If I still have my car next year I will do my best to come to the next event

 

I'm going to be flushing my brake and clutch fluid tonight and wanted to post a quick bit about it. I'm doing it in this thread because it's directly related to the pads I'm running. The Porterfield R4 pads are race pads, not street pads. Yes, I'm street testing them because I wanted to see if they'd be a feasible alternative for people that want a more aggressive pad.

After my track day at Lime Rock, I noticed my brake pedal was a lot softer. The pads felt the same, but the pedal was soft. In hindsight, it looks like I burned up my brake fluid. I've never burned up Motul RBF600 before, so I was a bit surprised, but I've also never run race pads on track before.

Here's what it comes down to, I think: I'm a big fan of balance, especially with cars. (Um, excess in life, balance in cars.. does that work?) That's especially true with brakes. I'm a huge fan of RBF600 for street pads or even track pads. But if you're going to run race pads like the R4, you need race fluid. The balance is that you have to match your fluid to your pads. Castrol SRF Racing and Motul RBF660 both fit the bill.

I'm going to be using RBF600 again when I flush my fluid tonight rather than moving up to RBF660. I'm doing this for two reasons: I'm going to continue doing some street testing on the R4 pads but then switching to yet another pad (something less aggressive) so the RBF660 shouldn't necessary and, more importantly, I already have a case of RBF600 sitting in my garage.

 

Are you sure you "burned up" the brake fluid? If the fluid was old it tends to absorb moisture, which can lead to a soft brake pedal (or no brake pedal at all - see my earlier post!). I change brake fluid after every 3-4 track days - probably overkill, but it's cheap and braking is kind of important at the track!

 

I think age definitely contributed to it. It was 2 yrs old with four track days on it prior to Lime Rock. Felt perfectly fine even with spirited driving the day before Lime Rock and then soft the day after. I was braking extremely hard on the front straight, at the very limits of the MPSS tires. So it wasn't just the fluid's age, it had to have been hard braking with the super-aggressive pads.

 

2 years is WAY too old for brake fluid - it's probably full of water, which boils off during hard braking leaving a soft pedal. Brake fluid is extremely hygroscopic. You got very lucky you didn't lose your brakes completely (especially going into turn 1 at Lime Rock!).

 

Two years is the service interval for the OEM fluid, and since I'm doing some work with Motul I decided to do some extra "what if" testing. You're absolutely right about the fluid age, intervals, and everything else. Definitely not arguing with you. My goal with this is to answer the questions about what if someone does go too long without changing the fluid, and what if someone runs a track day without fresh brake fluid...

Now that I've got some real-world testing done, I'm sending the old fluid to Blackstone for analysis. I've got a small case of fluids I'm sending in lol... Motul RBF600 brake fluid, Motul 10w60 engine oil, Motul Gear 300 75w90 gear oil, Castrol Syntrax 75w90 gear oil, and Shell/BMW 10w60 engine oil.

Lots of work being done behind the scenes

 

Might I suggest doing that sort of testing at New Jersey Motorsports Park rather than Lime Rock - lots more runoff before you hit something

 

lol I was being extremely careful with it - moderate braking if anyone was near, and did the hard braking earlier than necessary to give myself room to recover. Safety first Wouldn't have done anything that I wasn't comfortable with!

 

Here's a video of me from Mid Ohio a few years ago - skip to the end (around 14:10) if you want to see what losing your brakes completely from old brake fluid looks like

 

If it makes you feel any less OCD I do mine after every 2hrs of track time. Which I know is obsessive but it makes me feel a lot better. I really like to brake as late as possible and want the brakes to be at or near 100% at all times. Plus fluids like M600 or other track specified fluids absorb significantly more moisture than standard dot3,4 fluids so frequent flushing is all the more important.
The M660 will have an even shorter service interval I would consider the M5.1 if you are intent on getting a couple of yrs out of a fluid.

 

I'm FINALLY getting around to posting in my blog again, so here's the latest:

http://www.redpants.lol/blog/2016/11...parison-part-2

It covers my observations going from the Porterfield R4-S to the Porterfield R-4 pads.

 

Hi Rich,
I know you have hookups with Motul but have you consider Endless fluids?

 

I know of them and have heard great things, but I don't have any first-hand experience with them.

Motul was a perfect fit for me because of their top-tier quality, and their comprehensive product catalog. They make every kind of fluid needed for cars - brake fluid, engine oil, gear oil, coolant, hydraulic fluid, etc etc. Plus I'm trying to keep it streamlined so I don't go overboard with reaching too far.

 

Have you tried BG stop squeel on the porter fields, they make quiet them down completely and still provide max braking. You have to use two full bottles so it absorbs into the pad material all the way down to the backing plate

 

Castrol SRF is the best fluid. Motul 660 is a decent second place. Endless does make some crazy race fluid but they are definitely not DOT (endless 750 is what F1 uses now, they used to use Castro; SRF for over a decade)