Indexing Birdcage

Q:   Was wondering the effect of indexing the LR birdcage back on a 4 bar with the spring behind about 2 degrees would it load that spring harder and help the car get up on the bars easier? Also what about running the top link shorter than the bottom as this seems it would give you traction quicker by speeding up the indexing of the LR?

 A: If the upper links are shorter than say 17", the lower links have to be extremely short to minimize loose roll steer. But extremely short links change their angles radically whenever the suspension moves. When the rear links are too short forward bite and roll steer are overly affected and handling becomes inconsistent at best.
A 4-link b/cage rotates or "indexes" on the axle tube whenever the suspension moves (unless both upper and lower links are equal in length and parallel to each other). Indexing is greatest when there is a lot of length and/or angle difference in the upper and lower links.

If you clock the top ear back on the left b/cage you have slowed the speed of the rotation down as well as delayed the reaction (forward bite) also using a shorter lr top link will also generate less lift.

 A:   Since I'm JJ's technical advisor, I made him say that. But he answered your question for ya. Get to short and that sucker may have more forward bite than a Don O'neal Rayburn, but she may spin out like Miss Daisy driver coming back from the liquor store, with all the rear steer. And to answer another one of your questions will it get on the bars quicker "indexed" YES and turn thru the center better.

 A: Ok, so do you guys pre-index your birdcages? And how much? On my car the only thing I would worry about is over centering the birdcage. At full travel my upper link is pretty close to over centering already

 A: It is something to play with; your driver might kill you for it though. But the standard 6 and 12 positions or just that standard settings. Be careful not to cam her over to for or you will be buying shocks. I know I have this year. The new deal GRT and PPM have for the heim end to go the other way has fixed alot of that problem for me