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Re: transfer layer onto the disc, I had planned on doing a couple hundred miles of street driving with the PF pads in there before going to the track. I've done this in the past and it has worked well. I just wasn't sure why else machining would be recommended. if this is the only reason then I will pass.
As for the pagids heat cycling out, I guess what I meant was they are no longer stopping the car well. Particularly since they've worn down past 50%. I'd say there is currently 4 or 5mm of friction material remaining. This was my main reason for switching the PF as I understand they work the same down to the backing plates.
I guess I really need to get a measurement on the rotor thickness remaining. What is acceptable measurement within the minimum thickness? i.e. when do you change? Money is not "no object to me" and given the expense of the rotor I don't want to be changing them out before they're done. On the flip side, I'm sensible enough to realise brakes are there for a reason.
This is how the front rotor looks today (mid way through a track day). Slots are still there but starting to become quite shallow.
You cannot turn or machine floating 2 piece rotors because the machining will be uneven as the discs float.
The only other option is manually cleaning the old pad material off the disc using a fine sandpaper or scotchbrite. But generally PFC pads are more abrasive so it should take the old Pagid material off without any fuss.
Those discs do look a little worn but the other thing I notice too is that the pad material seems to be overheating and filling the slots. That's not normal and seen only at high temps. Also machining a disc which is heavily worn takes away even more "material" out of the disc, which is not good for the discs life or performance.
We replace rotors when there are large cracks to the inner or outer diameter of the disc on the race cars.
You cannot turn or machine floating 2 piece rotors because the machining will be uneven as the discs float.
The only other option is manually cleaning the old pad material off the disc using a fine sandpaper or scotchbrite. But generally PFC pads are more abrasive so it should take the old Pagid material off without any fuss.
Those discs do look a little worn but the other thing I notice too is that the pad material seems to be overheating and filling the slots. That's not normal and seen only at high temps. Also machining a disc which is heavily worn takes away even more "material" out of the disc, which is not good for the discs life or performance.
We replace rotors when there are large cracks to the inner or outer diameter of the disc on the race cars.
Thanks for that, I didn't even consider the two piece factor! The filling of the slots you mention, I thought that was more down to the disc getting so thin that the slots were wearing away. The track I was at yesterday is incredibly hard on brakes - a short 1.8 mile lap with three consecutive hard stops from 90 mph, 130 mph and 120 mph. That's why I can't really afford to cheap out on friction materials.
Thanks for that, I didn't even consider the two piece factor! The filling of the slots you mention, I thought that was more down to the disc getting so thin that the slots were wearing away. The track I was at yesterday is incredibly hard on brakes - a short 1.8 mile lap with three consecutive hard stops from 90 mph, 130 mph and 120 mph. That's why I can't really afford to cheap out on friction materials.
I recommend trying the Race Technologies pads we run on our cup cars and some of the australian porsche programs which we support. Not cheap but honestly these are the best we have tried so far for heavy duty use.
We work very closely with Brembo and Race Technologies (Brembo distributor) here in the US for fast support also.
Feel free to PM me for more information when ready.
The GT3 does have brake cooling, but more can be done. The Porsche Parts list is rather lengthy and $$$.
The 996 Cup car front deflectors are a good place to start, the 997 GT3 RS rear has some good bits that will work. I can get you part #'s if you need them
I run the PF 2 piece rotors & pads in the front - they are well matched, and not certain on this, but IIRC they are also cheaper. I am partial to PF and have used them exclusively for ~ 12 years now for the track, and the always seem to work, and this is with temps where they had no good reason to work!
WRT DBA - back in my STi days, their products were not the best (IMNSHO), but if they are 30% of the Brembo's then they could be an option...
I recommend trying the Race Technologies pads we run on our cup cars and some of the australian porsche programs which we support. Not cheap but honestly these are the best we have tried so far for heavy duty use.
We work very closely with Brembo and Race Technologies (Brembo distributor) here in the US for fast support also.
Feel free to PM me for more information when ready.
I have a new set of PF pads here that I need to get through but I will keep my ear to the ground with the Race Tech stuff and consider it when my next pad change comes up
Originally Posted by rbahr
The GT3 does have brake cooling, but more can be done. The Porsche Parts list is rather lengthy and $$$.
The 996 Cup car front deflectors are a good place to start, the 997 GT3 RS rear has some good bits that will work. I can get you part #'s if you need them
I run the PF 2 piece rotors & pads in the front - they are well matched, and not certain on this, but IIRC they are also cheaper. I am partial to PF and have used them exclusively for ~ 12 years now for the track, and the always seem to work, and this is with temps where they had no good reason to work!
WRT DBA - back in my STi days, their products were not the best (IMNSHO), but if they are 30% of the Brembo's then they could be an option...
Try to get more cooling air into the brakes
Good luck
Ray
Im running the 996 cup ducts up front and GT2 ducts at the back but have only recently put them on the car so cant comment on their effectiveness at this stage. These are the best "bolt on" ducting available for the 996 AFAIK, I know there is the option of running a 997 undertray to get NACA ducts to the rear also but its not exactly bolt on from what i've read.
I was keen to try PF rotors too as ive had them on other cars but stock is an issue here in Aus so not many resellers want to deal with them. Unfortunate as I have had them on other cars in the past and been happy. I'm fairly pleased with the brembos and will try them from new to see how long they last. If they disappoint I will have to look elsewhere for sure. I havent priced the DBAs but Id imagine they'd be about 60% of the cost of the brembos. You guys probably get them cheaper over there than we can here!
I was keen to try PF rotors too as ive had them on other cars but stock is an issue here in Aus so not many resellers want to deal with them. Unfortunate as I have had them on other cars in the past and been happy. I'm fairly pleased with the brembos and will try them from new to see how long they last. If they disappoint I will have to look elsewhere for sure. I havent priced the DBAs but Id imagine they'd be about 60% of the cost of the brembos. You guys probably get them cheaper over there than we can here!
I can get you contact details for the local distributor if you like. He got me a couple of sets 4 years ago for my 997 when they were not readily available here... Just PM me if you need details...
Ray, would be interesting to see the NACA duct setup. Did you change the under tray to the 997 version?
I run the rear 997 under tray with the NACA ducts, the 997 thrust arm air guides (those direct the air from the NACA ducts to the rear calipers), and the 997.2GT2RS rear LCA air ducts. The 997 tray is a direct bolt on in there center but the attachments points are different on the ends. I just cut off the ends off both the 997 and 996 tray and riveted the 996 ends onto the 997 tray. Looks and works like OEM. You will also need to trim the brake rotor heat shield to use the 997LCA air ducts.
I took a slightly different approach from powderhound. A little background 1st:
In the rear there are really 2 sources of air. On arrives by way of the NACA ducts and some plastic parts that mount on the rear diagonal arm and look like smaller versions of the front parts.
You can sorta see them here:
These are useless without the NACA ducts (they aren't really in any air stream) and these:
which take the air from the naca ducts and direct it to the curved plastic parts.
Then there are these:
Which move air into the bottom of the rotor. These attach to the LCA using the plastic parts you see - at least in mot cases. I have the rear cup car LCA (really really want the RSR parts)
Now the rear panel that is important:
If you are a bit lazy like me, all you really need to do is trim this around the edges. You can see where I cut things close to my feet.
Result is this:
This last shot is a metal screw I installed into the diagonal brace to hold the tray down.
Other than that the 3 original screws will fit well
10-04-2015, 08:13 PM
