This ‘Tech Tip’ feature originally appeared in the January 2007 issue of Sprint Car & Midget Magazine. We’ve pulled it out of the archives for all Print and Digital subscribers to enjoy.
This month we’re going to cover a little bit about bird cage timing. You’re probably asking: what does this have to do with routine maintenance? More than you would think!
Bird cage timing can change from race to race, therefore it is a good idea to check and adjust it before every race.
Be sure to always torque your bolts and check them frequently.
First things first: Get your car up on stands, making sure the ground is as level as possible. Then put the rear axle on six-inch blocks.
Disconnect the rear arms from the bird cages and disconnect the Jacobs ladder from the right side bird cage.
Next place a torpedo level (as shown in the picture) on the bottom of the lower frame rail, in between the front motor plate and the Jacobs ladder mounts.
Doing this ensures the frame is level. With the radius rods still in place, loosen the rod end jam nuts to allow the radius rods to turn freely.
Place the level on the flat portion of each bird cage. Turn the radius rods until each bird cage is level with the bottom frame rail.
Now reconnect your rear arms to the bird cages. Be sure and adjust each heim on the arm so that the bolt slides freely through the bird cage and the heim end.
This method is used for bird cages that have a flat machined area on the bottom. Maxim birdcages are a good example.
MEET JAMES MOSHER
For those readers not familiar with James, we felt it might be a good idea to let you know who’s offering our monthly advice for how to improve your racing operation.
A native of Albuquerque, N.M., he was raised in his father’s speed shop and at the racetrack where his father drove supermodifieds. He started racing karts at the age of three, then moved into 600cc mini-sprints, and currently races 410 winged sprint cars.
James spent the 2006 season racing events with the All Star Circuit of Champions and the World of Outlaws, and intends to run the full World of Outlaws schedule in 2007 in hopes of capturing the Kevin Gobrecht Rookie of the Year title. These days, his shop is based out of Brownsburg, Ind., where he lives with his wife Jessica and two-year-old daughter Cadence. If you’re at a race where the orange No. 12m is in action, feel free to stop by and say “Hi” to James Mosher.
Some other types of bird cages, such as the ones Sanders builds, have built in levels on top of the bird cages. You would adjust them the same way but use the level that is built in instead of your own.
There is also a level you can get that sits on top of a bird cage that has neither a built in level or machined flat spot on the bottom. This level has an arc shape that fits to the bird cage and makes up for there not being a flat surface.
When it comes to bird cage timing it is all about preference, there is no right or wrong degree of timing. Some teams prefer to run a positive two-degree angle in their bird cages, which is believed to add more forward bite.
Other teams run a negative two-degree angle, which is believed to “slow” the bird cage down and make the tires hook up more on entry.
“Zero degrees is a neutral point and it’s where the car is the most free,” said Mike Long of Maxim Racing. “There’s no point in adding another variable.”
To achieve a positive or negative angle you would place an angle finder on the cage after finding the level point of the bird cage and turn the radius rod until the angle finder moves two degrees forward or backward.
In my research on bird cage timing I have found that there is no accurate data out there to support either positive or negative timing in your bird cages.
There is only driver preference and opinion. I suggest you try the different bird cage timing and use the one that best suites your driving style.
Until next time, drive hard and be safe!