CUCV Throttle Vacuum Valve Adjustment


*** Before starting this procedure, check all the vacuum lines. Many times they are the issue. For a few bucks go ahead and replace them. ***

I have been piecing back together a GSA M1009. One of the many issues was the tranmission was shifting hard. I searched the CUCV forum and found a few threads.

The TM 9-2320-289-20 tells you how to adjust the Vacuum Valve, but you need the special tool J-33043. I found it in the internet for $150.

Instructions are in the TM 9-2320-289-20, Chapter 3-21.1 page 3-64. Adjustments are made with the engine off.


I found the size on another website of .646" or 323/500". I didn't have one laying around. So being the cheap Bas***d I am, I made my own..:cool:.

I took a piece of wood and cut it down to size. I added the wire so I wouldn't drop it into the manifold again....:twisted:

Instructions are in the TM 9-2320-289-20, Chapter 3-21.1 page 3-64. Adjustments are made with the engine off.

Here are the steps:

Before you begin, install a vacuum gauge on the vacuum pump and make sure the pump is functioning correctly. It should produce 20" of vacuum.

1. Replace bad vacuum lines
2. Loosen bolts on valve
3. Hooked up my MightVac to the bottom port
4. A vacuum gauge to the top port
5. insert block under throttle shaft per instructions, hold throttle against block
6. Apply 20" vacuum to bottom port
7. Rotate valve until you have 8" of vacuum at top port.
8. Tight bolts and put everything back where it belongs
(The vacumm pump hose to the bottom port, transmission line to the top
9. Take it for a test drive

If your valve is bad you will not find it at the usual parts houses. I have seen them at some of the Military Supply Houses and they run ~$90.

From the TM 9-2320-289-20p parts manual Figure 10 , Item #10 the GM part number is 14057219. Sometimes you can find them at the dealership or online.

Another item off of the check list. :beer:

Thanks Warthog!

A simple and great solution to replace an otherwise overpriced tool which one may possibly need but once in a lifetime!!

For those who want to build their own special tool J-33043, I found that a carpenter's ruler, you know the folding type, is just about 0.646" or 16,4mm wide, just a glimpse wider.
That is, I assume a carpenter's ruler dimensions will be the same in the US, or am I wrong?
I merely had to rub it on a sand paper for a couple of strokes to get the exact size.

So I took me a broken carpenter's ruler and cut 2 pieces of about 1.5" long and glued them together; this is to get sufficient thickness of course. This is curing now and tomorrow I just need to drill a hole and attach some sort of handle/wire.
Fast and easy and the wood from a carpenter's ruler is very solid/hard, so your tool retains it's exact size.

Last edited:


Active member
Steel Soldiers Supporter
San Diego, CA
Can an improperly adjusted VRV cause a transmission to fail in short order, like, less than 5k miles?
Not likely. The VRV would help control shift points. Even if you didn't use any vacuum to the trans, it would still work but would only shift at a high RPM level but still shift.

If you had a trans failed (especially a TH400), it was not built correctly (if recently rebuilt) or was already on it's way out.
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