anti dive

[jbh25]

how much anti dive do most mods run, and do they run different settings on lf and rf

[jbh25]

anyone?????

[racin6mod]

I think most of us are unclear on your question. shocks,bump stops,limiters?

[jbh25]

the anti dive in the front upper control arms, how much do most mods come from builders with, o deg or 2, 3 , or etc.

[blknblumod]

Anti-dive is the angle which the upper control arm tilts down as it goes rearward on the chassis. Just in case someone is wondering what it is.

[charcoal01]

its a tuning tool, mostly affects how the car reacts when you're on the brakes. i dont know what the most common setting is, but i'm sure that they vary depending on each chassis builder as they all seem to be looking for something a little different.

[racin6mod]

WoW 25 years of racing and never heard it called that.thanks for the info.

[Dirtrace54]

just to clarify so someone doesnt measure this wrong, isnt anti dive the amount of tilt the upper has according to the inner swing axis of the lower arm, not just the tilt on the chassis? The way I understand it is that to get true anti dive, the angle of the pivot points on the upper are compared to the angle of the lower. Generally most frames have a little bit of tilt do to ride hieghts. If you level the upper arm and the chassis has a higher rear ride hieght than front, the lower arm might be tilted so the pivot points wont be truely level.

Basically the anti dive is the relation of the mounting points of the upper arm in comparison to the lower arm mounting points. Is this the way everyone else understand it?

[FLYNBRYAN]

With corrected upper a arm mounts we use 2 deg on thright and 3 on the left.

[blknblumod]

Dirtrace54. You are correct.

[1Blacksheep]

I believe that is mostly correct , other than chassis attitude does not change it as the degree of dive is established by the solid mounts on the frame. If you want to go deep on the subject tilt and rake may affect the way the car feels the dive as it is a bind that is being created by this tuning tool. Basicaly cheating the car into feeling a different spring rate than is actually in the car. Caster gain, scrub radius, and bumpsteer,is also part of the equation the car feels. I have seen Pro dive and Anti dive incorporated into the same front end on different sides. :p

[racin6mod]

the following is a copy from another chassis forum.the photos did not copy over.hope this helps everyone understand anti dive.

The concept of anti-dive or pro-dive is to use the geometry of the front suspension to either encourage or resist dive of the front of the car under braking. The way it works is when the brakes are applied, the spindle will want to rotate with the wheel since the caliper is gripping the brake rotor.



When the upper and lower control arms are parallel, this force of the spindle wanting to rotate is countered by the upper and lower control arms. Since the forces are balanced, the control arms remain perpendicular to the spindle.

Anti-dive is where the angle of the upper control arm is changed to resist the dive of the frame under braking. Auto manufacturers along with racers use this idea. In the photo below, a 2007 Chevrolet 2500 pickup driver's side suspension is shown. GM designed this suspension with a great deal of anti-dive.


With anti-dive designed into the front suspension geometry, the rotation of the spindle will actually try to make the upper control arm lower, in turn, lifting the frame.





Pro-dive uses the same concept, yet just the opposite way. The more brake pressure, the more dive.



The Pros

- The more brake that is applied, the more effective the setting.

- Allows for a stiffer or softer feel to the RF or LF spring.

- Allows driver to drive into the corner and brake harder, and therefore resisting dive.

- Driver can use trail braking to continuously resist dive.



Things to Consider

- Anti/pro-dive is just another variable

- As the suspension travels, the angle change of the upper control arm could cause a bind in the front suspension.

- We have not created a calculator for this concept yet, so figuring out how much is needed is guess work.

- Too little really won't be noticeable.

- It is necessary to not only raise or lower one side of the upper control, but to also move the other side an equal amount.

- Depending on the amount of anti/pro-dive, a change in caster could be experienced when the car dives.

[HEAVY DUTY]

The angle of the upper A arm is only a small part of figuring anti-dive.The difference in angle from the top view of the A arms also effect anti-dive as well as the angle of the lower. Basicly anything that causes caster gain on compression changes anti-dive.More caster gain is more anti-dive.The only accurate way to figure anti-dive is to have a 3 dimensional front end program like William C Mitchell's Racing by the numbers program, which is quite expensive for the averaage guy to use.A GM style front end loses anti-dive as the chassis rolls on the RF and gains on the LF as it lifts.I think anti-dive makes the car to inconsistant because it is dependent upon how much brakes you are using. Too much anti can lock the RF up upon braking, it is probably best to carry the car with the springs as they would be more consistant.