Guys, has anyone out there done a brake pad change on the 991S yet? If so please advise on procedure and ease.

I just started tracking mine and i know i'll need to change the pads in no time -- would be great to be able to do it trackside as with the 997's.

As an aside, boy oh boy is this car epic on a track! For starters, i finally realized that PTV is just a fancy term for trail braking, meaning that the ECU now does it for you... perfectly. The result is you almost never miss an apex no matter how late the turn in. In the sweepers, the PDCC also makes itself most noticeable.

Overall, I was as fast in the 991S on Day 1 as I was in my track-modded 997T4S but only using 3/4 of the track width. I found myself not using the whole track because I am so used to the understeer in the 997 (at least the 4S) and haven't yet made the adjusment to unwind the wheel more slowly on tracking out. Also I am not yet comfortable pushing this car anywhere near it's limit -- familiarity, costs, no safety enhancements, etc).

On the downside, the car was worse than I thought it would be in the rain. I mean downright scary, to the point where I wouldn't track it even at modest speeds. I don't know if it has to do with the PDCC or what but the car was sliding even though I was very smooth. Luckily it was sunny for 3 of the 5 sessions .

Thx v much in advance for any brake pad swap advice.

 

Don't mean to derail the thread with this, but I am surprised about your comment. I also had a couple of sessions under the rain (at Road Atlanta) but the 991S did well (except for the frustration of getting passed by an Evo...)
http://www.flickr.com/photos/60293300@N06/7339798716/
Maybe it had to do with your tires. I am running Michelin PSS and they are doing OK on wet surfaces.

 

Most interesting.
SM_ATL, your car does not have PDCC right ?

This is not the first time I have come across comments like this and this was the reason I posted a somewhat inconclusive thread on the subject some time ago.
There has to be something going on here with PDCC - where there is smoke there is fire as they say.
No doubt tires come into play - but there might just be a tad more going on here. No, I have not got a clue but perhaps somebody with experience with the suspension can throw some light on this - does maintaining the relative angle and force of the tire thread surface to the road, which PDCC does great - somehow affect the tires ability to grip in the wet ? Does it perhaps plane easier that way ?
Would love to get some answers - this is, so far, the reason I have not added PDCC to my list of options and I'm quickly running out of time - my build should be locked soon. Friend of mine has a new 991 with PDCC and also is not exactly thrilled with the performance on a wet surface. Is it really the PDCC or something else altogether ?

Rainier

 

Guys, I don't want to overstate or draw conclusions from just 1 track day. For the record, the tires were the OEM Pirelli Zeros with just 1500 miles on them. on my 997 T4S I previously ran MPSS which is a better tire but not dramatically so in the wet.

It was raining very hard for the 2 sessions and the track had quite a bit of standing water. Most if not all the other 2WD cars came into the pits too. But certainly for the few laps I attempted, I was getting passed while I tried to keep it together.

Bottom line: I'm not ready to point the finger at PDCC just yet - it's just a slight hunch at this stage.

FYI, here is a video I shot at the same track (NJMP Thunderbolt) last year in my T4S as Hurricane Irene was coming to town. As you can see, the car was very planted:

https://www.youtube.com/watch?v=qa2th0sND-o

 

Since I am planning on ordering sometime soon I am interested in this conversation as the PDCC option is a ??? at this point.

I know that there is a difference between a wet and dry setup and my guess is that PDCC does not alter stiffness. My other question would be; does the PDCC change from front to back and side to side resistance based on what the car is doing in relation to turn of the wheel and load factors on the car?

I don't mind the nannies as long as I can choose when I want them and how much, however many of the modern electric gizmo's start to muck with the driver interaction with the car and ultimately the performance.

 

Yes, understood. But as mentioned, you are certainly not alone with the "hunch". Don't get me wrong please - PDCC may result in a change of chamber during cornering relative to the non PDCC car and that may just be a contributing factor. Something that may simply require a slightly different wheel alignment, different type of tyres, even perhaps just a different tyre pressure to bring out the advantages of PDCC in less than perfect conditions.
I'm just guessing - I'm an engineer and I suffer from "engineers desease" - if there is a problem that needs understanding I will lie awake at night trying to wrap my head around the problem. This is one of them.

My build is SPASM but without PDCC at this stage. I'm itching to add it at the last minute but everything I have read and heard so far points to leaving it off the list, considering use mainly as a DD with occasional track use for fun. The SPASM corners so flat anyway PDCC may perhaps not be that much of an advantage in this case.

Oh well, the joys of buying a toy... Better get back to work.

Rainier

 

not yet.. sorry!

 

Rainier -- I agree that you probably don't need both SPASM and PDCC. I chose PDCC because I believe SPASM may not have enough clearance for spirited street driving where both you and I live. (I've had the pleasure of driving from Capetown to Port Elizabeth). In the 997, I was always afraid of scraping the nose badly at that slowed me down. One of the joys of the 991 is that problem is almost completely gone, at least with the standard suspension. With what I've read, SPASM basically brings you close to GT3 clearance. It also stiffens the car which IMO is unnecessary if you can gain similar cornering performance with PDCC and still ride in comfort.

 

Ah ! Another 991 on S'effrican roads. Great ! (Excellent in fact).
Yes, I had the same concerns and started with just the PASM in my build originally. After having a closer look I realized that SPASM makes hardly a difference in ground clearance (relative to PASM) and is in fact quite comparable to the MX-5 I am driving (which has a slightly shorter wheelbase, I know).
Any scraping issues I have had on any of my cars are not due to ground clearance as such but rather soft springs as you go over obstacles perhaps a tad too fast. The stiffer springs actually help prevent this and the springs used with the SPASM are considerably stiffer. The only item that is in danger is the now extended front splitter so I'll have to take care with driveways etc.
The PDCC is not going to help the ground clearance in any way for normal driving - it just keeps the car level during spirited cornering which you are not likely to be doing on compromised surfaces.

The only thing PDCC will do, perhaps, is increase comfort as some have stated. I can't say - I have not had the opportunety to try a PDCC SPASM and non-PDCC SPASM in an otherwise identical car - that would be the only thing that would give a meaningfull answer.

I did drive a PDCC PASM - and that perhaps even beats my Merc in road isolation - it's very, very good - but perhaps not quite sports-car like (in the old-fashioned sense).

I'm pretty settled on the non-PDCC SPASM now, I'd like to bias the car on the sporty side and I think this is what it will be. Am I doing the right thing ? Time will tell...

Rainier

 

In last year's thorough test of the 911S with PDCC in the German magazine sport auto they found the OEM Pirelli tires to be almost as sticky in the dry as Michelin Pilot Cup tires. They also have the same downside: they need temperature to give good traction. Tires lose temperature in the wet thus the diminished traction despite the good tread pattern.

 

I left out PDCC from my build at the last minute bcos I want to reduce the electronic interfaces bewteen me and the road. I may be wrong but wanted to keep it simple as possible. I drove the 991s at Barber and man what addifference from the 997s. It feels so planted and so easy to drive....like KonaKai said you end up not using the entire width of the track bcos the car just stters so well at high-speed.

 

Funny nobody talked about the OP question on brake pad installation. I'd imagine its just like any other car. Be sure to bleed them.

 

Thanks. I spoke to the Porsche tech and he said the caliper must be removed (like the 997.2), but the brake line need not be disconnected (so technically you don't need to flush it every time). I still haven't tried it yet but if anyone out there has, please speak up!

It's a bit frustrating because the 991's and 997's are highly trackworthy and durable in almost all respects but whenever I do a track day (with stock pads), a bit of me fears burning through them early in the day or the middle of an event and getting stuck...

 

Bump.

Anyone have experience with changing pad compounds and fluid for track use?

If so, what are your thoughts and suggestions?

 

Bump. Maybe thigos or Konakai has to lead the way for DIY brake pad chane.