[Guest]

Was in Ralliart today , while waiting (I always go there with at least 30 mins in hand !) I scoped out their VII extreme , T1 RBO , with the AP 6 piston , big disc conversion.

Guess wot I saw ? about 20-30 holes in both front discs with radial cracks about 5 mm long in both directions , wud not expect this 2 b normal.........or is it ?

 

[Guest]

Evoboy, yeh it is actually, but it depends on the pads. Same thing happened to my AP 6 pots. If the discs aren't warmed up properly, and harsh pads such as Carbon Metallics are used, you get great braking but it destroys the discs. They get too hot without the ventilation also.

I found I had to go to AP grooved discs with the PE ducts (on a VI) - and switch to Pagid RS42 pads. No problems, and actually much better braking than before.

I killed my drilled APS in 200 miles! AP said - Tough, they aren't meant to be used with those pads...

Have a look at my new website (which isn't finished yet), at my brake history - http://homepage.ntlworld.com/tony.rodriguez/brakes.htm

Nasty - click on the pictures to get them full size.

Cheers

 

[Guest]

If I didn't respond to this topic then something must be wrong!

Tony is right, these must be heat cracks. This can easily happen when using carbon metallic pads which really store the heat and are very aggressive on the disc surface. To prevent from this using a good organic based pad (like the Pagid range) is very useful. Even the discs I rave about all the time would develop cracks when using these ultra harsh pads. I now use also organic pads and get the same stopping power as with the Mintex F4R/standard calliper combo. The big surplus is especially when cleaning the discs/wheels etc.. With those carbon/metallic stuff it builds up brake pad residue on the disc which is not easy to remove and can also lead to warping as some parts of the disc face is covered with this stuff so heat spots can occur.

As the holes on the AP are not cast drilled like the Porker discs they're also more prone to cracking.

Cheers

Mike

PS: I also use brake ducts to cool the stuff down

 

[Guest]

Eagle eyes!

Bear in mind that T1RBO has done 9000 miles including Autocar road test and quite a lot of test sessions and you'll see why cracks start around the vents.

For those doing track sessions I'd recommend the ones fitted to the eXtreme S (J1 WRC) which have a no cross-drilling - rather an endless groove around the surface of the disc.

 

[Guest]

Yeh, cross drilled helps ventilation, but IMHO is more of a fashion statement! Get the grooves and get ducting to keep the discs cool.

Scoobymike - was waiting for your response! Oh, and haven't you changed your name yet????

 

[Guest]

Tony

I don't quite agree about cross-drilled being a fashion statement. Especially when it rains a cross-drilled disc can get rid of the waterdamppressure immediately and so you have almost the same stopping power and brake feel as on a dry road.

Haven't changed my name yet, no good proposals yet!

Cheers

Mike

PS: Might be interested in buying your current downpipe when you switch to a bigger turbo!

 

[Guest]

ScoobyMike - I was just kidding 'bout the drilled discs! You are right, of course. One of the reasons why the brake ducts on the M5 are closed is that it diverts water onto the disc (DOH) - they aren't drilled, so that can drastically reduce brake force. Drilled discs solve that.

Grooves are definitely stronger, but not cooler. Water dispersal should be ok, as they are hot enough to boil the water away!

 

[Guest]

Tony

maybe I gonna paint my discs pink, this would be quite fashionable

What about the kit for your Beemer? I'm still interested in your opinion about the movit, especially when used on such a heavy car. Then you could also open the brake ducts with the cross-drilled discs!

Cheers

Mike

PS: Already lusting after your downpipe, buy this bloody big turbo!