I have a 996 with the following suspension:
-PSS10 coilovers
-5mm lowered (compared to EURO M030)
-coliover adjustments: 6 front and 7 rear
-Gt3 street wheel alignment
-Gt3 adjustable sway bars
-Swaybar adjustments: middle front and second stiffest rear
-adjustable uniball droplinks front
-standard droplinks rear

I am quite pleased the suspension, near neutral handling that enable balancing under/oversteer with the throttle and very good directional stablility. The only thing I would like to have is a little better steering response. This may be achieved with different wheel alignments. Previously I had a custom setup with a little more rear toe in, it was spot on regarding steering response, but at the expense of directional stability and tire wear.

Does anybody know if fitting stiffer rear drop links will improve steering response? Are there any other benefits?

 

I've noticed improved steering response from tires. No joke. Not an expert on drop links, but going from Pilot Sport Cups as a street tire to a cheap-o Sumitomo ($400 bones shipped) made a noticeable difference in turn in. Feels like the swaybars are disconnected. Did you recently switch tires?

 

Well, I replaced my front tires with identical Michelin PS2 N3's in August. Everything seems softer with new tires and to me it seems like no improvement in steering response.
Anyway, its hard to keep driving with worn tires all the time.

I wondered if slightly stiffer rear suspension from fitting uniball drop links would affect steering response?
Anybody with track experience out there that might know?

 

What do you mean that you want better steering response? What is the issue? Also, what are your alignment settings?

-td

 

By better steering response I mean a quicker turn-in.

I use the GT3 Street alignment settings.

 

1) Did you get a print out? It would help to be on the same page.
2) Are you only talking about street driving? At normal driving speeds, turn-in is significantly different than on the track at warp speed.
3) When you say "quicker turn-in" do you mean that you are turning the wheel but the car is slow to respond to your input (like the car body or tires are rolling over), or do you mean the car is responding properly (i.e., it is turning), just not rotating fast enough?
4) Have you checked your power steering pump/fluid and tire pressures?
5) A quick test would be to soften the front sway bar, and if that doesn't work, then soften the suspension as well.

-td

 

It should be the standard GT3 "street" wheel alignment settings used by Porsche. If you understand German, you can have a look below:




The "before" adjustment is the custom adjustment that gave a very good turn-in, but lacked a bit of directional stability.


I mostly do street driving, with the occasional track day.

I mean how fast the car responds to steering inputs. I do not mean that the car understeers.

Tire pressures are correct.
Have not checked power steering pump or fluid, but I have no reason to expect that they are not correct. There is nothing wrong with the car, the suspension is WAY better than stock when I experienced excessive understeer.

Although softening the front sway bar might improve the turn-in, I do not want the car to oversteer. I want it to keep the neutral handling it has today, so I'll think I'll keep the current swaybar settings.

Regarding softening suspension. Did you mean fitting softer (front) springs or softening the shocks? I have tried the Bilstein shocks on 1,2 and 3 softer as well as 1 harder setting than the current one. I have not experienced any significant change in steering response.

 

Too small for me to read. How much toe-in is there?

Also, how much steering input are you referring to when you say slow to respond? And how fast are you going?

Adjust the end of the car with the problem. That is, if the front is having issues, adjust the front. If you are oversteering, adjust the back. On this point, the car should not oversteer on the street even with the most agressive sway bar settings unless you are driving unsafe, in the rain, on bald tires, or on gravel/dirt.

Try changing the front bar and see what happens. If it oversteers, soften the rear bar. Changing both one notch should end up with similar balance while increasing grip in the front.

Based on your description, it sounds more like an alignment issue than a setup issue. That being said, since you upgraded to a GT3 bar, I bet your drop links are mounted to the pinch bolt and not the factory mounting point. This may cause some geometric issues with certain inputs, although I seriously doubt this is your issue - unless you are turning the wheel really far while going pretty fast.

My guess is still alignment.

-td

 

Lots of input here, thanks. I agree with your conclusion that a different alignment could improve the steering response. I have now uploaded the alignment pic in full resoultion, so you should be able to see it. The leftmost "before" alignment provided a very good steering response.

Again, the current setup is near perfect for my use, so I do not see any reason to make any major suspension changes, but I wondered if changing to more rigid rear drop links would have any effect at all?

 

Looking at your alignment settings, you have 2 minutes of toe-in on each side. You previously had 13 minutes of toe-OUT on the right, and 2 minutes of toe-in on the left. This would make the car turn right very quickly, but not so fast for turning left.

If you reduce your toe-in to 0 minutes, or a total of about 1 minute cross toe, you should have much better steering response - but your car won't necessarily drive straight when you let go of the wheel.

As for the rear drop link, I can't imagine anything you can gain by replacing it.

-td

 

Could such alignment settings make the car unstable?

What about an alignment like the one below? If you can understand the Norwegian (Spissing = Toe), or interpret the symbols.

 

The toe settings should be fine (0° 1' | 0° 0'). Those are within factory specs for the 1999-2005 GT3 RS (0.00 - 0.02) - and are what I run on my car now. All other specs are pretty close to what you currently have. That being said, I think your car is probably acting correctly with the slight toe-in hou have. You were probably used to it being darty from your previous settings, which was not correct, so what you have now feels much different. Having a little toe-in for the street is very good, especially at Autobahn speeds. The only downside is a bit faster tire wear.

-td

 

I do not know if there is a stiffer rear sway than the GT3 at the stiffest setting. Add some negative camber to the front. This will help with the turn in at the expense of tire wear and braking. It is all a compromise, you want a little here, give up some there. If you are an occasional track day driver and the track is short with a lot of turns, add the neg camber to the front, give up the braking, if the track is long with high speed turns and straights, remove the neg camber and increase braking. I run -3.5 on the rear and -1.7 (max with stock set up) on the front with neutral toe on each. I have the MO30 suspension. With coilovers and lowering the car, you will require adjustable dogbones in the rear to obtain the neutral toe. ALSO, add some air pressure to the front tires and experiment.
Good luck

 

Lots of good point here, thanks. I might try increasing the front tire air pressure a little to see how that feels. However, in order to keep modest tire wear I want to keep my currently moderate neg camber: -0,87 front and -1,78 rear. Since the car is currently near neutral and I do not want a too stiff setup as I drive lots of narrow, not-so-well maintained mountain roads. Therefore I'll keep the rear sway bar at the second stiffest setting.

I'll probably try to adjust the front toe closer to neutral as you suggest, can a good shop do this without having to do a full 4 wheel alignment?

I have a couple of more questions regarding the 3 different settings I have tired:


Setting #1

I had Setting #1 on my car prior to fitting the GT3 sways. With this setting the car felt very, very good. Steering response felt ideal, while directional stability was still OK.




Setting #2 (left) and Setting #3 (right)


After fitting the GT3 sways, I had a 4-wheel alignment done to have the car re-adjusted to Setting #1. However, the directional stability was awful, the car was wandering excessively and felt dangerous driving at the German Autobahn. Due to this I had the car in for another wheel alignment and adjusted to Setting #3 ("GT3 street"), as I feared that Setting #1 (the car had been adjusted to 1 week earlier) did not work with the GT3 sways.

When I later went back to the shop that (should have) adjusted my car to Setting #1, told them about the instability and showed them Setting #2 (measured 1 week later). They told me that the differences between the two readings were insignificant and could not be the cause of the instability I had experienced. They also said that the instability might have been caused by the fact that I had worn front tires or the wrong air pressure.

Although I admit that the front tires were more or less worn out, the air pressures were correct and the car was stable as a rock after the adjustment (Setting #3). Neither have I ever experienced this kind of instability even with completely worn out tires.


So regaring the instability I have two questions:

1) Could Setting #2 cause the instabiliy I'm describing?

2) Could something else have caused the instability?


Thanks,
Bjarne