Land Jet

Went to a local PCA tech session with my "new" to me 95 993, and was told I have adjustable sway bars, that were set full hard in the rear and toward soft on the fronts. Tech inspector suggested to set middle all around for a more neutral handling car. He told me the way the car was set, made it like a drift car where the back end is more likely to come around on you. He is someone I respect and know was raised around and participated in Porsche racing. He knows far more than I.
My questions:
1} Wouldn't setting hard all around accomplish the same thing?
2} How would that change the feel of the car?
3} Please, a primer on sway bars from race track guys.

mklaskin

Try soft rear and firm front. Softening the rear will allow the car to put the power down best. 911's seem to work best when powering through turns. Keeping the weight over the rear tires is key.

The way you're set now allows the front end to maintain grip, and the rear end to act like a pendulum. The slightest shift in weight will unsettle your rear tires, thus the effect of a drift car. Also, the soft front sway bars may contribute to understeer.

What tires and tire pressures do you run? Tire pressures will tell you quite a lot about how your tires are working. Ideally, once you establish a baseline tire pressure, the tires should increase in pressure at (about) the same rate.

This is just my advice of course and a lot depends on how you drive. I know a few guys who like the to slide their cars more than I do. And they are quick. If you really want to play with the sway bars, get a set of cockpit mounted adjustable sway bar levers. Go to www.hrpworld.com and look at the Genesis levers. Keep notes based on tire pressures, sway bar settings, and lap times. Remember to record weather conditions along with your set up notes.

Please let us know how your set up develops.

Others please chime in.

Land Jet

I was at an HPDC small track event, and i started cold at 36 front and 40 rear, my normal street pressure. We only got to do a few laps.

Could you explain more about how sway bar settings affect the feel of the car and how it handles?

Tom W

I don't believe the tech person and his advice is contrary to my experience.

A stock 993 has excess understeer. If your adjustable sways are the RS sways, the settings you have are what I found led to more neutral handling. Middle/middle settings gave excess understeer (similar to stock 993 non-adjustable sways). If the sways are not the Porsche RS, then you will have to experiment with what works best as there are many different sizes of bars available and the size of the bar will have a profound impact. Your shocks and spring rates will also play a role in handling, so simply focusing on sway bars and sway settings can't tell you how your car will handle.

A simple primer on handling is here.

bobt993

Tom has a good point. RS bars will make a different approach. If the car is "new" to you and also you have limited track events, then I would back off one notch or go neutral on the rear until I drove the car. You can get it dialed in at a track event in a couple of run sessions. I recently upgraded my car to Motons and the shop set my rear bar more neutral as a safety factor telling me I would likely enjoy it more. One hot lap and I was back in moving the setting to full stiff. It has not moved since then.

Land Jet

I guess I don't have enough experience to know the difference between settings, but when I had the settings changed to the suggested middles, I thought the car lost some of the "on rails" feeling. Is that my imagination? Maybe I just got used to the way it was.
Please explain what the difference in feel would be between full stiff all around and full soft all around. I'm just trying to get a reference point. The car has H&R coilovers and 2 TPC sway bars. Tire pressure as stated above. Going to be doing Shenandoah Circuit at Summit Point in June. Any suggestions are welcome.

bobt993

YES, I have alot of time at Shenandoah including a full 6 hour test day where we could try anything we wanted (small group of drivers). Track is very off-camber except of course the karrusel turn. If you car rotates to easily, you will be busy turning into the apex everytime. In the karussel, the car will attempt to "hop out" if you dial in oversteer (that can be real hairy). If this happens in the karussel you won't spin, but drive backwards into a tire wall at speed. (have a video of this happening to car in front of me). Set the bars neutral to slightly understeer since your getting used to the car. There is very little run-off and looping the car could cost you $$$$. You can make changes, but move one at a time ie: back bar one notch "more stiff". BTW what spring rates do you have? I found 650/800 to need the sways set past neutral to start. This can make a big difference.

If it rains at the track, you might want to actually disconnect at least the back sway bar.

DM993tt

I have TRG adj Front Sways, but I also have revalved PSS9's so not a good comparison. But you might find the link useful - 2 993TT's at Shenandoah. http://video.google.com/videoplay?do...85645518&hl=en

Land Jet

I don't know my spring rates since the car is as the PO had it.
The track videos are very informative. Virtual laps are good.

I'm still not getting the handling difference between full hard and full soft. I understand sway bars are supposed to keep the car flat so weight shift does not change steering trajectory. If that is correct then why not hard setting all around all the time?

joel-cs

My opinion is that the sway bars should be used to fine tune the suspension - not provide major changes to the handling characteristics. There are a number of very good threads on the topic here.

The idea is to first balance the car with springs and dampening. This should keep the car flat. Sway bars can then provide minor adjustments to the balance to correct for over/understeer.

Land Jet

Thanks Joel. The way you put it penetrated my hard head. Now could you clarify how the sway bars, through adjusting, correct for over/understeer? Sorry I'm so thick. Lack of experience.

Mark in Baltimore

It's been my understanding that sway bars should be used for gross adjustments in handling, and that shock settings such as nitro pressure, compression and rebound are more for fine-tuning.

FWIW, I've learned that I like having some understeer in the car so I can really get on the gas sooner in the corners that require big *****.

joel-cs

this is how you learn...no apologies!

Assuming a neutral setup:
- The premise is that more weight to a particular wheel = more grip
- stiffer front sway = more understeer (less weight will shift to the outside front wheel, because it is distributed to both front wheels, therefore the front outside has less grip)
- stiffer rear sway = more oversteer (same as above, but in back)

These are generalizations and there are many other factors that influence under/oversteer (alignment, etc). Bottom line is you should try to get it to neutral and then make changes to suit your driving style.

One more thing - if your car is a daily driver, it will impact how you set up your car. You may, in fact, want to stick with softer springs/shocks and dial out body roll with sway bar adjustment for comfort reasons. If this is the case, then the answer to your original question (why not go full stiff all the way around) might be that you should do so. Just make the adjustments gradually so you understand the car in a neutral setup.

John H

The stiffer the setting the quicker that part of the car will set in a turn. When you go full soft on the rear, you will feel the car wallow more before the rear end sets. Stiffer settings will make the car "twitchier". When oversteer happens on full stiff, it is more likely to be a snap oversteer than the slow oversteer type spin. That's why most go full soft on the sways in the wet.

Land Jet

Thanks guys. I'm much clearer now.