Maybe your non-turbo automatic shifts just a little too early or a little too late? Maybe your turbo diesel transmission jerks a little too much or flares during shifts? PROVIDED and I will repeat PROVIDED your vacuum system is working properly, your VCV valve is working properly and your transmission modulator valve is working and adjusted properly - you can use this adjustable orifice to "fine-tune" your transmission shifts. Version 2 Update March 10, 2022 - Kent revised the design and threaded the adjustment needle. So now you can more precisely adjust the vacuum by turning the needle in or out. Watch the video below and Kent will explain why an adjustable orifice is desirable on these older diesel automatics.
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WARNING: As I tried to stress above, this part will not fix your transmission shifting problems! You will need to troubleshoot and repair those other systems I mentioned above. I recommend you start by reading the manual I wrote on these many issues. I also have many other resources to help you if needed. Please see the related products below:
Related Products:
Diesel Automatic Transmission PEAK Performance Tuning Manual by Kent Bergsma
I have received so many emails on this topic that I had to sit down and write a very detailed manual over 130 pages in length! Let's face it! Diesel automatic transmissions can be troublesome, particularly those models that use vacuum to control shifts.
Adjusting Automatic Transmission Mechanical Shift Points for Peak Performance - On Demand Video
If your transmission is shifting too soon it can really rob your car of power and acceleration. If it is shifting too late it can be very loud and annoying and even affect fuel economy.
How to Test the VCV ( Vacuum Control Valve ) for Proper Operation - On Demand Video
Kent will explain the theory of operation in simple terms, why it is so important for proper transmission shifting performance, and how to test it hooked up to the engine's vacuum system with the engine running.
616 617 Diesel VCV Shift Control Rod and Clip
ONLY ONE LEFT. Good used activation rod and plastic clip as shown. Controls travel of vacuum control valve on the top rear of the injection pump. A plastic clip can easily break. May be some slight wear on the end of the metal rod but still usable.
Diesel Automatic Transmission VCV Vacuum Controls Testing Kit
This unique kit will allow you to hook up a 30 in HG vacuum gauge between your vacuum control shifting valve (VCV) and your transmission modulator to test the VCV for proper function and to tune it for peak shifting performance.