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991 Turbo front sway bar issues & 19" wheels rubbing

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991 Turbo Turbo and Turbo S

991 Turbo front sway bar issues & 19" wheels rubbing

 
Old 06-06-2018, 11:55 AM
  #16  
A/S
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I have the Forgeline GA1R on 19", they are lighter than the $30k magnesium offers in the Weissach packages or the 991 Turbo S Exclusive, on my GT3 RS these GA1R wheels/tires removed 27 lbs of unsprung weight.

The easy button is 20x9.5" ET 45 (6mm more agressive than stock, but gaining enough inner space for the 265x20 Hoosier, no need to roll fenders, no rubbing either) front and 20"x12" ET56 (same offset as stock, just 0.5" wider). Forgeline are super strong wheels, stronger than any stock wheel.
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Old 06-06-2018, 01:16 PM
  #17  
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Originally Posted by A/S View Post
This is Gold!!! where can we buy these wheels?

The front 20x9 and 20x9,5 ET45 would fit perfectly, I prefer the 9.5 as the 265 tire would fit better.

The rear that works is the 20x11.5 ET55. That 20x12ET44 is fine for the 991GT3RS but it will stick out beyond the rear fenders on the 991 Turbo S (I have a set of 19x12 ET46, the stick out 10mm too much in my 991 TTS and they could be 10mm more aggressive in offset in my 991GT3RS).

Although, Forgeline and Finspeed can make awesome wheels here in U.S. Personally, Forgeline is my preference.
I am not sure if you are familiar with Advan wheels, but they are made by Rays in Japan. Rays is right up there with BBS as one of the top wheel manufacturers in the world. Rays is an OEM supplier for a lot of car manufactures and in motorsports in Japan. The wheels are mold-form forged which basically means they are forged in to their basic shape as opposed to being cut to their shape. I believe that Rays and BBS are the only manufactures who are capable of this process. This allows the metal grains to flow in the direction of the shape of the wheel making them stronger and lighter than a traditional forged wheels: http://www.superstreetonline.com/how...-te37-is-made/

Not to take anything away from other wheel manufactures like Forgeline and Finspeed as their quality is excellent and I had Forgeline's on my 964 and I currently have Finspeed's on my 2016 Viper ACR Extreme, but Rays, along with BBS, are at another level when it comes to wheels.

I had these wheels on my GTR and the quality is amazing. Not only are the wheels of the highest quality, but they are cheaper than most of the other forged wheels out there.

There are a lot of distributors for these wheels in the U.S., the three biggest I can think of are:

http://www.evasivemotorsports.com

https://www.vividracing.com

https://www.ravspec.com

Last edited by Tay101; 06-06-2018 at 01:46 PM.
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Old 06-06-2018, 03:03 PM
  #18  
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Originally Posted by A/S View Post
I have the Forgeline GA1R on 19", they are lighter than the $30k magnesium offers in the Weissach packages or the 991 Turbo S Exclusive, on my GT3 RS these GA1R wheels/tires removed 27 lbs of unsprung weight.

The easy button is 20x9.5" ET 45 (6mm more agressive than stock, but gaining enough inner space for the 265x20 Hoosier, no need to roll fenders, no rubbing either) front and 20"x12" ET56 (same offset as stock, just 0.5" wider). Forgeline are super strong wheels, stronger than any stock wheel.
Winner, thanks much, GA1R in 20 w/R7 265/335 is what I have wanted once I knew they could fit w/no rubbing! Diameters are good, width was the question. Front may fit w std ET just a lot of caster, rears I had heard might be the problem.

Last edited by nolimits; 06-06-2018 at 03:25 PM.
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Old 06-06-2018, 07:00 PM
  #19  
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If you use the stock offset and run a 265, when the car compresses the 2nd ring on the bulky springs (normally under heavy braking), the springs will rub the inside tire sidewall. The 6mm extra spacing from running ET45 fixes the problem. The won't rub at offset 51mm until you get the front suspension to work hard. Any caster will work (I have adjustable caster via offset bushings), but maxed out front caster is 8.8 degrees, unless I install split LCA then add shims, but snapping a front axle from the wheel carrier is not something I want to deal with (there are axle spacers, but I don't want to have an opinion on the massive torque the front axle handles on turn exit and those spacers not keeping up).

I run the much wider (still do) 345x19 Hoosier in the back, my rear fenders are pristine and untouched, despite of using a rear ET46 (I went a little aggressive on the offset because I was planning on sharing the wheels with the GT3 RS, so I needed a happy medium). 12x20 ET56 will works perfect and you can fit that 315 R7 that Hoosier wrongly labeled 335.

By the way, on any racetrack I have driven, my 991 Turbo S produces better lap times than my 991.1 GT3 RS, but having a lightened TTS, massive extra power, and proper geometry/spring rates/bushings builds the TTS into one of the fastest road course cars (it is also good for drag racing, haven't done any official 1/4 mile pass but have done plenty of VBox runs).
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Old 06-07-2018, 12:54 AM
  #20  
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Originally Posted by A/S View Post
pdtp#16,

Point 1) As stated by TPC, there is very little room to play with an adjustable front sway bar in the way the front axle sits in the 996, 997 and 991 AWD cars. Unfortunately, the Turbo doesn't have PDCC, PDCC is magic. I have PDCC in my 991 Turbo S and conventional sway bars in my 991 GT3 RS. If you mount the top of that front drop link in an offset (with a spacer), it will allow you to eliminate rubbing, but you won't be able to use full stiff or one from full stiff on that sway bar. Also that drop link looks awfully short, you need at least another 3" on the drop link.

Point 2) The only 19" wheels that clear the rear suspension of the 991 (GT3 or Turbo) are these two brands: Forgeline and Finspeed. Finspeed was under some internal business conflicts and were delayed a little bit in Production. Additionally, even with these two wheels, if running Sebring on a mega heavy car and with all those bumps, the rear wheels are going to deflect, and the tolerances are pretty small. However, the quality of forging on these two brands (and their big inner drum size given the 19" diameter) is what makes them suitable for the 991 with Rear Wheel steering (RWS is what changes the location of rear suspension arms making 19" wheels challenging to fit). You can also replace the bolt on that rear lower arm with the version on the Panamera, or trim down the head of the bolt just a tad, and make sure that the bolt head had its flat portion parallel to the ground (the hexagon shape of the bolt head as you would draw an hexagon on paper).

Hoosier just released 20" tires. The 265 and 335 R7 will work perfectly with the AWD system and F/R wheel ratios in the 991 Turbo. In my Turbo S I ran 235/345, 265/345 and 295/345x19" (this last set was rubbing on the springs and requires rolling fenders and/or a new suspension with narrow springs). On 20" Hoosiers you gain an extra 12.7mm (1/2") of clearance on the rear suspension arm, and you could locate used 20" wheels a lot easier, as 991 GT3 and 991 Turbo wheels are all over the place, including a few affordable (but not that stiff) options from OZ.

Point 3) Just look at how much time Pro and Am team spend at Sebring tuning the suspension, and they always run out of time. Fly a shock engineer to Florida, pay for the weekend of tuning, get someone familiar with Tractive shocks and a DSC. Your settings for Sebring will only work for Sebring, every other track is different (even same track at different days).

Then there is the factor (the most important) on where is the driver's driving level. Pick up a track with easier access (PBIR) then get baselines for lap times, then get a Pro driver and a Coach (2 different people), the Pro to see what the car can do, the Coach to interpret the Pro and your data, and help you get better. If a Pro gains 1 second per minute of track time on me (given the same car) I'm happy with my performance, but if the gap is 2+ secs per minute, I have a lot of work to do, and that work needs a 3rd party (Coach) as the path of self-improvement and self-correction without external help can be simply eternal.


A/S

thanks for your reply.

1) spoke at length with TPC. They are sending me the drop links and extension brackets from Tarett. Hopefully this solves the issues. As you said still will be limited To the amount of adjustability that is available. If this doesn’t work, then the stock bar will go back in as suggested before

2) unfortunately I made the mistake to choose, upon bad advice, a wheel manufacturer that is not well known. I originally was going to order Forgeline as I know these wheels have worked for others. We have testing the car next week at two different tracks and hopefully see if we can get the issues with the rubing fixed. If not, I need to make a decision on going with 19” or 20” wheels. What would you suggest since you have tried both? I liked that on the 19” I would have more versatility on tire options as well as some reduction in weight as compared to the 20”. I am running both axle spacers, since we have widened the front track, as well as 7mm spacer for the wheels (this was only needed since the wheels offset on the 19” rims was rubbing the springs) will probably not needed with properly sized wheel.

3) I agree 100% with you. Unfortunately have not been able to run the car the two times we have taking to the track due to different issues. At Sebring, I was only running the Tractive shock suspension and the DSC box with stock wheels and Trofeo R tires. Was only able to run 1 1/2 sessions during the day since it was raining, and ran into other setup problems. The car ran ok specially taking into consideration that I hadn’t driven Sebring since 2003. Was able to get the car running in the mid 2:25 not pushing the car too hard. I can see that with the right setup and properly driving the car these times will drop considerably. During this event is were I first felt the issue with the shocks. As you properly said Sebring you are jumping all over the place so I couldn’t really know if it was a setup issue or just the way the shocks worked. After this I sent the car to Champion Motorsport who then finished the installation of all of the other items (by the way they have been great in helping sort out all of the issues created by the previous guys) Went to PBIR to test the car but noticed that rubbing really as soon as I started getting to speed (5 laps into first run).

After this his I took the 19” wheels of put in the stock wheels and stock tires and drove the car on the street for a couple of days just trying to see if I could spot other issues before sending the car back to Champion.

During these two days is that we noticed the continuance rubbing of the sway bars and continue to experience the wiredness (random bounce in the suspension). In further looking into it with TPC we figured it could be a couple of things

- shocks have not been zero out to the alignment done by Champion (much lower than stock) this could be creating an issue with the dampening settings
- the initial settings of the DSC box was not setup for track purposes. So we are going to be making some initial changes.

In summary, we have agreed to have Champion make all of the changes with the front sway bar that are needed and realigned the car. Once that is completed, we will zero the shocks and then record whats current happening when we go over bumps and send it to TPC. TPC will the. Help us setup a good baseline to address those issues

hopefully after this we can head back and test the car again.

Once we get the car in good working condition, I plan on doing exactly what you suggested. I did this many times in the past when I raced. I used to get someone who was very familiar with the specific track and have them help me setup the car and compare what I was doing vs them. Nothing helps more than learning from a good driver or teacher specially if they are familiar with the track and the type of car you are driving.

Thanks again for for all of your help. With fingers crossed I hope to solve this initial gremlins by next weekend!!
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Old 06-07-2018, 01:30 AM
  #21  
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Originally Posted by A/S View Post
If you use the stock offset and run a 265, when the car compresses the 2nd ring on the bulky springs (normally under heavy braking), the springs will rub the inside tire sidewall. The 6mm extra spacing from running ET45 fixes the problem. The won't rub at offset 51mm until you get the front suspension to work hard. Any caster will work (I have adjustable caster via offset bushings), but maxed out front caster is 8.8 degrees, unless I install split LCA then add shims, but snapping a front axle from the wheel carrier is not something I want to deal with (there are axle spacers, but I don't want to have an opinion on the massive torque the front axle handles on turn exit and those spacers not keeping up).

I run the much wider (still do) 345x19 Hoosier in the back, my rear fenders are pristine and untouched, despite of using a rear ET46 (I went a little aggressive on the offset because I was planning on sharing the wheels with the GT3 RS, so I needed a happy medium). 12x20 ET56 will works perfect and you can fit that 315 R7 that Hoosier wrongly labeled 335.

By the way, on any racetrack I have driven, my 991 Turbo S produces better lap times than my 991.1 GT3 RS, but having a lightened TTS, massive extra power, and proper geometry/spring rates/bushings builds the TTS into one of the fastest road course cars (it is also good for drag racing, haven't done any official 1/4 mile pass but have done plenty of VBox runs).
Good info, I'd heard the C2 265s worked but rubbed at full lock. Was told caster could take care of it, will inquire further. Agree the TTS is a beast in the right hands, easy to leave GT3 RS and Cup chase. All about seat time and getting folks to get good instruction/coaching, more so than parts spending before the skill set is there.
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Old 06-07-2018, 02:41 AM
  #22  
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OP

If you have to buy a new set of 19” wheels now, I would say stick to your 20” stock wheels.

If you go 19” you have a larger choice of tires of course, simply use 997 GT3RS/GT2RS wheel offsets/ sizes they fit perfectly. I have also wider front track and my car is lowered 25mm. I fit 265s wihout issues in the front, even full racing slicks 28/67 and 31/71 in the rear lowered 20mm. This with -3.8 camber.

By the way there are many more high quality 19” wheel choices that don’t rub, you don’t have to stick to those brands. OZ is one example but there is more.
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Old 06-07-2018, 11:42 AM
  #23  
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Originally Posted by Pdtp#16 View Post
- shocks have not been zero out to the alignment done by Champion (much lower than stock) this could be creating an issue with the dampening settings
- the initial settings of the DSC box was not setup for track purposes. So we are going to be making some initial changes.
I am sorry to beg the differ, and wanted to clarify that the DSC is setup for track use on OEM PASM dampers and for Tractive dampers. The DSC mapping, the Tractive dampers, and the spring rates on your car are exactly the same as our own 991TT, which in its first competition outing took P1 at NOLA road course in the Optima USC challenge.

I think your car's ride height and sway bar setting need some adjustment. The DSC can be tuned for how each driver prefers the car to feel on corner entry, our standard setting is soft for the beginning of corner entry phase to optimize weight transfer and to "set" the tire, and then stiffens up relative to the rate of change of the g-force and for suspension travel velocity(where zero'ing the ride height sensors is important for a much lowered car). This soft initial damping command may feel unexpecting to drivers who are expecting the initial roll stiffness of a non-electronic track setup. It took me a few track events to get used that feel and trust that when I commit to the turn it will stiffen up. Of course the DSC can be adjusted to increase the minimum damping value to achieve more initial roll stiffness to driver preference. And without the ride height sensors being zero'ed to the DSC for the much lowered ride height the damping commands won't be ideal. The zero'ing procedure is easy, glad to talk you though when you at that point. And looking forward to help you tune remotely. Our car is pretty close to stock ride height.

https://rennlist.com/forums/991-turb...itational.html







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Old 06-07-2018, 01:49 PM
  #24  
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Originally Posted by Tom-TPC Racing View Post
I am sorry to beg the differ, and wanted to clarify that the DSC is setup for track use on OEM PASM dampers and for Tractive dampers. The DSC mapping, the Tractive dampers, and the spring rates on your car are exactly the same as our own 991TT, which in its first competition outing took P1 at NOLA road course in the Optima USC challenge.

I think your car's ride height and sway bar setting need some adjustment. The DSC can be tuned for how each driver prefers the car to feel on corner entry, our standard setting is soft for the beginning of corner entry phase to optimize weight transfer and to "set" the tire, and then stiffens up relative to the rate of change of the g-force and for suspension travel velocity(where zero'ing the ride height sensors is important for a much lowered car). This soft initial damping command may feel unexpecting to drivers who are expecting the initial roll stiffness of a non-electronic track setup. It took me a few track events to get used that feel and trust that when I commit to the turn it will stiffen up. Of course the DSC can be adjusted to increase the minimum damping value to achieve more initial roll stiffness to driver preference. And without the ride height sensors being zero'ed to the DSC for the much lowered ride height the damping commands won't be ideal. The zero'ing procedure is easy, glad to talk you though when you at that point. And looking forward to help you tune remotely. Our car is pretty close to stock ride height.
Tom,

Regarding the file that’s weird as it matches the same that you have on the website dated 2017. I downloaded the one from may 2018 which was much better. I do still think its an issue with the overall settings of many of the different parts installed. It could also well be an issue with the way the rear schools were installed by the previous shop. Champion is going through them this week.

We we are definitely lower than Mike’s car. See attached.



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Old 06-07-2018, 02:17 PM
  #25  
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Originally Posted by nolimits View Post
Good info, I'd heard the C2 265s worked but rubbed at full lock. Was told caster could take care of it, will inquire further. Agree the TTS is a beast in the right hands, easy to leave GT3 RS and Cup chase. All about seat time and getting folks to get good instruction/coaching, more so than parts spending before the skill set is there.
The 20" Michelin front PSC2 from the 991 GT3 RS is actually a 285 tires. I placed a stack of 4 stock tires/wheels from my C7 Z06 (285 and 335 MPSC2 on 10"/12" wheels) next to a stack of 4 stock tires/wheels from my 991 GT3 RS (265/325 MPSC2 on 9.5"/12.5") and the two stacks were practically identical.

The 265 MPSC2 N-Spec is wider than the new R7 265.
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Old 06-07-2018, 02:41 PM
  #26  
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Originally Posted by Pdtp#16 View Post
Went to PBIR to test the car but noticed that rubbing really as soon as I started getting to speed (5 laps into first run).
As a reference, I don't have lap times from my current street cars at Sebring, but I do have PBIR times.

On my bone stock 2016 Z06, I ran a 1:27 (MPSC2 tires). Hot 100 degrees day, after lap 3 the car went limp and was being outrun on the back straight by a 405Hp C5-Z06. On my bone stock 991 GT3 RS (except side muffler deleted, Catless headers now removed, and proper corner weights, lowered and aligned to my specs) I ran a 1:23. My TTS on Trofeo-R, lowering springs and a stage2 powerkit a 1:23 too, and same TTS with Inconel headers/catless Inconel exhaust, tune for race gas, lightened (low fuel, Li-Ion battery and the massive reduction from the exhaust) same 245/305 trofeo-R (I have only used the tires 2 track sessions, they are for sale), the KW suspension, stiff front bushings, and properly corner weighed and aligned ran a 1:21.

I haven't tried any of these cars on Hoosiers at PBIR, and I have Hoosiers for them all (I prefer a nice drive in the middle of the week, no trailer, just show up run a few laps, have dinner on the way back, then home). TTS is now dismantled from some of the power mods (sold a few, others for sale), as it may get traded for an Italian exotic. From the 3 cars above, the one I enjoy the most is the GT3 RS, the TTS produces better lap times (with the mods), but the GT3 RS is just fun and even if it went 6 secs slower at PBIR (like my Z06) it would still be my favorite.

The TPC car (based on a 991.1 Turbo S) with the GT3RS Aero mods (and obviously lighter) plus the space to run wider front wheels/tires, and an even bigger wing than the 991RS must be a monster, it is one of my favorite street cars.
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Old 06-07-2018, 03:51 PM
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Beautiful car TPC The 991.2 GT3/RS front bumper looks amazing.

Just surprised how high it is run in the rear, my 991 TT is setup by Manthey at 335mm center of the wheel to fender, this must be 15-20mm higher. Rake-wise, bit more aggressive than stock, handling is incredibly neutral with all, 19" Trofeo R, Hoosier R7 and Pirelli full racing slicks.
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Old 06-07-2018, 05:52 PM
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The TPC car looks amazing. Just saw that they added a few new improvements!!!


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Old 06-19-2018, 12:56 AM
  #29  
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Guys,

Was finally able to get the car working well enough to get to the track and put some time on it. Did about four 20 minute sessions at PBIR this Saturday. It was Hot!!! This is what we were able to gather.

* Sway Bar
- seems not to be rubbing anymore. However seems like we are limited to the two softest settings. Is this right? See pics




* Wheel rubbing seems to have gone away

* Suspension and DSC Box
- Zeroing out the shocks made a huge difference.
- Not sure if there was something wrong with the prior installation but in order to install some of the new rear parts we ended up taking all of the shocks outs and re-installing everything again. The combination of this and re-calibrating the shocks took all of the suspensions weirdness away
- Did a bunch of different test runs. Tom I will send you the test files for your review.
- With this now working we can focus on getting the right settings for the right tracks. But i believe we still have some work to do with alignment etc. before getting here.

The guys at the shops used the following alignment as there baseline



These are my impression from my four sessions
- Other than the few laps I put in a few weeks ago at night, this was really my first time at PBIR. I ran Morosso quite a bit but never the new track.
- So my first session was really as much as making sure everything was working well as getting familiarized with the track.
- Once i got things going i found that i was struggling quite a bit with understeer and once the tires came up to temp i was sliding all over the place. I actually felt i had much more grip on the Trofeo's than the Hoosiers. We ended up lowering the tire pressures down to 30 front 32 rear (hot) and that seemed to neutralized things somewhat. Otherwise after 3 or 4 laps it felt like i was on a dirt track.
- Another issue I found with all of the heat was I started getting break fade. With all of the work that has gone in the car i couldn't remember if they flushed the whole system since the last event.

All in all it was a lot of fun to get out there and run the car even if i was expecting a bit more out of it. I was able to run in the lows 1.24's by fourth session. I'm sure with getting to know the track better (better lines etc), getting more confident on the breaks (specially turn 10 i was breaking really early) could have shaved another second or so. Hope that with better alignment, getting the car scaled, investing in some video / data login and some instruction I can get these times down. I wish i was taking her up north this summer. So i guess for now the car will go down to the shop to finish some of the rest of the build. Can't wait for this fall to get to track time back again. In the meantime she will go in a diet this summer and maybe get some exhaust and engine tuning!!!
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