Pads n Plugs

[Adam Southgate]

Hi Alistair,

The brake dust you get is from the pads, rather than the discs - as you say, the discs on 924s can last for a very long time. The 'bedding in' part of the EBC pads (red surface) treats the surface of the disc, putting the steel through a heat treatment cycle and adding an alloying material to it. This sinks about 1mm or so into the disc, and happens each time you use an EBC pad. The benefit is reduced fade with EBCs since they've had this coating, and pretty instant braking performance. The problem is that when you use a different pad it doesn't suit the hardened disc and with something like a CL (which are very coarse), you rip the surface of the disc.

Anyways, all 924 racers should change their discs as soon as they see surface cracks appearing - it's the cheapest thing that stop's you hitting something hard.

[Porsche917]

Okay, have ordered some new discs(thought I'd renew the front bearings at the same time) and am ready to go and try some EBC's (reckon my CL's have enough meat to do Snetterton). So, Adam what kind of deal can you wangle on the EBC's when ordered in quantity - I'll be up for 4 or 5 sets. Any chance you'll have them for Snetterton? I don't think I'll make Rockingham as the date clashes with my wife running a half marathon (support required apparently).
Cheers
Geoff

[A.Kirkham]

Adam - I don't want to argue but please google "EBC brake dust" and you will read on EBC's own website that....."brake dust is rotor material"...."many people mistake brake dust for pad material, this is not the case"...."studies show that 94% of brake dust is ferrous oxide from the rotor (disc)"
You can also find on EBCs own website information regarding the bed-in coating. There is no mention that I can see about any alloying effect or the disc being hardened by the coating. EBC simply say that their coating is a soft abrasive coating which wears away quickly and helps the harder pad to bed into any uneveness or grooves on the disc.

[Porsche917]

Hi Guys
Have just been on the EBC website - lots of interesting and useful information on it. This has turned out to be an interesting topic/debate.....just to add another dimension I gather CL's and EBC's aren't the only pads that are run in the championship - what else works? (Just interested).
Cheers
Geoff

[Adam Southgate]

Enjoying this debate quite a lot

Brake dust is mostly metallic for sure, however I'd imagine EBC used their RedStuff (dust reducing) pads when they did the test to say it is 94% ferrous. Research we have done has different results. We even looked at using magnets to reduce brake dust on the wheels, but found them to be ineffective for a multitude of reasons. For interest most road pads contain a significant amount of steel in their compound.

To get all material sciency - when a disc goes through a significant heat cycle the grains in the disc grow. Depending on the temperature reached (and how effective your brake cooling is), more martensite and austenite crystals are formed, replacing the softer ferrite and pearlite crystals. Grain growth is also instigated by alloying. The red material on EBCs causes the disc surface to heat significantly when used at pace on a racetrack. This has the benefit of conditioning the surface to be flat, but the issue of causing the disc to be heat treated (with dust coming from the pads at this stage being able to be absorbed into the very hot steel).

EBC themselves suggest a slow bedding in process with gentle cooling, even with the red surface - the sort of abuse we give them causes this harsh heat cycles, and causes the disc surface to become hard and brittle, which in turn will result in crazing (cracks in the surface). I'm amazed a set of discs has lasted you so long Alistair - I've been through 2 sets in my limited running - can I be cheeky and ask what brake cooling you run and how you bed in your pads?

[A.Kirkham]

Hi Adam. You sure can.....no brake cooling ducts, my car just has the 924 Turbo style slotted front valance. No special bed-in procedure either, just clean/inspect the condition of the discs and away we go!
Cheers, AK.

[A.Kirkham]

Hi Geoff. I have been given a set of Mintex to try, won't be using them yet as my current set of EBCs still have lots of life left in them, but will let you know what I think when I do get round to trying them.
Best regards, AK.

[harryh]

Enjoying this debate quite a lot

Brake dust is mostly metallic for sure, however I'd imagine EBC used their RedStuff (dust reducing) pads when they did the test to say it is 94% ferrous. Research we have done has different results. We even looked at using magnets to reduce brake dust on the wheels, but found them to be ineffective for a multitude of reasons. For interest most road pads contain a significant amount of steel in their compound.

To get all material sciency - when a disc goes through a significant heat cycle the grains in the disc grow. Depending on the temperature reached (and how effective your brake cooling is), more martensite and austenite crystals are formed, replacing the softer ferrite and pearlite crystals. Grain growth is also instigated by alloying. The red material on EBCs causes the disc surface to heat significantly when used at pace on a racetrack. This has the benefit of conditioning the surface to be flat, but the issue of causing the disc to be heat treated (with dust coming from the pads at this stage being able to be absorbed into the very hot steel).

EBC themselves suggest a slow bedding in process with gentle cooling, even with the red surface - the sort of abuse we give them causes this harsh heat cycles, and causes the disc surface to become hard and brittle, which in turn will result in crazing (cracks in the surface). I'm amazed a set of discs has lasted you so long Alistair - I've been through 2 sets in my limited running - can I be cheeky and ask what brake cooling you run and how you bed in your pads?

Juratek's technical website confirms what Adam is saying about disc damage caused by high temperatures generated during severe and often braking.

[Porsche917]

Hi All
Have just spoken to 'Bart' one of the technical guys at EBC (the other is Bob). He told me that it's no problem to switch the pads over - no need to change the discs BUT give them a serious clean including a damned good rub down with something scratchy (as Alastair mentioned several pages ago). Anyway; just run an EBC sticker on the car and they offer a 50% discount off retail so they come in at £25.95 + VAT per set - or £31.14 per set inclusive - shipping is another £6.90.
The good bit (aside from the price) is to get that deal there is no minumum order - 1 set or 100 makes no difference - and they'll do a set of rear shoes for £10 a set (but he did say they don't last very well - one race and they are history).
So, no need to dig deep and order a pile of pads - stock is not an issue either (they have lots available at the moment). Bart (or Bob's) number is 01604 583344
Cheers
Geoff

[A.Kirkham]

Thank you Geoff.....that's great.
AK