4 Kurves

From the left front outside on my Cup car. All the other pads had the normal spider type cracks but this one is cracked all the way to the metal backing.

Never seen this before. This is after a weekend at Laguna which is a pretty hard braking track.

Sean F

yup...all too often. Almost every time I switch out pads.

dan212

I've seen pads start to show slight hairline, closed cracks after hard, heavy use in extremely hot temperatures.

My pads had plenty of material left - at least 2/3. Only when they were pulled off to replace rotors could the beginning signs of hairline cracking be seen. Nothing as bad as what you have, but I replaced them.

The last outing on them, we got red flagged (nothing bad thank god, just a blocked track) in the middle of a VERY hot session. Sitting with everything hot in the car going "tick tick tick".. That might have done some harm. Things were HOT.

mooty

although not every time, i do have many pads like that. usually after LS. T2 is a pad killer.

Veloce Raptor

What pads are those?

Sean F

BTW, I had a long running correspondence with a Performance Friction engineer over just what you describe. I sent them 2-3 samples of similar wear/cracking. They were "surprised" by what they saw.

Here was their first response:

I have showed your pads to a couple of our guru's here. I was worried that the pads might be sticking in the calipers just a bit, overheating and then cracking. I do not believe this to be the case, as we see no bending or heavy witness marks in the abutment areas of the backing plates.

It does look like the pads may have been run hard when when wet. This does not necessarily mean in a rain race, as I do not typically see cracked pads after a full wet race. The type of cracking on your pads we commonly see in series where cars get washed frequently (dirt track racing as an example) and then run. Water is able to penetrate the pad material (it is porous, as are all brake pads). When the pad material heats up to 1000 degrees during a braking event, the water turns to steam and escapes violently through the pad material causing cracks.

We didn't find anything wrong with the pads necessarily and it does look like the calipers are probably in good condition as well. I am not sure if the above scenario makes sense to you, but I look forward to hearing what you think.


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I wrote back saying it wasn't water causing the problem and here was his response back:



As far as thermal shock, that is really not a concern. That is the job that brakepads are designed to do, and 97 is a very robust compound in that way. We have won the Rolex 24 at Daytona 2 years on the trot with 97, which is a worst case scenario for "thermal shock", and way worse than Watkins Glen in that respect.

The engineers are pretty firm in their evaluation. From a performance or safety standpoint, I would be more concerned if the friction material were separated from the backing plate or if the backing plates themselves were bending.

Let me know your thoughts.

mooty

very interesting.
my cars are washed evey time it gets home from track, so the "water" response may be my problem.

also, my material doesn't SEPARATE from backing per se, but i do see some deep crack like the pix that goes from face of pad material to the backing.

i never paid much attention to the cracks and i can't tell any braking degradation.

4 Kurves

Pagid Yellow. E2405 140 10 I think is the part number - for a Cup car front.

Probably 30% or so left in pad material.

Veloce Raptor

Pad flaw?

Streak

That's not a crack, this is a crack!

James-man

Whoa! That looks like detonation!

4 Kurves

OMG - I don't feel so bad now!

todinlaw

Did you bed them in. a build up of heat in the pad and then bed the pad and let cool once before the next big heat cycle. I think pads like tires benefit from a bedding heat cycle. CDOC has a nice little piece about pad bedding and i read it that the bedding process kind of cures the pads. that is how I remember it anyway.

Streak

I am not sure what happened. I pulled these off the car after a 3 day DE at WGI. They were brand new. Either I way way overbroke every single corner in every single session for 3 days or I did a terrible job of bedding them in. Probably a combination of the two. I am, after all, really scared of turns

amondc

Very common in the cup cars. Just about every time we change pads thats what they look like. The brakes get so hot I think it just cooks the pads. Nothing to worry about as long as there are not large chunks missing.