Hi-Temp brake fluid

[wepsbee]

Great, now how do I know if I am boiling the fluid. I assume using the brakes too much is only an issue if you are going fast enough to begin with.

[wepsbee]

Excellent help. I will get the ATE. I notice there are 2 colors to help with flushes. Great idea!!

[JeffYoung]

Greg, I've always wondered about the wet v. dry deal. I've had some people I trust tell me what you said above, and others say that basically once you open the bottle you start taking on water and unless you are flushing every weekend you really should pay more attention to the wet boiling point.

Not sure which is correct, although it certainly seems to me that even fluids like Motul that are notorious for soaking up the moisture can't get all that bad right way.

Here's a discussion on this from a motorcycle racing site:

http://www.sportbikesolutions.com/mo...es/brake-fluid

I'll do some more reading later. Note that the biggest advantage of SRF is that its wet boiling point is a LOT higher than the other top flight brands.

I've boiled Motul, finned drums and all! (actually my drums don't have fins, but those pesky Z cars do). I've never done so with Castrol, but the key point is the one you made above. Cooling is more important than 20 or 30 degree differences in boiling point on the fluids. Once I maximized my brake cooling efforts (nice hats with splitters on the solid rotors, moving the ducts as far in board as possible, and going to a less aggressive pad compound, I solved most of my problems. It certainly was not the fluid.

[rsportvolvo]

I ran across a chap who worked for Prodrive for @ 15 years and based on their testing they use Motul RBF 600 for the brakes and Castrol SRF for clutches. Not to just play copy cat, but if Prodrive did the research for those selections I'll take heed.

For racing use the wet boiling point shouldn't be a huge factor (negating the need for the liquid gold Castrol SRF). Some of the cheaper hi-temp fluids are available from Wilwood (EXP 600) and Brembo (LCF 600). Motul RBF 600 is only slightly more expensive. All are cheaper by the case, which is a reasonable consumption amount for a full race season.

[JeffYoung]

Generally agree, but my guess is Prodrive is flushing the entire braking system every weekend.

I'm pretty religious about bleeding, and flushing every few weekends, but I'm not doing it every weekend......so I still am not sure that the SRF's wet boiling point doesn't have value.

For what it is worth, the NASCAR guys use SRF.

[wepsbee]

Great, now how do I know if I am boiling the fluid. I assume using the brakes too much is only an issue if you are going fast enough to begin with.

[QUOTE=rsportvolvo;304937]I ran across a chap who worked for Prodrive for @ 15 years and based on their testing they use Motul RBF 600 for the brakes and Castrol SRF for clutches. Not to just play copy cat, but if Prodrive did the research for those selections I'll take heed.

For racing use the wet boiling point shouldn't be a huge factor (negating the need for the liquid gold Castrol SRF). Some of the cheaper hi-temp fluids are available from Wilwood (EXP 600) and Brembo (LCF 600). Motul RBF 600 is only slightly more expensive. All are cheaper by the case, which is a reasonable consumption amount for a full race season.[/QUOTE]


Anybody have some wisdom on question 1??
I have bled my brakes twice a year, I gather this is not sufficient.

[Greg Amy]

When you boil brake fluid, the pedal usually goes right to the firewall -- THUNK! -- and you can pump it back up, though the pedal feels "spongy". Each time you hit the pedal after that it wants to go to the firewall again, and you'll have to pump it back up. It feels similar to when you're bleeding the brakes and someone opens the valve. And, when you subsequently bleed the brakes after boiling the fluid, you'll see air in the lines (air that boils out of the fluid is not re-absorbed.)

This is a distinctly different feeling from "brake pad fade", which is when you exceed the optimal temperature of the pad compound you're using. In that case you'll feel the brake pedal get longer and spongier, and the transition to the firewall is usually slower and longer. Unless you completely explode the pads, you'll rarely get a THUNK! moment with pad fade.

This should also not be confused with pad "kickback", where variations in rotor, bearing, or wheel "true-ness" - or even spirited hits over curbs - cause the caliper pistons to move back into the caliper a bit too far, forcing you to have to pump the brakes to get the piston back in position against the rotor (it's the reason you'll occasionally see a fast driver lightly tapping the brake lights a few times along the straights). The difference there is that when you do pump up the brakes after kickback the pedal feels nice and hard again, versus a still-soft pedal in the case of boiled fluid.

Finally, you could buy temperature-sensitive paints or labels and stick them to your calipers. These devices change colors when a specified temperature is reached, allowing you to note how hot the calipers got. If the caliper temp is exceeding 600 degrees (for example), then you can be pretty confident your fluid is getting that hot, too.

Bottom line, though, Dan? It's not something to worry about at this point; it takes a lot of performance to boil brake fluid, and long before that happens you're gonna start slagging pads, rotors, and possibly even piston seals. Instead, take the time to ensure your brake system is in good shape, bleed the brakes properly and regularly, and just "shut up and drive".

Greg

[wepsbee]

When you boil brake fluid, the pedal usually goes right to the firewall -- THUNK! -- and you can pump it back up, though the pedal feels "spongy". Each time you hit the pedal after that it wants to go to the firewall again, and you'll have to pump it back up. It feels similar to when you're bleeding the brakes and someone opens the valve. And, when you subsequently bleed the brakes after boiling the fluid, you'll see air in the lines (air that boils out of the fluid is not re-absorbed.)

This is a distinctly different feeling from "brake pad fade", which is when you exceed the optimal temperature of the pad compound you're using. In that case you'll feel the brake pedal get longer and spongier, and the transition to the firewall is usually slower and longer. Unless you completely explode the pads, you'll rarely get a THUNK! moment with pad fade.

This should also not be confused with pad "kickback", where variations in rotor, bearing, or wheel "true-ness" - or even spirited hits over curbs - cause the caliper pistons to move back into the caliper a bit too far, forcing you to have to pump the brakes to get the piston back in position against the rotor (it's the reason you'll occasionally see a fast driver lightly tapping the brake lights a few times along the straights). The difference there is that when you do pump up the brakes after kickback the pedal feels nice and hard again, versus a still-soft pedal in the case of boiled fluid.

Finally, you could buy temperature-sensitive paints or labels and stick them to your calipers. These devices change colors when a specified temperature is reached, allowing you to note how hot the calipers got. If the caliper temp is exceeding 600 degrees (for example), then you can be pretty confident your fluid is getting that hot, too.

Bottom line, though, Dan? It's not something to worry about at this point; it takes a lot of performance to boil brake fluid, and long before that happens you're gonna start slagging pads, rotors, and possibly even piston seals. Instead, take the time to ensure your brake system is in good shape, bleed the brakes properly and regularly, and just "shut up and drive".

Greg

This is the kind of information newer drivers and rookie crew chiefs really need. This info is much appreciated, Thanks