Sebro slotted performance discs (rear)

[sevenfourate]

9 minutes ago, Dougle_turbo said:

Interesting, why do you say that? The fronts have been crazed like that since the first track day I did on them. The rears are exhibiting the sort of hairline cracks I've seen on every car with drilled discs that I've owned. 

 

The Porsche specialist who serviced and MOT'd it didn't bat an eyelid to them either. Am I missing something?

 

I'm certainly not trying to eek extra life out of them, they have minimal overall wear and I wouldn't risk the car or myself if I thought they were in any way dangerous.

Doug: you asked the question. I’ve replied with my thoughts. Again - perhaps a conservative approach borne from seeing and often trying to repair stress / age / work hardened / heat cycle cracks in various metals most days of my working life. But I must also add I’m not a metallurgist. Just the man tasked with trying to repair various cracking / although not on cast items subject to severe heat cycles like a brake disc.....

 

**For reference my MOT station ‘noted’ and felt the need to also mention cracks / crazing way less than yours on the last MOT of my daily. Which I duly changed if that’s relevant.

 

I think you’ve taken my ‘eeking’ slightly the wrong way. I wasn’t trying to imply you were stretching a component behind it’s useful life. I don’t know enough to genuinely quantify that. Just that I’m aware how a racing environment is harsh on parts like you cannot reproduce on the road - and it would be all to easy change for change sakes when it’s not absolutely needed. I think and hope we agree to agree on that 😎

 

I still stand by what I’d do. But in no way am I suggesting that’s the only way and is entirely the ‘right’ thing to do. Why did you post the pic and ask for opinions if you’re  seemingly so certain they are ok to continue using ? (And again: I can’t say they aren’t either).
 

Something must be niggling at you to ask, or have I misunderstood your post ?

 

 

[Dougle_turbo]

9 minutes ago, sevenfourate said:

Doug: you asked the question. I’ve replied with my thoughts. Again - perhaps a conservative approach borne from seeing and often trying to repair stress / age / work hardened / heat cycle cracks in various metals most days of my working life. But I must also add I’m not a metallurgist. Just the man tasked with trying to repair various cracking / although not on cast items subject to severe heat cycles like a brake disc.....

 

**For reference my MOT station ‘noted’ and felt the need to also mention cracks / crazing way less than yours on the last MOT of my daily. Which I duly changed if that’s relevant.

 

I think you’ve taken my ‘eeking’ slightly the wrong way. I wasn’t trying to imply you were stretching a component behind it’s useful life. I don’t know enough to genuinely quantify that. Just that I’m aware how a racing environment is harsh on parts like you cannot reproduce on the road - and it would be all to easy change for change sakes when it’s not absolutely needed. I think and hope we agree to agree on that 😎

 

I still stand by what I’d do. But in no way am I suggesting that’s the only way and is entirely the ‘right’ thing to do. Why did you post the pic and ask for opinions if you’re  seemingly so certain they are ok to continue using ? (And again: I can’t say they aren’t either).
 

Something must be niggling at you to ask, or have I misunderstood your post ?

 

 

Sorry mate, I didn't mean to come across in a defensive manner - knor did I mean to diminish your reply in anyway.

 

I'm genuinely interested in why you thought that - I had started thinking about changing them purely from a 'they might need doing a some point this year' point of view. I was surprised that you wouldn't even drive a car with discs in that condition - so I wanted to check I wasn't missing anything, and potentially risking my own or someone elses. Whilst I know a bit about cars I'm always of the opinion that I don't know as much as I'd like, so happy to hear others thoughts. 

 

If everyone says I must be mad for driving the car with discs like that then I'll get them changed, and probably owe you guys a beer for saving me a major headache or worse!

[sevenfourate]

Just now, Dougle_turbo said:

Sorry mate, I didn't mean to come across in a defensive manner - knor did I mean to diminish your reply in anyway.

 

I'm genuinely interested in why you thought that - I had started thinking about changing them purely from a 'they might need doing a some point this year' point of view. I was surprised that you wouldn't even drive a car with discs in that condition - so I wanted to check I wasn't missing anything, and potentially risking my own or someone elses. Whilst I know a bit about cars I'm always of the opinion that I don't know as much as I'd like, so happy to hear others thoughts. 

 

If everyone says I must be mad for driving the car with discs like that then I'll get them changed, and probably owe you guys a beer for saving me a major headache or worse!

 

No offence taken. No apology needed Doug. A forum to me is an idea / knowledge sharing platform. All opinions and thoughts are good. And even if clearly incorrect - it often leads the thought process in another direction which then itself provokes good content on the flip-side ! 

 

I'm just so aware of how once a bad crack starts in most metals, it's almost impossible to stop. However deep you grind. However many holes you drill past the cracks to try to stop them spreading etc. Many of the parts i / we repair are from machines with massive RAMS, large forces etc and used in mass producing products. Often here you can shore up the part with extra bracing, gussets etc. And then strengthen with multi-runs of weld. However that's not the case with a brake disc clearly ! I'm also aware of how what you see visually is often the tip of the ice-burg so to speak.  But again - i'm no expert in brake discs. However i do know from experience cast material can be extremely finnicky. I'd have my doubts is how i'm leaving it !!! 😎

[Dougle_turbo]

1 minute ago, sevenfourate said:

 

No offence taken. No apology needed Doug. A forum to me is an idea / knowledge sharing platform. All opinions and thoughts are good. And even if clearly incorrect - it often leads the thought process in another direction which then itself provokes good content on the flip-side ! 

 

I'm just so aware of how once a bad crack starts in most metals, it's almost impossible to stop. However deep you grind. However many holes you drill past the cracks to try to stop them spreading etc. Many of the parts i / we repair are from machines with massive RAMS, large forces etc and used in mass producing products. Often here you can shore up the part with extra bracing, gussets etc. And then strengthen with multi-runs of weld. However that's not the case with a brake disc clearly ! I'm also aware of how what you see visually is often the tip of the ice-burg so to speak.  But again - i'm no expert in brake discs. However i do know from experience cast material can be extremely finnicky. I'd have my doubts is how i'm leaving it !!! 😎

👍

[jcm987]

@Dougle_turbo I would personally change those rear disks before the next track day. Just from experience my stock rear discs looked like that for a while, not technically finished or too bad for road use or standard pads. But as soon as I put race pads on, they cracked through immediately.

 

Also I run AP Racing brake temp sensor strips and get nerdy with the infra red temp gun and those rear discs get really hot. Often hotter than the front due to reduced cooling and PSM/PASM occasionally applying some pressure. 

[Dougle_turbo]

5 minutes ago, jcm987 said:

@Dougle_turbo I would personally change those rear disks before the next track day. Just from experience my stock rear discs looked like that for a while, not technically finished or too bad for road use or standard pads. But as soon as I put race pads on, they cracked through immediately.

 

Also I run AP Racing brake temp sensor strips and get nerdy with the infra red temp gun and those rear discs get really hot. Often hotter than the front due to reduced cooling and PSM/PASM occasionally applying some pressure. 

 

Man, I'm sure glad I posted these pictures now. Thanks guys.

 

Thoughts on the fronts?

[crafty1]

I'd change both fronts and rears looking at those. When I was looking at upgrading disks I saw Tarox do a slotted gront disc for the 987/997. I've never used their products so no idea what they are like.

 

I also noticed EBC are now making an aftermarket 'floating' set up for various cars so like the Girodisc, but so far I have not seen an option for our cars I did send them an email to see if they would be doing so but sadly no reply. That said I am not a huge fan of their pads so im not sure what to expect if they did.

 

For now I will just stick with Brembos from design911 but I am only doing 2 or 3 track days unlike you guys.

[Dougle_turbo]

 

13 hours ago, crafty1 said:

I'd change both fronts and rears looking at those. When I was looking at upgrading disks I saw Tarox do a slotted gront disc for the 987/997. I've never used their products so no idea what they are like.

 

I also noticed EBC are now making an aftermarket 'floating' set up for various cars so like the Girodisc, but so far I have not seen an option for our cars I did send them an email to see if they would be doing so but sadly no reply. That said I am not a huge fan of their pads so im not sure what to expect if they did.

 

For now I will just stick with Brembos from design911 but I am only doing 2 or 3 track days unlike you guys.

 

Thanks @crafty1 I hadn't thought about Tarox, their kit is great. I've started a new thread as I'm de-railing this one!