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C4 alignment/sways settings to minimize understeer
I am getting a new-to-me C4 -- for this AWD car, I have read posts and seen YouTube videos saying that thru 4-wheel alignment and sway bars one car can try to reduce/minimize the tendency for the car to push through turns.
Would be appreciative if any C4 owners can shed light on this. My car is on Euro height lowering springs and Bilstein shocks, otherwise stock, with updated/refreshed bushings etc etc. I would be happy to leave it at this height. Not contemplating coilovers (although KW V3's have been recommended to me). This is a weekend road car, not a track rat. |
Congrats on the new purchase!
Others will chime in soon with more experience or detail, but this series is definitely worth a read:
https://rennlist.com/forums/964-foru...-4-pt-1-a.html |
thanks jetta! just what the doctor ordered :) :cheers:
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Steve W. of Rennsport did manage to make my C4 completely neutral with the right combination of ride height, corner balance and RS adjustable swaybars, on stock 17" cups and the ubiquitous HR Green/Bilstein HD setup. No perceptible understeer with the PDAS in full function. If you have budget, it might be worth an hour of his consulting time to get the right setup... or he can help you source parts. 503 244 0990
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Originally Posted by tbennett017
(Post 14886636)
Steve W. of Rennsport did manage to make my C4 completely neutral with the right combination of ride height, corner balance and RS adjustable swaybars, on stock 17" cups and the ubiquitous HR Green/Bilstein HD setup. No perceptible understeer with the PDAS in full function. If you have budget, it might be worth an hour of his consulting time to get the right setup... or he can help you source parts. 503 244 0990
thx tom steve w is the man, we have crossed paths often before, i have benefited from his knowledge and will continue to do so! |
Bilstein/HR purple springs here, with a "semi-aggressive" alignment done by a shop that set up lots of race cars, including a few 964s. I really can't complain of any understeer right now. Certainly has less of it than my Cayman when stock.
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I just finished installing B6 and H&R lowering springs. Car is set up at RS height and alignment. The car is handling well and a lot more direct. However, I am still working on eliminating that push / understeer feeling in deep corners. I have sourced a new Porsche C2/C4 21mm rear sway bar to replace the 18mm rear sway bar. I haven’t installed it yet, but I am looking forward (hopefully) to another improvement. |
not sure given the nature of the car and its AWD/PCAS that it will ever be understeer-free under track conditions pushed near its limits in mid/tight turns, for that matter C2's aren't either
what i am getting from the wonderful, old articles is: use thicker/stiffer rear sway lower and apply some forward rake add more front camber use stickier wider rubber lower tire pressures all of which makes perfect sense... load up the front into turns and help the front end turn i am sure more modern coilover kits (since the old articles were written just after the C4 was launched) like pss10 and kw series can also be set up this way like the old B6's/H&Rs |
Just to throw another couple of other thoughts in the mix.
My RUF suspension package included a 23mm front ARB and 22mm rear ARB. I don't find understeer a problem, but actively drive to suit the C4. Brake heavy while turning to the apex then power on early when pointing at the apex. It feels like the hook up they talk about in the article. At some stage soon I'm going to investigate the theory that feeding voltage to the brake line sensor in the PDAS disables it, thereby making it a simple four wheel drive car and avoiding the diff locking leading to understeer. |
Originally Posted by John McM
(Post 14889920)
At some stage soon I'm going to investigate the theory that feeding voltage to the brake line sensor in the PDAS disables it, thereby making it a simple four wheel drive car and avoiding the diff locking leading to understeer.
disable the PDAS for the duration of a drive by twisting the diff-lock console switch for +10 seconds and clear the red ! warning. Cycling Ignition off/on (whilst stopped :) ) to return to normal operation. Search this forum for "disable PDAS" for a number of related threads. There are two modes of understeer, one attributable to suspension alignment and set-up under spirited driving. The other when the PDAS intervenes to vector torque and more is demanded of a driven wheel than traction available (at that moment) leading to understeer. Most of the threads settle in on tuning the suspension first, as playing with the PDAS doesn't cure the first understeer condition: tires, toe, pressure, anti-roll bars, springs, ... Enjoy your car! |
Originally Posted by ezinternet
(Post 14890142)
Not a theory. Tap the brakes, or
disable the PDAS for the duration of a drive by twisting the diff-lock console switch for +10 seconds and clear the red ! warning. Cycling Ignition off/on (whilst stopped :) ) to return to normal operation. Search this forum for "disable PDAS" for a number of related threads. There are two modes of understeer, one attributable to suspension alignment and set-up under spirited driving. The other when the PDAS intervenes to vector torque and more is demanded of a driven wheel than traction available (at that moment) leading to understeer. Most of the threads settle in on tuning the suspension first, as playing with the PDAS doesn't cure the first understeer condition: tires, toe, pressure, anti-roll bars, springs, ... Enjoy your car! |
Adjustments++++++++++++++++++++Decrease Understeer++++++++++++++Decrease Oversteer++++++++++++++++++++++
Front Tire Pressure--------------------------Higher---------------------------------------------Lower-------------------------------------------------------- Rear Tire Pressure--------------------------Lower----------------------------------------------Higher-------------------------------------------------------- Front Tire Section----------------------------Larger-------------------------------------------Smaller------------------------------------------------------ Rear Tire Section----------------------------Smaller--------------------------------------------Larger------------------------------------------------------ Front Wheel Camber-----------------------More Negative-----------------------------------More Positive--------------------------------------------- Rear Wheel Camber-----------------------More Positive-------------------------------------More Negative-------------------------------------------- Front Wheel Toe----------------------------Toe-Out---------------------------------------------Toe-In------------------------------------------------------- Rear Wheel Toe-----------------------------Toe-In-----------------------------------------------Toe-Out---------------------------------------------------- Front Wheel Caster-------------------------More Positive-------------------------------------More Negative------------------------------------------- Front Springs---------------------------------Soften-----------------------------------------------Stiffen----------------------------------------------------- Rear Springs----------------------------------Stiffen-----------------------------------------------Soften----------------------------------------------------- Front Anti-sway Bar-------------------------Soften (Thinner)----------------------------------Stiffen (Thicken)---------------------------------------- Rear Anti-sway Bar--------------------------Stiffen(Thicker)-----------------------------------Soften (Thinner)----------------------------------------- Weight Distribution---------------------------More Rearward----------------------------------More Forward--------------------------------------------- These variables are quite dynamic in nature. As with all setups, one parameter effects the other. So there are infinite amount of adjustments. These guidelines are not absolutes and there are other parameters such as tire pressure, rubber compound, track conditions, temperatures, driver preference etc..... |
Originally Posted by henryting
(Post 14890249)
Adjustments++++++++++++++++++++Decrease Understeer++++++++++++++Decrease Oversteer++++++++++++++++++++++
Front Tire Pressure--------------------------Higher---------------------------------------------Lower-------------------------------------------------------- Rear Tire Pressure--------------------------Lower----------------------------------------------Higher-------------------------------------------------------- Front Tire Section----------------------------Larger-------------------------------------------Smaller------------------------------------------------------ Rear Tire Section----------------------------Smaller--------------------------------------------Larger------------------------------------------------------ Front Wheel Camber-----------------------More Negative-----------------------------------More Positive--------------------------------------------- Rear Wheel Camber-----------------------More Positive-------------------------------------More Negative-------------------------------------------- Front Wheel Toe----------------------------Toe-Out---------------------------------------------Toe-In------------------------------------------------------- Rear Wheel Toe-----------------------------Toe-In-----------------------------------------------Toe-Out---------------------------------------------------- Front Wheel Caster-------------------------More Positive-------------------------------------More Negative------------------------------------------- Front Springs---------------------------------Soften-----------------------------------------------Stiffen----------------------------------------------------- Rear Springs----------------------------------Stiffen-----------------------------------------------Soften----------------------------------------------------- Front Anti-sway Bar-------------------------Soften (Thinner)----------------------------------Stiffen (Thicken)---------------------------------------- Rear Anti-sway Bar--------------------------Stiffen(Thicker)-----------------------------------Soften (Thinner)----------------------------------------- Weight Distribution---------------------------More Rearward----------------------------------More Forward--------------------------------------------- These variables are quite dynamic in nature. As with all setups, one parameter effects the other. So there are infinite amount of adjustments. These guidelines are not absolutes and there are other parameters such as tire pressure, rubber compound, track conditions, temperatures, driver preference etc..... |
Originally Posted by Lorenzoh
(Post 14890772)
WTF are you talking about?? |
Seems like my post was reformatted and the layout changed, making it unreadable. Please disregard the post. I'll try to redo it.
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