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View Full Version : Shock mounting point on bird cage importance



racefastnow
08-24-2015, 11:43 AM
How does the point where the shock mounts on the bird cage effect the car. The height from the ground to the center hiem point, also how far back it horizontally from the rear end???

JustAddDirt
08-24-2015, 11:55 AM
it effects a lot.
Front to back more than height.

billetbirdcage
08-24-2015, 12:36 PM
All the mounting points can really change a car, sometime how much one changes the car is dependent on the other one.

racefastnow
08-24-2015, 06:50 PM
Was looking for an example of what effects it has one way or the other, maybe some experience from doing so! Usually like to have some theories before just moving things yes, lol

billetbirdcage
08-24-2015, 08:54 PM
Assuming LR behind: Typically Down and/or back will tighten exit, notice I didn't use the words "add forward drive".

Matt49
08-24-2015, 09:07 PM
It's all about motion ratios and how the birdcage rotates/indexes which is dependent upon your 4-bar angles and lengths. But assuming you don't adjust bar angles and lengths at all, you can make some assumptions and come up with a concrete example.
The further you have the shock mount AWAY from the center of the axle, the more movement of the shock mount is created by birdcage rotation/indexing. For and aft will have a greater effect but higher and lower have an affect also. For and aft has a greater "initial" effect but the motion ratio decreases as the axle moves further. Higher and lower has very little "initial" effect but the motion ratio increases as the axle moves further.

Moving the RR shock mount further forward or further down (and resetting ride height) will theoretically tighten deceleration handling.
Moving the LR shock mount further back of further down (and resetting ride height) will theoretically acceleration handling.

It's difficult to explain without drawings and even demonstration but I'll say this: with the million other ways you can adjust your race car, this isn't likely something you're going to mess with much.
I would recommend setting your shock drop to where you are in the ideal range of motion for your shocks. Meaning not bottoming out your RR and not topping out your LR.