M1009 tranny

[jag7720]

First question... does the M1009 have a TH-350?

Mine doesn't have an over-drive like my 87 van and I thought the over-drive meant TH-400.

Second question... What is a good shifting pattern on an medium pedal... not flooring it or trying to race off the line?

The reason I ask is, if I accelerate with an average pedal, my M1009 shifts harder than my van (both are diesel) from first to second... then my M1009 won't go into third until about 40 or 45 mph. If I cruise at 35, it will stay there for miles unless I give the pedal a quick jab.

Is there something I can troubleshoot or an adjustment I can make?

 

[tklm539]

I am not sure on the first question. But on the second, mine shifts out between 30-35 mph. Seems fairly smooth to me without a comparison

Tom

 

[FMJ]

TH 400, no overdrive. Check your Vac lines between the Vac pump and the IP. Also check the electric kickdown switch thats mounted on the accelerator pedal bracket, make sure it opens and closes (continuity) with a meter, or measure voltage coming out of it make sure it goes from 0 to 12v

Easier way to figure out if your kickdown solenoid is stuck/energised, unhook the orange (I think) wire that hooks to the drivers side of the transmission and see if the shifts are still messed up. If it seems to shift normally you've found your problem, if not you may have more serious tranny probs.

 

[CARNAC]

Normally it is the vaccum pump/lines. Personally I would try this easy fix first. Easy change. Download the -20 manual follow the instructions.

 

[SmokeyDod]

As was said above M1009 has TH400 which is 3-speed trans. What most likely is your problem is that the vaccum line that is pluged in to the modulator on side of transmission has come off or it could be between there and the vac pump located at rear top of engine. If you disconnect the vac. line from modulator it will cause the transmisson to shift very hard and stay in 1st & 2nd gear for long time , until you get going fast enough for it to change. Check that. Hope it helps. Smokey

 

[CCATLETT1984]

ALL CUCV's got the TH400 transmission. Most of the cucv's got the NP208 transfer case (except for some of the contact trucks that got the NP205)

The overdrive transmission is the 700R4, the TH350 is simpley a less "robust" version (lighter duty) of the TH400

My truck shifs from 1st to 2nd gear @16mph under light throttle, the shift to 3rd gear occurs @35mph under light throttle when the engine is warm.
When the engine is cold it will rev higher before shifting.

Please look at the unit manual that is listed in the sticky post at the top of this forum. you will be adjusting the module on the side of the injector pump, i dont remember which way you need to turn it to move the shift points down.

 

[jag7720]

I changed the hoses... they were very cracked and rubbery... some were hard.

We will see how that changes things tomorrow morning.

As far as the manuals... thanks. I keep for getting to use them. I even have them on my server.

 

[jag7720]

Ok, so I put new vacuum hoses on it last night and I drove it this morning and it seems to shift smoother but the shift points are still high

1st to 2nd = about 25
2nd to 3rd = about 40-45

So, now I will print out 3-21 and 3-21.1 and adjust the shifting points.

 

[FMJ]

Did you check the electric downshift circuit?, try unhooking the wire that goes to the tranny. see if the shift points change. Modifying the shift points in a TH400 (I think) will require work on the valve body in the tranny....

 

[jag7720]

I did not try that. I will on my way home this afternoon.

One thought though...(huh, one letter and a totally different word) anyway... When I push the pedal down enough to kick it down... the kick down works... That would seem to indicate that is is functioning as it should... I am new to the CUCV and could be wrong... just a thought. I will try it.

 

[FMJ]

Ok, nevermind then, if it works as a kickdown should, then your problem is elsewhere. You may be looking at a trip to a tranny shop......

 

[Djfreema]

Mine had the same problem, it was an easy fix by loosening the 2 bolts that hold the vacuum modulator thing on the side of the injector pump then rotating it a little so that the transmission doesnt think its wide open throttle. It regulates how much vacuum goes to the transmission to tell how much load is on the motor. The more vacuum, the least amount of load and the shifts will be much sooner. With almost no vacuum the transmission will think its wide open throttle and will hold on to the gears longer. Its probably rotated all the way to one side, if it is, find the middle setting and start from there and see if it helps. Might have to try it a few times to get it where you want it. It literally only takes 5 minutes and you wont get dirty.

 

[FMJ]

Dj, I forgot about that regulator valve......its the one that the lines from the Vac pump and the Tranny Modulator connect to on the IP right?

 

[dilvoy]

Don't forget the transmission modulator on the right side of the trans towards the front end of the trans pan. The hose could be cracked or disconnected or maybe the modulator itself is bad. It's easy to change from the outside of the trans and only costs about twenty bucks.

 

[Goatwerks]

My many years of transmission repairs screams bad vac pump or leaking modulator(fluid will come out of the vac line if bad). Check for vac with a guage. Lack of vac = delayed harsh shifting, High vac= early soft shifting. Some people use adjustable modulators to dial in a desired shift pattern.

 

[CCATLETT1984]

My many years of transmission repairs screams bad vac pump or leaking modulator(fluid will come out of the vac line if bad). Check for vac with a guage. Lack of vac = delayed harsh shifting, High vac= early soft shifting. Some people use adjustable modulators to dial in a desired shift pattern.

all cucv's have a "adjustible modulator" its on the side of the injector pump and can be adjusted to fine tune the shift points.

 

[JohnFire]

Mine has shifted around those speeds for the 9 years I have owned the truck, unless under hard acceleration. Some times if I am right near where I know it will shift, I just go up to the shift point, let it shift and then back off the throttle. Never has seemed to bother me cause it acts like the 77 k5 I had. Doesn't shift hard and a few of the ones I have driven from the Military were all around the same points.

 

[cleb]

I second the vac pump could be the issue. In the 2 yrs I owned my M1009, I went through 2-3 junkyard pumps. They wouldn't produce enough vac, and cause very high shift points. The plastic modulator on the side of the IP can also get old and leak. First, as other have suggested, replace every single piece of rubber between the modulator and the vac pump. Second, check how much vac the pump is actually creating. Not sure what it should be, but its probbly in the manual. Third, adjust the modulator, its not too hard, but one of the adjustment bolts is a little hard to get to. Bear in mind the modulator on the IP may need replaced. Its a tad rare, but the modulator on the tranny could also fail. My high shifting problem was solved by new rubber, take off vac pump, and adjusting/replacing the IP modulator. Good luck.

 

[n1vbn]

Parramore in Florida has NOS vacuum pumps for the CUCV. I bought two at less then 1/3 the price Chevy wanted

http://www.parramore.com/

TM 9-2320-289-20 is the manual you want to download from steelsoldiers and go to page 197 and it
shows the unit and how it mounts to the fuel injection pump. It's name is the VRV Vacuum Regulator Valve, the modulator
is mounted on the transmission.

I was told before I bought my M-1009 the tranny needed rebuilding. I replaced the VRV, the 2 inch rubber line that
connects the steel line to the modulator and the third adjustment of the VRV was the charm.

The vacuum pump should have 25 to 27 inches or mercury when new but the tranny will work correctly down to 15 inches of mercury.

Shifts a little higher and harder when cold but fine when warm.