WRC Rally & F1 cars were using this stuff & you can't get a better recommendation than that!

If you decide to go this route then make sure that you either, start with a dry braking system, or flush the system thoroughly with the SRF, as you do not want any inferior brake fluid left in the system, as this will reduce the performance considerably if you plan on taking the fluid to it's limits.

 

Castrol SRF it is then. Thanks for the advice, it does look a little pricey, but Iv had fade on the road before so I'm certain to get it on track unless I use a decent fluid.

 

The performance friction stuff is very good and a lot cheaper than the SRF, from my research when I bought it it actually had better specs that the SRF if I remember right

 

Just had a look & the PF stuff is half the price of the SRF, has anyone tried both, don't mind paying extra for SRF if it's really better but if PF is as good I'll go for that

 

I use Castrol SRF in all our race cars, never had an issue with it.

 

dot 5

 

RBF 600 for road cars as SRF needs changing regularly. Nobody here has mentioned that either - hope they know that?!


This technical article I wrote for a magazine should help you understand the best fluids for your situation.

http://www.motorsport-developments.c...AF275_tech.pdf

 

Preferably not mate!! I would Never put that in any car other than in very certain circumstances.

 

+1

 

I recall there is a new RBF that's worth a look now, we are still holding stock of 600 so I haven't investigated that option yet.

 

Thanks Paul, that's a good enough recommendation for me. I understand Castrol state it must be changed evry 18 months, but I do mine evry year anyway so not an issue for me.

 

Maybe he meant 5.1?

JohnD

 

dot5 is a specific silicone based fluid and as above i would certainly not use...........

we have converted the bulk of our customers on to PFC RH665 b/fluid and in particular many sidecar guys........the PFC not only performs equally as well as SRF BUT most important to the 3wheeled guys offers far better "feel" and feedback

we also stock & supply RBF600/RBF660 as well as various more road orientated fluids

brake fluid timescale changes should be adjusted with use/abuse and not simply rely on manufacturers guidelines IMO

 

Sounds good, can you post some specifications up for it please?

 

I use the performance friction dot 4, never had a probloem.

Unlike other brake fluids, Performance Friction RH665 has been specifcally developed for racing applications where high temperatures are acheived within the braking system.

The RH665 fluid offers the versatility of being street legal, conforming to FMVSS 116, allowing cars such as track day cars which are driven to and from the track a 'best of both' scenario. The Performance Friction fluid has the highest GUARANTEED minimum dry boiling point of any DOT 4 brake fluid, not only guarding against vapor locks but also maintaining a solid pedal under tough track conditions.

The fluid provides a reliable, predictable and versatile brake fluid solution. The fluid can be installed with existing DOT 4 brake fluid however is not recommended due to higher dilution from a inferior brake fluid which may affect the fluids excellent effectiveness.

Minimum dry boiling point: 325 degrees C

Typical Dry boiling point: up to 330 degrees C

Sold per 500ml

Please note, this product is not suitable for use in contact with magnesium components or in mineral based systems

 

Are you sure those figures are correct?

**Edit**
I just noticed those are both dry. Do you have the wet figures too?

 

PFC RH665 DOT 4 RACING BRAKE FLUID

Type Synthetic Specification FMVSS 116 DOT 4

ERBP Dry Boiling Point 325oC*

ERBP Wet Boiling Point 195oC*

Viscosity at 100oc 2.6 cSt

Viscosity at – 40oC 1475 cSt pH 7.12

*Guaranteed Minimum Specification



Density at 20oC 1.073

Compressibility at 100oc 1.01 x 10 -3 MPa-1

 

That looks interesting - Its time the M5 had a fluid change actually so I think I will give this a try.

Thanks for the info.

 

Dot 5.1 has a higher boiling point than dot 4, as dot 4 has a higher boiling point than dot 3.

DO NOT USE Dot 5 !! Dot 5 is not suitable for cars equipped with ABS and will not mix with dot 3 , 4 or 5.1. Dot 5 is normally used in old classic cars i believe.

Dot 3 ,4 and 5.1 is glycol-ether where as dot 5 is silicone-based .
I personally use Motul 5.1.

 

Dry boiling point Wet boiling point Viscosity limit Primary constituent
DOT 2 190 °C (374 °F) 140 °C (284 °F) Castor oil/alcohol
DOT 3 205 °C (401 °F) 140 °C (284 °F) 1500 mm2/s Glycol Ether
DOT 4 230 °C (446 °F) 155 °C (311 °F) 1800 mm2/s Glycol Ether/Borate Ester
DOT 5 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s Silicone
DOT 5.1 260 °C (500 °F) 180 °C (356 °F) 900 mm2/s Glycol Ether/Borate Ester

These are normal brake fluids, however the dot 5.1 is usually 270 / 275, the dot 4 from Performance Friction is a minimum of 325 dry and 195 wet. I used to run 5.1 but not anymore.

 

Motul 5.1 is as follows

Dry boiling point 270 °C / 518 °F

Wet boiling point 185 °C / 365 °F

 

see Bob has already posted some stuff but link here to data sheet

http://asperformance.com/product-new...g-brake-fluid/

as one of THE major distributors can happily help out on supply/pricing Stu.......(trade or retail)

 

Note that DOT5.1 fluids are more hydrophobic than DOT4 so will need more regular changes.

 

do you mean "hydroscopic" ?? and actually its the other way round as dot5.1 was specifically specced for slightly extended service life to suit ABS systems........

also worth pointing out that in general terms the rising DOT number does not actually signify increased performance

 

I bet the OP is rather confused now!

 

Just noticed that your first reply to the thread states that you have "suffered from fade on the road before, so you need a decent b/fluid to solve this for the track"...

Are you sure it's "Fade" that you are suffering from?? or are you suffering from the brake fluid boiling??... If you read my original reply, it explains that the difference between the two are quite different.

If you really are suffering from "Brake Fade" & "this is more likely on the road", then changing your brake fluid will make no difference what so ever to your problem when on the track... It's the friction material that you need to be looking at upgrading... It follows of course that if you fit uprated discs/pads to your car then the next component in the system to fail on the track will be the std fluid, so it makes sense to upgrade it at the same time so that it can deal with both the prolonged track environment & the extra heat produced by the uprated discs/pads.

 

Lol,,,dot 4 racing stuff is better than your 5.1 stuff.

Ate blue is a good contender too along with rbf600/660, pf.

 

off topic slightly does any body know how much brake fluid I need 1liter be enough?, its a 1999 uk 2000 with 4pots front 1 pot rears, im refurbing my caliper pots and changing the brake lines for braided, fluid wise im goint to use Motul RBF600 I think, cheers