O2GO

Me too. Chasing is good. May need to toss a coin to decide who goes first, ha ha.

964X33

Thanks all, for the brake info. Like most questions on these cars, you aspire for the best solution, but there really isn't one. DBA don't seem to do 3.3 Turbo discs. Will probably stick with Dr Porsche; prob a safe bet.

O2GO

Targa and Targa Tour starts Friday morning next week. Day 1 starts at Bombay and we end up overnighting in Whitianga. Day two takes us to Rotorua for our overnight there then day three is in the Rotorua area. Normally a two day event it is now three.

Got got my Boxster serviced with fresh oil, filter, fluids checked and a brake health check at CCS today. Last year's "incident" with my front pads and rotors at Mansfield caught up with me.... New front rotors as the cracking was looking too dodgy for this kind of event in their opinion. Faced with having to make a quick decision they got replaced with new Porsche rotors. Ouch.

The brakes now feel soft which I assume is a result of them needing to bed in. Running with Porsche OEM pads. May need a practice session in preparation this weekend to get some heat and use into them.

More of you fellas should be doing Targa Tour. Several regulars have pretty much said "best fun driving ever" :-)

Starting to get pretty excited.

John McM

No need, I'll fluff around with the GoPro until you've lined up

John McM

I'll be interested to hear the download after you've done it. Especially whether a 964 would work. Just reading the above list confirms my desire to have just one car doing Motorsports.

gt38088

Matt - that's a pretty decent run out of those discs. Can't expect any more than that and they are still going ok so that's great. More cooling as Macca suggests definitely will reduce pad wear which is good for a pure race car but for a DD the cooling means that the temps are way low and depending on pad specs you will get much more screech and squeal which becomes tiresome in town

gt38088

John - just one car doing motorsport is a good idea. I am not good at following this advice ....

Ridgeline911

Got car back today, raised 50mm. Aligned and corner weighted for 2 people. Installed monit tonight.
Got Shakedown for all Targa entrants at HD tomorrow.
Oh, New turbo tie rods, the old ones were sloppy. new Discs all round (porsche OEM) new wheel bearings, new pads.

Still to get skid plates, for fuel tank and engine.
Pretty excited for first Targa.

Macca

You guys are going to have the best time. Jealous!!

Doug factory pads more than fine for this type of event. It's not hard on brakes like track. Plenty of time for them to cool down between applications...

Maxem

Chartreuse green. The non obvious alternative to Viper green. (This page needed some colour).

gt38088

Nice colour suits the older cars- 70s?
For the touring guys there is lots of time for cool down as after the stage you just keep driving.
for the race guys there can be a car or more in front at the timing booth which causes heat soak 200metres after the end of stage which is no good for rotors.

996tnz

Yes, it is unusual (and pad transfer, the most common cause of juddering, is obviously why we don't use the handbrake after coming off track), but it can happen and I have seen an early 90s Mitsi Galant company car after a Coromandel run with visually warped front rotors. Rotors for our Porsche cars are a lot stronger though so yes, I can see them cracking instead.

Thanks for your pic - a real eye opener on how much slotteds can still do that - so I hunted into it a bit:

Those considering a PhD in braking can find more info here: http://scialert.net/fulltext/?doi=jas.2008.3583.3592, but the interesting bit said:

"Disc brakes are exposed to large thermal stresses during routine braking and extraordinary thermal stresses during hard braking. High-g decelerations typical of passenger vehicles are known to generate temperatures as high as 900°C in a fraction of a second. These large temperature excursions have two possible outcomes: thermal shock that generates surface cracks and/or large amounts of plastic deformation in the brake rotor. In the absence of thermal shock, a relatively small number of high-g braking cycles are found to generate macroscopic cracks running through the rotor thickness and along the radius of the disc brake (Mackin et al., 2002). "

High-G braking is what we do so even careful cool downs (and warm-ups?) would only help so much then, though I'm sure Porsche rotors are better designed for high-G hammering than most. Plastic deformation includes the warping that poor Mitsi suffered instead of course.

While my rotor condition may eventually be headed your way , I'm still pleased with the Sebros. No cracks yet (just checked ) and others like '996twins' report that they're getting almost twice the track miles out of theirs (on the same pads) than they did from their OEM drilleds. That at about $1250 or so per set of 4 landed from the States (they were USD 735 + some combined shipping). There are nicer, but pricier picks out there too of course, as pointed out by Macca for instance.

Macca

Graeme heres Chartreuse green on a PTS order 4.0RS. It actually looks better than this on a bright day so this photos isnt the best.

Walter and others. We all subscribe to the no handbrake after a hot track session theory. Do the rear callipers get activated by the handbrake?

This doesnt make sense to me so someone please help me understand. The rear parking brake calipers are of the drum brake liner variety located within the hub of the rear wheels and activated by springs and a cable.

The caliper is operated by hydraulic pressure via the brake pedal using fluid.

Am I missing something here. Are we just trying to save our parking brake linings or are we really worried about pad transfer to disc?

Macca

4.0RS

996tnz

You're right Macca. Made the mistake of applying general track thinking and should be swatting up more on my car. Just confirmed your point that the parking brake (on the 996 at least) acts on the inside of the drum shaped base of the rotors, rather than operating on the area swept by the calipers so wouldn't cause juddering in our cars. The only technical reason left for us to avoid using it when the brakes are really hot is, like you said, potential heat cracking of the friction surface on the parking brake shoes.

Personally though, I'll still foster the habit of avoiding it's use at track anyway, if only to save a mistake in some other car down the line where the calipers are employed.

While we have some keen technical minds watching the board, here's another poser:

A while back I tried to check whether its safe to do repeated handbrake turns in AWD 996s like my Turbo and drew a blank. Wasn't thinking so much about the physical handbrake mechanism but more about the viscous front transfer box handling the fronts rolling on with the rears stopped. Finally just tried it at an Ardmore motorkhana and it worked fine with nothing going bang (won a cap for my efforts). Looking at the handbrake setup now, that end looks fine but does anyone have better info about how much of that action the front diff can handle? Anyone know if it is an asymmetric coupling that just slips happily when the fronts go faster than the rears as opposed to trying to throw torque backwards for instance? As I said, it felt fine doing the turns, but would still like to know for next time.