Sway Bar Adjustment? When?

[pmajka]

During the Grand-Am race, one of the commentators mentioned loosing the sway bars for restarts after a  long yellow period to get grip.  I am assuming that later the drivers are stiffening their sway bars (in car adjustable).


How do you know when to stiffen a sway bar, and which one?

Pocno North for example.  I thought my new suspension worked great.  (as a novice, (read white driver) staying on the track is great).  I felt comfortable coming off the bowl at speed, braking a cone 2 and turning in at 1.5.  In turn 2, the car would push  a little if I was in a little too hot and 19/20 times a little throttle modulation would correct the problem.  The rear of the car never really stepped out on the infield. I understand that Pocono is a rougher course.

1. With Thunderbolt in mind, I expect some push in the puss and in turn 3.  To correct this ( or just make a little more manageable), would i stiffen the rear or loosen the front?

2. If the car handles all around fine, but I'd like to try to squeeze a little more handling out of the car, should I stiffen both front and rear equally (although incrementally)?


88 911
23/31 torsion
tarret sway
Urethane bushings
Dougherty track alignment
toyo r1 235F 275 R on 17's
220 HP to tires.

--peter

[Larry Herman]

I'm not sure why the announcer would say that (some are pretty unknowledgeable about racing) unless the cars balance would hcnage as the tires cooled off.

What I have learned and agree with is that you adjust the front end of the car to deal with corner entry, and adjust the back of the car for corner exit.  So if it pushes while you are turning in, softening the front will have a greater effect.  It will make the car understeer less on trackout too, but not to the same degree. 

Sway bars are basically an overall balance adjustment, like changing spring rates.  To specifically address one portion of the turn, other things like camber settings, toe settings and shock adjustments are required.

For example, I added in a full degree more camber to our 951 for the Glen event.  It got rid of all of the initial understeer on turn-in without making the car feel loose on turn exit.

As far as just tightening up your sway bars, it is kind of like tire pressure.  Just because you get a little better grip if you add some pressure, adding more may not produce the same results.  There are many more factors at work.  But experimentation is what it is all about, so by all means, make the change and see if you like it.

 

[997S22]

I have found the attached link helpful in understanding sway bars.  It does not mention adjustment, it mentions thicker and thinner bars, but thicker = stiffer and thinner = softer so it is easy to translate to adjustment if you have adjustable bars.  My own experience is once you get the bars right there is little cause to adjust from event to event although certainly some do tinker all the time.

http://www.stealthtdi.com/SwayBars.html

[michael lang]

Peter, not to change the subject but I'm curious about 1 thing, only because I'm torn about which way I want to go. I noticed in your set up that you are on 23/31 torsion bars. Why did you go with 31's? I'm very interested because I keep going back & forth as to which ones I want for my car. This is one of the things that I will be upgrading this winter. My thinking is that the 31's will be better for the track which is mostly where my car gets driven now but I thought 30's w/the 23's in the front is more like the factory balance on stiffer ride. I keep talking myself into going with one over the other and then I talk myself into thinking the other is better.

[pmajka]

I made the decision based theory, opinion, sale and moonphase.

The more HP/Tq in a 911 the more it can squat under throttle.  Most of the 3.2L cars are 29 or 30mm in Rear (for track).  My car has 265hp (at crank), so i opt'd for elephant racing's recommendation 31mm as a track option.  I also have AirConditioning and heat, so car has more weight than a stripped track car (2780lbs w/o driver). 

If you have a turbo, you might opt for the 33mm on the track.


Also note some of the 993s in our club are using 600LB or more springs.  The car barely moves when you press down on the rear bumper.  (like the Haas mobile)

When all is said and done, the 23/31 torsion bar combo is streetable on 17" street tires, without extra visits to the dentist.

Note my rear sway bar settings are soft with the 31s. ymmv.


However , 30mm v 31mm  you are splitting hairs....pick one.