Macca

Yes. Would be worth investigating.

The 964 C4 is (surprisingly) 100 Kg heavier than the C2 (that must be worth 2 seconds at HD?) and probably uses a different brake bias (unique to C4 as with ABS ECU etc) so this would be a good place to start. Check Rennlist for other C4 owners regularly tracking their cars. Most may have lightened the car so look for posts by those who have a street stock car and maybe PM them with a few questions.

You can certainly upgrade the front brakes (to large calipers & discs) but I would look to see if quality slotted or cold cast "holed" front discs are available in your size as a first (and cheaper) stop. I assume its your fronts that are warping. My advise is buy a replacement set of slotted or holed front discs AND improve ventilation to the discs via a brake cooling kit. No point in putting the kit in to find the next set of rotors do it again (they arent cheap).

Remember you are driving a 4WD 1475kg car on R compound tyres and you are getting better and better at this so you are holding more speed, braking later and really working the car. This will always shake out the weakest link. Doing 1.22 in your car is like doing 1.20 in a C2 so you are starting to move the game on and need to fortify components of wear for reliability and durability.

Look on the AP site for front discs that are slotted/holed. Im sure they are there in standard sizes as direct bolt on's. I doubt you will find such in NZ. In 2007 when I was at the ring ALL the 964 track style cars were running drilled fronts. Many were Big Red 993 upgrades but some were not.

John. Excellent photos (as always). I think in the meantime you have become RSC's official photographer!

Macca

PS. Spinning a 4WD 911 in the rain must take some doing LOL!

PPS. If you still have meat on those OEM rotors you must be getting some serious heat into the discs. may be worth having CCS check a few other things to make sure everything is working properly. ANS sensor, valve etc

John McM

Everyone was better after the spins, but you can still see the weight transfer that caused it.

Macca

I remember that corner. Are you shifting to 3rd on the apex or carrying second through the corner?

gt38088

fair enough macca
Peter, there can be some other issues that cause brake judder too, I would take them off the car run them up to make sure they are actually hot spotted and out of true. If they are then fair enough go for cooling solutions. Ducting is best but aimed at the centre of the rotor so that the cooling occurs by air being sucked up and out the internal vanes as the rotor spins. That way both sides of the rotor are equally cooled.

You might have true rotors but pad material build up on rotors causing the judder. Usually its caused by high performance pads running too cool during road driving and some of the material that would normally be burnt off on track (hot rotors) building up. You might be able to see it some discolouration.
I have had this problem on Targa. The crew hand sanded the front rotors overnight and fixed it. Comes back though if it is the problem. So then you need to think about different pad material and blocking off cooling/ducting during touring.

peterC2S

Thanks for that. What I've read so far, plus the discussions with Steve and PB:

- Almost certain that its pad material transfer. I'm using OEM pads because its a daily driver. I should be changing them out for trackdays so that sounds like a future plan.
- I will try hand sanding the rotors with garnet paper. Sounds laborious, esp getting around the rear side. If that doesn't help then probably have to get them skimmed on the car. i've read that bad build up sometimes won't skim off so we'll see.
- Macca's right re observation of it being a heavy car, getting more confident so carrying more speed and braking later - it all adds up. Unfortunately reinforces that a C4 is not an ideal track car unless its been significantly lightened and even then, still a compromise. But its still a lot of fun
- And JMac is most definitely voted RSC team photographer!

peterC2S

3rd all the way from turn 1, through 2 and up over the rise at 3.

Have tried shifting to 2nd for turn 2 but then need to shift to 3rd right on the apex of 3 and always feels clumsy and unsettles the car. Find carrying 3rd means less speed through 2 but much cleaner and better speed/balance through 3.

Macca

Peter, Makes sense. I tried that but found the C2 needed plenty of traction in turn 2 to really catapult out so learnt from Paul that changing into 3rd precisely on the apex of 3 whilst the chassis is momentarily neutral/flat just before loading again coming on the power. I was wringing it out through 2 and 3 apex in second gear and just running to the limiter as you catapult by centrifuge to the edge before setting up 4. Problem is changing to third on the centrifuge in my car doesn't work well right now (probably a shifter bush) and I did notice it wasn't a smooth move under power.

I dont know if that makes any sense but its really interesting to compare notes. Im guessing being a 6 speed Im between your your gears. Also with 4WD I suspect you dont need to "drive" around front wheels quite as much and you probably get the torque down quicker with 4WD so can carry a slightly giver gear through turn 2...

Macca

...goes to show there are a number of ways to drive that track dependent on favorite line and maybe the more power you have the more you can experiment. Wider band to try things without loosing significant time. Watching that "commited" silver 997.2 GT3 driver absoulutely hose me coming out of the sweeper while I was accelerating onto the front straight I quickly realized that hes driving any line he wants and can get away with it. Power and brakes help....

Kiwi Carguy

I agree with the comments around bake pads. I used to always run Pagids on the track but they were noisy on the road and you run into problems mentioned here already.

Best to have pads for the track and ones for the road.... or buy a race car

Maxem

I was on tirerack and specced up a set, only to get this back from them upon a shipping quote; "Yes we do ship Internationally. Unfortunately due to our dealer agreement we are not allowed to ship OZ wheels outside of the US".
A bit contradictory. I imagine NZ sourced OZ wheels would be a rip off.

Macca

Yes. Peter tried ordering these and had the same issue. I didn't go any further as I was still trying to figure out a US address work around. I use Myus.com as a freight forwarding point for most of my US purchases but I suspect the freight on these might be high (they use dhl).

If you find a work around let me know....

PS. to the best of my knowledge no one stocks OZ wheels in Porsche PCD (5 stud 130) fittings in NZ. But I only looked on the interweb so could be mistaken...

964X33

There are a few middle man US post box options. Have a search through this thread from maybe a couple of months ago. You have to pay a fee but it is apparently not exorbitant.

peterC2S

I think I found them on the Vivid website (NZ) section - so worth at least asking the question. Be interesting if they would ship them direct. Design911 is an option as well.

Kiwi Carguy

In regards to the Oz wheels I have a friend that works for the importer. If someone can post up the exact model/specs etc I'll let you know if he is able to do a deal.

To give you an example I got my full set of Nitto's for around $800 so considering my last set of tyres was $1800 he was able to do a good price.