(I thought I’d start another!) I’m going to treat my 250 Cup to some new discs and pads (and fluid & hoses), there has already been some discussion on here regarding the plain discs (Brembo HC’s) being better suited for track work with more aggressive pads than the grooved Cup discs. I’m going to use CL RC5+ or may be RC6 pads as have used these in the past and thought they were excellent, I came across a bit of interesting reading on the Kam Racing site which seems to support the plain disc theory: “For trackday cars driven to the circuit we recommend starting with RC5+ front and rear. If you want more bite then the RC6 Endurance pad works well for road/track. Dedicated trackday and race Meganes use the RC6 or RC6E up front with the RC5+ for wet or slippery conditions, RC6 for dry. The Carbone Lorraine pads work best with a plain disc such as the Renault OEM Discs.” And then: “The plain disc option will work with aftermarket race brake pads like the CL Brakes (Carbone Lorraine) range. Grooved CUP discs tend to be popular due to their cosmetic appeal but the grooves can deglaze the surface of a brake pad if you drive the car hard and overheat the braking surface. High quality aftermarket pads for these would be Ferodo Race Pads and Mintex pad.” I thought the idea was that we wanted the pads to deglaze, and that the glazing was the result of light-use?? So are they saying that plain discs will work better specifically with CL pads, but if you want to use grooved discs (I’m not bothered either way) then Ferodo Race pads would suit these?? Any thoughts please on any of the above? Thanks
As I have said previously give Alyn a call at AS Performance he can advise you and supply you everything you'll need at very competitive prices tell him I recommended you. 0191 410 3370
I had a really interesting long chat with Alyn, he advised there was absolutely no science behind plain discs being better than grooved in any way regardless of what pads are used. He's looking into the PFC separate bell & rotor V3 kit for me or possibly some one-piece DBA T3 discs which he rates higher than the one-piece Brembo discs. As to pads he wouldn't recommend CL pads over PFC pads due to various reasons and recommended in particular PFC Z-rated pads for fast-road/occasional track with what ever discs I choose. Along with RBF 600 fluid.
I wish you could speak French. It's a bit frustrating as I know there is zero rationale behind this, just empirical evidence. When on a 5 year long thread about what pads/discs work best on track for a Megane 3RS every single track billy reports very rapid wear on quality pads including the Z rated when used it with the slotted discs but much better stability on plain discs, one can either ignore it or not. It would be good if Alyn clarified if he has personally used that very combination of car/discs/pads on track. I am not sure Renault switched to plain discs for cost saving reasons either.
The thread Nick means is a very interesting read indeed. Quite some similar threads on other car forums.
Nick, Increased pad wear is to be expected with any type of grooved discs, The J hook ones i had were the worst by far for wear but they were also the best in terms of feel and bite from higher speeds, Just a shame they were so noisy. Curious as to the stability comment as well, IME from the countless various compounds I've ran on mine it seems that sort of issue comes from compound choice front and rear. Mine feels so much more balanced with a more aggressive pad in the rear than say stock or mild, XP10's and RS29's are my favourite however I'm going to try some XP12 or XP20's up front. Did fancy trying one of the RS-T or RS-L Pagid compound as the 29's were excellent just "lacking" if you can call that in terms of outright stopping power. Not that they were bad by any means by when compared to my Favourite Carbotechs they just down have the power behind them. Interesting to find out what its going to be like on my new AST setup with stiffer fronts. I recon the rears are going to be a lot more effective now
Sorry Jamie, by stability I meant stability of the pad compound where the binding agent doesn't have a tendency to sip out to the surface and crumbles the pad. But I agree an aggressive rear pad does help to "sit" the car in the braking zone.
Hi Nick, it's a case of me just being the messenger on this occasion, I note and understand the theory but it just dosnt make sense does it?! Alan apparently has 30 years experience building race cars and has never come across the plain disc theory before. He reitterated that every race car out there has grooved or drilled discs and that AP and PFC wouldn't design them like that if they didn't perform better. There is always the argument that yes he hasn't tried the specific Megane/plain disc/aggressive pad combo before and may be for some reason it does work better, but other than this one potentially isolated case I have never come across this anywhere else, nor had Alyn. On this occasion I'm going to go with logic and the expert's advice, I would be stupid not to. I'll either put some like for like Renault/Brembo grooved discs, the DBA T3's if we can get them in the correct size or may be bite the bullet and go for the PFC V3's.
I know it's counter intuitive but people in France simply upgrade to plain discs when they track their Megane RS. But you might be just fine on grooved.
Thanks Nick, agreed, and if it's just increased wear I probably won't notice as I do and will be doing so little mileage in it.
Interesting thread this one. Are the cl rc5 + pads good for fast street use and occasional track days? Or would that be a over kill? What's brake squeal like? I'm in dilemma with what brake pads to run on the Megane. I only plan on doing 3track days this year I'm not biggest fan of standard pads on my RS265. Mine only gets used for weekend blasts.
Only quoting what I was told but he recommended the PFC pads over CL. Based on this I am going for the Z-rated pads or possibly the next grade up which I think are the 01's.
I have this set-up on my Cup-S. The CLs have no anti-noise design features and do squeal under light braking such as pulling up outside the house or into a parking space. The noise is quiet and I live with it based on the theory of BRC (because race car) and mine isn't a daily driver (DS3000s on my Clio were much worse). On track they were good but not class leading, no fade and good bite. They are fine on the road even from cold. For the money I'm happy with them and I have the OEM pads as spares, my main advice would be get some good quality fluid, this will help maintain a consistent brake pedal on track and help massively with confidence. It doesn't have to stop the fastest just stop the same way every time. Oh and keep on top of cleaning the wheels, door shuts and where the rear arch trim meets the quarter panel.
Oh just to add, the high carbon content of the CL's means they can sometimes stick to the disc after you've parked up and you get a little clonk when you move off again.
No doubt someone will prove me wrong, but I cant find anything on here with the front calliper bolt torque....? Also as I will be replacing the rear discs I need those as well, and from memory (when I did the same to an old 172) the central bearing nut torque. Any others I need to know? Thanks in advance!!
Rear hub nut is 220nm IIRC. I was told 175nm mind you so thats what i done them a few weeks back, Turns out that was for the Mk2. Haven't bothered doing them tighter as i cant be asrsed and 175nm is still bloody tight. Caliper bolts, i just give them an ugga dugga
Apologies if this is grandmother and eggs, the rear bearing is a gen1 type and thus the torque controls the preload and stiffness of the bearing. Both these impact durability.
I doubt it makes a difference in the real world. My last set were done to the same torque and were fine for a year and a half and 30k. Only changed as my PF pads ruined them.
Could someone please explain in laymen terms what the difference between DOT 4 and 5.1 is? I’ve Googled it and am still really none the wiser, why go for one rather than t’other? Dot 5.1, from what I can make out resists moisture better but has lower boiling points. RBF 600 has been recommended on here, which has very high dry and wet boiling points of 312 & 216, but it’s Dot 4. PF 665 DOT 4 is 325 & 195. Ferrodo Racing 5.1 is 270 & 185. Am I correct in thinking that DOT 5.1 is more a fit & forget fluid that will resist moisture better, whereas DOT 4 doesn’t boil as easy but attracts moisture more therefore possibly needs to be changed more regularly. The MK3 comes as standard with DOT 4, but presumably its not as high boiling points as the examples above??
Replacing my fronts tomorrow and reading this confused hell out of me lol. I got scared and just got basic brembo oem set of pads and discs for £270. I only drive it on country lanes on weekends and not track so I guess they will do. Maybe next time Ill see a thread that is easy to comprehend for complete car noobs lol.
As far as i am aware dot 5.1 is synthetic and dot 4 is mineral, dot 5.1 also dissolves old type rubber, so you can't use dot 5.1 in older cars 15 years + (if i remember correctly), but you can use dot 4 in a system that was designed for dot 5.1
Thanks Ian, why is one better than the other? And why would Renault have used Dot 4 specificaly in the 'new' megane?
Sorry to disagree, RBF 600 dot 4 is fully synthetic. Product Description 100% Synthetic Racing Fluid - DOT 4 Very high boiling point : 325°C / 617°F For hydraulic actuated brake and clutch systems. All types of hydraulic brake and clutch actuators requiring non-silicone synthetic fluid. Specially designed to resist to extreme temperature generated by racing carbon and ceramic brakes allowing to minimize air entrance for brake cooling. Can also be used with conventional steel rotors and clutch systems. Widely exceeds DOT 3, DOT4 and DOT 5.1 standards (except for DOT 5.1 viscosity at - 40°C).
I fitted RBF600 in May 16 - 6 track days later and 7,000 miles and still can't boil it - ask BIG E ;-). I will change it again in May though. Too cheap to scrimp on.
Thanks everyone, I will use some RBF 600 regardless then, but still intrigued as to why there is DOT 5.1 and who would use it and when?
The ratings are to do with their minimum legal properties. i.e. viscosity, wet and dry boiling points, chemical composition etc. So a bare minimum dot 5.1 will always be "better" than a bare minimum dot 4.0 etc. The best fluids are as you alluded to above the dot 4 racing fluids like rbf600, ate super blue etc. As far as I'm aware the only reason they don't meet dot 5.1 specification is to do with their viscosity as mentioned in Big E's post. Most likely the same reason that the OE stuff is DOT 4 TBH the Dot system is all American twaddle anyway! They are all glycol ether based except 5.0 From what ive read the viscosity of the brake fluid can effect some cars ABS systems etc so perhaps they need 5.1 for the lower viscosity?
Thanks for the explanation. Right, I've finally made my mind up and have ordered most of the brake bits.... I went for Reylands 355mm separate bell & rotor kit for the front with black bells and straight grooves. Then they're obtaining a pair of Renault/Brembo plain rear discs and then machining the same straight grooves in so I will have sided discs front and rear. Then have gone for DS2500 pads front and rear. Will then get a set of black Goodridge hoses, new calliper pins & plate things and the RBF600 fluid.
All fitted now, the hoses and fluid will be done in a couple of weeks but the difference already over standard is really noticeable.
