On track experiences and video's 991 GT3 only.
09-05-2014, 06:21 PM
#316
We had a good look today and running a 20” 265 up front might be risky. There isn’t much clearance even with the 245. I plan to get a set of 19” wheels to run Hoosiers but I have 2 more full sets of Cup2’s to burn through before I make that investment. I’m definitely going for more negative camber in a week or 2 though.
We confirmed the knocking was my front Sway. This started after we moved the setting one softer. It seems to have been loosening because the nut was on a painted part (see pic below). We cleared that paint today and used Loctite (or something like that) so hopefully no more loosening.
I just installed FVD steel brake lines & RBF600 Fluid today and Pagid Yellows are going on in the morning, then I’m off to Mosport.
Will report back!
09-06-2014, 10:07 PM
#317
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That is one of the peculiar joys of driving street cars on the track: a/c for 100 degree days ... : )
As for the throttle vs understeer, that's the nature of the 911 -- there's just never going to be enough weight on the front with a neutral or balanced throttle for any given steering angle if the objective is to rotate the car, so you have to get the weight fully on the nose under brakes to turn in, then transferred to the rear under power once the car rotates enough to peg the apex. You might also be running just a hair too much negative camber up front just eyeballing the car the other week at Laguna -- the maximum 2.7-2.8 might be more than the Sport Cup 2's want (might be ideal or even not enough for the Hoosiers) but heavier straight line braking to get weight on the fronts, then turn in at higher speeds ... at least that's the way I was taught at the Porsche school (PSDS) which also means better brake cooling at higher road speed, less "ask" of the fronts to both slow and turn the car at the same time, greater distance for the traction of the fronts to achieve the rotation, more momentum in the rear to carry the rotation and feed in power to "feel" out the rear traction and throttle steer the nose till it kisses the apex with (in the hands of the pro's) inch-by-inch precision.
Or so the story goes. : )
Did you get tire temps? I'm guessing even if you were managing the fronts down to say 32psi (I was finding 32 "good" from my notes taken hot in the pi
uts, but 32-36 is the optimal range, though I found 36, reading off the TPMS, was a "little vague" in the fronts and "greasy?" in the rears) the tire temps may still be screaming for mercy up around 220 deg F at the very upper or even beyond the upper limits of the Sport Cups window.
As for the throttle vs understeer, that's the nature of the 911 -- there's just never going to be enough weight on the front with a neutral or balanced throttle for any given steering angle if the objective is to rotate the car, so you have to get the weight fully on the nose under brakes to turn in, then transferred to the rear under power once the car rotates enough to peg the apex. You might also be running just a hair too much negative camber up front just eyeballing the car the other week at Laguna -- the maximum 2.7-2.8 might be more than the Sport Cup 2's want (might be ideal or even not enough for the Hoosiers) but heavier straight line braking to get weight on the fronts, then turn in at higher speeds ... at least that's the way I was taught at the Porsche school (PSDS) which also means better brake cooling at higher road speed, less "ask" of the fronts to both slow and turn the car at the same time, greater distance for the traction of the fronts to achieve the rotation, more momentum in the rear to carry the rotation and feed in power to "feel" out the rear traction and throttle steer the nose till it kisses the apex with (in the hands of the pro's) inch-by-inch precision.
Or so the story goes. : )
Did you get tire temps? I'm guessing even if you were managing the fronts down to say 32psi (I was finding 32 "good" from my notes taken hot in the pi
uts, but 32-36 is the optimal range, though I found 36, reading off the TPMS, was a "little vague" in the fronts and "greasy?" in the rears) the tire temps may still be screaming for mercy up around 220 deg F at the very upper or even beyond the upper limits of the Sport Cups window.
I took tire temperatures and found them to be at the middle of range Michelin publishes. Did you actually experience the 220ish temps you mention in your post? That's very hot.
09-06-2014, 10:15 PM
#318
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Did my 4th trackday on Friday. The car continues to impress. I think the rear tires still have 3 days left, and very even wear (which is surprising because I’ve been intentionally sliding the car and pushing it hard). Front Left is toast, 1 more day on FR. Understeer became progressively worse each session Friday as the FL tire eroded. This was a tight course though, only had understeer issues in a few tight ones. The car is absolutely brilliant in fast sweepers and also making directional adjustments at high speed. I think that’s where RWS is really shining. The GT3 lap times (with just an alignment) were on par with well-driven and set-up Scud & C6 Z07 (both on Hoosier R6). Pad/Rotor life looking good. Getting ABS under hard braking (even with all systems OFF) and pedal feel could be firmer. I will do lines & fluid soon (hopefully this week) and I’ll definitely go with a more aggressive pad once the stocks are closer to done.
I finally tried Auto mode on track. For me, the only benefit was not having to watch the Tach to nail a 9k upshift on straightaways but it reduced the fun/control factor significantly and I didn’t always like where it downshifted. After 3 laps I went back to manual and I doubt I’ll repeat that experiment.
Has anyone tried a 265/35 Cup2 up front? If it fits, this may help fight understeer in the tight stuff.
Anyone having knocking sounds from the front suspension? After my 3rd trackday I had some knocking so my shop looked everything over, found everything to look ok, but they gave everything a slight tighten. Knock disappeared. Then I did trackday #4, everything was fine (even for the 250km round trip to/from the track) but the next day (yesterday) the knock returned on my way to the detailer. Just sounds like something is loose, very noticeable knocking around when on uneven road surfaces, entering driveways, etc. Something seems to be loosening after hard use. Will have it checked out again this week.
I’m doing Saturday & Sunday @ Mosport GP Track (CTMP) next weekend, a much faster track than what I’ve been hitting on my 1st 4 outings so REALLY looking forward to it.
Here is an exhaust clip from Friday (old GoPro Hero1, no external mic). Just got a new GoPro 3+ Black Edition that will be running next weekend.
I finally tried Auto mode on track. For me, the only benefit was not having to watch the Tach to nail a 9k upshift on straightaways but it reduced the fun/control factor significantly and I didn’t always like where it downshifted. After 3 laps I went back to manual and I doubt I’ll repeat that experiment.
Has anyone tried a 265/35 Cup2 up front? If it fits, this may help fight understeer in the tight stuff.
Anyone having knocking sounds from the front suspension? After my 3rd trackday I had some knocking so my shop looked everything over, found everything to look ok, but they gave everything a slight tighten. Knock disappeared. Then I did trackday #4, everything was fine (even for the 250km round trip to/from the track) but the next day (yesterday) the knock returned on my way to the detailer. Just sounds like something is loose, very noticeable knocking around when on uneven road surfaces, entering driveways, etc. Something seems to be loosening after hard use. Will have it checked out again this week.
I’m doing Saturday & Sunday @ Mosport GP Track (CTMP) next weekend, a much faster track than what I’ve been hitting on my 1st 4 outings so REALLY looking forward to it.
Here is an exhaust clip from Friday (old GoPro Hero1, no external mic). Just got a new GoPro 3+ Black Edition that will be running next weekend.
09-07-2014, 07:55 PM
#319
Went to Texas World Speedway this weekend with a DE (Driver's Edge) and Jason Hart was there as well (hanging with his wife and some friends). My very first time to TWS and by golly, I wish I went there before, lovely track. Car was incredibly well balanced. I kept the rear sway bar at the firmest setting but tightened the front a notch (now in the middle). With that, there was no high speed over steer, thank goodness as this is a fast track. Predictable understeer in one corner only (I think turn 2) but otherwise, the car was awesome. I messed up turn one yesterday (scary turn, as those who know the track are aware) and went straight into the greens, loosing the splitter (again). Went to retrieve it later but it was in two pieces. Still good enough to clip back on.
Today, with much needed discipline, did much better. My best time was 1:56:xx, and there is more on the table for later. Jason Hart's time, with me in the car, an astounding 1:51:xx He was pleasantly shocked at how phenomenal this car is.
Can those who know this track comment on the 1:51:xx time (with a 240lb passenger)?
On a side topic, heard rumors today that another track may get built neer TWS, which closes next May.
Today, with much needed discipline, did much better. My best time was 1:56:xx, and there is more on the table for later. Jason Hart's time, with me in the car, an astounding 1:51:xx He was pleasantly shocked at how phenomenal this car is.
Can those who know this track comment on the 1:51:xx time (with a 240lb passenger)?
On a side topic, heard rumors today that another track may get built neer TWS, which closes next May.
09-07-2014, 09:54 PM
#320
Went to Texas World Speedway this weekend with a DE (Driver's Edge) and Jason Hart was there as well (hanging with his wife and some friends). My very first time to TWS and by golly, I wish I went there before, lovely track. Car was incredibly well balanced. I kept the rear sway bar at the firmest setting but tightened the front a notch (now in the middle). With that, there was no high speed over steer, thank goodness as this is a fast track. Predictable understeer in one corner only (I think turn 2) but otherwise, the car was awesome. I messed up turn one yesterday (scary turn, as those who know the track are aware) and went straight into the greens, loosing the splitter (again). Went to retrieve it later but it was in two pieces. Still good enough to clip back on.
Today, with much needed discipline, did much better. My best time was 1:56:xx, and there is more on the table for later. Jason Hart's time, with me in the car, an astounding 1:51:xx He was pleasantly shocked at how phenomenal this car is.
Can those who know this track comment on the 1:51:xx time (with a 240lb passenger)?
On a side topic, heard rumors today that another track may get built neer TWS, which closes next May.
Today, with much needed discipline, did much better. My best time was 1:56:xx, and there is more on the table for later. Jason Hart's time, with me in the car, an astounding 1:51:xx He was pleasantly shocked at how phenomenal this car is.
Can those who know this track comment on the 1:51:xx time (with a 240lb passenger)?
On a side topic, heard rumors today that another track may get built neer TWS, which closes next May.
I just got back from 2 days @ Mosport. Car was brilliant. No understeer at all at this track (as Dan39 found as well). The car is extremely well-suited to a fast track like Mosport. Brake upgrades & fresh tires worked really well.
Only issue was I had a bit too much castor for the loads at this track so my FR tire started eating through the wheel liner and I had to cut today short.
Aside from that, most fun I’ve had in the car to date.
09-07-2014, 10:11 PM
#321
Nice! I’m taking my car to COTA Nov 15/16 – you should see if you can get in (Chin Motorsports event).
I just got back from 2 days @ Mosport. Car was brilliant. No understeer at all at this track (as Dan39 found as well). The car is extremely well-suited to a fast track like Mosport. Brake upgrades & fresh tires worked really well.
Only issue was I had a bit too much castor for the loads at this track so my FR tire started eating through the wheel liner and I had to cut today short.
Aside from that, most fun I’ve had in the car to date.
I just got back from 2 days @ Mosport. Car was brilliant. No understeer at all at this track (as Dan39 found as well). The car is extremely well-suited to a fast track like Mosport. Brake upgrades & fresh tires worked really well.
Only issue was I had a bit too much castor for the loads at this track so my FR tire started eating through the wheel liner and I had to cut today short.
Aside from that, most fun I’ve had in the car to date.
Don't get me wrong, the car is extremely well balanced and the understeer was mild, predictable and in one turn only (2).
I think Dan39 may have his sway bars set different than mine as he experienced high speed over steer and I didn't. Interested in his input.
Yes, most wonderful car.
09-08-2014, 08:52 AM
#322
Went to Texas World Speedway this weekend with a DE (Driver's Edge) and Jason Hart was there as well (hanging with his wife and some friends). My very first time to TWS and by golly, I wish I went there before, lovely track. Car was incredibly well balanced. I kept the rear sway bar at the firmest setting but tightened the front a notch (now in the middle). With that, there was no high speed over steer, thank goodness as this is a fast track. Predictable understeer in one corner only (I think turn 2) but otherwise, the car was awesome. I messed up turn one yesterday (scary turn, as those who know the track are aware) and went straight into the greens, loosing the splitter (again). Went to retrieve it later but it was in two pieces. Still good enough to clip back on.
Today, with much needed discipline, did much better. My best time was 1:56:xx, and there is more on the table for later. Jason Hart's time, with me in the car, an astounding 1:51:xx He was pleasantly shocked at how phenomenal this car is.
Can those who know this track comment on the 1:51:xx time (with a 240lb passenger)?
On a side topic, heard rumors today that another track may get built neer TWS, which closes next May.
Today, with much needed discipline, did much better. My best time was 1:56:xx, and there is more on the table for later. Jason Hart's time, with me in the car, an astounding 1:51:xx He was pleasantly shocked at how phenomenal this car is.
Can those who know this track comment on the 1:51:xx time (with a 240lb passenger)?
On a side topic, heard rumors today that another track may get built neer TWS, which closes next May.
I sure hope the new track concept outside Brenham comes true, It sounds really great- 3+ miles 18 turns, elevation change, etc.
09-08-2014, 09:39 AM
#323
Hi Sam, I was there and stopped by briefly early Sat am to see your car and say hi. It looked and sounded great! I was in the yellow group in a 986 running 2min ++. Met a driver there few months ago in a 997.2 RS and he was runing low 1:50s and goal to get below 1:50. Not sure if he did, Think he was on Hoosiers. Anyway 1:51 is fast. Also know a guy with an MP4 and he runs mid 1:50s. For first time at that track 1:56 is impressive. There is a thread over on Trackjunkies.org where drivers list there best times at TWS and other tx tracks.
I sure hope the new track concept outside Brenham comes true, It sounds really great- 3+ miles 18 turns, elevation change, etc.
I sure hope the new track concept outside Brenham comes true, It sounds really great- 3+ miles 18 turns, elevation change, etc.
09-22-2014, 02:50 PM
#324
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Few more updates from track. Did Sonoma. Disappointing performance from the driver. Only got to very low 1.51s. I have a valid excuse - I had a big off right in the beginning at over 90MPH in turn 1, barely short of the wall. After that I was taking it very easy, especially in T1, and focusing on the line rather than lap times. I also tried focusing on one section at a time, which I found a good way for me to learn a new track - do one turn or sequence of turns at top of my ability and relax for the rest of the lap focusing on line, vision etc there. It had some dividends - I think I have good grip of all turns except T1 and the carousel, which are still weak.
Adding all those laps together best theoretical lap was 1.47.4 (still lifting through most T1 and part of carousel), which demonstrates that the car is capable of at least 1:45s or even better.
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
4. When I turn off the fan before going out to the track, and then turn off the engine, the fan and AC would turn on when the engine is started again, even if AC Off button was pressed before the fan was turned off. I ended up doing some sessions with AC on inadvertently because of that.
5. Brake pedal travel increases after a session, and does not come back to normal between sessions, but comes back to normal after some street driving. I'll see if that persists after pad and fluid change. I did not feel any brake fade and was diligent with cool down laps.
Adding all those laps together best theoretical lap was 1.47.4 (still lifting through most T1 and part of carousel), which demonstrates that the car is capable of at least 1:45s or even better.
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
4. When I turn off the fan before going out to the track, and then turn off the engine, the fan and AC would turn on when the engine is started again, even if AC Off button was pressed before the fan was turned off. I ended up doing some sessions with AC on inadvertently because of that.
5. Brake pedal travel increases after a session, and does not come back to normal between sessions, but comes back to normal after some street driving. I'll see if that persists after pad and fluid change. I did not feel any brake fade and was diligent with cool down laps.
Last edited by MaxLTV; 09-22-2014 at 03:24 PM.
09-22-2014, 03:02 PM
#325
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^ Regarding the oversteer, I'd try equal F and R hot pressures and work from there.
For the brake pedal softening, try using Castrol SRF. If you're already doing that, look into better brake cooling ducts.
For the brake pedal softening, try using Castrol SRF. If you're already doing that, look into better brake cooling ducts.
09-22-2014, 03:23 PM
#326
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To clarify, the pedal was not soft. It just had some travel without resistance, but was hard/normal once resistance point reached. So it did not feel like boiled fluid.
09-22-2014, 04:12 PM
#327
Few more updates from track. Did Sonoma. Disappointing performance from the driver. Only got to very low 1.51s. I have a valid excuse - I had a big off right in the beginning at over 90MPH in turn 1, barely short of the wall. After that I was taking it very easy, especially in T1, and focusing on the line rather than lap times. I also tried focusing on one section at a time, which I found a good way for me to learn a new track - do one turn or sequence of turns at top of my ability and relax for the rest of the lap focusing on line, vision etc there. It had some dividends - I think I have good grip of all turns except T1 and the carousel, which are still weak.
Adding all those laps together best theoretical lap was 1.47.4 (still lifting through most T1 and part of carousel), which demonstrates that the car is capable of at least 1:45s or even better.
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
4. When I turn off the fan before going out to the track, and then turn off the engine, the fan and AC would turn on when the engine is started again, even if AC Off button was pressed before the fan was turned off. I ended up doing some sessions with AC on inadvertently because of that.
5. Brake pedal travel increases after a session, and does not come back to normal between sessions, but comes back to normal after some street driving. I'll see if that persists after pad and fluid change. I did not feel any brake fade and was diligent with cool down laps.
Adding all those laps together best theoretical lap was 1.47.4 (still lifting through most T1 and part of carousel), which demonstrates that the car is capable of at least 1:45s or even better.
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
4. When I turn off the fan before going out to the track, and then turn off the engine, the fan and AC would turn on when the engine is started again, even if AC Off button was pressed before the fan was turned off. I ended up doing some sessions with AC on inadvertently because of that.
5. Brake pedal travel increases after a session, and does not come back to normal between sessions, but comes back to normal after some street driving. I'll see if that persists after pad and fluid change. I did not feel any brake fade and was diligent with cool down laps.
09-22-2014, 06:09 PM
#328
Few more updates from track. Did Sonoma. Disappointing performance from the driver. Only got to very low 1.51s. I have a valid excuse - I had a big off right in the beginning at over 90MPH in turn 1, barely short of the wall. After that I was taking it very easy, especially in T1, and focusing on the line rather than lap times. I also tried focusing on one section at a time, which I found a good way for me to learn a new track - do one turn or sequence of turns at top of my ability and relax for the rest of the lap focusing on line, vision etc there. It had some dividends - I think I have good grip of all turns except T1 and the carousel, which are still weak.
Adding all those laps together best theoretical lap was 1.47.4 (still lifting through most T1 and part of carousel), which demonstrates that the car is capable of at least 1:45s or even better.
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
4. When I turn off the fan before going out to the track, and then turn off the engine, the fan and AC would turn on when the engine is started again, even if AC Off button was pressed before the fan was turned off. I ended up doing some sessions with AC on inadvertently because of that.
5. Brake pedal travel increases after a session, and does not come back to normal between sessions, but comes back to normal after some street driving. I'll see if that persists after pad and fluid change. I did not feel any brake fade and was diligent with cool down laps.
Adding all those laps together best theoretical lap was 1.47.4 (still lifting through most T1 and part of carousel), which demonstrates that the car is capable of at least 1:45s or even better.
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
4. When I turn off the fan before going out to the track, and then turn off the engine, the fan and AC would turn on when the engine is started again, even if AC Off button was pressed before the fan was turned off. I ended up doing some sessions with AC on inadvertently because of that.
5. Brake pedal travel increases after a session, and does not come back to normal between sessions, but comes back to normal after some street driving. I'll see if that persists after pad and fluid change. I did not feel any brake fade and was diligent with cool down laps.
I run Sport Cup 1's and from what i can read online, the recommendation seems to be same from Michelin but I find that 36rear to be greasy at times and just perfect other times. In all honesty, I'm learning that TP's mean little so I plan to get a pyrometer and make sure my temps are in the right range and even across the tire.
As for oversteer and such, I've never felt my car planted at Sears so I think part of it is just the track with all its variations. If I'm not understeering, then I'm oversteering or trying to avoid ABS kicking in due to bump in the braking zones. Regards, it's all good fun.
09-22-2014, 07:32 PM
#329
Rennlist Member
Thread Starter
Adding all those laps together best theoretical lap was 1.47.4 (still lifting through most T1 and part of carousel), which demonstrates that the car is capable of at least 1:45s or even better.
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
I don't know about tire pressures, so cant help but start measuring temps.
I don't go for best grip, I try to get the tires to wear even as I love money more than lap times.
Why are your fronts replaced and your rears not? Is the car wearing more front than rear? That's nutty. How do they cord.
Try to get the tires to wear even with pressure and camber, than make the car work to your liking with sway bars. I'm sure the pro's do it different and its all back asswards but my goal is to make tires last.
Don't worry about oil use, just keep some in it.
Put SRF in it.
Thanks again for posting.
09-22-2014, 08:04 PM
#330
Few more updates from track. Did Sonoma. Disappointing performance from the driver. Only got to very low 1.51s. I have a valid excuse - I had a big off right in the beginning at over 90MPH in turn 1, barely short of the wall. After that I was taking it very easy, especially in T1, and focusing on the line rather than lap times. I also tried focusing on one section at a time, which I found a good way for me to learn a new track - do one turn or sequence of turns at top of my ability and relax for the rest of the lap focusing on line, vision etc there. It had some dividends - I think I have good grip of all turns except T1 and the carousel, which are still weak.
Adding all those laps together best theoretical lap was 1.47.4 (still lifting through most T1 and part of carousel), which demonstrates that the car is capable of at least 1:45s or even better.
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
4. When I turn off the fan before going out to the track, and then turn off the engine, the fan and AC would turn on when the engine is started again, even if AC Off button was pressed before the fan was turned off. I ended up doing some sessions with AC on inadvertently because of that.
5. Brake pedal travel increases after a session, and does not come back to normal between sessions, but comes back to normal after some street driving. I'll see if that persists after pad and fluid change. I did not feel any brake fade and was diligent with cool down laps.
Adding all those laps together best theoretical lap was 1.47.4 (still lifting through most T1 and part of carousel), which demonstrates that the car is capable of at least 1:45s or even better.
I have some new observations about the car:
1. Data seems to indicate that it's slightly slower with exhaust not in sport mode (I'm looking at rate of speed gain on straights). I would not expect that because AFAIK it does not make any difference at high revs. Maybe there is something else involved (tire pressure or head/tail wind).
2. My car is very oversteery - even when turning in too hot, it snapped into oversteer almost immediately after turn in. Off-throttle, on throttle - almost always rear lost traction first. I have several hypotheses:
a) tire pressures - I was running 31 front 35 rear hot. I will try lower in the rear. I was setting higher pressure because the tire was rolling a bit.
b) much lower camber at the rear that at front (almost 1 degree difference). I'll try adding camber at the rear anyway to make tires last longer, so I'll know soon enough if that's what's going on.
c) new tires at the front and worn at the rear (PSC2). Now this one is interesting - if that's the case it can be one of two things. The obvious one is that rears probably lost grip because of heat cycles (9 track days or so, but not very intense). That would be a bummer because tires still have quite a bit of thread, except outside shoulders. Another possibility is that it's because of the dual-compound structure of the tires. When you get new tires, soft outside compound and harder inside compound are pressed again the road equally (let's assume ideal camber setting). But as you use tires, softer compound should wear quicker, so more of the pressure would shift on to the harder compound, making the tire grip less on average. This could explain why I have so much more grip at the front, with newer tires there. It would be a bummer as well because it would be great to be able to change front and rear tires independently without upsetting the car balance much.
3. The car does not consume oil during daily driving but takes about 150-200ml of oil per track day. Are others seeing the same?
4. When I turn off the fan before going out to the track, and then turn off the engine, the fan and AC would turn on when the engine is started again, even if AC Off button was pressed before the fan was turned off. I ended up doing some sessions with AC on inadvertently because of that.
5. Brake pedal travel increases after a session, and does not come back to normal between sessions, but comes back to normal after some street driving. I'll see if that persists after pad and fluid change. I did not feel any brake fade and was diligent with cool down laps.
Brake pedal feel – I upgraded to steel lines & Motul fluid and it made a huge difference in feel. The lines are a great, relatively cheap upgrade. The pedal is extremely firm now, minimal travel, and stays up high. Much better than stock, I don’t know why Porsche doesn’t do this @ the factory (on all 911’s, really). I forget if you’ve upgraded your pads? The Pagid RS29’s are much better than stock. And for some reason they aren’t anywhere near as noisy as on previous cars. Maybe in time…
Tires – I think all of your thoughts make sense. Interesting point about the dual compound. I ran one trackday with very worn fronts and the car pushed really badly. I would agree you should get the camber ratio closer F/R. I’m at -2.7/-2.3 F/R now and the car feels great. I also recommend lower pressures – I’m usually ending up at 29F/30-31R but anywhere in the very low 30’s feels good.
Oil – I’m going through 500+ ml per track day. And basically none on the street.