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Looking for some input in the state of my rear rotors. Quite a few cracks as the pictures show; a few of them are about 7mm long, no cracks connect holes, no cracks reach the edge of the disk. My hope is to get 1 more track day out of these (at Laguna Seca).
Prevailing wisdom says they are ok if cracks as you describe and they dont look bad. Would definitely check that they are still in spec width ( i think 26 mm but please double check)
Those are developing cracks but don't appear more than surface level yet. Width and depth are good indicators of wear- you cannot put a fingernail in them, they aren't an inch long, and they aren't connecting to other holes or edges.
It will be time to replace soon but as to how soon that is up to you.
How quickly did the cracks develop? Likely not in one session nor one day. I'd get a set of rotors on hand and monitor the current set session by session, day by day. I suspect you have more than one day left in them.
Here are my fronts, for reference. I'm taking them to Circuit of the Americas in two weeks:
I appreciate all the input, leaning towards replacing them.
To address the various questions: 'why risk it/just get new rotors/they are only $400/it is your life' questions:
I am not trying to save a buck, this is more a matter of time and timing: next event is soon and I have a busy/tight schedule and it will be a challenge to get the parts and get them installed in time. If it is a must, I'd get it done; if not, I'd prefer to wait. When I do buy new rotors, I am planning to upgrade the entire system to, at a minimum, Girodiscs, but quite likely I will upgrade to a BBK -- this makes it far less attractive to pull of the rear rotors, only to replace them again in the very near future.
Those are barely broken in.
The surface crazing is normal with drilled rotors. No significant cracks at all.
Should be good for several more track days, depending on your driving style, etc.
I doubt even the most ham-fisted driver could destroy those in just one more day.
Porsche WSM says any single crack from a hole longer than 5mm (about .200") is not acceptable, or any single crack that starts from or extends to the outer edge of the rotor .
I appreciate all the input, leaning towards replacing them.
To address the various questions: 'why risk it/just get new rotors/they are only $400/it is your life' questions:
I am not trying to save a buck, this is more a matter of time and timing: next event is soon and I have a busy/tight schedule and it will be a challenge to get the parts and get them installed in time. If it is a must, I'd get it done; if not, I'd prefer to wait. When I do buy new rotors, I am planning to upgrade the entire system to, at a minimum, Girodiscs, but quite likely I will upgrade to a BBK -- this makes it far less attractive to pull of the rear rotors, only to replace them again in the very near future.
Cheers,
DJM
Take advantage of the lifetime warranty from FCP Euro when you buy new rotors. ~$500 for a set of Sebro OEM replacements. When they wear out again after half a dozen track days you get them replaced for the cost of shipping. Just replaced mine as they have similar cracks. While I can appreciate the functional upgrade Girodisc provides, they are still a wear item that you'll replace every couple years. I don't see the point in spending all that money just to spend 80% of again 2 years later.
Also, when you get to replacing things check the dust boots on the caliper pistons if you don't already do that regularly. I was surprised to find 14 of 16 boots were cracked and torn from the heat. This is after 7 track days, 6 of them with Pagid yellows. Added titanium shims in hopes that it doesn't happen again.
The Porsche Shop manual puts an acceptable limit of 5mm on the crack length. The also say that if any crack extends to the perimeter, the disc needs to be replaced. Oh, I just saw that Okie already said this...
Agree with this. I found the same especiallyon the rear calipers. Dried and cracked.
Originally Posted by Scooby921
Take advantage of the lifetime warranty from FCP Euro when you buy new rotors. ~$500 for a set of Sebro OEM replacements. When they wear out again after half a dozen track days you get them replaced for the cost of shipping. Just replaced mine as they have similar cracks. While I can appreciate the functional upgrade Girodisc provides, they are still a wear item that you'll replace every couple years. I don't see the point in spending all that money just to spend 80% of again 2 years later.
Also, when you get to replacing things check the dust boots on the caliper pistons if you don't already do that regularly. I was surprised to find 14 of 16 boots were cracked and torn from the heat. This is after 7 track days, 6 of them with Pagid yellows. Added titanium shims in hopes that it doesn't happen again.
05-02-2019, 12:46 AM
Are these rotors toast?
