zero index birdcage

[brett4]

what would your guys opinion be on just moving the left rear lower bar forward on zero index plate and leaving the top bar alone??? so on the birdcage with the car on the ground to top bar would be at 12 o'clock and the bottom would be at 7 o'clock.

[Kromulous]

I believe it would almost index away from the spring, the further it traveled down, it would be a small amount, maybe even zero indexing. If the bars are perfectly parallel, i think it would index away from the spring.

[brett4]

I agree just wondering all your opinions..

[ukydude]

It would not index away from the spring. Moving the bottom rod forward and keeping it the same distance from axle centerline will not change indexing all that much but it will change how much load that bar carries and how the car lifts and falls.

[Kromulous]

Ok, more or less loading? and how so on the lifting and falling?

Interested in this, something i have never done before.

[billetbirdcage]

Ok, more or less loading? and how so on the lifting and falling?

Interested in this, something i have never done before.

Too lazy to figure out just moving the lower bar only but this will give you an idea:

if you take a std cage set up with 25* LRU and 9* LRL and let it travel till the upper bar reaches 45.7* and compare that to the bars moved 1" each forward/backwards the difference isn't much (granted drawn in CAD and only looking at the LR cage movement not the whole rear end movement which will be exaggerated at the LR wheel):

Both set to 45.7* of LRU bar angle at drop

STD: 4.89" of drop at cage
2.587" of Steer
12.384 degrees of index

Bars moved 1 back and 1 forward: 4.999" of drop
2.646 of steer
11.356 degrees of index

Difference of .060 drop and .100 steer.

[powerslide]

what would your guys opinion be on just moving the left rear lower bar forward on zero index plate and leaving the top bar alone??? so on the birdcage with the car on the ground to top bar would be at 12 o'clock and the bottom would be at 7 o'clock.

Could you create similar effect by indexing the birdcage back instead of forward?

[ukydude]

If you want to alter indexing you need to work on your combination of upper and lower bar angles/lengths. Placement on the birdcage has more to do with load and timing. Moving the top back and bottom forward have different effects and both have advantages and disadvantages. I can tell you exactly how and why but I would suggest just trying out different configurations. Something that looks great on paper might be excellent for driver A but terrible for driver B. And yes you can index the cage back and that will have a similar effect of moving top back and bottom forward but now you have altered the shock mount location and the spring's input/resistance will also be altered.

[Kromulous]

More steer, and less indexing, might be worthwhile. I have run the top bar back 1" but not the bottom bar.

[7uptruckracer]

So I see these “zero Index” cages they almost look like the old school where we had a few series of holes. Is that how to zero index? Which some say here is good or bad or run longer upper bars and shorter lowers if we have the corresponding holes on the 4 link brackets? I’m trying to do this on a mod ALSO SECONDLY is it true if you run the zero index being CAM over isn’t a problem you have guys running much steeper angle in the LRU?

[billetbirdcage]

No idea who came up with the name but it's a horrible name. They still index, but just can't over center nowhere near as easy unless you change bar angles/lengthen chain.

Again the name is misleading, the cage still indexes. Should be called "no over center cage"

[7uptruckracer]

Just birdcage plates with another row of holes? Or are we just running longer bars and a different series of bracket holes? I’ve seen the plates with top holes behind center and bottom holes ahead of center.

No idea who came up with the name but it's a horrible name. They still index, but just can't over center nowhere near as easy unless you change bar angles/lengthen chain.

Again the name is misleading, the cage still indexes. Should be called "no over center cage"

[billetbirdcage]

Yes, top bar back on cage and bottom bar forward on cage. Then you either have to move bars on frame the same amount or change lengths if you don't have holes there. Typically you will move on frame and not change bar lengths but you can and people do but your changing a lot more doing that. The bar length change is typically done because guys don't have replaceable 4 link brackets or holes to allow the bar to just be moved.

[Punisher88]

If you did have to lengthen the bar in the top, I would assume moving it closer to center of the axle would help negate the effects of the longer bar..

[ukydude]

No idea who came up with the name but it's a horrible name. They still index, but just can't over center nowhere near as easy unless you change bar angles/lengthen chain.

Again the name is misleading, the cage still indexes. Should be called "no over center cage"

Exactly!!!!!

[sam73]

My car has a 20in ride height# and 23 3/8 droop# on the LR. What if without any loss of droop height, you could keep the spring at the 20in RH and at full droop spring centers would be 21in? It was mentioned what goes up must come down. Kinda wonder about the going down part.

[MasterSbilt_Racer]

My car has a 20in ride height# and 23 3/8 droop# on the LR. What if without any loss of droop height, you could keep the spring at the 20in RH and at full droop spring centers would be 21in? It was mentioned what goes up must come down. Kinda wonder about the going down part.

Not possible and be within the rules. Air shocks are popular because what you are asking can't be done.

[PayinDaPurse]

I’m a little Confused when guys are running this “zero index”? Is this the new normal setup or is there a track condition that would make you go to “zero index”.

I don’t have this option on my cages, should I update them to the brackets that allow the “zero index”?

Thanks

[Jking24]

Dont get to caught up in it. With the added droop and the increased rf travel the lr suspension is in danger if flipping the birdcage or over centering. When you get near this condition the lr suspension goes ridged ie. No shock and spring. When you have no shock and spring in play you have no control over what's happening on that corner (bad). Yes you need to look closely at your lr bar angles in full droop. No you don't necessarily need some magic bird cage

[MasterSbilt_Racer]

There is speed to be had by getting your spoiler in the air. There is speed to be had not rotating your cage too far. Take those 2 facts and sharpen your pencil.