birdcages?

L

liquidqwik

Justin Anderson
Could someone explain to me how a bird cage works for a Rayburn swingarm? The swingarm is bolted to the bottom of the birdcage and the rear trailing bar is mounted to the top. Bird cage timing is supposed to be set a 90 degrees(I am assuming), when the car is at its preferred ride height. Anyway, what exactly does the birdcage do? which way does it pivot? How far does it travel, and when you let off the gas, does it go back to its original position? When you accelerate off the corner, how is the birdcage affecting the travel the car gets? Thanks for your time.
 
The birdcage rotates on the axle tube as the suspension moves up and down. Under compression it will cause the rearend to move to the rear and under rebound it will move to the front thus
you get a determined amount of rear steer. Typically you will get less rear steer with a swingarm than you will get with a 4-bar setup which is also mounted on birdcages.
 
To really understand what they do just take the rear c/os of your car and the pull bar loose at one end, place the rearend on 4"blocks, and lift up and down on your latter bar, then take the block out of the left and add acouple inches to the right block and lift the latter bar. That should give you all the understanding of what goes on. Make sure you lube the birdcages often, and if the bars are the right lengths for the mounts you should never have to worry about indexing on a rayburn.
 
reply to dean

Dean

Thank you for your insight on the bird cages. That will help me answer my question. This week I set the ride height blocks under the rear end. I did not take one bar loose, but I just lifted up and down on the rear end(like when the car is on the track) until the axle tubes were 1 inch above the correct ride height on each side, and I let it down slowly until the axle tube hit the frame only on the left side. I then took the angle measurement for both. I know the way I am saying this seems simplified, but I believe it is what you said to try. So my last question would be, where exactly to set the bird cage angle if you have 1/2 inch lead in the left rear. If the bars are set at the lengths Rayburn wants, the bird cage is around 90 degrees. Should it still be 90 if you want lead in the rear end. Or should you push it up/back to get more travel. Thanks for all your help!

liquidqwik
 
If you need to turn the rearend in the car for a really pushy track, just lengthen the lr trailing arm 2 rounds and shorten the rr two rounds be sure and mark them and put them back to 17" when the track slicks up aliitle. That is realy a crutch and should only be used if you cant get the stagger or your just on a track thats really pushy. Rayburn has a tech line before 9am weekdays 317-535-8232. I'm not real sure if your wanting to lead/trail your rearend for the same reason I have had to.
 
Dean

From what I was told, leading the left rear tire causes the cross weight to go up faster when you get on the gas because the left rear and right front wheel are moving closer together. This is just what I was told by a fellow racer. So, I figured when the track gets slick as the night goes on, add a little more left rear lead. But, I was not sure what that would do to the bird cage timing. The reasons you moved your rear end seems more sophisticated than what I am trying to figure out, because I never moved the rear end last year at all. I really do not know what to do with the rear end when the track gets slick. But, for some reason the cars with the 4-bar rear suspensions pull harder off the corner than my swing arm. I am trying to devise a way to get more off the corner bite. Thanks again for all your help.
 
qwik

There are several ways to get to where you want to be. For instance, you could actually lead the right rear 1/2 inch; it will tighten the hell out of the car all the way around, but will give up good corner entry. It will however hook coming off. This will also increase weight on the RR somewhat. Your best bet is to call the tech line like Dean said, to get the best set up for your needs.
 
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