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991 Turbo front sway bar issues & 19" wheels rubbing

 
Old 06-02-2018, 05:55 PM
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Pdtp#16
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Unhappy 991 Turbo front sway bar issues & 19" wheels rubbing

I recently purchased a 2014 991 Turbo and have performed the following upgrades
-Overall Suspension
*Tractive Coil Overs
* DSC V3

- Front Suspension:
* Tarett Pro Series Front Lower Control Arms
* Tarett Adjustable Tie Rods
* Tarett 10m Axle Spacer's
* TPC Front Sway Bar and Drop Links

- Rear Suspension
* Tarett Engineering Rear Control Arm Inner Monoball Bearing Rear Control Arm Outer Monoball Bearing Rear Forked Control Arm Monoball Bearing Rear Monoball Bearing, Toe Link Rear Upper Control Arm Link, Long
*TPC Rear Sway Bar and Drop Links

- Tires & Wheels
* Wheels: 19" Signature Track Series
* Tires: Hoosier R7 265 & 325

- Brakes
* Currently on OEM Rotors with Yellow Pagids. Looking to upgrade the breaks later on.

I decided to focus on the handling first then deal with the rest later. With that said i have ran into several issues. Some which i have read int he forum and not sure if there is a solution.

- The first is with the front sway bar. See pictures attached. We have tried everything but it still rubs the front axle. I have it at its softest setting. I have spoken several times with the guys at TPC who have tried to help. THe latest i heard is that this type of setup doesn't allow you to turn the wheel 100% without the bar rubbing. Has anyone else found this issue? I know that Tarett offers different droplinks on the 997 TT but haven't been able to find anything online regarding the 991's.

- Second issue is the rear lower wishbone is rubbing the inner wheel under heavy loading. We shaved a bit of off it in order to make sure there was art least a 5mm space between the wheel and the metal but its still rubbing. Called the wheel manufacturer as my shop said the wheel just has too bend and doubts that they are Forged as advertised but can't get any answer from anyone. I was sucked into buying these wheel by the old shop that was helping me and now i think it was a big mistake. Has anyone been able to properly correct this issue. Would hate to have to buy new wheels and still have the same problem still.

- Third issue has been with the DSC Box or the Tractive Suspension. With all of the other issues i haven't really been able to really focus on this but first impression was that the shocks where way too soft for the springs and the car would bounce around all over the place. We then switch the DSC Box for the PASM and it took most of it away but made it of course pretty stiff at that point. Still wasn't supper stiff per say but the ride was then much more firmer. I was able to download the software and make some modifications to the DSC Box (essentially just stiffen the shock rates) and made it much better but still find that the car bounces around when i hit a bump and i'm either under heavy braking or cornering. It almost feels like putting really stiff springs on an old Cadillac and the car just keeps bounding after the first shock. Has anyone deal with this? Didn't seem to do it on the track, but again i only drove Sebring and was only able to do one and half session because of all the other issues. So most of the other stuff that i'm feeling is on street driving while the car is not being pushed.

Sorry for all the rambling but i have now taken the car to three different shops bought alot of suspension parts and don't feel that i'm making much improvements. Luckly i found a really good shop now they just have never worked with any of the TPC Suspension stuff.






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Old 06-02-2018, 11:02 PM
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Default 991 Turbo rubbing

I think you said it, a lot of aftermarket unsprung suspension components not harmonizing. Maybe something simple, faulty metallurgy, mismatched parts, sway bar/ drop link tension?
Back in the day, PCA racing infancy, one of the fastest GT1 cars own/oper. by independent P car race/service shop could not keep the car on track, medium speed lazy slow motion spins. After countless hours, setups, adjustments, etc. one weak mismatched spring was the cause. Good luck.
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Old 06-03-2018, 04:58 PM
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I know TPC does great products, but honestly changing the front sway bar is totally unnecessary, especially with the V3 fitted. I would get rid of it quickly. Been racing my car for over a year in many different environments and it is very competitive with stock bar, initially it was simply lowered with Eibach springs, and now with full racing suspension and no PASM...stock sway bars. I run the same 19" wheel and tire size setup, and also the Tarrett bits and others. My OZ initially rubbed a little and it was apparent on the wishbone but its gone once the wishbone gave in some minimal thickness.
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Old 06-04-2018, 03:28 PM
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I'm not sure about the fit of the TPC front bar, but it looks similar to ours. With the suspension hanging, the bar should be close to or lightly touching the control arm. It moves up and away as the suspension gets compressed, so make sure you have enough clearance to not contact the axle under compression. It looks like you are close to running out of drop link adjustment, so you may need to get longer ones to provide the safe axle clearance needed.

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Old 06-04-2018, 07:21 PM
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For the record, I've been in contact with the OP.

1) The front sway bar- since the 996 Turbo/C4 days it has been a little bit of a challenge using GT3-shaped adjustable front sway bar on Turbo/C4 cars needing tight turning radius. This challenge carries on in the same manner from the 996 to 997 to 991 Turbo/C4 since the positioning of the front axle to the control arm to the drop link is similar. The issue usually presents itself when turning more than a full turn of the steering wheel from center, which then the gap closes between the links and front axle. Some companies make a curved drop link in an effort to increase the clearance when making a tighter turn. Tarett Engineering now offer a very nice and effective extension kit for Tractive dampers.

We did install a Tarett extended drop link kit recently on a 997TT and we were impressed by the turning radius it offers on Turbo/C4 cars. Here are some pics.



Note: The pic directly above show contact on the axle. The contact is not from the Tarett link, it was from the old link that was on this car for 9 years.

I made a made an assumption on sending the OP our standard race links thinking the tighter turns won't be an issue on a mostly track car. For example, Cup cars are limited by the steering rack have to three-quarter turn of the steering wheel from center. And most track car customers have been fine with one full turn of the steering wheel from center. In this particular case I made a bad assumption. I will work with the OP to resolve.


2) Aftermarket wheel rubbing stock control arm- sorry I have nothing useful to contribute since I don't know the wheel.


3) DSC tuning too soft- this is an easy fix, I can email a stiffer mapping. The current DSC file does command up to 100% damping force to higher loads, usually its the initial turn-in that some users feel is too soft. In the DSC active command this is done on purpose to "set" the tire then as the tire loads up and g-force increases the damping command increases to the load. The mapping can be easily changed to start at a higher damping rate or get to 100% sooner or both.
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Old 06-04-2018, 09:44 PM
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Tom,

i saw saw that you called today. I will call you tomorrow to catch-up. I see the pics on the drop links from Tarett. Does these fit the 991 as well? I will check with Ira as well and double check his comment on the sway bar position.

Trying to schedule a test day next week to try to solve some of these issues. (hopefully it doesn’t rain). Also regarding the DSC Box I’m trying to see how to record what’s going on so that I can send you guys the actual data of what we are feeling.

The guys down here are checking in with the wheel manufacturer but my guess is that I might have to buy a new set from a different company. Want to try to make sure the issue does not persist thereafter. Could ride height / alignment be a contributor? I know that they setup the car similarly to what how they setup their cup cars.

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Old 06-05-2018, 12:07 PM
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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.
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Old 06-05-2018, 12:26 PM
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Originally Posted by A/S View Post
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.
Do those Hoosiers fit the standard OEM TTS wheels? If your car is lowered, do you experience any rubbing?
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Old 06-05-2018, 01:33 PM
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Originally Posted by Randyc151 View Post
Do those Hoosiers fit the standard OEM TTS wheels? If your car is lowered, do you experience any rubbing?
If you have center locks, you're out of luck, the front 265x20 R7 needs a 6mm spacer to not rub on the stock springs, but you can run the 245/35R20 R7 with the 335x20 in the back on stock 991 Turbo S center lock wheels (I don't know why Hoosier called it a 335x20 when it truly is a 315). The advantage of the 265 is that it reduces the understeer the car has on slow or tight turns.

You could also get custom made 20" with offset 45mm for center lock, make them 20x9.5 instead of 20x9, then no spacers needed and 265 fits under the fender. If going custom, get a 12"x20" for the back and make it same as stock offset (56mm), I would rather do a 51mm offset as the stock rear wheels stick a little too much under the rear fenders).

Hoosiers have massive grip compared to any street rubber, and these tires have been engineered for full track use, so they are strong (construction and consistency).

No rubbing, and my car is very lowered ( and re-indexed on corner weights and geometry for bump steer, thanks to KW and some bushings), it is lower than my 991 GT3 RS and my RS is maxed out lowered at the back, and set in the front to match factory rake.
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Old 06-05-2018, 11:40 PM
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Originally Posted by A/S View Post
If you have center locks, you're out of luck, the front 265x20 R7 needs a 6mm spacer to not rub on the stock springs, but you can run the 245/35R20 R7 with the 335x20 in the back on stock 991 Turbo S center lock wheels (I don't know why Hoosier called it a 335x20 when it truly is a 315). The advantage of the 265 is that it reduces the understeer the car has on slow or tight turns.

You could also get custom made 20" with offset 45mm for center lock, make them 20x9.5 instead of 20x9, then no spacers needed and 265 fits under the fender. If going custom, get a 12"x20" for the back and make it same as stock offset (56mm), I would rather do a 51mm offset as the stock rear wheels stick a little too much under the rear fenders).

Hoosiers have massive grip compared to any street rubber, and these tires have been engineered for full track use, so they are strong (construction and consistency).

No rubbing, and my car is very lowered ( and re-indexed on corner weights and geometry for bump steer, thanks to KW and some bushings), it is lower than my 991 GT3 RS and my RS is maxed out lowered at the back, and set in the front to match factory rake.
This is exactly what I've been waiting to hear more about. So you are running 265/335 20" R7 with no rubbing or issues in stock TTS 991.1 or 2, wheel wells? Most aftermarket wheels start w 9.5 x 20 and 12 x 20. Offsets were my question and whether it could all work. I have suspension done w lots of camber and adjustability, axel extension up front, OEM CL wheels etc. OEM ride height and DSC set up very firm in Sport + for track. What exactly are you running now that is proven and works? Your track background and experiences would be helpful to hear more about. Good discussion for Tracking the Turbo thread. Thanks in advance.
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Old 06-06-2018, 12:33 AM
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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.
Really great info A/S.

Do you by chance know the part number to the Panamera bolt you are referring to?
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Old 06-06-2018, 12:36 AM
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Originally Posted by nolimits View Post
This is exactly what I've been waiting to hear more about. So you are running 265/335 20" R7 with no rubbing or issues in stock TTS 991.1 or 2, wheel wells? Most aftermarket wheels start w 9.5 x 20 and 12 x 20. Offsets were my question and whether it could all work. I have suspension done w lots of camber and adjustability, axel extension up front, OEM CL wheels etc. OEM ride height and DSC set up very firm in Sport + for track. What exactly are you running now that is proven and works? Your track background and experiences would be helpful to hear more about. Good discussion for Tracking the Turbo thread. Thanks in advance.
Here is a start with the 20x9.5 fitment. Advan makes their GT in that size and they state that it fits the front of the Turbo. They list the offset at +45. I am not sure how it fits as they also offer a 20x9 with the same offset:

http://www.yokohamawheel.jp/brand/ad...x_porsche.html
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Old 06-06-2018, 02:47 AM
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Originally Posted by nolimits View Post
This is exactly what I've been waiting to hear more about. So you are running 265/335 20" R7 with no rubbing or issues in stock TTS 991.1 or 2, wheel wells? Most aftermarket wheels start w 9.5 x 20 and 12 x 20. Offsets were my question and whether it could all work. I have suspension done w lots of camber and adjustability, axel extension up front, OEM CL wheels etc. OEM ride height and DSC set up very firm in Sport + for track. What exactly are you running now that is proven and works? Your track background and experiences would be helpful to hear more about. Good discussion for Tracking the Turbo thread. Thanks in advance.
Actually, I was running front 235/265/295 Hoosiers and rear 315/345, did a lot of testing on combinations, Found the best balance with 295 front and 345 rear. Keep in mind this is with 19" diameters in a 991.1 Turbo S and custom wheels. But the 295 requires fender work or narrow (2.25" springs) to barely fit under the fenders.

If you're on Center Lock stock wheels, your only Hoosier choice is 245x20 front and 335x20 rear. Again, the 335 is truly a 315 in size. No rubbing, just set front camber at -3.5 and rear camber at -3.0 and keep the same toe settings as stock (same for rake).

I'm a certified track instructor with PCA and NASA at national level, with over 500 track days in a large variety of cars.
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Old 06-06-2018, 03:05 AM
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Originally Posted by Tay101 View Post
Here is a start with the 20x9.5 fitment. Advan makes their GT in that size and they state that it fits the front of the Turbo. They list the offset at +45. I am not sure how it fits as they also offer a 20x9 with the same offset:

http://www.yokohamawheel.jp/brand/ad...x_porsche.html
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.
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Old 06-06-2018, 04:44 AM
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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.
Great info, Forgeline custom is what I have been considering, or something more standard that has better resale capability later but maybe use spacers or whatever on suspension etc to make things work. A lesser ET sounds promising. Rolling or extending fenders would be a last resort.
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