CUCV Throttle Vacuum Valve Adjustment

Warthog

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*** 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.

http://www.steelsoldiers.com/cucv/6748-whats-part-called.html
http://www.steelsoldiers.com/cucv/33767-m1009-vacuum-lines.html

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.

Kent-Moore Tools J-33043 VACUUM GAUGE BLOCK ASSEMBLY

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
port)
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:
 

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Westech

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you dont need that bock to adjust it.... thats just a wast of time. All you have to do is to adjust it..... move it towards the fire wall for lower shift points, towords the radiator to higher shift points. and adjust the modulator on the transmission for the fine shift point adjustments. its a real simple system to work on and adjust, just it may take a couple trys to get her just right.
 

papercu

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For those that just have to have the store bought stuff, there are two on ebay BIN for 17.39 ea. Wayne
 

allenhillview

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you dont need that bock to adjust it.... thats just a wast of time. All you have to do is to adjust it..... move it towards the fire wall for lower shift points, towords the radiator to higher shift points. and adjust the modulator on the transmission for the fine shift point adjustments. its a real simple system to work on and adjust, just it may take a couple trys to get her just right.
Can you tell me about the fine shift points at the modulator on transmission, which is what I've not looked at yet but I'm going to try this tomorrow. I want my truck to stay in 1-2 longer for east Tn hills. I know of the Modulator but what takes place to adjust it one way or another?
 

Keith_J

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Great write-uo! I've been having soft shift issues with very sluggish downshifting at wide open throttle. I checked all vacuum lines, no leak. Vacuum pump pulls a pulsating vacuum 18-20 " Hg, vacuum at the modulator is 15" Hg and rising slowly, not responding to any throttle position.

From the photos, it appears to be adjusted incorrectly. Now off to make the 0.646" block on my friend's table saw with micrometer fence :jumpin:. If that doesn't work, I will try to clean the modulator. If that doesn't work, guess I will have to drop some coin on a new unit. Found the AC-Delco part for a good savings at that online mall named after a large South American river
 
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Keith_J

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The vacuum regulator would not adjust. I got it to move, regardless of position, vacuum out was the same as vacuum in. So I did what I always do, I tore into it. The main sealing element for the regulator is shot, causing it to leak regardless of tension on the spring. The tension is set by a cam which is keyed to the throttle shaft.

I ordered a new one which will be in the 13th. Not bad, that is the day after tomorrow :grd:
 

Keith_J

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Got the new valve installed. Adjusted it to "that looks about right" before hooking the vacuum pump and gauge to it. Pulled the vacuum and BAM!, 8" Hg on the first attempt with my home made wood block. Buttoned it up and took it for a test spin, like new shifting.

This should help the PTO generator too.
 

donalloy1

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you dont need that bock to adjust it.... thats just a wast of time. All you have to do is to adjust it..... move it towards the fire wall for lower shift points, towords the radiator to higher shift points. and adjust the modulator on the transmission for the fine shift point adjustments. its a real simple system to work on and adjust, just it may take a couple trys to get her just right.
Westech, thanks for cut and dry adjustment parameters. That's what this site is all about. DMLII sends respectfully...
 

rodman68

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I tried to find some info on this in the tm but cant find it. What is the output vacuum on the VRV at idle? I have hard and late shifts and the input vacuum is constant 28" and the output vacuum at idle is 8". I dont wont to adjust unless I am sure what I am doing I have a mityvac on order.
 

Keith_J

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I tried to find some info on this in the tm but cant find it. What is the output vacuum on the VRV at idle? I have hard and late shifts and the input vacuum is constant 28" and the output vacuum at idle is 8". I dont wont to adjust unless I am sure what I am doing I have a mityvac on order.
18" Hg. If the vacuum is high all the time, shifts will be sluggish. Hard shifts are a sign of vacuum leakage or modulator fail, not regulator issues. The TH400 is designed for a gasoline engine which has high vacuum at idle and coast, medium vacuum at mid power and low vacuum at high power. Hence, shift nature must be tailored for such conditions. If the engine is at full throttle, it needs fast, hard shifts to prevent engine overspeed between shifts.
 

camp9

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I tried to find some info on this in the tm but cant find it. What is the output vacuum on the VRV at idle? I have hard and late shifts and the input vacuum is constant 28" and the output vacuum at idle is 8". I dont wont to adjust unless I am sure what I am doing I have a mityvac on order.
If I remember right there is a little silver round thing on the passenger side of the transmission that has a very short vac line on it. You'll probably find it is dry rotted.
 

toyrunner95

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I had the same issue on my truck. To narrow it down from a vrv (vaccuume regulator valve) or the sm ( shift modulator) I by passed the vrv with a simple placstic t hose fitting with one end capped off. The truck shifted normally so I found my problem.
 

rodman68

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I will see if I can adjust it up to 18" at idle, and see what it does. I will make the block to adjust it when I get my mityvac in should be here next week. The lines are ok since I replaced them all, I believe the issue lies with the vrv at this time since the output vacuum is only at 8". It was shifting just fine maybe a little on the lo side but it slowly got higher and higher shift points so I will think the vrv is bad but testing needs to be done.
 

rodman68

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Thanks for the help it was that stubid little rubber block on the VRV it didnt look bad at first glance but under closer inspection it had a crack in it
 

dmilkman589

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what size bolts are holding on the vacuum valve thingy. i have to adjust mine a bit but the bolts are really tight. i dont wanna strip them, i want to make sure i have the right size on there first..
 

gebirgsoldat

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Well, I replaced the vacuum valve and I am getting 15" at the Valve but only 4" at the modulator... still shifts late... I bypassed the metal hoseline altogether and am still getting 4" at the modulator? Is it my vacuum pump? :drool:
 
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