Orthojoe's GT4 track thread and ramblings
09-25-2016, 01:24 PM
#916
Three Wheelin'
I recently changed the rear toe and added the tpc toe links and found that under hard breaking it is very different and a little better....
Instead of sharper shorter oscillation it now is a slower oscillation with potentially (this is perception) larger amplitude.
First session out it worried me but now I seem more comfortable with it than previous setup.
I talked to my shop about it and they say both experience are fine; just get comfort out of the fact that you know the car can handle it.
Instead of sharper shorter oscillation it now is a slower oscillation with potentially (this is perception) larger amplitude.
First session out it worried me but now I seem more comfortable with it than previous setup.
I talked to my shop about it and they say both experience are fine; just get comfort out of the fact that you know the car can handle it.
09-25-2016, 01:47 PM
#917
Nordschleife Master
Thread Starter
Originally Posted by Spyerx
That hard brake jiggle seems to be more emphasized in a 911. If you've never experienced braking from a 5th to 2nd corner with a crap diff in a 911 I highly recommend it :-)
Joe how is lockup on apex exit with stock diff tc etc off?
Joe how is lockup on apex exit with stock diff tc etc off?
09-25-2016, 03:24 PM
#918
Rennlist Member
Ah fk. I didn't realize he left it on lol. Because it certainly didn't work "all" the time :-)
09-25-2016, 03:47 PM
#919
Nordschleife Master
Thread Starter
09-25-2016, 04:03 PM
#920
Rennlist Member
It might create a bit more brake wear but that's cheaper than body parts.
09-26-2016, 07:59 AM
#921
best to run every thing off to stop brake disks over heating and added rear brake disk wear>
981 Spyder eat disks as PTV cuts in all the time on that car !!!
981 Spyder eat disks as PTV cuts in all the time on that car !!!
09-26-2016, 10:10 AM
#922
Nordschleife Master
Thread Starter
Originally Posted by mrd_spy
best to run every thing off to stop brake disks over heating and added rear brake disk wear>
981 Spyder eat disks as PTV cuts in all the time on that car !!!
981 Spyder eat disks as PTV cuts in all the time on that car !!!
PTV cannot be turned off. It is supposed to make you faster.
Last edited by orthojoe; 09-26-2016 at 11:00 AM.
09-27-2016, 10:29 AM
#923
Epic thread! A must read to any new GT4 owner. Thanks a lot for taking the time to share all your insights Joe. Porsche should include a synopsis of it in their gt4 manual 
Only tracked the car once so far but more action still to come this year.
Tirewear was my main concern, so it's great that all those pics have been posted so that one can build a frame of reference.
Vid of best lap at Poznan Racetrack:
At 1:10 you can really see and hear the corner exit understeer everyone is on about - would have run out of track had I not lifted there.
The cars in front are GT3s which ended up being 2-2,5 s faster around the 4 km track (2,5 miles). I also could not keep up with a well driven 991 CS PDK on TrofeoRs (0,5 s ahead). I see myself shaving 1-1,5 s on a cooler day with a cleaner run. Full results of the day here: http://tptd.pl/2016/15ed2016/ZB%20WSZYSCY.pdf
In the effort to keep the tire pressures below the greasy levels in the high temp (31 C - 88F) I ended up bleeding too much and that somewhat compromised the day's running. I only reached 29/33 f/r towards the end of the afternoon sessions and by that time the surface of the tire was clearly overheated and sliding a lot.
Great impressions overall. Was not expecting to run such a time first time out. Because the power is not so overwhelming the GT4 seems much easier to run hard than the GT3. The setup is bone stock as it left the showroom.
Next up Spa-Francorchamps (Belgium) beginning of October. Anyone ran there? What would be a respectable time to aim for?
Only tracked the car once so far but more action still to come this year.
Tirewear was my main concern, so it's great that all those pics have been posted so that one can build a frame of reference.
Vid of best lap at Poznan Racetrack:
At 1:10 you can really see and hear the corner exit understeer everyone is on about - would have run out of track had I not lifted there.
The cars in front are GT3s which ended up being 2-2,5 s faster around the 4 km track (2,5 miles). I also could not keep up with a well driven 991 CS PDK on TrofeoRs (0,5 s ahead). I see myself shaving 1-1,5 s on a cooler day with a cleaner run. Full results of the day here: http://tptd.pl/2016/15ed2016/ZB%20WSZYSCY.pdf
In the effort to keep the tire pressures below the greasy levels in the high temp (31 C - 88F) I ended up bleeding too much and that somewhat compromised the day's running. I only reached 29/33 f/r towards the end of the afternoon sessions and by that time the surface of the tire was clearly overheated and sliding a lot.
Great impressions overall. Was not expecting to run such a time first time out. Because the power is not so overwhelming the GT4 seems much easier to run hard than the GT3. The setup is bone stock as it left the showroom.
Next up Spa-Francorchamps (Belgium) beginning of October. Anyone ran there? What would be a respectable time to aim for?
Last edited by greenhorn; 09-28-2016 at 08:11 AM.
09-27-2016, 11:50 PM
#924
Joe driving out of the garage to get on track today:
And thanks for the quick ride shotgun. Nice to see what the GT4 can really do!
And thanks for the quick ride shotgun. Nice to see what the GT4 can really do!
09-28-2016, 02:16 AM
#925
Nordschleife Master
Thread Starter
Epic thread! A must read to any new GT4 owner. Thanks a lot for taking the time to share all your insights Joe. Porsche should include a synopsis of it in their gt4 manual
Only tracked the car once so far but more action still to come this year.
Tirewear was my main concern, so it's great that all those pics have been posted so that one can build a frame of reference.
Vid of best lap at Poznan Racetrack:
At 1:10 you can really see and hear the corner exit understeer everyone is on about - would have run out of track had I not lifted there.
The cars in front are GT3s which ended up being 2-2,5 s faster around the 4 km track (2,5 miles). I also could not keep up with a well driven 991 CS PDK on TrofeoRs (0,5 s ahead). I see myself shaving 1-1,5 s on a cooler day with a cleaner run. Full results of the day here: http://tptd.pl/2016/15ed2016/ZB%20WSZYSCY.pdf
In the effort to keep the tire pressures below the greasy levels in the high temp (31 C - 88F) I ended up bleeding too much and that somewhat compromised the day's running. I only reached 29/33 f/r towards the end of the afternoon sessions and by that time the surface of the tire was clearly overheated and sliding a lot.
Great impressions overall. Was not expecting to run such a time first time out. Because the power is not so overwhelming the GT4 seems much easier to run hard than the GT3. The setup is bone stock as it left the showroom.
Next up Spa-Francorchamps (Belgium) beginning of October. Anyone ran there? What would be a respectable time to aim for?
Only tracked the car once so far but more action still to come this year.
Tirewear was my main concern, so it's great that all those pics have been posted so that one can build a frame of reference.
Vid of best lap at Poznan Racetrack:
At 1:10 you can really see and hear the corner exit understeer everyone is on about - would have run out of track had I not lifted there.
The cars in front are GT3s which ended up being 2-2,5 s faster around the 4 km track (2,5 miles). I also could not keep up with a well driven 991 CS PDK on TrofeoRs (0,5 s ahead). I see myself shaving 1-1,5 s on a cooler day with a cleaner run. Full results of the day here: http://tptd.pl/2016/15ed2016/ZB%20WSZYSCY.pdf
In the effort to keep the tire pressures below the greasy levels in the high temp (31 C - 88F) I ended up bleeding too much and that somewhat compromised the day's running. I only reached 29/33 f/r towards the end of the afternoon sessions and by that time the surface of the tire was clearly overheated and sliding a lot.
Great impressions overall. Was not expecting to run such a time first time out. Because the power is not so overwhelming the GT4 seems much easier to run hard than the GT3. The setup is bone stock as it left the showroom.
Next up Spa-Francorchamps (Belgium) beginning of October. Anyone ran there? What would be a respectable time to aim for?
Unfortunately, with temps hitting 94 degrees by 10am, no new PBs could be pulled off. My slowest visit to Laguna so far at 1:40. I'll have to try again on 10/14. Give me cool weather!!!! With no rain.
The car felt pretty much the same to me with the springs, but it does look like my tire wear will be fairly even. Tough to say exactly since they already have some outer edge wear from the last day which was on stock springs. I'll know for sure after the next set of tires. However, it looks like my goal for mostly even tire wear may finally be in sight... If I can get 5 days out of a set of re71R. I'll be super happy
09-28-2016, 08:27 AM
#926
Tried fixing the link, seems to be working now.
Other points you make that totally match my experience:
- corner entry oversteer - neutral mid corner - corner exit understeer
- the rear end has never broken loose on exit (happened in a GT3 I've driven)
- TC and ESP stay on - can't feel any interference slowing me down so far
Don't seem to be experiencing any of the twitchiness under braking you mention on stock rear alignment. Don't know if running PCCBs makes any difference in that department. Maybe I'm still not braking hard enough.
Isn't more rear toe-in contributing slightly to your understeer issue? The car is less eager to rotate?
Other points you make that totally match my experience:
- corner entry oversteer - neutral mid corner - corner exit understeer
- the rear end has never broken loose on exit (happened in a GT3 I've driven)
- TC and ESP stay on - can't feel any interference slowing me down so far
Don't seem to be experiencing any of the twitchiness under braking you mention on stock rear alignment. Don't know if running PCCBs makes any difference in that department. Maybe I'm still not braking hard enough.
Isn't more rear toe-in contributing slightly to your understeer issue? The car is less eager to rotate?
09-28-2016, 10:38 AM
#927
Nordschleife Master
Thread Starter
Originally Posted by greenhorn
Tried fixing the link, seems to be working now.
Other points you make that totally match my experience:
- corner entry oversteer - neutral mid corner - corner exit understeer
- the rear end has never broken loose on exit (happened in a GT3 I've driven)
- TC and ESP stay on - can't feel any interference slowing me down so far
Don't seem to be experiencing any of the twitchiness under braking you mention on stock rear alignment. Don't know if running PCCBs makes any difference in that department. Maybe I'm still not braking hard enough.
Isn't more rear toe-in contributing slightly to your understeer issue? The car is less eager to rotate?
Other points you make that totally match my experience:
- corner entry oversteer - neutral mid corner - corner exit understeer
- the rear end has never broken loose on exit (happened in a GT3 I've driven)
- TC and ESP stay on - can't feel any interference slowing me down so far
Don't seem to be experiencing any of the twitchiness under braking you mention on stock rear alignment. Don't know if running PCCBs makes any difference in that department. Maybe I'm still not braking hard enough.
Isn't more rear toe-in contributing slightly to your understeer issue? The car is less eager to rotate?
No rear twitching is a good thing! Any modifications to the car?
I'm very happy with how my car feels at this point. It likes to understeer on slow hairpin turns, but trail braking is all you need.
09-28-2016, 01:59 PM
#929
Nordschleife Master
Thread Starter
Originally Posted by greenhorn
Good to hear.
The car is fully stock. It's likely to stay that way.
280 miles one way to get to this track. Unfortunately there's nothing else nearby.
The car is fully stock. It's likely to stay that way.
280 miles one way to get to this track. Unfortunately there's nothing else nearby.
09-28-2016, 02:56 PM
#930
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I'm wondering if the stiffer springs (front more importantly) might cure some of the rear instability (less dive)...?
The back end is really planted under power which is great, but not as much fun. More power might help and that's gonna change here shortly.