Swaybars, Who uses what around here? I am looking into the Eibach kit...
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What's interesting is the fact that the GT3 bar is smaller than the stock 996tt bar.
GT3 rear sway: 20.8mm 4way
996tt rear sway: 21.7mm non adjustable
This would indicate that the GT3 bar is actually softer than the stock bar. It is adjustable however which might make it a bit stiffer than stock at its stiffer setting.
My adjustable H&R rear bar at 24mm (set on medium) combined with the stock front bar (also 24mm) seems to work well on JRZ coilovers with 600/800 springs on a RWD 40/60 LSD set up. Car is neutral but will oversteer fairly easily with throttle input. Your sway bar setting, spring rates, shock settings, and alignment will all play a role in how the car will behave. I think any of the adjustable sway bars can be set up to work well and by the same token they can also be set up to work lousy. It's no rocket science, you are dealing with a piece of steel with a certain amount of elasticity which you have control over on the adjustable bars. Combine that with the other adjustable variables mentioned above and you have plenty to play with to make it suit your tastes. Just my $0.02......
GT3 rear sway: 20.8mm 4way
996tt rear sway: 21.7mm non adjustable
This would indicate that the GT3 bar is actually softer than the stock bar. It is adjustable however which might make it a bit stiffer than stock at its stiffer setting.
My adjustable H&R rear bar at 24mm (set on medium) combined with the stock front bar (also 24mm) seems to work well on JRZ coilovers with 600/800 springs on a RWD 40/60 LSD set up. Car is neutral but will oversteer fairly easily with throttle input. Your sway bar setting, spring rates, shock settings, and alignment will all play a role in how the car will behave. I think any of the adjustable sway bars can be set up to work well and by the same token they can also be set up to work lousy. It's no rocket science, you are dealing with a piece of steel with a certain amount of elasticity which you have control over on the adjustable bars. Combine that with the other adjustable variables mentioned above and you have plenty to play with to make it suit your tastes. Just my $0.02......
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You might find this interesting.
As you stated, the GT3 bar is a smaller diameter, but it's stiffer in its two stiffest settings. The next to stiffest setting is actaully very close to the stock turbo bar.
FYI a typical design would have the f/r wheel rate % similar to the f/r weight distribution of the car. Of course you wouldn't want a rear engine car being quite that "balanced".
This would have a rear wheel rate percent around 62%.
As an example, the 997.2 GT3 RS has a rear wheel rate percent around 55% and our stock turbo has a rear wheel rate percent of 45.5%.
Below is a quick analysis I did for my car that may help.
Later, Steve
As you stated, the GT3 bar is a smaller diameter, but it's stiffer in its two stiffest settings. The next to stiffest setting is actaully very close to the stock turbo bar.
FYI a typical design would have the f/r wheel rate % similar to the f/r weight distribution of the car. Of course you wouldn't want a rear engine car being quite that "balanced".
This would have a rear wheel rate percent around 62%.
As an example, the 997.2 GT3 RS has a rear wheel rate percent around 55% and our stock turbo has a rear wheel rate percent of 45.5%.
Below is a quick analysis I did for my car that may help.
Later, Steve
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You might find this interesting.
As you stated, the GT3 bar is a smaller diameter, but it's stiffer in its two stiffest settings. The next to stiffest setting is actaully very close to the stock turbo bar.
FYI a typical design would have the f/r wheel rate % similar to the f/r weight distribution of the car. Of course you wouldn't want a rear engine car being quite that "balanced".
This would have a rear wheel rate percent around 62%.
As an example, the 997.2 GT3 RS has a rear wheel rate percent around 55% and our stock turbo has a rear wheel rate percent of 45.5%.
Below is a quick analysis I did for my car that may help.
Later, Steve
As you stated, the GT3 bar is a smaller diameter, but it's stiffer in its two stiffest settings. The next to stiffest setting is actaully very close to the stock turbo bar.
FYI a typical design would have the f/r wheel rate % similar to the f/r weight distribution of the car. Of course you wouldn't want a rear engine car being quite that "balanced".
This would have a rear wheel rate percent around 62%.
As an example, the 997.2 GT3 RS has a rear wheel rate percent around 55% and our stock turbo has a rear wheel rate percent of 45.5%.
Below is a quick analysis I did for my car that may help.
Later, Steve
That's a pretty interesting chart. Nice work. My corner balance has me at 1320 lbs. front (37.4%) and 2210 lbs. rear (62.6%) which includes driver and 3/4 fuel.
Assuming my math is correct, I just plugged in the numbers on my car and this is what I came up with using 600F/800R rates, a stock front sway, and a rear H&R sway set in the middle.
Total Front wheel spring rate (spring+sway): 477.9 lbs (56.2%)
Total Rear wheel spring rate (spring+sway): 372.6 lbs (43.8%)
At these settings my car has almost no push and oversteers quite easily with throttle. I do have an LSD and no PSM so you have to take that in mind. I can't imagine wanting a higher rear wheel spring rate as it would only increase oversteer. I have actually considered softening the rear a bit and have played with shock setting at the track to get it right.
Are you sure the motion ratios for the front at .88 and rear at .59 are correct???? This seems like too much of a difference. Shouldn't they be almost the same since our car use the same lower control arms and the shocks are located at roughly the same locations front and rear? It would seem that using a much smaller .59 motion ration in the rear is understating the rear wheel spring rate by quite a bit. It doesn't quite seem right..... Hmm..
What I also found interesting is that according to your chart, the H&R rear sway bar on the middle setting is almost 3x as stiff as the GT3 rear sway bar on the firmest setting (102 lbs./inch v. 35.2 lbs./inch sway bar wheel rate). That is a huge difference! How did you determine the lbs./inch. deflection rate of the swaybars??
It's interesting that the 997 GT2 RS would have a rear wheel spring rate of 55% because in order to get that you would have to run a very large difference in spring rate front to rear or a huge rear sway. It's interesting to note that most track 996tts or GT3s are running very small front to rear spring rate spreads usually on the order of 200 lbs and sometimes less. GMG for example favors 600/800 rates for their 996 track cars with 500/700 and 700/900 being also very popular. A 996 Cup car uses 1370/1484 spring rates which will give you a 67% front and 33% rear wheel rate!!! Sway bar setting will alter those numbers a little but only a couple of percent especially with such high spring rates.
For example, in order for me to get a 55% rear wheel rate with my 600/800 spring rates I would have to run a rear sway bar that would give a sway bar wheel rate of 305 lb./in. or roughly 3x that of the H&R at the middle setting or 9x that of the GT3 bar at the firmest setting!!!!! It's interesting to note that the KW club coilovers for the 996tt / GT2 use something like 400F/1100R spring rates and those would get you right at the 55% rear wheel rate. However, most race teams will tell you that the KW rates do not work well at all on the 996tt / GT2 platform as the car ends up way too under sprung in the front.
Even in your case, you can see that in order to get to a 55% rear wheel rate (like the 997GT3 RS) you would have to run the GT3 rear sway on full stiff and also run 260/700 spring rates giving you a 440 lbs front to rear spread. I don't think you would find any one that would recommend those rates as the front would be way too under sprung compared to the rear....
John...
Last edited by pwdrhound; Nov 2, 2012 at 01:02 PM.
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KW might recommend those rates. I've seen ~400/1000 rates they suggested for 911's.
Too much math for me..... Headache. LOL. I get in drive, tell mechanic what car is doing, we fix, then I drive again. GT3 sways and 700/1000 springs.
Too much math for me..... Headache. LOL. I get in drive, tell mechanic what car is doing, we fix, then I drive again. GT3 sways and 700/1000 springs.
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You're saying a Turbo's stock front bar is 24mm? So why replace with an aftermarket bar (e.g., Eibach) which is also 24mm (aside from the adjustability factor)?
What's interesting is the fact that the GT3 bar is smaller than the stock 996tt bar.
GT3 rear sway: 20.8mm 4way
996tt rear sway: 21.7mm non adjustable
This would indicate that the GT3 bar is actually softer than the stock bar. It is adjustable however which might make it a bit stiffer than stock at its stiffer setting.
My adjustable H&R rear bar at 24mm (set on medium) combined with the stock front bar (also 24mm) seems to work well on JRZ coilovers with 600/800 springs on a RWD 40/60 LSD set up. Car is neutral but will oversteer fairly easily with throttle input. Your sway bar setting, spring rates, shock settings, and alignment will all play a role in how the car will behave. I think any of the adjustable sway bars can be set up to work well and by the same token they can also be set up to work lousy. It's no rocket science, you are dealing with a piece of steel with a certain amount of elasticity which you have control over on the adjustable bars. Combine that with the other adjustable variables mentioned above and you have plenty to play with to make it suit your tastes. Just my $0.02......
GT3 rear sway: 20.8mm 4way
996tt rear sway: 21.7mm non adjustable
This would indicate that the GT3 bar is actually softer than the stock bar. It is adjustable however which might make it a bit stiffer than stock at its stiffer setting.
My adjustable H&R rear bar at 24mm (set on medium) combined with the stock front bar (also 24mm) seems to work well on JRZ coilovers with 600/800 springs on a RWD 40/60 LSD set up. Car is neutral but will oversteer fairly easily with throttle input. Your sway bar setting, spring rates, shock settings, and alignment will all play a role in how the car will behave. I think any of the adjustable sway bars can be set up to work well and by the same token they can also be set up to work lousy. It's no rocket science, you are dealing with a piece of steel with a certain amount of elasticity which you have control over on the adjustable bars. Combine that with the other adjustable variables mentioned above and you have plenty to play with to make it suit your tastes. Just my $0.02......
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Really no reason. That's why most guys keep the stock front bar and just upgrade the rear.
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With weak link (pun intended) with these bars are the drop links. The OEM bend and snap all the time. If you lower your car sometimes they are too short. PSS10's come with longer sway bars for the front but not the back.
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Hey Steve,
That's a pretty interesting chart. Nice work. My corner balance has me at 1320 lbs. front (37.4%) and 2210 lbs. rear (62.6%) which includes driver and 3/4 fuel.
Assuming my math is correct, I just plugged in the numbers on my car and this is what I came up with using 600F/800R rates, a stock front sway, and a rear H&R sway set in the middle.
Total Front wheel spring rate (spring+sway): 477.9 lbs (56.2%)
Total Rear wheel spring rate (spring+sway): 372.6 lbs (43.8%)
At these settings my car has almost no push and oversteers quite easily with throttle. I do have an LSD and no PSM so you have to take that in mind. I can't imagine wanting a higher rear wheel spring rate as it would only increase oversteer. I have actually considered softening the rear a bit and have played with shock setting at the track to get it right.
Are you sure the motion ratios for the front at .88 and rear at .59 are correct???? This seems like too much of a difference. Shouldn't they be almost the same since our car use the same lower control arms and the shocks are located at roughly the same locations front and rear? It would seem that using a much smaller .59 motion ration in the rear is understating the rear wheel spring rate by quite a bit. It doesn't quite seem right..... Hmm..
What I also found interesting is that according to your chart, the H&R rear sway bar on the middle setting is almost 3x as stiff as the GT3 rear sway bar on the firmest setting (102 lbs./inch v. 35.2 lbs./inch sway bar wheel rate). That is a huge difference! How did you determine the lbs./inch. deflection rate of the swaybars??
It's interesting that the 997 GT2 RS would have a rear wheel spring rate of 55% because in order to get that you would have to run a very large difference in spring rate front to rear or a huge rear sway. It's interesting to note that most track 996tts or GT3s are running very small front to rear spring rate spreads usually on the order of 200 lbs and sometimes less. GMG for example favors 600/800 rates for their 996 track cars with 500/700 and 700/900 being also very popular. A 996 Cup car uses 1370/1484 spring rates which will give you a 67% front and 33% rear wheel rate!!! Sway bar setting will alter those numbers a little but only a couple of percent especially with such high spring rates.
For example, in order for me to get a 55% rear wheel rate with my 600/800 spring rates I would have to run a rear sway bar that would give a sway bar wheel rate of 305 lb./in. or roughly 3x that of the H&R at the middle setting or 9x that of the GT3 bar at the firmest setting!!!!! It's interesting to note that the KW club coilovers for the 996tt / GT2 use something like 400F/1100R spring rates and those would get you right at the 55% rear wheel rate. However, most race teams will tell you that the KW rates do not work well at all on the 996tt / GT2 platform as the car ends up way too under sprung in the front.
Even in your case, you can see that in order to get to a 55% rear wheel rate (like the 997GT3 RS) you would have to run the GT3 rear sway on full stiff and also run 260/700 spring rates giving you a 440 lbs front to rear spread. I don't think you would find any one that would recommend those rates as the front would be way too under sprung compared to the rear....
John...
That's a pretty interesting chart. Nice work. My corner balance has me at 1320 lbs. front (37.4%) and 2210 lbs. rear (62.6%) which includes driver and 3/4 fuel.
Assuming my math is correct, I just plugged in the numbers on my car and this is what I came up with using 600F/800R rates, a stock front sway, and a rear H&R sway set in the middle.
Total Front wheel spring rate (spring+sway): 477.9 lbs (56.2%)
Total Rear wheel spring rate (spring+sway): 372.6 lbs (43.8%)
At these settings my car has almost no push and oversteers quite easily with throttle. I do have an LSD and no PSM so you have to take that in mind. I can't imagine wanting a higher rear wheel spring rate as it would only increase oversteer. I have actually considered softening the rear a bit and have played with shock setting at the track to get it right.
Are you sure the motion ratios for the front at .88 and rear at .59 are correct???? This seems like too much of a difference. Shouldn't they be almost the same since our car use the same lower control arms and the shocks are located at roughly the same locations front and rear? It would seem that using a much smaller .59 motion ration in the rear is understating the rear wheel spring rate by quite a bit. It doesn't quite seem right..... Hmm..
What I also found interesting is that according to your chart, the H&R rear sway bar on the middle setting is almost 3x as stiff as the GT3 rear sway bar on the firmest setting (102 lbs./inch v. 35.2 lbs./inch sway bar wheel rate). That is a huge difference! How did you determine the lbs./inch. deflection rate of the swaybars??
It's interesting that the 997 GT2 RS would have a rear wheel spring rate of 55% because in order to get that you would have to run a very large difference in spring rate front to rear or a huge rear sway. It's interesting to note that most track 996tts or GT3s are running very small front to rear spring rate spreads usually on the order of 200 lbs and sometimes less. GMG for example favors 600/800 rates for their 996 track cars with 500/700 and 700/900 being also very popular. A 996 Cup car uses 1370/1484 spring rates which will give you a 67% front and 33% rear wheel rate!!! Sway bar setting will alter those numbers a little but only a couple of percent especially with such high spring rates.
For example, in order for me to get a 55% rear wheel rate with my 600/800 spring rates I would have to run a rear sway bar that would give a sway bar wheel rate of 305 lb./in. or roughly 3x that of the H&R at the middle setting or 9x that of the GT3 bar at the firmest setting!!!!! It's interesting to note that the KW club coilovers for the 996tt / GT2 use something like 400F/1100R spring rates and those would get you right at the 55% rear wheel rate. However, most race teams will tell you that the KW rates do not work well at all on the 996tt / GT2 platform as the car ends up way too under sprung in the front.
Even in your case, you can see that in order to get to a 55% rear wheel rate (like the 997GT3 RS) you would have to run the GT3 rear sway on full stiff and also run 260/700 spring rates giving you a 440 lbs front to rear spread. I don't think you would find any one that would recommend those rates as the front would be way too under sprung compared to the rear....
John...
Let me answer what I can.
First of all remember alignment, tire sizing and tire pressures can all affect the balance as well as personal preference. Some people perfer more oversteer.
Your calculation are spot on for your car.
I'm not sure what alignment and tire sizes you're running, but I can say that my car currently is 222.8lbs. (53.2%) front and 196.1lbs. (46.8%) rear and has a ton of understeer. The turn-in is very crisp, but the car immediately goes to understeer in steady state cornering. I'm currently running a street alignment and a 245/295 tire combo.
The motion ratio front and rear is correct. In the front we have a strut type suspension where the shock is mounted in the upright. On the rear, we have a multilink suspension were the shock is mounted near the middle of the rear lower control arm. You are correct in the assumption that this diminishes the effectiveness of the rear spring.
One of the key stiffness differences of the swaybars is the fact that the H&R bar is solid, making it much stiffer than the stock hollow bars. Hopefully the information below will help.
Formula for swaybar stiffness of a solid steel bar
500,000D^4
K (lbs/in)= --------------------------------
(0.4244xA^2xB)+(0.2264xC^3)
A-Length of end perpendicular to B (torque arm-inches) on the rear of our cars this is the same as C since our rear bar has a 90 degree bend
B-Length of center section (inches) the longer section mounted to the chassis
C-Length of end (inches) from bend to droplink mounting hole
D-Diameter bar (inches)
Spring rate for hollow bar=
D^4 is substituted for (OD^4-ID^4)
As far as the GT3 RS (997.2) is concerned, the spring rates are 228lb. front and 657lb. rear (a 429lb. difference front to rear, direct from Porsche). The swaybars are 27mm front and 25.5mm rear.
Front
Spring wheel rate: 170.5lbs.
Swaybar wheel rate: 42.7lbs. (makes up 20% of the total wheel rate)
Total wheel rate: 213.3lbs. (43.8%)
Rear
Spring wheel rate: 220.9lbs.
Swaybar wheel rate: 52.7lbs. (makes up 19% of the total wheel rate)
Total wheel rate: 273.6lbs. (56.2%)
As spring rates go up, so do swaybar diameters, so I believe the swaybars can still make a noticeable difference.
Some of this difference may be due to tire sizing. I run a 245/295 combo which is a 45% front and 55% rear ratio. The 997.2 GT3-RS runs a 245/325 combo which is a 43% front and 57% rear ratio. I'm not sure about your tire sizing.
I would assume a track car would run significantly more front camber and larger front tires (relative to the rears), so you would have more front grip without using the springs and swaybars.
It will be interesting to see what others post.
Later, Steve
Last edited by Steve Jarvis; Nov 5, 2012 at 08:18 AM.
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Later, Steve
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I'm definitely no expert and hopefully there are others that can help shed some light on your questions.
Let me answer what I can.
First of all remember alignment, tire sizing and tire pressures can all affect the balance as well as personal preference. Some people perfer more oversteer.
Your calculation are spot on for your car.
I'm not sure what alignment and tire sizes you're running, but I can say that my car currently is 222.8lbs. (53.2%) front and 196.1lbs. (46.8%) rear and has a ton of understeer. The turn-in is very crisp, but the car immediately goes to understeer in steady state cornering. I'm currently running a street alignment and a 245/295 tire combo.
The motion ratio front and rear is correct. In the front we have a strut type suspension where the shock is mounted in the upright. On the rear, we have a multilink suspension were the shock is mounted near the middle of the rear lower control arm. You are correct in the assumption that this diminishes the effectiveness of the rear spring.
One of the key stiffness differences of the swaybars is the fact that the H&R bar is solid, making it much stiffer than the stock hollow bars. Hopefully the information below will help.
Formula for swaybar stiffness of a solid steel bar
500,000D^4
K (lbs/in)= --------------------------------
(0.4244xA^2xB)+(0.2264xC^3)
A-Length of end perpendicular to B (torque arm-inches) on the rear of our cars this is the same as C since our rear bar has a 90 degree bend
B-Length of center section (inches) the longer section mounted to the chassis
C-Length of end (inches) from bend to droplink mounting hole
D-Diameter bar (inches)
Spring rate for hollow bar=
D^4 is substituted for (OD^4-ID^4)
As far as the GT3 RS (997.2) is concerned, the spring rates are 228lb. front and 657lb. rear (a 429lb. difference front to rear, direct from Porsche). The swaybars are 27mm front and 25.5mm rear.
Front
Spring wheel rate: 170.5lbs.
Swaybar wheel rate: 42.7lbs. (makes up 20% of the total wheel rate)
Total wheel rate: 213.3lbs. (43.8%)
Rear
Spring wheel rate: 220.9lbs.
Swaybar wheel rate: 52.7lbs. (makes up 19% of the total wheel rate)
Total wheel rate: 273.6lbs. (56.2%)
As spring rates go up, so do swaybar diameters, so I believe the swaybars can still make a noticeable difference.
Some of this difference may be due to tire sizing. I run a 245/295 combo which is a 45% front and 55% rear ratio. The 997.2 GT3-RS runs a 245/325 combo which is a 43% front and 57% rear ratio. I'm not sure about your tire sizing.
I would assume a track car would run significantly more front camber and larger front tires (relative to the rears), so you would have more front grip without using the springs and swaybars.
It will be interesting to see what others post.
Later, Steve
Let me answer what I can.
First of all remember alignment, tire sizing and tire pressures can all affect the balance as well as personal preference. Some people perfer more oversteer.
Your calculation are spot on for your car.
I'm not sure what alignment and tire sizes you're running, but I can say that my car currently is 222.8lbs. (53.2%) front and 196.1lbs. (46.8%) rear and has a ton of understeer. The turn-in is very crisp, but the car immediately goes to understeer in steady state cornering. I'm currently running a street alignment and a 245/295 tire combo.
The motion ratio front and rear is correct. In the front we have a strut type suspension where the shock is mounted in the upright. On the rear, we have a multilink suspension were the shock is mounted near the middle of the rear lower control arm. You are correct in the assumption that this diminishes the effectiveness of the rear spring.
One of the key stiffness differences of the swaybars is the fact that the H&R bar is solid, making it much stiffer than the stock hollow bars. Hopefully the information below will help.
Formula for swaybar stiffness of a solid steel bar
500,000D^4
K (lbs/in)= --------------------------------
(0.4244xA^2xB)+(0.2264xC^3)
A-Length of end perpendicular to B (torque arm-inches) on the rear of our cars this is the same as C since our rear bar has a 90 degree bend
B-Length of center section (inches) the longer section mounted to the chassis
C-Length of end (inches) from bend to droplink mounting hole
D-Diameter bar (inches)
Spring rate for hollow bar=
D^4 is substituted for (OD^4-ID^4)
As far as the GT3 RS (997.2) is concerned, the spring rates are 228lb. front and 657lb. rear (a 429lb. difference front to rear, direct from Porsche). The swaybars are 27mm front and 25.5mm rear.
Front
Spring wheel rate: 170.5lbs.
Swaybar wheel rate: 42.7lbs. (makes up 20% of the total wheel rate)
Total wheel rate: 213.3lbs. (43.8%)
Rear
Spring wheel rate: 220.9lbs.
Swaybar wheel rate: 52.7lbs. (makes up 19% of the total wheel rate)
Total wheel rate: 273.6lbs. (56.2%)
As spring rates go up, so do swaybar diameters, so I believe the swaybars can still make a noticeable difference.
Some of this difference may be due to tire sizing. I run a 245/295 combo which is a 45% front and 55% rear ratio. The 997.2 GT3-RS runs a 245/325 combo which is a 43% front and 57% rear ratio. I'm not sure about your tire sizing.
I would assume a track car would run significantly more front camber and larger front tires (relative to the rears), so you would have more front grip without using the springs and swaybars.
It will be interesting to see what others post.
Later, Steve
Front camber: -2.3
Rear camber: -2.0
Tires: 235/40/18 and 315/30/18 Nitto NT01 R compound
Front swaybar: stock
Rear swaybar: H&R on middle setting
Springs: 600F/800R Eibach ERS
Shocks: JRZ
PSM: None
LSD: Guard 40/60
Drive: RWD
All the testing that I have done with the car has been on the track where I have a consistently repeatable environment and can push the car to the limit as opposed to on the street. The interesting thing is the fact that after I changed from my prior H&R coilovers set up that used 260F/515R springs to the JRZ coilovers with 600F/800R rates (with everything else remaining the same) is that the oversteer of the car increased a little contrary to what I expected. I expected the car to push a bit more with the much stiffer front rates compared to the rear but the result was the exact opposite. Another interesting observation is the fact that the ride only feels a touch stiffer compared to the much softer spring rates I had on the car before. My front is more than twice as stiff as before (600 v. 260). Also, I'm not sure if you have an LSD or not but after I added an LSD the initial turn in remained unchanged but the mid turn and exit oversteer increased depending on throttle input. My Guard LSD has a preload of around 60 ft/lb. (about 8x that of the stock GT2/3 LSD) and there is no increased push at all that I am aware off. If anything, I have to be constantly ready to make tiny corrections to keep the back end from stepping out under aggressive power mid turn. As a result, the rumors of an LSD increasing push on these car seems to be hogwash. When I ran the car in AWD form it behaved very much the same as RWD. The difference was very very subtle and maybe just a touch more forgiving at the limit. Back to the swaybar, I fully expected to have to stiffen the rear bar with the much stiffer front rates in order to maintain balance but the exact opposite seems to be the case. Go figure.....
Last edited by pwdrhound; Nov 5, 2012 at 12:17 PM.
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I should have an H&R bar added to the rear of my car this month, so I will report the change with my current spring setup.
I don't take the 911 to the track, but have done 1,000's of track miles in other cars. I also instruct, so I have a pretty good idea of the balance of a car and the experience to find the limit.
Interestingly, I believe a little more tail happy car will be safer as my car turns in well, but then pushes. As soon as the front takes a set, it wants to snap the rear out. This is reasonable easy to avoid with a smooth entry while staying at or below the limit of the front tire, but it's not fun or fast. This is very similar to the stock GT2 I drove. Having a front end that stays planted and a rear that prograssively wants to break lose will be much more predictable.
My car is awd with PSM (though I turn it off as much as possible).
I will eventually add an LSD as I firmly believe the spinning inside rear wheel of the open diff 996 turbo forces power to be transferred to the front causing a power on push on exit. The LSD will keep the inside rear wheel from spinning, requiring very little power to be transfered to the front tires and less understeer.
Later, Steve
I don't take the 911 to the track, but have done 1,000's of track miles in other cars. I also instruct, so I have a pretty good idea of the balance of a car and the experience to find the limit.
Interestingly, I believe a little more tail happy car will be safer as my car turns in well, but then pushes. As soon as the front takes a set, it wants to snap the rear out. This is reasonable easy to avoid with a smooth entry while staying at or below the limit of the front tire, but it's not fun or fast. This is very similar to the stock GT2 I drove. Having a front end that stays planted and a rear that prograssively wants to break lose will be much more predictable.
My car is awd with PSM (though I turn it off as much as possible).
I will eventually add an LSD as I firmly believe the spinning inside rear wheel of the open diff 996 turbo forces power to be transferred to the front causing a power on push on exit. The LSD will keep the inside rear wheel from spinning, requiring very little power to be transfered to the front tires and less understeer.
Later, Steve
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Steve, a little more rake might help that understeer problem. Also could be street surface, tire temps (since you don't track it, your front tires are probably cold and less grippy).
The TT has a minimum amount of power going to the front, and it seems that it's never much more than that from what we've seen (guys spinning in the snow and front wheels not turning).
Does it still snap out with the PSM off? PSM does a lot to make the car try to handle, sometimes being over active. I found mine to be more snappy with the PSM on than off.
You SHOULD NOT drive with PSM on and an LSD. I'm pretty sure I've heard that from Guard's and OSGiken.
The TT has a minimum amount of power going to the front, and it seems that it's never much more than that from what we've seen (guys spinning in the snow and front wheels not turning).
Does it still snap out with the PSM off? PSM does a lot to make the car try to handle, sometimes being over active. I found mine to be more snappy with the PSM on than off.
You SHOULD NOT drive with PSM on and an LSD. I'm pretty sure I've heard that from Guard's and OSGiken.
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Joined: Jul 2010
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I should have an H&R bar added to the rear of my car this month, so I will report the change with my current spring setup.
I don't take the 911 to the track, but have done 1,000's of track miles in other cars. I also instruct, so I have a pretty good idea of the balance of a car and the experience to find the limit.
Interestingly, I believe a little more tail happy car will be safer as my car turns in well, but then pushes. As soon as the front takes a set, it wants to snap the rear out. This is reasonable easy to avoid with a smooth entry while staying at or below the limit of the front tire, but it's not fun or fast. This is very similar to the stock GT2 I drove. Having a front end that stays planted and a rear that prograssively wants to break lose will be much more predictable.
My car is awd with PSM (though I turn it off as much as possible).
I will eventually add an LSD as I firmly believe the spinning inside rear wheel of the open diff 996 turbo forces power to be transferred to the front causing a power on push on exit. The LSD will keep the inside rear wheel from spinning, requiring very little power to be transfered to the front tires and less understeer.
Later, Steve
I don't take the 911 to the track, but have done 1,000's of track miles in other cars. I also instruct, so I have a pretty good idea of the balance of a car and the experience to find the limit.
Interestingly, I believe a little more tail happy car will be safer as my car turns in well, but then pushes. As soon as the front takes a set, it wants to snap the rear out. This is reasonable easy to avoid with a smooth entry while staying at or below the limit of the front tire, but it's not fun or fast. This is very similar to the stock GT2 I drove. Having a front end that stays planted and a rear that prograssively wants to break lose will be much more predictable.
My car is awd with PSM (though I turn it off as much as possible).
I will eventually add an LSD as I firmly believe the spinning inside rear wheel of the open diff 996 turbo forces power to be transferred to the front causing a power on push on exit. The LSD will keep the inside rear wheel from spinning, requiring very little power to be transfered to the front tires and less understeer.
Later, Steve
Can you weight the H&R rear solid sway and the GT3 rear hollow sway? I am curious to the difference in the weight of the two. Thanks....
Last edited by pwdrhound; Nov 5, 2012 at 01:23 PM.
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From: Lewisville, NC
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Steve, a little more rake might help that understeer problem. Also could be street surface, tire temps (since you don't track it, your front tires are probably cold and less grippy).
The TT has a minimum amount of power going to the front, and it seems that it's never much more than that from what we've seen (guys spinning in the snow and front wheels not turning).
Does it still snap out with the PSM off? PSM does a lot to make the car try to handle, sometimes being over active. I found mine to be more snappy with the PSM on than off.
You SHOULD NOT drive with PSM on and an LSD. I'm pretty sure I've heard that from Guard's and OSGiken.
The TT has a minimum amount of power going to the front, and it seems that it's never much more than that from what we've seen (guys spinning in the snow and front wheels not turning).
Does it still snap out with the PSM off? PSM does a lot to make the car try to handle, sometimes being over active. I found mine to be more snappy with the PSM on than off.
You SHOULD NOT drive with PSM on and an LSD. I'm pretty sure I've heard that from Guard's and OSGiken.
The surface etc. should effect both the front and rear grip.
Keep in mind, I'm referring to steady state grip, not power induced under/over steer. Just for laughs, here's a video of me in my E46 daily driver/track car on the skidpad.
Interesting about not using LSD with the PSM, not that I would miss PSM for a second. I wish all of these systems from the late 90's through the early 2000's would give you the choice to leave them off. It's a pain to have to hit the off button every time you start the car.
I would definitely like to know more about why they won't work together.
What's involved in fully disabling PSM?
Later, Steve