You can read about the components we installed, the before-and-after test results, and our comments about the combined effects in "Suspension Ascension" found on page 66 of this issue.
A Rear Gear To Compliment Lt4 Upgrades
I have a couple of questions regarding gear ratio. I own a '95 Trans Am with a six-speed to which I have recently added the LT4 hot cam kit. Now I am thinking of installing the LT4 intake and changing my axle out for a beefier one. Will the LT4 intake work on my year T/A? What gear ratio should I go with? I am thinking 3.73, but I am not sure. My neighbor said that my gearing is going to depend on what kind of cam I have.
Robert Meidam
Hortonville, WI
Ray Bohacz responds:The LT4 intake needs to be used with the matching cylinder heads due to the raised intake port runner this package employed, so the intake manifold is not a bolt-on to the LT1 castings.
When it comes to the gear ratio, the camshaft is important since it will determine the speed at which the engine makes peak power. As the cam profile gets more aggressive, bottom end torque suffers, while top end power improves. Hence, a larger cam requires numerically larger gears to avoid soft performance at lower speeds. Since your T/A has the six-speed overdrive transmission, you may want to consider a 4.10:1 rear gear ratio to provide more performance down low and mid-range. The double overdrive of the sixth gear will still allow the engine to cruise comfortably at highway speeds while returning good fuel economy.
Does My '79 T/A Need To Be Locked Out?
I have mechanical questions that I hope you can help me answer. I have just added some Summit headers on my '79 Trans Am and there is a bar connected to the steering column that goes down to the transmission. Now the car has the shifter on the floor, and the bar is hitting the headers. My questions are: Do I need that bar on the steering column? Is it a lock mechanism for the steering wheel? Please help.
Rick Padilla
Via Internet
Rocky Rotella responds:You're experiencing the same scenario that many hobbyists who've added tubular headers have encountered for years. The solid rod you refer to is known as the upper gearshift control rod, and it's part of the mechanical back-drive linkage. It has a couple of designated purposes in your '79 Firebird.
The first is to engage the internal steering column lock mechanism. Designed as a theft deterrent, when the shifter is placed into Park with an automatic transmission, or Reverse with a manual, the rod rotates the steering column collar, which allows removal of the ignition key from the lock cylinder, subsequently locking the steering column and the shifter position.
The collar rotation is directly related to the rod's second purpose. It controls the column-mounted Reverse light switch (both transmissions) and combined neutral-safety switch (automatic only). The latter prevents the engine from turning over while the automatic transmission is in gear (the manual transmission safety switch is located on the clutch pedal).
You can certainly remove the upper rod from your Trans Am and drive it without significant issue. Your column must, however, remain in the "Lock" position in order to remove the ignition key, and you must disconnect the power lead from the Reverse light switch and/or neutral-safety switch combination, or the Reverse lights will illuminate anytime the ignition is "on," regardless of gear position if it's a manual trans.
Just remember that while operating the vehicle without this rod, the engine will turn over with the transmission in any gear, and the lock cylinder can be rotated to the lock position at any time and/or vehicle speed, locking the steering wheel and severely limiting vehicle control. As long as you keep those points in mind, you should have no real problem.