Brake Failure into hungry

[MossRatt]

I was running well at the Open Sprints Saturday at Lakeside till I had a fairly decent brake failure going into Hungry.
No major damage just ripped the front lip from hitting some long grass at speed, but the brakes are the concern.
The rear left Winmax W3 pad has shattered and completely broken away.
So I'm looking to replace all 4 pads now as they have been on the car since I bought it 12 months ago. And it was sitting in the last owners workshop for a good 18 months before I picked it up.
The other noticeable item that's appeared are on the front rotors. I have RDA slotted and dimpled rotors (also on the car from purchase) now with tiny fractures running vertically. They are only about 5mm long, and I havent seen any that run the whole length from the inside diameter to the outside, but there are a lot of them. Have a look at the attached pictures, I'm not too sure if thats normal....
So I'm putting it out there to ask the forum, if I should run those disks any longer? If not, what is the best setup for track only disks and pads, and where's the best place to buy them from?

Thanks

Mossratt

[Alex 2550]

not much help here but....
i'm pretty certain Manga_blue got cracks in RDA rotors as well.
when time comes for upgrading for me ill be going DBA rotors as i have used them before on my FC RX7, most likely T2's but perhaps T3 on the front but haven't looked into it enough yet to say for certain.
i have also been hearing that the genuine mazda rotors have proven to be pretty good depending on how serious the car is.
speaking to my local supercheap (that has one girl there who is brilliant for customer service) and they told me that they will beat any price on DBA's and i asked if that included EBAY which they said yes.

[manga_blue]

Yep, I've cracked new RDA front rotors in their first session at Wakefield Park, where I normally get 30-40 track days out of a set of DBA rotors. The cracks I got were pretty similar to yours, only much worse. I know several people who have done the same. So I'd have to say that RDAs are not suitable for track work.

I think the best setup for a still relatively stock car and a driver who knows how to take it to the limit is DBA 4000 series rotors. Slotting or no slotting is personal preference although there's a growing body of opinion here that they work best with no slots. Dimples and cross drilling MUST be avoided - they focus the stresses but provide no performance advantage on our cars.

I don't know anything about WinMax pads but if I had one that broke then I would take them back to the supplier with a huge please explain. It smells badly of quality control problems.

[Magpie]

Those cracks look very superficial, that is the crack is in the pad material deposited on the rotor and are not very deep. Trust me you will be able to feel a crack in the rotor through the brake pedal!

Are the cracks radiating out from the 'dimples'?

What do you think caused the brake failure?

This is a crack! Notice the smaller cracks, these are just in the pad material.
DSCN4547 by Eipeip, on Flickr

DSCN4546 by Eipeip, on Flickr

With respect to the W3's, how much pad material was left on them? It could be that they were down to 'rivets' and this is what has given the 'shattered look'. Further what heat levels have they been subjected to. I have run W3's and never had a pad shatter yet.

At the moment I'm running OEM rotors on the track with no issues. A bit like heat cycling tyres you can heat cycle your rotors. That is gradually bring the heat up and then let them cool. The pad bedding in routine helps with this 'conditioning' of the rotors.

Change your brake fluid often, especially if a track car.

[Lokiel]

:
This is a crack! Notice the smaller cracks, these are just in the pad material.

:

- great photo illustrating the difference

[plohl]

Glad there was no damage dude. It can be a forgiving corner provided you just roll up the hill, but I bet it was bloody scary.
I have heaps of small surface cracks on my discs and have never really been too concerned about them. I use the DBA T2 discs and check the discs after each session generally to make sure there is nothing bigger appearing.
I haven't heard of the winmax pads failing like that, but it's not uncommon when pads get low... some pads they don't even need to be that low

I haven't used the w3s, but i think highly of the w5s. Might be a good idea to talk to motorsport brakes about it...

Given it was a rear.... I would check your calipers, make sure the they're not leaving excess load on the pads, and you handbrake is adjusted correctly.

[mazlot]

Check the rotor thickness, they look rather thin.

[manga_blue]

Just to be clear. The cracks in RDAs that I had seen on my car and others were about half as bad as Magpie's. They mostly went across about 1/2 to 3/4 of the width of the rotor. They were genuine cracks through the metal but at least they didn't break through the outer edge like that. Magpie's are just plain scary. Here's one of mine:

RDA rotor cracks.jpg

On the other hand I've used RDAs in ordinary (i.e. non-race) cars a few times and they've been fine. It's just track use that exposes their weaknesses.

[Magpie]

Magna_blue your picture also shows the tell tale sign of missing pan material near the crack.

On mine, hence my comment on you can feel the crack through the pedal comment

[manga_blue]

I could only just feel it through the pedal. I suppose there was some rotor warping associated with the cracks, enough to cause a tiny flutter and leave those uneven deposition marks.

[greenMachine]

Anyone here heat treat their new rotors before use? I do it for the willies on the racecar, I think I'd do it for any car I tracked. I get good life from mine, and never had a crack - but the heat treatment is meant to extend life, not (AFAIK) to prevent cracking. The Wilwoods are slotted, but for stock rotors I go plain.

[Luke]

I had those RDA's on the back of my SE with hawk Blues.
They would be the 2nd worst rotor I have used on my MX-5.
I believe the metal used on them is just to soft.
All the slots and dimples were gone before the pad and the noises they made were annoying on the road.
The pads also wore out way faster than they did on the Factory plain rotors, which I actually re-used later on again and am still using now on their 4th set of pads.

I have heaps of those fine looking crack as well, but as Magpie said those are just really on the surface mainly in the pad material deposit.

I have also had proper cracks like Magpie has shown, both times with DBA 4000's, the old 6 Slot design and the new T3. The cracks started in the slots. By the way The T3 is the worst rotor I have used with the pad I chose to run it with(Carbotech XP10), and the most expensive.
I now use el-cheapo plain Protex rotors up front with the OEM rears which I still have not cracked and they have done a lot more work than the DBA's for 1/3 of the price!!! To be fair I added 2 inch brake ducts as well to prevent cracking.
I use them with Carbotech XP12 pads up front and XP10 at the rear.

Anyone here heat treat their new rotors before use? I do it for the willies on the racecar, I think I'd do it for any car I tracked. I get good life from mine, and never had a crack - but the heat treatment is meant to extend life, not (AFAIK) to prevent cracking. The Wilwoods are slotted, but for stock rotors I go plain.

I heat treat mine, sort off.
First I clean all the factory goo off.
Then I paint the hat with High Heat Ceramic paint, normally in cast iron colour.
I then put them in the oven to bake the paint.
That's my heat treatment LOL.

[MossRatt]

Thanks to everyone for your input and assistance. This is a great forum and I learn so much everytime.

I have some photo's attached of the pad that has broken. its the outside pad of the rear left disc.
There's plenty left on the pads and no scarring, fractures or splits on the disc.
So it must have been something else??? I'll contact Winmax and have a chat.

I will most likely change out all pads and discs now, not only for peace of mind, but to prep for next year.

The video below starts from the Karussel because just after the exit, there's a funny noise that at first I thought was a rock or dirt being flicked up. The usual noises you get on the track. But it may be half the pad letting go.....
The usual gopro errors with non-synced audio are in there so apologies.
https://youtu.be/ikcdt0rsqvc

Thanks again everyone. I appreciate the feedback, time to go shopping.

[Magpie]

Contact Winmax and discuss. Are there any rivets in the pad? Looks like that pad had a fair bit of heat.

Was the rotor shinny?

I have issues with hungry as well, however mine is grip related

[madjak]

wow... looks like fun! You have reminded me to check all my pads for cracks!

I think the cracking of the rotor is pretty much solely due to the heat cycling. I find my 11.75" Wilwood rotors don't get any surface cracks which comes down to a larger heat soak due to the larger area and pad choice. My first set of NA6 DBA rotors cracked when I was running Ferodo Ds3000 pads but they could be seen glowing even during the day. The larger wilwood rotors don't get anywhere near as hot and with the endurance pads I run don't see as much wear.

Do you leave your handbrake on when you stop the car after a track run? I've seen a couple of pad failures and it's almost always due to parking it up with the handbrake on and cooking the pad.