Tarett sway bar initial settings

[Flieger]

I got the hint. I only continued it because it is so much fun getting him worked up and I thought it might be educational for others.

[Driven97]

This seems like a good place to post this question:

Assuming steady state cornering, with enough front sway & grip to have the inside front up. What is the practical difference between:
1. stiff springs & no rear bar
2. medium springs and enough rear bar to achieve the same roll stiffness as case #1?

Signed,
The village (suspension) idiot

[safe]

2. => broken swaybar mounts.

The difference would be adjustability. Its easier to adjust an anti roll bar than changing springs/t-bars. I could be wrong, if so I'm up for some education!
It's also my experience that a big anti roll bar gives a harsher ride than stiffer springs.

[Flieger]

If you are not going over bumps and you have no longitudinal acceleration then there is no difference. If you hit a bump then the sway bar setup will have less force transmitted to the chassis, but will transfer load from the other tire more quickly so will probably handle worse. If you have any drive or brake force then the sway bar setup will squat more.

[Driven97]

Originally Posted by Flieger

If you are not going over bumps and you have no longitudinal acceleration then there is no difference. If you hit a bump then the sway bar setup will have less force transmitted to the chassis, but will transfer load from the other tire more quickly so will probably handle worse. If you have any drive or brake force then the sway bar setup will squat more.

A) Big spring / minimal swaybar
B) Moderate spring / moderate swaybar
C) Conservative spring / big swaybar

Let's see if I have this right. Assuming similar total roll rates for all three above cases:

Car A will have the highest ride frequency, so will have the worst ride, but will handle single wheel bumps well. It will transfer longitudinal load quickest, so it will least forgiving to overly aggressive throttle and brake inputs. It will, however, react best to one wheel bumps mid-corner since it isn't transferring as much load.

Car C will have the lowest ride frequency, so it will have the best ride, but will handle sing wheel bumps the worst. It will transfer longitudinal load slowest and pitch most. On a perfect surface it will have the same ultimate loads and therefore grip, but it could be unforgiving on mid corner bumps.

Too soft and the car is sluggish to respond, and can roll / pitch into bad areas of the camber curve.

Too stiff and both bumps and inputs can shock the tires into skittering / chattering across the surface.

If you change tires, weight, surface smoothness, surface grip, alignment, lateral or longitudinal acceleration, or driver input speeds, everything goes out the window and you have to start all over again?

[Flieger]

Yes, that is what theory says. There are certain geometries/kinematics that can get around those points but for a 911 that should hold true.

[bkreigsr]

FWIW, I installed a Tarrett RSR bar in the front over the winter, and left the rear alone......big mistake - first time out at VIR two weeks ago, the front wheel was off the ground 3-5 inches on every turn - very disconcerting.
I was holding off on the rear RSR bar because I plan to weld in the Wevo supports when I upgrade.
(on the plus side - I saved a ton of front rubber and brake pads. )
This weekend is Watkins Glen but all I can do was back the front bar down to 'full soft' and increase the rear pressures.

- (same tb's as the op on 85 Carrera)

Hopefully rear will be done before Summit Pt, 7/17
Bill K