SH || NC

Yep.

Valid point. The concept is also to move to non-drilled rotors, so they should last much longer in my case. I put these [pic1, pic2, pic3] (minor) cracks in my rotors over the course of 4 days. My rotors were not brand new when I started (~43k), but had only seen mild street braking with stock pads and no cracks whatsoever.

Solid rotors I think would last much longer, considering I will swap back in stock pads when I am not at the track.

Keep the feedback coming!

mdrums

Tht is what mine look like after a few DE's too. You can do some more driving on those.

If you've got $2500 burning in your pocket I say go with the Girodisc. Or for $2500 you can buy 4 sets of stock rotors that will last you probably 3.5-4 years. How many DE days (depends on the track) can you get out of a set of Girodic or any other brand of slotted rotors?

himself

Your rotors are starting to crack, but they still have some life in them. And, that's actually pretty good wear for 4 DE days + 43K street miles! You will definitely benefit from solid dimpled/slotted rotors though. They are a little more expensive up front (for 2 piece), but you get more life and then only have to buy rotors and not hats.

Below are some pics I previously posted in another brake rotor thread. First set are cross-drilled rotors off my old car after only 10 sessions (2 days) and minimal street miles. Almost no wear, but significant cracking - even in the metal away from the holes. The second set of pics are the PFC dimpled rotors I upgraded to after 26 sessions. I ended up running these for almost 50 sessions (before I sold the car), and they was only minimal cracking.

CROSS DRILLED - 10 SESSIONS



CROSS DRILLED - ALMOST NO WEAR ON ROTORS



DIMPLED - 26 SESSIONS - MINIMAL CRACKING

Land Jet

I've been using 2 sets of stock front rotors per season. Hoping the Girodiscs last a full season plus. There are some other benefits to factor in. The aluminum hats save unsprung weight, and the replacement discs are cheap compared to Brembo, etc. Unless it's an aesthetic thing for you, I just run the slotted rotors on the front and leave the stock rotors on the rears. I get 2 full seasons from the stock rear rotors.,

PogueMoHone

You might want to do a little more checking then, I couldn't make this stuff up if I tried, and I am pretty sure that my memory is still intact!

PogueMoHone

And here is more from a Google search relating to GT3 brake problems and the "stated" input from a couple of Motorsports engineers....

'Had a chat with a couple of motorsport engineers and they agreed the brake problem could be related to your upgrade to Castrol SRF brake fluid. The benefits of running with a motorsport brake fluid are obvious: the higher dry boiling point (above 300’C) certainly reduces the chance of the brake pedal unexpectedly going to the floor! It should provide that great feeling of confidence from a stiffer brake pedal and the ability to run for extended track sessions.

However, changing from the standard brake fluid to Castrol SRF does also have some potential risks. By design, Castrol SRF allows the brake fluid to operate at a significantly higher temperature during track driving, meaning that the braking system will soak up more heat - so the brake callipers, lines, seals and discs are also pushed to operate at higher temperatures than they may have been designed. Hence, the use of a motorsport brake fluid such as Castrol SRF potentially increases the brake cooling requirement.'

Land Jet

I just read the article that your quote came from and one of the GT3 owners mentions that the GT3 handbook recommends using racing brake fluid for the track. Did you see that part?

PogueMoHone

^
Do they (in the handbook) recommend Castrol SRF?

I wonder which fluid Manthey uses?

Also, let's not lose sight of the fact that this topic is related to a C4S, so what is appropriate for the GT3 may not be suitable for a C4S. I suspect the above comments about Castrol SRF are somewhat related to the Dealers refusal to put it in US cars. The GT3 in question was a UK car. You have to think that the above whisperings on the other side of the pond by Motorsports Engineers have to be more than coincidence; and maybe related to something internal from Porsche. Otherwise, how would the US dealers know or advise against using Castrol SRF?.

Anyway, I suspect when it comes to fluids this could become an "endless" topic.

PogueMoHone

And there is more:

I don't know why the UK handbook would be different but there is no mention of racing fluids in the US handbook, so I for one would like to see that reference....

US Cars

Porsche brake fluid is only recommended:-

See page 247 of the 08 US GT3 RS and page 239 of the 10 US GT3 handbook, they say:-

RonCT

This is all good information and I'm thankful (on Thanksgiving no less) that you are sharing it with passion. I go back to what I typed earlier. My Porsche dealer installs Castrol SRF, has done so on my Porsches for years. It's right there in the service write up, so it's not like he write it up as "flush brake fluid using Porsche XYZ". It's listed properly showing they are using Castrol SRF. This is not the only dealer that does so. Also, every one of the Porsche shops in my region pretty much exclusively have used Castrol SRF, since the fluid was invented. I don't know how many years (or decades) that has been, but there has never been an "issue" with using this fluid. So, whether it's on some list somewhere in Porsche land to "only use Porsche fluid" or not, common practice in the Northeast, including by dealers, has been to use Porsche fluid, ATE, Motul, Castrol SRF, etc. All are DOT approved...

Land Jet

Personally I think Porsche says to use Porsche brake fluid so they can make a profit by putting their name on the manufacturer's bottle of generic brake fluid. I could be wrong but in this case I doubt it.

And when I think about the heat generated in each fluid, it would be equal under the same conditions. SRF is better able to handle it and won't boil. I don't know the temp range of the Porsche fluid, but under the same conditions it will reach the same temp, and may boil, and we all know that is not good. I don't see that the argument holds up. Now if SRF had a chemical in it that was corrosive to the brake system, that is another story.

boss351

Intended pun? Manthey appear to use the same as me, Endless 650. Its excellent.

I went around in circles looking at what to use to replace the Motul fluid I had been using (works well, just wanted to eliminate the constant need for bleeding - before every track event). It came between SRF and Endless in the end and Endless won. I was always concerned about SRF mixing with remnents of the older fluid which I have read can cause problems, since I had no idea how to get old fluid out of the ABS circuits I was swayed more to Endless. Its in, done some events now after the flush without bleeding and the performance is great. I'd certainly recommend it.

Quinlan

You might want to double check on the Brembo rotors. I got a set of fronts earlier this year (I think they were 1200 or so from Dan at Vivid), and I am very happy with them - 10 DE days in white run group, very little wear and no spider webbing. However, I was looking into slotted rotors at the time, but I am sure that Brembo offers only cross-drilled, and not slotted, in the size that fits the 996tt and c4s. The ones listed on the Vivid site are 350mm, which would require an adapter kit, since the stocks are 330mm.

mdrums

Is Endless a DOT4 fluid and do they make pads for a 997S? Can't find much info on there limited website.

boss351

There is a fair amount of dicussion on Endless on the internet forums etc, including one here that has some info:

https://rennlist.com/forums/6654070-post60.html

They have a DOT4 product but the 650 is not 4 or 5.1, but it is 3 and 4 compatible.