Anti-Roll Bars
- Thread starter malibuj
- Start date
You've got a pretty strong case of what the corner-carvers in this group would call roll steer. What happens is that as the car rolls to the right, the axle steers slightly to the left. It's a geometric function of the rear control arm inclinations in side view and the amount of roll.malibuj said:
In the A/G body, the factory builds in quite a bit of rollsteer just to keep things safe for the not-so-capable drivers. Actually, that's a rate of rollsteer, and is usually described as degrees of steer per degree of roll. Usually this might somewhere around 7% or 0.07° of axle steer for each degree of roll. If you've added hop-stop bars for the uppers, it'll be more, if you've lowered the lower arm axle pivot with relo/anti-squat brackets, slightly less.
Then you have to figure in the actual amount of roll, which in your case is now much larger since you've disconnected the front sta-bar (aka front sway bar or front antiroll bar). And more than OE by reason of having a bit more power to torque it over with.
Bottom line - a large rear antiroll bar should help your launch considerably by keeping the amount of roll down to something sane, which will minimize the amount of rear steer that happens. Just be real careful on the street (or reconnect the front bar and disconnect the huge rear one).
And thanks for the explanation.
Norm
I drove for years without front or rear bar, and when I installed my HRPartsNStuff bar, it made a world of difference on the track, and off the track.
Of course I'm not trying to carve any corners, but a good rear bar should help the street manners of any car.
Of course I'm not trying to carve any corners, but a good rear bar should help the street manners of any car.
Best overall street manners really requires a balance between the front and rear bars. Otherwise, there is the potential for being "loose" if you ever find yourself in a situation where you do have to corner hard. Normally, this is based on having front and rear wheel/tire packages of at least similar sizes.
What may be a partial "save" (and hopefully is the case here if there is still no front bar) is if the front tires are skinnies with much larger/grippier rubber out back. In that case, rear grip has been improved, even laterally (although it may be difficult to actually use it). And front lateral grip has been given away. It still won't like hard corners, but it's more likely that the back end will stay behind the front.
Norm
What may be a partial "save" (and hopefully is the case here if there is still no front bar) is if the front tires are skinnies with much larger/grippier rubber out back. In that case, rear grip has been improved, even laterally (although it may be difficult to actually use it). And front lateral grip has been given away. It still won't like hard corners, but it's more likely that the back end will stay behind the front.
Norm
Thanks for that explaination Norm, I learned somthing today
Is this strictly geometry or do the bushings play into the amount of designed rate?
Thinking poly vs rubber effect.
TIA,
Jp
No problemJP86SS said:. . .
Thanks for that explaination Norm, I learned somthing today
Is this strictly geometry or do the bushings play into the amount of designed rate?
Thinking poly vs rubber effect.
TIA,
Jp
Bushing material does figure into it, if you're looking at a kinematic (geometry) & compliance model rather than just the pure geometry effect that I was describing above. Since a bushing's stiffnesses (compliances) affect how accurately it approximates a spherical rod end, that means that the effective construction lines through the UCAs and LCAs aren't precisely along the link axes as defined by the centers of the holes in the axle and chassis-side brackets. As a side note, the LCA-attached OE rear sta-bar has a similar effect. That slightly affects the locations of the intersection points, which then comes back to re-defining the axis that the axle is trying to roll about. I suspect that the overall geometric effect of out-of-the-box poly bushings vs rubber is a slightly greater rate of roll steer.
That's a separate effect from the additional suspension roll stiffness that poly control arm bushings provide when installed in just about any stick axle suspension.
My turn to thank you - something related to this just 'clicked'.
Norm
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