The GM 700-R4 and 200-4R transmissions have been some of the most widely used transmissions for transplanting into hot rods and customs. They’ve also been some of the most misunderstood transmissions of their time. The predecessors to these transmissions operated in a way that was similar, but completely different. Because of that, many guys end up with issues of clutch failures in the 700-R4 & 200-4R due to improperly set throttle valve (TV) cables. The TV cables resemble the kick down cables of the previous non-overdrive transmissions, but they perform a much different function.
The TV cable on the 700-R4 and 200-4R transmissions controls line pressure, shift points, shift feel, part throttle downshifts, and detent (full throttle) downshifts. So if the TV cable is not adjusted properly, it can cause numerous transmission problems. The TV cable is connected to the carburetor on one end, and the TV plunger assembly mounted on the valve body at the other end.
The function of the TV cable is to transfer the movements of the throttle at the carburetor to the TV plunger in the valve body. This allows TV pressure and line pressure to increase according to throttle opening for gear up shifting, and also controls when the transmission downshifts.
When the TV cable is properly adjusted, the movement of the TV plunger in the valve body is calibrated to the movement of the carburetor. This means the transmission will always have the correct line pressure and shift feel regardless of engine torque. Traditionally it has been stated that as long as you have the cable adjusted all the way out at full throttle, you’re good to go. Yes, that is important, but just as important is the adjustment on the closed throttle side as that is where most failures occur due to inadequate line pressure off idle.
When GM designed the TV cable systems they were set up for a specific carburetor/throttle body system on a specific intake with the correct bracketry to continually duplicate the settings they calculated for line pressures. If a change is made, such as a different carburetor installed, the change in geometry could disrupt this balance and proper adjustment may never be achieved.
Many times the adjustment gets close enough for proper operation, but it is never calibrated to what it should be, and therefore the performance and longevity of the transmission is compromised. All too often though, you hear the stories of how a newly rebuilt transmission was burned up in only a few miles. This is almost always due to improper TV cable adjustment. It really is that critical.
Many years ago as we were working on more and more 700-R4 & 200-4R transmissions that were being used in hot rods we noticed how common it was to see units with burned up clutches due to improper TV cable adjustments. This got the gears turning and we decided to develop a solution that was so easy to use that there was virtually no way to get it wrong. This led to the creation of the Bowler Tru-Shift system.
We spent countless hours developing a correction arm and bracket system that would allow installation of the TV cable onto a variety of popular 4-barrel carburetors without fear of burning up your transmission. By studying the geometry that GM designed for their system and adapting it onto our brackets, we are able to consistently and repeatedly achieve proper line pressure with a one-time adjustment of the cable during installation. This also allowed us to make a few tweaks to the system that creates a little higher pressure off idle to better apply the clutch packs when they are seeing the greatest amount of stress getting the vehicle moving from a complete stop.
By creating a non-linear cable pull we are also able to apply the pressures at different rates throughout the entire throttle range producing a much smoother response in the valve body for gear shifts. There is truly no other TV cable kit on the market today that does what our Tru-Shift system can.
We are confident that the Tru-Shift system will produce the results needed to give your transmission the life expectancy and performance you are looking for. The precision of the Tru-Shift system eliminates any need for checking line pressures, further cable adjustments, and worries of burned up clutch packs. It is a simple bolt on solution that comes with all the components needed to get your carburetor connected to your transmission.
Bowler Tru-Shift Throttle Correction System For Sale
We even go as far as verifying the length of the cables we send so that we know without a doubt that the system will deliver the results needed. Regardless of your experience with setting up TV cables we can assure you that following our instructions will result in a successful installation. It may be tempting to go with a less expensive cable and bracket system, but those types of kits cannot duplicate the correct geometry needed and those savings will quickly disappear when you are paying someone to rebuild your transmission again after only a short time of use.
