Will upgrading sway bars make justifiable difference?
 

I currently have Weltmeister adjustable sways front and rear on my car with 22mm bar. My car still seems to lean too much even with 22/30 torsion bars and revalved Bilsteins.

Will upgrading to a larger swaybar front/rear such as a Smart Racing make an improvement in lean and handling? Has anyone been down this road?

Excessively large sway bars will only increase suspension harshness and stress the chassis sheet metal unless reinforcement is added.

IMHO, you will attain your objective by increasing the F/R torsion bar size to match the Bilsteins you now have. Owners of like vehicles typically use 21-22mm fronts and 27-28mm rears for the street. Torsion bars won't add as much harshness as large sway bars.

Sherwood

I have 22/30mm tbars, valved to matched RSRs and SRP #27 anti sways. I love the #27 bars with my car. My previous set up was 22/28 tbars with off the shelf bilstein sports and stock carrera sway bars. I was tearing up the outside tires on the track with all the body roll.
I have the #27s set to the softest settings and am getting almost even tire wear on the track. I also don't feel they added any harshness on the street. IMO the valved shocks make a huge difference. I feel the car is less harsh on the street now.

The brand of bar isn't going to make a big difference in how much body roll you get. The size of the bar will. The advantage of the higher-end swaybars is ease of adjustibility (which is important if you're tuning for different tracks) and long-term durability, although a swaybar is a pretty simple thing.

Why do you think your car is rolling too much?

Jon:

Great suggestions from Don,.........be aware that stiffening a Targa beyond a threshold suffers diminishing returns due to body flex.

Is this a street-only car or do you do run DE events?

23mm Smart Racing bars would be a nice upgrade as long as you install the WEVO swaybar consoles as well. I would not use larger rear torsion bars than 31mm unless the car gets some major chassis upgrades to stiffen it.

Where are your swaybars adjusted to?

What size wheels and tires are you running?

Here is pic of the car at a DE. I do 5 or so DE's annually. My wheels are 17x7.5 up front and 17x9.5 rear with 245/45/17 and 275/40/17 Victoracers. I still have some room to tighten up my current sways which I will try at my next DE in October. Rear is still set pretty soft which may explain the lean in the picture. The car understeers a bit and the rear end is difficult to get to rotate and get the front end pointed where it needs to be. This is still a street/track car although the street time has diminished with all the suspension stiffening that I've done. The shocks are revalved Bilsteins to match the torsion bars and weight of vehicle.
http://forums.pelicanparts.com/uploa...1189026312.jpg

I'm kind of where Jack and Steve are. Unless you put a full cage in the car, you're going to be hard pressed to get the Targa body sheel to transfer the load that the bigger sway bars are trying to do. There are a lot of other (and also cheaper) ways to tune your cars handling, especially since we're talking about DE's rather then some form of competition where absolute time matters. So spending a lot of money to improve the chassis by a tenth of a second for DE use is pretty much a waste of money.

Since I don't like to propose anything without understanding the situation fully...
1) What sort of tire pressures are you running on your car for DE's?
2) What are your alignment settings?
3) Are you running an open diff or something else?

Could you break this down as far as corner: entry/middle/exit?

High speed/low speed corners?

Based on what you've said so far, I've got a couple of ideas, but I'll hold on to them until I see your responses to the above questions. Sway bars aren't so much about controlling roll as they are about transferring load (excepting C. Chapman's comments below). The fact that your car is rolling X degrees isn't really an issue unless this roll is beyond what the designers intended as evidenced by positive camber or the car hitting the bump stops when cornering. For the most part, Porsche's designers are better then that.

Sorry. I completely missed the description of your current torsion bars. I interpreted them as sway bars. My bad.

It seems like you can either go to larger sway bars or graduate to coil-overs after you max out on the torsion bar OD. I would think the current setup is pretty stiff on typical city streets already. But heed the advice about stiffening the suspension on a relatively flexible chassis. The chassis can't be adjusted the way the suspension can, and you don't want to be twisting the chassis unnecessarily.

Tightening up the rear bar will tend to reduce the push/create more oversteer.

Sherwood

How long have you been running the victoracers?
Have you tried stiffening up the rear sway bar?

I have a question related to this problem.
I currently have a 930 with the stock torsion bars. However, I have upgraded the front to Smart Racing 27mm sways and the rear to 31mm Sways. The idea was that the sway bars will be controlling the roll in cornering while keeping the stock torsion bars will keep the ride streetable.
My question is that most people stiffen the torsion bars alot before going to bigger sway bars or at the same time that they get bigger swaybars. I have never heard anyone comment or try to do bigger sway bars with stock torsion bars.
Is there any downfalls with my approach?
Is there any disadvantage to staying with soft springs and hard sway bars? As I said my logic being that sway bars do nothing in straight line/bump absorption where the normal street ride is felt. Only under hard cornering will they have any effect such as track driving, where you want them to work.

I don't think the original poster, JonT, has a problem. Rather than larger bars or sways, I'd go for a cage to rid the Targa of all that twist. (More likely, I'd just be happy with what I had.)

It's not a bad theory. But it's not perfect. I think you're better off going to larger t-bars first. You get better fore/aft as well as side/side balance. And if you run heavier t-bars with stock sways, you'll have no increase in "cross talk" from larger sway bars. The down side to this approach is the labor involved in installing the t-bars.

Larger sways are easy to install, but offer no fore/aft balance. And as mentioned , big sway bars induce "cross talk". (The two wheels are mechanically linked by a somewhat compliant spring. Hit a bump on one wheel and it will affect the opposing wheel . As the bar gets larger, you end up withg a straight axle with some twist.)

I haven't ever tried setting up a 911 with soft springs (torsion bars) and big sway bars. I can tell you that I have done this with circle track racing and that I prefered it over stiff springs and soft sway bars but they were the same time wise. If I recall correctly Carrol Smith actually recommends in one of his books (Tune to Win?) that you use the softest springs that the track will allow (without rubbing, bottoming out, etc) and control body roll with the sway bars. Keep in mind that with softer springs there will be more suspension movement and this will make your camber curves, bump steer, etc all that more important. All that said my car is set up with stiffer t-bars and decent sway bars because that is what all the fast guys in my class are doing and I want to stick with something that is working for the others until I get consistent enough and gather enough info from the usual tracks before I try anything else...

Also keep in mind that Carrol Smith worked with significantly different cars then us.

Hope this helps.

Also keep in mind that t-bars for a 911 do not offer modern, heavy-duty, wheel rates. That's why some convert to coil overs.

fred,

Stiff sways and soft "springs" transfer the weight though the sway bar mount and can cause them to fail. Pretty common with stock mounts. There are improved mounts available. I feel that sways and spring rates (torsion bar sizes) are directly related, and should be modifed with this in mind. On my race car I moved to coil-overs to get better adjustability and higher spring rates. If you want to be able to drive the car on the street, you need to understand that you are not going to be able to the ultimate in track handling, and a comfortable ride. It's all a compromise.

Jon,

Doesn't sound right to me, are you running factory height? I put Koni sport adjustables on first, then lowered, then put 21/27 T-Bars on and have not changed sways. ( I love to see the difference with each change that's why they're in stages)
I have little to no body roll (when Koni's are set to full stiff) and I have stock sways.

Did you ever try your setup with the 16" 's?

Seems strange to me you have that much roll........

This thread is getting somewhat mixed. but this is for Fred:

930's are sprung quite softly for their intended useage (road) and they tend to squat under power & dive under braking pretty severely, given the power that these cars have.

Big swaybars do nothing to prevent this so I prefer to distribute the suspension loads by upgrading both springs (larger torsion bars) and larger adjustable swaybars to tune the cars's balance.

Bob--I have not tried my setup with 16" wheels/tires. My ride height is below factory but I'm not sure exactly what it is without going out and measuring.

Shawn--I had street tires on my car for 2 DE season and now Victoracers for the past 3. I have tightened up the rear sway bar but have some room to go, probably 2" remaining to move the bracket.

John--to answer your questions-- Tire pressures 32 fr/34r cold. They end up around 38/fr/40r after a 20 min session. Alignment settings are 2.5 neg fr/3.0 neg rear camber. Stock differential--not limited slip. Understeer and leaning problem seems most obvious in sharp low to mid speed corners at turn entry and apex.

Thanks again for helpful comments.

OK JonT, that's a start but you didn't answer the question about alignment settings completely -- I was also interested in your toe and castor settings. Both of these can had a significant impact on your car's handling. Here are some cheap and relatively easy things to try to get your car to "point" into the turns better...

1) I'm guessing that you've got toe-in both front and rear. You might want to try dialing that out a little bit, starting with the front. The rear is going to be far more sensitive to toe changes, so you may not want to mess with that unless you are autocrossing around tight corners. Reducing the front toe will tend to make the car "hunt" a little more over uneven pavement, but that's the trade-off for having it point immediately when you start to turn the wheel.

2) Try increasing the rear tire pressures incrementally.

3) Make sure that you've got your castor maxed out. This will increase steering effort some, but it will help to recover some camber when you've got the steering wheel hard over in tighter corners, especially in the middle of the corner.

Some follow-on questions...
1) How low is your car set-up? People like to drop the cars by indexing the T-bars which looks cool on the street, but can compromise your suspension geometry on the track. Especially if you're running wide sticky tires. Do a search here and on the racing forum for "suspension geometry" for a lot of information, pictures and drawings. Basically if you've lowered your front end to the point where the A-arm is flat or rises on the outside, you've put yourself into a situation where the front end will "jack down" during heavy cornering, which will increase positive camber (and thus understeer). This is even more pronounced while braking and turning in since the front end will be compressed even further. This jacking down will also decrease the front end's resistance to roll (which will make it feel like the sway bar is too soft) which will also further increase your positive camber. If you want to lower your car I strongly suggest that you look into raising the front spindles rather then indexing the T-Bars.

2) How does your line compare to others on track? Are you "king of the late brakers"? Driving style can also influence the car's handling. How you turn in can increase or decrease understeer. The same applies to how you trail brake, or transition off of the brakes prior to turning in. Have you tried modifying your line by taking a slightly later turn-in and apex? Making too shallow of an entry into a turn and then trying to crank the wheel over at the apex can also induce understeer. This may or may not be the case for you, but since I don't know anything about your driving style, I figured that I'd throw it out there for consideration.