If you’ve ever researched the right transmission for your hot rod or custom transplant, you’ve probably heard of the GM 700-R4 and 200-4R transmissions. The GM 700-R4 and 200-4R transmissions are widely used for custom builds. They’re also some of the most misunderstood transmissions of their time, and have some notorious throttle valve cable hurdles. After years of hard work on repairing and rebuilding these transmissions, we created the Bowler Tru-Shift system to help you out.
Because these transmissions are considerably different from their predecessors, many guys end up with clutch failures in the 700-R4 and 200-4R. These problems are mainly due to improperly set throttle valve cables. Throttle valve cables resemble the kick down cables of the previous non-overdrive transmissions, but they perform a very different function. The throttle valve cable on the 700-R4 and 200-4R transmissions controls line pressure, shift points, shift feel, part throttle downshifts, and detent (full throttle) downshifts. If the throttle valve cable is not adjusted properly, it can cause numerous transmission problems.
The throttle valve cable is connected to the carburetor on one end, and the throttle valve plunger assembly is mounted on the valve body at the other end. The throttle valve cable’s function is to transfer the movements of the throttle at the carburetor to the throttle valve plunger in the valve body. This allows throttle valve pressure and line pressure to increase according to throttle opening for gear upshifting. It also controls when the transmission downshifts. When the throttle valve cable is properly adjusted, the movement of the throttle valve 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. The adjustment on the closed throttle side is equally important, as that’s where most failures occur.
When GM designed the throttle valve cable systems, they were set up for a specific carburetor/throttle body system on a specific intake with the correct bracketry. This setup continually duplicates the settings they calculated for line pressures. If a change is made, such as installing a different carburetor, the change in geometry could disrupt this balance and you may never achieve proper adjustment. Often the adjustment gets close enough for proper operation, but it’s never calibrated to what it should be. Therefore, the performance and longevity of the transmission is compromised. All too often, you’ll hear stories of how a newly rebuilt transmission was burned up in only a few miles. This is almost always due to improper throttle valve cable adjustment. It really is that critical.
Many years ago, as we were working on more and more 700-R4 and 200-4R transmissions, we noticed how common it was to see units with burned-up clutches from improper throttle valve cable adjustments. 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 you to install the throttle valve 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 the Bowler Tru-Shift installation. This also allowed us to make a few tweaks to the system to create a little higher pressure off idle. Now, you can better apply the clutch packs when they see 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. This produces a much smoother response in the valve body for gear shifts. There is truly no other throttle valve cable kit on the market today that does what our Bowler Tru-Shift system can.
We are confident that the Bowler Tru-Shift system will produce the results you want and give your transmission the life expectancy and performance you need. The precision of the Bowler Tru-Shift system eliminates any need for checking line pressures, further cable adjustments, and worries of burned up clutch packs. It’s a simple bolt-on solution that comes with all the components you need to get your carburetor connected to your transmission. We even verify the length of the cables we send so that we know without a doubt that the system will deliver the right results. Regardless of your experience with setting up throttle valve cables, we’re confident that following our instructions will result in a successful installation and a great end result.
Throttle Valve Cable System for GM 700-R4 & 200-4R Transmissions
If your hot rod or custom project needs a reliable, accurate throttle valve cable setup, check out our Bowler Tru-Shift kit. Each kit comes with detailed, easy-to-follow instructions. If you have any questions about our kit or its installation, feel free to give us a call! We’re here to help you build the car of your dreams, and give you the equipment you need to make sure it runs perfectly.