Art Carr's r4 tv cable adjustment guide from badz.info
Introduced in the early eighties, the General Motors Throttle Valve cable of the many transmissions it was used in, the ThR and the ThR4. We have read lots of General Motors manuals explaining how to "adjust" the factory TV cable. As far as we know, this system was never designed nor intended to be a . With close inspection you will see it has sort of a "D" shaped button you can depress and slide the sleeve R4/R TV Cable Adjustment Instructions. Jul 8, how to adjust tv cable on an older GM car. The car in the video is a 84 Buick Regal v6. Its the same process for a v8 4 bbl or tbi.
Pulling and releasing of the TV cable during normal driving, reciprocates the TV plunger back and forth inside the TV bushing.
Adjusting TV Cables - Tech Article - Chevy High Performance Magazine
Shown at left in the fully extended and fully depressed positions Whenever the TV plunger Red arrow is moved inward inside the TV bushing Blue arrowit pushes on the TV spring Green arrow which in turn pushes on the TV valve Yellow arrow. The sole purpose of the TV valve is to direct TV Feed fluid into the orifice shown with the red circle.
The volume and pressure of this TV Feed fluid, being directed into this passage, will progressively increase, as the accelerator pedal is being depressed. This increasing TV feed volume and pressure entering into this feed passage is directed to all of the transmissions pressure regulating and shift control circuits. This increase in volume and pressure is not designed to increase in a progressive straight line; it's heavily biased towards increasing pressure and volume more rapidly during the initial movement of the Throttle valve and to have delivered its full influence by slightly over half throttle opening.
This feature works hand and glove with the transmissions pressure boost system controlled by the line bias valve to more closely match increases in engine torque.
It would be a gross understatement to say that the TV valve and the fluid feed hole it manages are critically important to the ThR4 and ThR! Let's get into the details! A rubber sleeve type seal placed between the TV cable housing and the case hole prevents fluid from leaking out of the transmission. At the "carburetor linkage" end of the TV cable there's a special plastic housing molded onto the end of the TV cable assembly indicated by the red arrow in the picture a right. This "housing" snaps into a metal mounting bracket shown by the yellow arrow.
This bracket is typically mounted to the engines intake manifold. The inner wire cable indicated by the blue arrow above located inside the TV cable assembly typically has a tear drop shaped plastic connector at one end and a metal connector at the other.
The "tear drop" connector Green arrow above snaps onto the "carburetor linkage". The metal connector at the transmission end is connected to a rigid wire link shown in picture 2 earlier which is in turn connected to a rotateable throttle lever and bracket assembly orange arrows at left.
A fully extended TV plunger is not able to touch the activating cam surface of this lever when the cable is in its non adjusted full "out" position.
Let's run through the stock TV cable set up procedure! General Motors Corporation is very specific when describing the correct method for "Setting" the TV cable system. The most "common" factory TV cable design has a metal "D" shaped button built into the housing of the cable assembly located where it snaps into the mounting bracket on the intake manifold. There are other TV cable designs but all of them are designed to establish the proper starting and ending relationships of the TV system components.
We will explain what the proper starting and ending points are once we've walked through what happens when we execute the factory TV cable "set" procedure. The manual states the TV system is set correctly when the TV lever touches the face of the TV bushing at the same time as the engines "carburetor linkage" is at its wide open throttle position and the accelerator pedal is fully depressed.
Once everything is connected correctly, the first step of the factory TV "set" procedure is accomplished by first pushing in on the TV cable housings "D" shaped cable slider release button, then pushing the cable slider towards the transmission until it stops as far into the cable housing as it will go. Release the "D" button to hold it in this preset position. By sliding the "cable slider" back into the cable housing like this, you're increasing the actual length of the TV cable's outer sheath that's located between the transmission case and the TV cables mounting bracket located on the intake manifold.
As the cable sheath gets longer between these two connection points, it will preload the TV plunger into the TV bushing as shown in the picture at the left. The manual states you properly "set" the TV system by manually rotating the "carburetor linkage" to its wide open throttle position. However, as you attempt to rotate the "carburetor linkage" towards its wide open throttle position, the TV lever quickly comes into contact with the outer end of the TV bushing as shown by the blue arrows in the picture below.
The TV lever stops at the TV bushing well before the throttle reaches its wide open throttle position as shown by the orange arrow in the picture above.
Notice the TV cable slider position as indicated by the white arrow. You must "force" the "carburetor linkage" to its full W. This action has "forced" the TV cable "slider" mechanism to "ratchet" out to its correct "set" position! The white arrow in the picture at right shows the TV "slider" in its new extended position.
We have just established the correct wide open throttle relationship between three key TV system components. First, the "throttle linkage" is at W. Orange arrow above picture Second, the TV cable slider mechanism is correctly positioned. White arrow above picture Third, the TV lever is positioned up against the TV bushing as shown by the blue arrows in the picture at the left. As long as the vehicles accelerator pedal will cause the "carburetor linkage" to rotate to its full W.
Experience has taught us to go one step further and check to be certain the vehicles accelerator pedal will rotate the "carburetors linkage" to the wide open throttle position. When the General Motors procedure is followed, it establishes the correct wide open throttle position of the TV plunger when the vehicles accelerator pedal is fully depressed.
Nothing else is supposed to be done! This wide open throttle position "set" is designed to calibrate the relationship of the vehicles accelerator pedal mechanism to the TV system. This position will then automatically establish the correct working relationship between the TV system components as the "carburetor linkage" rotates back to its idle position. What happens when the "carburetor linkage" is permitted to rotate back to the idle position is at the very heart of understanding these transmissions TV cable systems!
As the "carburetor linkage" is allowed to rotate back to idle, the distance the inner wire of the TV cable is allowed to travel back out is the sole determining factor of where the "starting position" of TV valve will position in the TV bushing.
Watch how this happens in the following pictures When we left off last in our effort to "set the TV cable up, we were holding the "carburetor linkage" at is wide open throttle position.
An unhooked or damaged throttle lever spring. Reconnect the spring if it is unhooked. If it is damaged, replace the throttle lever and bracket assembly. An incorrectly adjusted TV cable. A If the cable is adjusted too long, one of the following conditions may result: B If the cable is adjusted shore, or not hooked up at all, line pressure and shift points will rise and full throttle operation may not be possible.
This can cause problems similar to a malfunctioning transmission. This can cause detract from vehicle performance and cause transmission malfunction. Check the TV cable to insure that it is the right part for the vehicle. Check the cable to insure that it is properly connected at the transmission. Adjustment procedure self-adjusting cable 1.
Depress the adjusting tab and move the slider back through the fitting away from the carburetor until it stops. Release the adjustment tab. Move the throttle linkage to rest against the full throttle stop, then release it. Check the cable to insure that it is not sticking or binding. Road test the vehicle. If the problem still exists, refer to the cable diagnosis section. Proper installation and adjustment of the TV cable is the most important aspect of a transmission.
Don't think of it as "just a kick-down cable" - on the nonvacuum-modulated ThR4 and ThR the TV cable controls line pressure, shift points, shift feel, part-throttle downshifts, and detent downshifts! As the accelerator pedal is depressed and the throttle opens, the TV linkage relays the motion to the valve body's throttle plunger. In stock installations, the geometric relationship between the TV cable and carb throttle shaft bellcrank produces the required TV cable extension pull for the transmission to function properly under different degrees of throttle opening.
Failure to preserve the correct geometric relationship in custom installations will inevitably lead to early transmission failure. Measure your TV cable to establish its particular mounting dimension as follows: Have no fear, these trannies are as simple to adjust as the venerable TH and If the TV is not properly adjusted, the trans will shift too soon, too soft, too late, or not at all. Take the car for a testdrive with the shifter in Drive.
At light to medium throttle, make a note of the shift-point mph. Our test car shifted from First to Second at 10 mph and Second to Third at 20 mph. He recommended a First-to-Second shift at about 20 mph and a Second-to-Third shift at about 30 mph.