Ap Discs and pads?

"M" Specific discussion
Tom Dick
Newbie
Newbie
Posts: 31
Joined: Thu Oct 12, 2017 9:50 am

Ap Discs and pads?

Post by Tom Dick » Wed Feb 14, 2018 2:03 pm

My pad of choice on the evo is the XP8 from Carbotech. Speak to Ian, he's very knowledable & can supply any pads & compounds to suit your needs.
http://www.carbotech-europe.com/

User avatar
ph001
Senior Member
Senior Member
Posts: 1814
Joined: Mon Oct 31, 2016 5:53 pm
Location: N. Yorkshire.

Ap Discs and pads?

Post by ph001 » Wed Feb 14, 2018 2:04 pm

I don't understand how higher friction pads gives the discs an easier life. From my high school physics, surely you are just converting the kinetic energy of the car to heat energy in the disc. The AVERAGE of the two must match, whichever way you do it to arrive at the same corner speed.

If you use a higher friction pad (which presumably reduces the DURATION of the braking), surely this results in a HIGHER peak temperature but for less time. The thermal shock on the disc is INCREASED! You also get closer to the traction limit of the tyres. Seems a little disingenuous to me, although I'm no expert by any means.
2007 E85 Z4 3.0Si manual :driving:
19" CSL's | Eibach Springs | Aeroskirts | Z4M front bumper | Clear brake light | ZHP | RCH+| Stubby

2004 E46 M3 coupe manual.

User avatar
TomK
Senior Member
Senior Member
Posts: 1608
Joined: Fri Jan 25, 2013 11:50 pm
Location: Gloucestershire

Ap Discs and pads?

Post by TomK » Wed Feb 14, 2018 2:13 pm

Lower wrote:
Wed Feb 14, 2018 2:00 pm
You're looking at it from slightly the wrong angle.

If you go for a higher friction pad (coefficient of friction at 0.4 or higher) you get more initial bite for a lower pedal pressure and the disc/pad temperatures reduce as a consequence. You also don't necessarily want a pad that keeps working at massively high temperatures on a car you're using to track days because you have no way of knowing that you're overheating the discs. A little bit of fade at high temps can actually be a good indicator that you should allow the brakes to cool a bit.

I had success with Dixcel pads in the S2000 (R01 on the front and Z on the back), but i don't know if you can get them for the Z4M and different makes/compounds do seem to perform differently in different types of car so i can't really help with specific advice. It is quite hard finding the proper coefficient of friction figures for some pads so i ended up trying loads and cracked a number of discs along the way. Ferodo DS2500, Spoon, Porterfield R4S, RS9, etc etc. but the dixcel pad on a DBA4000 disc worked the best where the discs survived with excellent braking performance that didn't tail off. Worked well enough from cold too.
Yeah, I see what you mean. Thing is the friction coefficient is pretty high (0.49) already, I'm also weary of putting anything with even more bite will be like head butting the steering wheel on even the lightest application with these calipers.
The discs should also be able to cope with those temps I was seeing.
I'll see how I get on with some more cooling and perhaps switch to RSL-1 next time round (pagid seem to have a new lineup of pads these days http://www.pagidracing.com/en/products/racing-brake-pads/product-family-rsl.html), I'm hopeful the PF discs will be better in any case.
Cheers
MC IB, CSL intake, Schrick 288/280 cams, SS race bbox, APs, RS-29s, Apex ARC-8, AD08-Rs, KW ClubSport, Turner arms & RTAB limiters, Vibratec mounts, Rogue pulleys & RSMs, Sparco carbon w/ 6 point, CDV delete, UUC ssk, M5 knob, oem strutbrace

User avatar
TomK
Senior Member
Senior Member
Posts: 1608
Joined: Fri Jan 25, 2013 11:50 pm
Location: Gloucestershire

Ap Discs and pads?

Post by TomK » Wed Feb 14, 2018 2:15 pm

Tom Dick wrote:
Wed Feb 14, 2018 2:03 pm
My pad of choice on the evo is the XP8 from Carbotech. Speak to Ian, he's very knowledable & can supply any pads & compounds to suit your needs.
http://www.carbotech-europe.com/
Cheers, yes I've heard good things about that brand. :thumbsup:
MC IB, CSL intake, Schrick 288/280 cams, SS race bbox, APs, RS-29s, Apex ARC-8, AD08-Rs, KW ClubSport, Turner arms & RTAB limiters, Vibratec mounts, Rogue pulleys & RSMs, Sparco carbon w/ 6 point, CDV delete, UUC ssk, M5 knob, oem strutbrace

User avatar
exdos
Senior Member
Senior Member
Posts: 2436
Joined: Wed Feb 22, 2012 12:58 am

Ap Discs and pads?

Post by exdos » Wed Feb 14, 2018 8:31 pm

In devising my brake cooling method, I had read that proper brake cooling has the equivalent effect as using a larger disc which is 1" greater in diameter. That's the way to go.

User avatar
RedUn
Member
Member
Posts: 606
Joined: Sat Jun 16, 2012 7:33 pm
Location: Hertfordshire

Ap Discs and pads?

Post by RedUn » Thu Feb 15, 2018 12:36 am

Tom Dick wrote:
Wed Feb 14, 2018 2:03 pm
My pad of choice on the evo is the XP8 from Carbotech. Speak to Ian, he's very knowledable & can supply any pads & compounds to suit your needs.
http://www.carbotech-europe.com/
Couldn't agree more, they are the way to go and would be my recommendation too :thumbsup:
IMOLA Z4///MR

User avatar
RedUn
Member
Member
Posts: 606
Joined: Sat Jun 16, 2012 7:33 pm
Location: Hertfordshire

Ap Discs and pads?

Post by RedUn » Thu Feb 15, 2018 12:49 am

exdos wrote:
Wed Feb 14, 2018 8:31 pm
In devising my brake cooling method, I had read that proper brake cooling has the equivalent effect as using a larger disc which is 1" greater in diameter. That's the way to go.
Air flow is the answer for sure!

Custom backing plates would be ideal with some nice ducting 8)

Be prepared for rust down the sides of your car paint work though after heavy use :driving: :cry:
IMOLA Z4///MR

Post Reply