Mark from Gearstar went on, “The TV cable is the only communication between the engine and transmission, and perfect alignment of the TV cable is critical for proper operation.” If the cable becomes loose or out of adjustment, the car will experience relatively early shifts across the range of throttle position and no kick-down passing gear.
Things to remember when maintaining a performance transmission:
- Keep your transmission fluid level full and clean
- Run a high-capacity pan
- Install a transmission cooler
- Replace your filter/screen with an OEM unit
- Never substitute rubber hoses for metal vacuum lines
When you reinstall or adjust a TV cable, you must always make sure it isn’t too far out of adjustment, especially on the loose side. Otherwise, it will trigger a safety feature inside the transmission that will spike line pressure as to slip the clutch, which could ultimately damage the clutch packs due to the insufficient line pressure rise. This condition normally occurs if the TV cable becomes disconnected from the carburetor or throttle body.
Unfortunately, the TV cable is usually attached to the throttle body or carburetor with a clip-on plastic fastener, and overtime, the underhood heat from the engine will degrade the fastener, causing it to break. However, this doesn’t apply to everyone since they are sometimes fitted with a metal unit. In the event that the TV cable should ever fail, you can still pick up a quality replacement from the dealership or an aftermarket parts source.
If your 700R4 refuses to upshift, then it’s most likely due in part to a failed governor. Made from a combination of plastic and nylon, the gear-driven governor can eventually break off from wear overtime, resulting in a loss of upshifting. A replacement unit can be found at your local transmission shop.
Other issues with the 700R4 include the loss of the second, fourth (overdrive), and reverse gears. While many of us would write this off as a burnt transmission, it’s more than likely just a destroyed 3-4 clutch pack. This can be caused from a misadjusted throttle-pressure cable. It turns out that the 3-4 clutch pack in the factory configuration is the weakest link in the 700R4.
A common issue we see are failed band servos in the 700R4. This is usually stems from a low or dirty transmission fluid level. -J.C. Beattie
Mark, Scott, and J.C all pointed out that inadequate line pressure due to an under-adjusted TV cable will ruin both the third- and fourth-gears quickly. Walk continued, that whether or not that the transmission in question had already received a fresh overhaul or has over 100k miles under its belt, proper adjustment of this cable is absolutely crucial.
The final fault with the 700R4 is a non-functioning overdrive gear. If yours refuses to shift into overdrive, but operates perfectly from 1-3, it’s highly recommended that you get it home or to your local transmission shop quickly, but carefully.
When this occurs, the input spring is more than likely destroyed, and the only component engaging forward is the overrun clutch, which is totally inadequate to hold engine torque for acceleration.