C2 vs C4 Understeer?
01-05-2020, 12:33 AM
#16
Three Wheelin'
As long as you stay at less than 2% difference between front and rear..
Much more and the coupling will die..
The viscous coupling behaviour can vary depending on age and mileage,,
The coupling limits the amount of power that can get to the front.
Based my std C4 cab, I've noticed the front end doesn't come to the game really
until your pushing pretty hard.. And the traction and stability control will throttle you
back if the rear wheels spin.. Mine seems to want classic 911 inputs,,
Break before the turn and be on the throttle through the turn.
Much more and the coupling will die..
The viscous coupling behaviour can vary depending on age and mileage,,
The coupling limits the amount of power that can get to the front.
Based my std C4 cab, I've noticed the front end doesn't come to the game really
until your pushing pretty hard.. And the traction and stability control will throttle you
back if the rear wheels spin.. Mine seems to want classic 911 inputs,,
Break before the turn and be on the throttle through the turn.
01-05-2020, 01:19 AM
#17
Three Wheelin'
As long as you stay at less than 2% difference between front and rear..
Much more and the coupling will die..
The viscous coupling behaviour can vary depending on age and mileage,,
The coupling limits the amount of power that can get to the front.
Based my std C4 cab, I've noticed the front end doesn't come to the game really
until your pushing pretty hard.. And the traction and stability control will throttle you
back if the rear wheels spin.. Mine seems to want classic 911 inputs,,
Break before the turn and be on the throttle through the turn.
Much more and the coupling will die..
The viscous coupling behaviour can vary depending on age and mileage,,
The coupling limits the amount of power that can get to the front.
Based my std C4 cab, I've noticed the front end doesn't come to the game really
until your pushing pretty hard.. And the traction and stability control will throttle you
back if the rear wheels spin.. Mine seems to want classic 911 inputs,,
Break before the turn and be on the throttle through the turn.
01-05-2020, 01:34 AM
#18
Three Wheelin'
So far I've never got in to full traction control on the street in the dry,, My car has both it and stability control,,, the combo inspires.. 
The TC only kicks in for me on Wet or Icy pavement,, I have noticed on "dirty" roads that If I gas it hard enough in a turn I'll
feel just a tick of understeer then it pulls through the turn..
I'm assuming that's the Viscous coupler "locking" up to push power forward.
They don't work instantly in my experience unless its an electrically enhanced coupling.
The TC only kicks in for me on Wet or Icy pavement,, I have noticed on "dirty" roads that If I gas it hard enough in a turn I'll
feel just a tick of understeer then it pulls through the turn..
I'm assuming that's the Viscous coupler "locking" up to push power forward.
They don't work instantly in my experience unless its an electrically enhanced coupling.
01-05-2020, 05:44 PM
#19
Three Wheelin'
As long as you stay at less than 2% difference between front and rear..
Based my std C4 cab, I've noticed the front end doesn't come to the game really
until your pushing pretty hard.. And the traction and stability control will throttle you
back if the rear wheels spin.. Mine seems to want classic 911 inputs,,
Break before the turn and be on the throttle through the turn.
Based my std C4 cab, I've noticed the front end doesn't come to the game really
until your pushing pretty hard.. And the traction and stability control will throttle you
back if the rear wheels spin.. Mine seems to want classic 911 inputs,,
Break before the turn and be on the throttle through the turn.
Are you running 40mm wider stagger in the back, 225/265?
01-06-2020, 01:08 AM
#21
Three Wheelin'
01-06-2020, 01:40 PM
#22
Three Wheelin'
If the original specification was 265 35 then increasing to 285 30 would help decrease oversteer. I would like to do the same if it does not exaggerate understeer. it does satisfy the 2% difference requirement.
01-06-2020, 03:11 PM
#23
Race Director
The driving dynamics of my C4 changed dramatically when I did the "RWD conversion." Regardless of whether power is going through the viscous coupling, the front wheels are still connected via the front differential when the front-drive hardware is installed. I was not satisfied with how my C4 "pushed" through corners in ways I did not expect/want. It also seemed to me that there was far more PSM intervention in corners that didn't seem to warrant it when the front diff was installed.
After removing the FWD components, my 996 behaves much more predictably with no other suspension/tire size/etc. changes.
After removing the FWD components, my 996 behaves much more predictably with no other suspension/tire size/etc. changes.
01-06-2020, 04:59 PM
#24
Three Wheelin'
The driving dynamics of my C4 changed dramatically when I did the "RWD conversion." Regardless of whether power is going through the viscous coupling, the front wheels are still connected via the front differential when the front-drive hardware is installed. I was not satisfied with how my C4 "pushed" through corners in ways I did not expect/want. It also seemed to me that there was far more PSM intervention in corners that didn't seem to warrant it when the front diff was installed.
After removing the FWD components, my 996 behaves much more predictably with no other suspension/tire size/etc. changes.
After removing the FWD components, my 996 behaves much more predictably with no other suspension/tire size/etc. changes.
01-06-2020, 05:22 PM
#25
Rennlist Member
The driving dynamics of my C4 changed dramatically when I did the "RWD conversion." Regardless of whether power is going through the viscous coupling, the front wheels are still connected via the front differential when the front-drive hardware is installed. I was not satisfied with how my C4 "pushed" through corners in ways I did not expect/want. It also seemed to me that there was far more PSM intervention in corners that didn't seem to warrant it when the front diff was installed.
After removing the FWD components, my 996 behaves much more predictably with no other suspension/tire size/etc. changes.
After removing the FWD components, my 996 behaves much more predictably with no other suspension/tire size/etc. changes.
01-06-2020, 07:59 PM
#26
Race Director
I didn't change anything else - the only change at that time was removing the front drive unit and "converting" the front CV assemblies into stub axles. In hindsight, I probably should have just purchased stub axles, but I was eager to prove my indie wrong (at the time, he was convinced that what I was doing would wreck the ABS encoders and render PSM permanently confused).
It could also be that my CV joints were working less efficiently than they should have been. Both joints felt smooth, and the boots were intact and full of clean grease (before I wrecked 'em).
It could also be that my CV joints were working less efficiently than they should have been. Both joints felt smooth, and the boots were intact and full of clean grease (before I wrecked 'em).
I agree on PSM. But I would have thought that alignment settings would have a greater effect on handling than 4 vs 2-wheel drive. So the pushing was due to the diff and/or PSM, or was it something else? Also, is there a sway bar in the rear on the C4 versus the C2? As I understand it, if we want to stiffen up or loosen up the front end, we’d want to adjust the rear sway bar, correct?
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Mike Murphy (01-06-2020)
01-06-2020, 08:33 PM
#27
Rennlist Member
I didn't change anything else - the only change at that time was removing the front drive unit and "converting" the front CV assemblies into stub axles. In hindsight, I probably should have just purchased stub axles, but I was eager to prove my indie wrong (at the time, he was convinced that what I was doing would wreck the ABS encoders and render PSM permanently confused).
It could also be that my CV joints were working less efficiently than they should have been. Both joints felt smooth, and the boots were intact and full of clean grease (before I wrecked 'em).
It could also be that my CV joints were working less efficiently than they should have been. Both joints felt smooth, and the boots were intact and full of clean grease (before I wrecked 'em).
01-07-2020, 09:14 AM
#28
My new-to-me 996.2 C2 is far less nosey at turn-inn than my 996TT is. The Turbo has Ohlins and GT2 alignment.
I’m so enthralled with the C2. A RWD narrowbody feels very light on its feet, quick, and is notably more eager to turn in than most modern 911s I’ve driven recently.
I’m so enthralled with the C2. A RWD narrowbody feels very light on its feet, quick, and is notably more eager to turn in than most modern 911s I’ve driven recently.
01-09-2020, 01:58 AM
#29
Three Wheelin'
My new-to-me 996.2 C2 is far less nosey at turn-inn than my 996TT is. The Turbo has Ohlins and GT2 alignment.
I’m so enthralled with the C2. A RWD narrowbody feels very light on its feet, quick, and is notably more eager to turn in than most modern 911s I’ve driven recently.
I’m so enthralled with the C2. A RWD narrowbody feels very light on its feet, quick, and is notably more eager to turn in than most modern 911s I’ve driven recently.
What size are your front tires/wheels on both?
01-09-2020, 10:37 PM
#30
Drifting
I've owned a C4 and C2, but haven't pushed either to the limit, so can't comment on understeeriness. I don't think it's been mentioned, but it seems relevant to the discussion to take note the weight differences. The C4 weighs 131 lbs more than an identically equipped C2 and I'd guess that the vast majority of that weight is in the front of the car. The C4S weighs 281 lbs more than an identically equipped C2 (presumably only about half of that weight (the AWD and middle radiator?) is biased towards the front of the car).
