Discussion
Perhaps with cheap nasty drilled disks, but if they are so bad why are they standard issue on Porsche ?
I completely disagree with this easy to jump on opinion of drilled disks. I run drilled & grooved front 300's with DS2500 pads, enough to boil th fluid this year and in 30k miles i have no issues with the disks.
Yet a set of big disks, grooved only and green stuff pads in my old S and they cracked in less than 5k miles. . .
Buy good quality disks and pads and you won't have an issue.
I would leave that disk alone, keep an eye on the crack trying to gauge depth and spread. If it gets worse then change the disk or have them skimmed, but i wouldn't panic . . . .
I completely disagree with this easy to jump on opinion of drilled disks. I run drilled & grooved front 300's with DS2500 pads, enough to boil th fluid this year and in 30k miles i have no issues with the disks.
Yet a set of big disks, grooved only and green stuff pads in my old S and they cracked in less than 5k miles. . .
Buy good quality disks and pads and you won't have an issue.
I would leave that disk alone, keep an eye on the crack trying to gauge depth and spread. If it gets worse then change the disk or have them skimmed, but i wouldn't panic . . . .
Johno said:
Perhaps with cheap nasty drilled disks, but if they are so bad why are they standard issue on Porsche ?
I completely disagree with this easy to jump on opinion of drilled disks. I run drilled & grooved front 300's with DS2500 pads, enough to boil th fluid this year and in 30k miles i have no issues with the disks.
Yet a set of big disks, grooved only and green stuff pads in my old S and they cracked in less than 5k miles. . .
Buy good quality disks and pads and you won't have an issue.
I would leave that disk alone, keep an eye on the crack trying to gauge depth and spread. If it gets worse then change the disk or have them skimmed, but i wouldn't panic . . . .
Porsche are another issue, what's the point of stating that, it is meaningless in this context?I completely disagree with this easy to jump on opinion of drilled disks. I run drilled & grooved front 300's with DS2500 pads, enough to boil th fluid this year and in 30k miles i have no issues with the disks.
Yet a set of big disks, grooved only and green stuff pads in my old S and they cracked in less than 5k miles. . .
Buy good quality disks and pads and you won't have an issue.
I would leave that disk alone, keep an eye on the crack trying to gauge depth and spread. If it gets worse then change the disk or have them skimmed, but i wouldn't panic . . . .
The point is that there is no good reason for normal use to fit the drilled grooved disc, it is an irrefutable fact that the drilling is a stress raiser and the photo shows a typical stress crack formation. To say carry on and watch it is senseless, change it and do not risk a failure.
I have spent the last 40 odd years dealing with High Speed Gas Turbines, where such turbine disc cracking is common place and to ignore such a failure is the height of stupidity, because it can shut an installation down and lose millions of pounds a day, but this relates potentially to someone's life!
That you have had 30k miles on yours without problem is a benefit to you, but do not confuse your good fortune with the fact that this guy has a failure in the making, so the sensible thing is to change the discs. As ray-von stated it is pertinent if it is either a surface crack or it is through the web of the disk, the photo looks as though it has cracked through the web as it is a relativley thin section.
My S has run 10k + miles without issue on 260mm discs and they were the best mod I fitted to the car.
YB
How can you relate high speed turbines to brake rotors ? 
My dad works on commercial aircraft
engines and he can't see the connection unless you mean they both rotate. In that environment they get tested by X ray etc . And they come under far more stress than a brake disk does.
The point is that Porsche seem perfectly happy to use drilled disks for an application that you're stating is over the top and unnecessary.
Any change to the disk will cause stress, grooves, dimples, drilled holes.
My experience is that cracks are normally surface depth rather than deeper and this is probably the case here. Skimmimg them would be wholly adequate.
I do not know anyone who has a had a disk break on them on a TVR in 10yrs of ownership. That is also true for other friends cars in 18yrs opf driving. The point here being that the vast majority of people rarely look at their disks in the first place.
To suggest I would imply something that would threaten someones life is in fact offensive and I'd ask that you consider making such an emotive statement.
My dad works on commercial aircraft
engines and he can't see the connection unless you mean they both rotate. In that environment they get tested by X ray etc . And they come under far more stress than a brake disk does.
The point is that Porsche seem perfectly happy to use drilled disks for an application that you're stating is over the top and unnecessary.
Any change to the disk will cause stress, grooves, dimples, drilled holes.
My experience is that cracks are normally surface depth rather than deeper and this is probably the case here. Skimmimg them would be wholly adequate.
I do not know anyone who has a had a disk break on them on a TVR in 10yrs of ownership. That is also true for other friends cars in 18yrs opf driving. The point here being that the vast majority of people rarely look at their disks in the first place.
To suggest I would imply something that would threaten someones life is in fact offensive and I'd ask that you consider making such an emotive statement.
Porsche use cast holes rather than drilled (and they still crack). Cracking can occur with any disc, plain drilled grooved or whatever. But it's far more common with drilled discs. If you need ventilation I suggest sticking to grooved discs (and you only need 6-8 grooves per side). If you don't need it, stick to plain discs and you will get more braking and less wear and noise.
I was at Snetterton with Ted in his GT3 RS last month where the front disks are absolutely covered in cracks, I mean dozens and dozens of cracks.
It's a track car only and get's an absolute hammering and Porsches view of the cracks. No problem . . .
It goes back to my point of buying good quality disks in the first instance, not saying to the OP's disks aren't . .
It's a track car only and get's an absolute hammering and Porsches view of the cracks. No problem . . .
It goes back to my point of buying good quality disks in the first instance, not saying to the OP's disks aren't . .
The point of relating to the turbine rotor is that whilst they both rotate I have rarely seen a crack propogating from a stress raiser that resulted in a surface crack only either on the high speed or low speed rotors, invariably they crack through.
Surface cracking, if you've seen those on Ted's Porsche, will have an entirely different appearance to the one in the photo, it has a crazed patterning, very light hairline cracks all over the surface and not radiating from the drilling.
My point about a persons safety is that you were dismissive of the potential problem, I happen to have a contrary view to you and think that the best thing to do is change it. We have differing views, the OP will now make up his own mind.
YB
Surface cracking, if you've seen those on Ted's Porsche, will have an entirely different appearance to the one in the photo, it has a crazed patterning, very light hairline cracks all over the surface and not radiating from the drilling.
My point about a persons safety is that you were dismissive of the potential problem, I happen to have a contrary view to you and think that the best thing to do is change it. We have differing views, the OP will now make up his own mind.
YB
Turbine blades are placed under different stresses to a brake rotor.
A differing opinion which you suggest was dismissive of the possibility of the OP's death . . Utter nonsense that I would ever post something that would be so foolhardy.
If you refer back to my original post I suggest he checks whether it is only a surface crack.
I'm glad you have X ray vision and can tell all this detail from a photo, I on the other hand suggested he check it.
We do have differing opinions and evidently a different way of expressing them
A differing opinion which you suggest was dismissive of the possibility of the OP's death . . Utter nonsense that I would ever post something that would be so foolhardy.
If you refer back to my original post I suggest he checks whether it is only a surface crack.
I'm glad you have X ray vision and can tell all this detail from a photo, I on the other hand suggested he check it.
We do have differing opinions and evidently a different way of expressing them
Johno said:
Turbine blades are placed under different stresses to a brake rotor.
A differing opinion which you suggest was dismissive of the possibility of the OP's death . . Utter nonsense that I would ever post something that would be so foolhardy.
If you refer back to my original post I suggest he checks whether it is only a surface crack.
I'm glad you have X ray vision and can tell all this detail from a photo, I on the other hand suggested he check it.
We do have differing opinions and evidently a different way of expressing them
1. We are not talking about turbine blades, a cracked rotor disc will react in a similar way to a cracked brake rotor partly due to heat cycling and in the case of a brake disc this is far more frequent than with a rotor disc which faces constant high temperature.A differing opinion which you suggest was dismissive of the possibility of the OP's death . . Utter nonsense that I would ever post something that would be so foolhardy.
If you refer back to my original post I suggest he checks whether it is only a surface crack.
I'm glad you have X ray vision and can tell all this detail from a photo, I on the other hand suggested he check it.
We do have differing opinions and evidently a different way of expressing them
2. I made reference to the safety of the individual because for the price of a set of discs it isn't worth leaving them.
3. I don't think you were as clear in your original statement as you now make out....
"I would leave that disk alone, keep an eye on the crack trying to gauge depth and spread. If it gets worse then change the disk or have them skimmed, but i wouldn't panic . . . ."
there was no reference to it being a surface crack.
However all this results in is us to having a disagreement about a £100 pair of discs!!
Is it worthwile not changing them at that price?
YB
LordGrover said:
Once they were off, both sides had two cracks right through.
£80 and two new shiny discs now stopping me nicely.
LG glad you are sorted out, did you go for dimpled/grooved or just grooved?£80 and two new shiny discs now stopping me nicely.
YB
PS, I wish my bill was £80, I'm now into a full rebuild on my 500 after a cam failure but hey, I've only had the car three weeks so it's going to be an investment for the future!!!
Providing I keep it for the next decade
Yellabelly said:
LordGrover said:
Once they were off, both sides had two cracks right through.
£80 and two new shiny discs now stopping me nicely.
LG glad you are sorted out, did you go for dimpled/grooved or just grooved?£80 and two new shiny discs now stopping me nicely.
YB
PS, I wish my bill was £80, I'm now into a full rebuild on my 500 after a cam failure but hey, I've only had the car three weeks so it's going to be an investment for the future!!!
Providing I keep it for the next decade
I'll get me coat huh
Yellabelly said:
Johno said:
Turbine blades are placed under different stresses to a brake rotor.
A differing opinion which you suggest was dismissive of the possibility of the OP's death . . Utter nonsense that I would ever post something that would be so foolhardy.
If you refer back to my original post I suggest he checks whether it is only a surface crack.
I'm glad you have X ray vision and can tell all this detail from a photo, I on the other hand suggested he check it.
We do have differing opinions and evidently a different way of expressing them
1. We are not talking about turbine blades, a cracked rotor disc will react in a similar way to a cracked brake rotor partly due to heat cycling and in the case of a brake disc this is far more frequent than with a rotor disc which faces constant high temperature.A differing opinion which you suggest was dismissive of the possibility of the OP's death . . Utter nonsense that I would ever post something that would be so foolhardy.
If you refer back to my original post I suggest he checks whether it is only a surface crack.
I'm glad you have X ray vision and can tell all this detail from a photo, I on the other hand suggested he check it.
We do have differing opinions and evidently a different way of expressing them
2. I made reference to the safety of the individual because for the price of a set of discs it isn't worth leaving them.
3. I don't think you were as clear in your original statement as you now make out....
"I would leave that disk alone, keep an eye on the crack trying to gauge depth and spread. If it gets worse then change the disk or have them skimmed, but i wouldn't panic . . . ."
there was no reference to it being a surface crack.
However all this results in is us to having a disagreement about a £100 pair of discs!!
Is it worthwile not changing them at that price?
YB
I can understand how that wasn't clear . . . !
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