surf

I have a 911 R S America that has too much understeer .She really pushes.Some have suggested a 19m rear sway bar,Any thoughts ?

joey bagadonuts

Surf,

Can you be a little more specific? When do you experience this understeer? What size and type of tires are you using? What are your cold tire pressures? What are you trying to accomplish ... better track performance, autocross handling, etc.?

Here's a nice summary of suspension mods you can make to dial in the handling you want. A bigger rear sway bar may help with corner exit handling but I wouldn't consider it a panacea. Perhaps if you let us know your goal, someone knowledgeable can offer some suggestions.

Bill Gregory

Surf,

Joey asks some good questions. Our 964's tend to push or understeer by their nature. If you look at any of the generally available suspension charts, you'll see there are a number of things that can be done to tame understeer. one action involves the size of the front tires, which can go larger to 225's, another is the use a larger rear anti-sway bar, and there are a number of things that can be done. If you can let us know better how you use your 964, that will help with recommendations. Of course any suggestions assume your suspension parts are in working order and your alignment is at least at stock settings (which is not the best for sporting usage).

chris walrod

Do you see understeer on entry or just exit? My 993 tends to push on exit, while turn in is pretty good. I added an RS rear bar set full stiff and it seemed to help, in autox setting that is. At a recent POC driving school, there was no way to spin my car, even with the most violent throttle lift and a good dab of the brakes. Too much on-power understeer.

When my tires are done, I will be 'upping' the size to 225's from 205's. Almost forgot, I did add more negative camber and less toe, helped a lot as well.

9caregiver

Greetings,

I used to autocross alot with my first RSA. I had two tricks to solve the understeering problem. The first was to keep the gas tank full. The second was the change to stock C-2 swaybars front and rear. Although you could probably solve the problem by changing just the front bar I changed both. I had seen an neighboring region champ run a yellow 993 with the softer bars. He was fast! Anyway that RSA is long gone and I think I still have the bars if your interested in trying them. Thanks.

Best,

Don

www.don@porsport.com

surf

I use the car for DE events.I am currently running Yoko Avs for tires 235/40/17 fronts with 7/55 rims.Rear is 275/40/17 with9/55 rims I feel most of the push on turn in and a fair amount on exit.worse at higher speeds.I have played with tire pressures as well.The car has been lowerd and has so called Rs coil over spring set up.I bought the car with this set up but I am not sure of the spring rates .the car is very stiff.I am trying to sort out what was done.The work was done by European Performance Eng.,a respected shop in the area.

91C2wrencher

Surf, interesting stuff. I recently changed from YOKO A032 to TOYO RA1's and found I had a lot of unexpected understeer where before I had NONE! I played with tire pressures at an autox with no real results. Then I looked at the TOYO tire website and found the recommended camber settings for these tires is -2 to -5 deg. I think for my YOKO's it is at -1.8 or so. So I'm guessing the problem is in the camber/toe area. I'm gonna have this looked at next spring b-4 any events. My car was rock solid with the YOKO's so I'm kinda bumm'in

joey bagadonuts

Surf,

Since you're experiencing push on corner entry and exit, I'm wondering if your tires aren't the problem. How old are the AVS's? A buddy of mine who drives a 911 3.2 said they got pretty hard and slick after several events.

And what pressures were you using? I ran some street tires at the track not too long ago and used a pyrometer to determine the correct pressure for my 225/255 P-Zeros: 38 psi cold and mid 40's hot. Unlike R compounds, street tires do not have the same sidewall strength and require more pressure to optimize grip.

It sounds like you have a pretty good suspension setup already, so I'd suggest you play with pressures first and then maybe buy new tires as your next step. BTW, the tire sizes you're using may be a little much for 7 and 9 inch rims. An overly wide tire increases sidewall flex, so I'd stick with a 225/255 combo with those wheels.

0.02

joey bagadonuts

Surf,

Here's a pertinent thread from another Rennlister with the same problem:

New Tires Fixed Understeer!!

surf

Thanks for all the imput.I have also used 225/45/17 front and 255/40/17 rear Kumho V Racers.It did not help with the under steer.
What would you reccomend for sway bars ?size/brand/settings?

joey bagadonuts

Surf,

The short answer is that your RSA already has an adequate rear sway bar: 20mm. You can spend $300 for a 3-way adjustable, 22mm bar from The Racers Group but the difference may be negligible.

Here's another thread which covers the same topic at length and well worth a read:

Sway Bar Confusion

buckdr1

Greetings all, Even though topics get repeated they do strike a cord now & then. Thanks all for the threads that all I had to do was click & read.
As you might surmise I'm considering @ least a full cage for Xmas. Happened to get a quote just today for suspension upgrades, from full Track to perhaps just exit understeer improvements on the cheap/er.
Got myself a great refresher course for tommorrow's discussion/s on the suspension upgrades.
Rennlist, Rennlist, Rennlist
Cheers
Bill