PaulW - swaybar question.
05-25-2004, 08:37 AM
#11
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One other consideration ...
My guestimates in the post above probably aren't far off, which means that even a 20mm bar is unlikely to induce oversteer. However ...
Note in <A HREF="https://forums.audiworld.com/a8/msgs/36145.phtml">Weight Distribution Revisited</a> that in steady state cornering, there's only 313 lb on the inside rear tire. If the 20mm sway bar deflects 2", you've reduced the load on this tire to about 210 lb. At some point, the load will be light enough to spin that inside rear tire ... something you'd definitely like to avoid. The bottom line is that it's probably too close to call. Do you want to give it a try and let us know the result?
<img src="http://pictureposter.audiworld.com/17157/weightdistribution.jpg">
Note in <A HREF="https://forums.audiworld.com/a8/msgs/36145.phtml">Weight Distribution Revisited</a> that in steady state cornering, there's only 313 lb on the inside rear tire. If the 20mm sway bar deflects 2", you've reduced the load on this tire to about 210 lb. At some point, the load will be light enough to spin that inside rear tire ... something you'd definitely like to avoid. The bottom line is that it's probably too close to call. Do you want to give it a try and let us know the result?
<img src="http://pictureposter.audiworld.com/17157/weightdistribution.jpg">
05-25-2004, 08:58 AM
#12
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How is that data changed with stock suspension...
I figure if i have all stock suspension that my roll would be very high.. therefore making that inside tire even more prone to lift off the ground. Another thing to think of is that i have the 16inch tires with the 255/55/16's They are currently at 40psi to give me the 18 inch rim feel and stability. When i drive in to Jersey city i drop them to 32, so i can absorb bumps of the rough streets. I also have about 200 lbs of stereo equip in the trunk that is right against the rear seat.. that will probably change things.
05-25-2004, 10:51 AM
#14
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A stiffer rear bar increases the load carried ...
by the outside rear tire during cornering and decreases the load carried by the inside rear tire. Tires provide maximum grip when they're equally loaded. The increase in the difference in load that the tires at the rear of the car carry reduces their combined grip.
Since the amount of load carried by the left (and front) of the car remains constant, the load carried by the outside front tire decreases, and the load carried by the inside front tire increases. The difference in load carried by the front tires decreases, which increases their combined grip.
The result is reduced understeer.
Since the amount of load carried by the left (and front) of the car remains constant, the load carried by the outside front tire decreases, and the load carried by the inside front tire increases. The difference in load carried by the front tires decreases, which increases their combined grip.
The result is reduced understeer.
05-25-2004, 11:12 AM
#15
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Very minimal change. ...
The only difference is that a car with an S8 or H&R suspension has a slightly lower center of gravity. The result is that at the same cornering g's, they carry slightly more weight on the inside tires.
Perhaps surprisingly, a car with softer springs and increased body roll is not more likely to lift an inside tire than a stiffly sprung car. The left-right load distribution is only a function of cornering g's, the height of the center of gravity (lower is better), and the track width (wider is better).
You do bring up, though, another benefit of stiffer sway bars. The less the body rolls, the better job the suspension will do keeping the tire upright and the tread flat on the road. Even from the side, you can see in this pic that body roll has tilted the front tire in too much at the top (too much negative camber).
<img src="http://pictureposter.audiworld.com/17157/grattan_t7.jpg">
Perhaps surprisingly, a car with softer springs and increased body roll is not more likely to lift an inside tire than a stiffly sprung car. The left-right load distribution is only a function of cornering g's, the height of the center of gravity (lower is better), and the track width (wider is better).
You do bring up, though, another benefit of stiffer sway bars. The less the body rolls, the better job the suspension will do keeping the tire upright and the tread flat on the road. Even from the side, you can see in this pic that body roll has tilted the front tire in too much at the top (too much negative camber).
<img src="http://pictureposter.audiworld.com/17157/grattan_t7.jpg">
05-25-2004, 11:31 AM
#16
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So at the very worst i will gain even tire wear on turns for the rear :-)
I think i will try the 20mm bar, let me get the car back from the head gasket repair and i will see where i am.. I would be interested in seeing what it results in. I have a feeling the 20mm would benefit me more with the stock suspension. With your and paul's set up the 17mm would be amplified by the suspension upgrade, then the 20mm might be too much.
05-25-2004, 11:47 AM
#18
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I just ordered a 20mm bar, bushings.
It will be around $250 all up, including shipping. More expensive than the 17.3mm bar.
Their parts catalog doesn't show it as fitting any U.S. cars. But the links are the same for all the bars. I'll roll the dice; I bet it fits.
Their parts catalog doesn't show it as fitting any U.S. cars. But the links are the same for all the bars. I'll roll the dice; I bet it fits.