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+--- Thread: Pocono MAW pictures (/showthread.php?tid=846)
- bobt993 - 09-27-2007
Eric, there's no blurrrrr technique on Jim's pict?:X
- JIMK - 09-27-2007
bobt993 wrote:
Quote:Eric, there's no blurrrrr technique on Jim's pict?:XBoy, I DO drive slow.... it that parked?
- Mike Andrews - 09-27-2007
Darren wrote:
Quote:bobt993 wrote:Quote:You notice alot of picts with cars getting inside wheel lift in T4. I have been working hard on avoiding this by braking almost to the apex instead of early throttle at turn in.
I was suprised to see this -- certainly couldn't feel it. There must be tons of grip on that left rear wheel. I suppose braking later and trailing through would help keep some weight forward, but that is compensating for the real problem which I'm thinking is not enough rear spring rate...There is a lot of compression on that left rear.
Darren,
It's all about weight transfer. And suspension travel.... You hit the nail on the head, the car needs more spring rate.
To compound the problem most people put bigger anti-sway bars on their cars (instead of stiffer springs) and that then limits the downward movement of the inside wheel.
If the car is street driven you reach a point of compromise where you don't want to go stiffer and then you simply live with lifting the inside wheel.
- Darren - 09-27-2007
Mike Andrews wrote:
Quote:Darren,Thanks Mike, I was already trying to figure out what springs to change to but you're right that I should consider this part of the street/track compromise. I'm happy with the balance of the car for the most part, and if I make it much stiffer I'm not going to want to drive it on the street.
It's all about weight transfer. And suspension travel.... You hit the nail on the head, the car needs more spring rate.
To compound the problem most people put bigger anti-sway bars on their cars (instead of stiffer springs) and that then limits the downward movement of the inside wheel.
If the car is street driven you reach a point of compromise where you don't want to go stiffer and then you simply live with lifting the inside wheel.
- catchacab - 09-27-2007
Darren
PSS9's are not great for the track. You can get custom Motons, JRZ's or Cross adjustables with a spring package of your choice. You can also have your PSS9's re-valved and sprung. It will firm up the ride on the street, but you should be able to come to a good comprise. Performance had a PSS9 set re-valved and sprung. There is a 996 that runs in black that has the Cross system that is used for both street and track.
The difference between yours and Bob's style of cornering, shows the difference between what PCA teaches at DE's for safely driving rear and mid engined cars and what many racers do.
- Darren - 09-27-2007
catchacab wrote:
Quote:PSS9's are not great for the track. You can get custom Motons, JRZ's or Cross adjustables with a spring package of your choice. You can also have your PSS9's re-valved and sprung. It will firm up the ride on the street, but you should be able to come to a good comprise. Performance had a PSS9 set re-valved and sprung. There is a 996 that runs in black that has the Cross system that is used for both street and track.
The difference between yours and Bob's style of cornering, shows the difference between what PCA teaches at DE's for safely driving rear and mid engined cars and what many racers do.
The main difference between what Bob and I am doing is that Bob is left foot braking, which I can't do on my e-gas car. About 2 seconds after I hit the brake, the throttle is electronically cut. This allows him to get on the throttle and modulate the throttle and brake to balance the car and keep it on the edge of the limit of adhesion through T4. I also think (I'd like to walk that track) that the camber falls off a little on the wider line, which contributes to the lifting problem.
I think the PSS9 is quite good for a compromise street/track car. I've replaced all of the rubber bushings on my car, so it's a lot more modified than most cars with PSS9's. I have the rear upper adjustable spherical control arms, spherical toe link, solid radius arm bushings (front and rear) and of course spherical upper strut mounts (front and rear). To me, I'd rather have NO rubber bushings and lower spring rates than rubber bushings and higher spring rates -- the latter just adds to an already existent geometry problem by causing even more bushing deflection!
All of these mods help keep the suspension aligned correctly throughout a corner. I'm able to run about 1/8" LESS rear toe-in (1/16" total rear toe in!) than someone on PSS9 with rubber bushings. They also allow the struts to do their job better because the bushings aren't deflecting (undampened shock). I was able to even adjust the length of the rear upper control arms to dial out most of the Porsche designed rear toe change with ride height.
Because the suspension is working so well, I'm able to maintain a decent contact patch -- I don't think many 996's on PSS9 w/sport cups lift tires there.
The main problem with PSS9 is that the spring rates are low, about 230 front and 520 rear, about twice the stock rates. The fronts are too low, causing too much front dive in braking and too much body roll on initial turn-in.
To keep that wheel on the ground, and solve these other problems, I'm thinking of upping the front spring rate +100 lbs, which according to Bilstein "is probably ok" without re-valving, and probably going to a smaller front sway-bar, which like Mike said, will help keep that wheel on the ground. Basically I want to keep the effective spring rate about the same but do it with springs instead of sways.
I really don't want to go to a double adjustable setup on this car right now because of the cost and because I don't want to spend the time necessary to maximize that kind of setup. I like 1 adjustment knob. If you ask guys in our club who have double adjustable setups, you'll find that very few of them make changes track to track, and most of them will openly admit that they don't know how to fine tune them.
- catchacab - 09-27-2007
JRZ and Cross have single adjustables
http://www.cross-na.com/ViewProduct1.aspx?ProductID=83&CarModelID=121&CarMakeID=14
- Darren - 09-27-2007
They do look nice, probably would have been a better option. I'm sort of stuck with what I nave now I think.
- Sechsgang - 09-27-2007
Seriously, if you can, just go with some JRZ shocks...they are soooooo much of an upgrade than the pss9/pcs system. They transformed my elephant on wheels into an elephant on wheels with TOOOOONNNNSSS of grip and suprising poise...
Your outcome will only be better...
- Sechsgang - 09-27-2007