Help me plan a suspension upgrade please
05-20-2017, 09:47 PM
#16
Rennlist Member
my comments:
1 - i think it is pretty unrealistic to take a stock plane jane 95 993 and make it handle like a 996 gt3, without the harsh ride. the 996 gt3 is about as harsh and controlled as it gets and the tightness/responsiveness of the suspension is what gives it the tremendous connectedness (but also lack of forgiveness/compliance) that is the hallmark of the 996 gt3 handling
2. pss9/10 kit in a 993 is NOT soft at all. short of a race suspension with solid links/monoballs all around it is one of the firmest sporty street suspensions you can put on a 993
3. you can go h&r springs and bilstein hd's which will ride even harder than pss9/10, and maybe FEEL more controlled, but i don't think it will handle any better, just be harsher
4. some have had good luck with higher level kw's - you may want to check with spyerx on the 964 board - he swears by the kw's and of course singer installs them on their cars but i doubt those spring/damper rates would be any softer than the bilstein kit ... i have not driven a singer yet but every review says you feel every ripple in the pavement
to be honest, only in the current day 991 generation gt3 do you really 'get to have your cake and eat it too' - meaning super responsive super sharp handling coupled with smooth compliant semi-comfy ride (you definitely don't get that in 997 gt3's imo, albeit 997 gt3's are one level more compliant than 996 gt3's)
1 - i think it is pretty unrealistic to take a stock plane jane 95 993 and make it handle like a 996 gt3, without the harsh ride. the 996 gt3 is about as harsh and controlled as it gets and the tightness/responsiveness of the suspension is what gives it the tremendous connectedness (but also lack of forgiveness/compliance) that is the hallmark of the 996 gt3 handling
2. pss9/10 kit in a 993 is NOT soft at all. short of a race suspension with solid links/monoballs all around it is one of the firmest sporty street suspensions you can put on a 993
3. you can go h&r springs and bilstein hd's which will ride even harder than pss9/10, and maybe FEEL more controlled, but i don't think it will handle any better, just be harsher
4. some have had good luck with higher level kw's - you may want to check with spyerx on the 964 board - he swears by the kw's and of course singer installs them on their cars but i doubt those spring/damper rates would be any softer than the bilstein kit ... i have not driven a singer yet but every review says you feel every ripple in the pavement
to be honest, only in the current day 991 generation gt3 do you really 'get to have your cake and eat it too' - meaning super responsive super sharp handling coupled with smooth compliant semi-comfy ride (you definitely don't get that in 997 gt3's imo, albeit 997 gt3's are one level more compliant than 996 gt3's)
05-20-2017, 10:12 PM
#17
Three Wheelin'
Well said. Jackal addresses this question here: http://www.jackals-forge.com/lotus/gt3/gt3_vs_993.html
He's comparing his RS clone with the GT3 and in the end he feels the GT3 is more capable but the 993 is more emotionally appealing. He can't pick a favorite.
Its worth noting that his 993 is taken as far down the RS road you can go - much further than any of the suggestions above.
He's comparing his RS clone with the GT3 and in the end he feels the GT3 is more capable but the 993 is more emotionally appealing. He can't pick a favorite.
Its worth noting that his 993 is taken as far down the RS road you can go - much further than any of the suggestions above.
05-21-2017, 10:10 AM
#19
My two cents, replace the rubber as a matter of course when doing the suspension upgrade. New shocks/springs with old bushings is not going to provide the end result you are seeking. I have the HR&bilstein suspension. Love it. It's very tight and you feel the road. That said, its not my daily.
05-21-2017, 06:42 PM
#20
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When it comes to handling, torsional stiffness and the location (height) of the centre of gravity are the first two measurements that professional chassis engineer needs to know before doing a kinematic analysis of the suspension motion. That's why, at the time Porsche introduced the 996 model, one of the most quoted design improvements over the previous (993) model was the 45% increase in torsional stiffness. Given this insight, the "solution" you desire should begin with increasing the body shell stiffness of your 993 which can be partially achieved with seam welding, local reinforcement or ultimately - a fully comprehensive welded in roll cage like the RS Clubsport M003.
The next priority is to lower the centre of gravity and reduce the mass of the car. Think sunroof delete, lightweight glass, lightweight seats, lightweight panels, etc. to reduce mass, lowering the ride height to drop the CoG. Unspring weight is also important, so a set of lightweight wheels won't go amiss either. Whilst we are thinking about round things on the corners, fit a good set of tyres which are suited to your intended purpose.
Then look at the kinematics. What this means in layman's terms is suspension deformation under load (bushes, top mounts, subframe bushes) and bump steer reduction. Upgrading bushes to RS specification is a given, for a road car I recommend harder RS specification rubber bushes rather than rose joints. My preference for rear subframe bushes are the GT2 Evo solid mounts (aka stiff axle kit) which also addresses excessive kinematic steer of the rear end (this was the best mod I ever did to my RS). A pair of 993RS uprights would be next on my shopping list. Finally, consider RS top mounts although new standard top mounts might be a better choice if NVH (Noise, Vibration, Harshness) is of concern.
The last items on the shopping list are springs, dampers and anti-roll bars. Get all of the above right and you will not need to go overboard on the spring and damper stiffness to achieve a great handling package - in my opinion the majority of set ups are run too hard deliberately to reduce suspension travel and limit the kinematic errors of the suspension movement. Finally, RS arb's will offer adjustment for fine tuning the set up to suit your driving style.
I hope this helps you to understand that every component to be thoroughly considered and selected in order to complement each other, resulting in an optimal solution which fulfils all your requirements.
05-22-2017, 04:09 PM
#22
Three Wheelin'
When it comes to handling, torsional stiffness and the location (height) of the centre of gravity are the first two measurements that professional chassis engineer needs to know before doing a kinematic analysis of the suspension motion. That's why, at the time Porsche introduced the 996 model, one of the most quoted design improvements over the previous (993) model was the 45% increase in torsional stiffness. Given this insight, the "solution" you desire should begin with increasing the body shell stiffness of your 993 which can be partially achieved with seam welding, local reinforcement or ultimately - a fully comprehensive welded in roll cage like the RS Clubsport M003.
The next priority is to lower the centre of gravity and reduce the mass of the car. Think sunroof delete, lightweight glass, lightweight seats, lightweight panels, etc. to reduce mass, lowering the ride height to drop the CoG. Unspring weight is also important, so a set of lightweight wheels won't go amiss either. Whilst we are thinking about round things on the corners, fit a good set of tyres which are suited to your intended purpose.
Then look at the kinematics. What this means in layman's terms is suspension deformation under load (bushes, top mounts, subframe bushes) and bump steer reduction. Upgrading bushes to RS specification is a given, for a road car I recommend harder RS specification rubber bushes rather than rose joints. My preference for rear subframe bushes are the GT2 Evo solid mounts (aka stiff axle kit) which also addresses excessive kinematic steer of the rear end (this was the best mod I ever did to my RS). A pair of 993RS uprights would be next on my shopping list. Finally, consider RS top mounts although new standard top mounts might be a better choice if NVH (Noise, Vibration, Harshness) is of concern.
The last items on the shopping list are springs, dampers and anti-roll bars. Get all of the above right and you will not need to go overboard on the spring and damper stiffness to achieve a great handling package - in my opinion the majority of set ups are run too hard deliberately to reduce suspension travel and limit the kinematic errors of the suspension movement. Finally, RS arb's will offer adjustment for fine tuning the set up to suit your driving style.
I hope this helps you to understand that every component to be thoroughly considered and selected in order to complement each other, resulting in an optimal solution which fulfils all your requirements.
The next priority is to lower the centre of gravity and reduce the mass of the car. Think sunroof delete, lightweight glass, lightweight seats, lightweight panels, etc. to reduce mass, lowering the ride height to drop the CoG. Unspring weight is also important, so a set of lightweight wheels won't go amiss either. Whilst we are thinking about round things on the corners, fit a good set of tyres which are suited to your intended purpose.
Then look at the kinematics. What this means in layman's terms is suspension deformation under load (bushes, top mounts, subframe bushes) and bump steer reduction. Upgrading bushes to RS specification is a given, for a road car I recommend harder RS specification rubber bushes rather than rose joints. My preference for rear subframe bushes are the GT2 Evo solid mounts (aka stiff axle kit) which also addresses excessive kinematic steer of the rear end (this was the best mod I ever did to my RS). A pair of 993RS uprights would be next on my shopping list. Finally, consider RS top mounts although new standard top mounts might be a better choice if NVH (Noise, Vibration, Harshness) is of concern.
The last items on the shopping list are springs, dampers and anti-roll bars. Get all of the above right and you will not need to go overboard on the spring and damper stiffness to achieve a great handling package - in my opinion the majority of set ups are run too hard deliberately to reduce suspension travel and limit the kinematic errors of the suspension movement. Finally, RS arb's will offer adjustment for fine tuning the set up to suit your driving style.
I hope this helps you to understand that every component to be thoroughly considered and selected in order to complement each other, resulting in an optimal solution which fulfils all your requirements.
05-23-2017, 11:35 AM
#25
Three Wheelin'
For me it 140 front, 130 rear combined with an RS alignment and a low KT setting. Along with all the other work done on the suspension its a car transformed. I'm running camber of 1.2/1.7 and that feels pretty good. You can go more aggressive, especially in front and on my next alignment I'll bump the front up to match more closely to the rear. I'm running very little toe in front (1/32 total) and that seems to help with turn in. KT is set to 3.5 and I'm told by BillV I can go lower and I may want to try that next time.
05-23-2017, 11:52 AM
#26
Rennlist Member
Good advice here...
Agree. "...MO33 springs and Koni FSD shocks with new bushings. Good enough for street use. People even run 18" wheels on this setup and find it compliant."
I have riden in a car with the above set up, very nice, and comes with an improvement in ride height (aka lower). I am comparing the M033 springs and the Koni suspension to memories of various suspension iterations I have had on my car, past and present:
1.) M030 (RoW), sporty and more than adequate for the track, good on the street too,
2.) PSS9s with TRG sways, and later 993 RS sways, good at the time,
3.) Presently, (From Steve Weiner) MCS 3 way suspension, H&R springs, with 993 RS sways and a complete ERP rear suspension component set (Tarrett Engineering) up, 993 RS wheel carriers and ERP GT2 toe links, TRG camber plates, -3.5 degrees of camber front, -3.0 negative camber rear, 0 toe on the front (There is no flexing rubber in my tie rods). The cabin noise with all these monoballs is noisy, and one would expect. The track performance, over the top.
If the suspension bushings are worn, replace them. Since you are not developing a track car, stick with the 17" (7" F, 9" R) wheels, better ride, sidewalls on 17" tires are generally taller. Tires are lighter and cheaper too. You will be pleasantly surprised on how nicely this set up handles with decent tires.
I have riden in a car with the above set up, very nice, and comes with an improvement in ride height (aka lower). I am comparing the M033 springs and the Koni suspension to memories of various suspension iterations I have had on my car, past and present:
1.) M030 (RoW), sporty and more than adequate for the track, good on the street too,
2.) PSS9s with TRG sways, and later 993 RS sways, good at the time,
3.) Presently, (From Steve Weiner) MCS 3 way suspension, H&R springs, with 993 RS sways and a complete ERP rear suspension component set (Tarrett Engineering) up, 993 RS wheel carriers and ERP GT2 toe links, TRG camber plates, -3.5 degrees of camber front, -3.0 negative camber rear, 0 toe on the front (There is no flexing rubber in my tie rods). The cabin noise with all these monoballs is noisy, and one would expect. The track performance, over the top.
If the suspension bushings are worn, replace them. Since you are not developing a track car, stick with the 17" (7" F, 9" R) wheels, better ride, sidewalls on 17" tires are generally taller. Tires are lighter and cheaper too. You will be pleasantly surprised on how nicely this set up handles with decent tires.
05-24-2017, 01:07 PM
#27
Rennlist Member
05-24-2017, 01:12 PM
#28
Three Wheelin'
Colin, you mention RS bushings in every location except for the subframe where you recommend solid. Why is that? Why not use RS hardness bushings there as well?
05-24-2017, 02:15 PM
#29
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If you recall, I own a 993RS Clubsport and as an upgrade fitted the GT2 Evo stiff axle kit. I rate that single modification as the most significant upgrade I ever did to my car, it knocked seconds off my lap times with the confidence it gave me that the back end finally stayed where I put it. I had the RS bushes, the stiff axle kit is night and day better on track.
05-24-2017, 02:20 PM
#30
Three Wheelin'
Interesting. Maybe this is impossible to tell, but how much of this do you think is due to the revised rear geometry vs. reduced movement in the subframe?
I'm wondering if this is a useful upgrade over RS subframe bushes on a street car that is closer to RoW Sport height than RS height?
I'm wondering if this is a useful upgrade over RS subframe bushes on a street car that is closer to RoW Sport height than RS height?