I’d welcome some advice please. I have a 2020 RS Trophy-R, with steel brakes and the optional carbon fibre wheels. I love the car on road and track. A couple of years ago I upgraded the brake pads to Pagid RS, as I was beginning to experience a longer brake pedal after a couple of track days at Anglesey and Bedford. On inspection the front pads were beginning to disintegrate (no great surprise). At the same time, I had dot 5.1 brake fluid fitted. Roll onto the summer of this year and I suffered total brake fade at Brands Hatch (GP circuit) on an RMA event. There was a hint of a problem at one corner, and by the next the pedal went straight to the floor. Fortunately the hint of a problem meant I had backed off, and so I drove gently for a lap before returning safely to the pits. Clearly the fluid had boiled. This was after around 6 laps. (I am an experienced track day driver - over 20 years in various cars.) Frankly I was amazed and have been asking myself two questions: 1) Why did the fluid boil given the pad and fluid upgrades? 2) What can I do to guarantee this never happens again? On the first question, my friends (at the track day) and I concluded that it may have been a combination of more aggressive front pads increasing the temperature load (and it was a reasonably hot day); along with the carbon wheels being less effective at radiating the heat from the rotors and hubs. (I have all but ruled out water in the fluid as it was measured only a few months before with 0% water recorded.) On the second question, I am much less sure what to do. And so would welcome advice based on experience: 1) Is there a better brake pad option? 2) I am going to replace the brake fluid - it was dot 5.1 supplied by a local mechanic; what is the best option - Motul RBF660 seems popular, or Castrol SRF (which I have used in other track cars in the past)? 3) Is the problem here simply lack of cooling (I suspect it is). I know the very small number of Nurburgring spec cars (with front ceramic brakes) have cooling ducts where the front DRLs are - is this actually the key modification I need to make? 4) Am I missing something else I should do? It was a scary experience at Brands - I don’t want to ever repeat it - so collective wisdom most welcome! Thank you.
I was using RBF660 fluid and Carbon Lorraine RC8 pads on my 265, it was running 386hp, coilovers, semi slicks or slicks and never had any signs of brake fade ever, ohhh and i.ve done a trackday or 2.
Thanks Ian - I think? Mine is a genuine enquiry. I used to race (VLN at the Nurburgring) so with all respect I don’t think it’s my braking technique. What do you think about the theory of the carbon wheels being less effective at radiating heat than alloy wheels? Could that have contributed to pushing the temps above boiling point? Thank you.
You asked a question, i have given you what i have experienced on many trackdays with a lot of trial and error. It's possible that the carbon wheels aren't helping. So then, what do you do when you come up to a corner to do some braking ???? and is this just the ring or are you having trouble at a race circuit ???? There aren't really any hard braking point on the ring, not like a race track in this country. I have done numerous track days and TF laps at the ring, probably not as many as you though. My R26 has mk3 brakes and they are so so much better than my 265 brakes ever were, i'll be back in a mk3 again soon and there are a few other pads i need to try, but initially i will be using CL rc8's
At 83 years old, I do fewer track days than I used to, health and all that, running 360bhp, MK3 plain disks, ds1.11, OR winmax 5 pads, never had fade/shudder, and I learnt to only brake hard when death appears to be imminent, then get off the brakes, don't linger, and I cannot remember the last time I heard of boiling brake fluid. Go onto Facebook Megane, and speak to Steve Holland, he runs an R and has carbon wheels, although I do not know if he runs them on track.
Thanks. Again, I can say with certainty technique is not the issue (and I am not being defensive, I just know that after over a hundred track days on many different circuits here and abroad, and in dozens of different cars, this is the first time I’ve had fade too and so it makes no sense for it to be the driver). It has to be a mechanical issue - perhaps some water had got into the system (fluid was approaching two years old); perhaps the mechanic who bled the brakes left a tiny air pocket in the system - or as I suspect, the fluid wasn’t quite up to the temperatures generated on what is a very hard braking circuit (I agree Ian, more so than the Ring - not because there aren’t big stops at the Ring - there are - but because those big stops are a long way from each other). I note that the non ceramic brake cars do not have the cooling ducts fitted on the ceramic brake cars, so Renault clearly knew the car could do with more cooling. I am going to fit some temperature sensors to the callipers to see what I learn from that…and thank you for the advice to speak to Steve Holland - I will try that!
Fluid not up to the temps incurred and past its best at 2 years old. Replace it for fresh race fluid, castrol srf or similar high temp fluid.
I’d say it’s got to be a fluid issue, either got air or water in it or whatever was put in originally wasn’t high performance fluid just bog standard stuff that boils at a lower temp than you were expecting.
Please don't take any offence when we mention braking technic, it's only pointed out in case you linger on the brakes.As people on here state, maybe change the fluid, and maybe the pads as well. Let us all know how you get on.
It's possible that the brake fluid you've used it does boil at lower temperatures than Motul RBF660 or Castrol SRF or it got water in it. I've used RSL29 and RBF660 brake fluid on the road and for a few track days. What I've noticed on a hot day(34C+) was that the pads have been wearing way more than on colder days but I did not experience any brake fade
Specs from Motul and Endless "MOTUL RBF 660 FACTORY LINE very high wet boiling point (204 °C / 399 °F) is superior to conventional brake fluids DOT 5.1 non-silicone base (180 °C / 356 °F mini) and DOT 4 (155 °C / 311 °F mini)" "Endless RF 650 Brake Fluid Dry boiling point: 323°C (622°F) Wet boiling point: 218°C (424°F)" If it is related to your carbon rims, Endless will give you an extra 40C buffer over 5.1 I switched from Motul to Endless to try and improve compressibility - found it to be a little better than Motul, but not as big an improvement as suggested by this (old) review. Also I would flush my brake fluid 2-3 times a year based on 8-10 track days a year. I'm using (for track days only) ME20 front pads and found them superior to RSL29. https://thebuildjournal.com/tech-guides/ultimate-brake-fluids-review-analysis/ Finally, you might want to use some (or similar) Racetech Brake Disc Temperature Paint Kit, to see if you are getting excessively high rotor temps.
