Trans R&R

[gasser]

My transmission in the M1009 has finally given up and its time to R&R it. I do have another TH400 in my parts truck that I can use, however I don't know the condition of it and I would hate to put it in to only have to take it out in a few months.

Has anyone complete taken out, rebuild the trans, and put it back in? I presume the R&R is kinda straight forwards, but what about the rebuilding part?

I ordered an overhaul kit, which has the steel plates and the rear band - along with a TransGo shift kit and overhaul manual.

I guess the manual would give me the general insight to the trans rebuild, but if any of you can comment, that would be terrific.

Thanks all,

-graham

 

[CUCVFAN]

Never rebuilt one, but the R&R is not difficult, as you guessed. It's much nicer if you have a lift

The -34 manual pretty much covers most of the internals. I'm not sure if there is a specific manual the Army uses on rebuilding the TH400 (there is a manual on the 6.2)?

 

[motorolanut]

Had mine rebuilt by a local guru, put another 10,000 miles on it then sold it. Ran great, don't waste time on shift kits I was told by the guru that they were bad ju ju for anything but a race tranny

 

[devilman96]

As long as your not getting into hard parts the job should be pretty easy, 400's are very straight forward transmissions.

I don't know if I agree with a shift kit being a bad idea but due to the application you need a higher end clutch kit... (My preference Alto) If your kit is "clutch only" make sure you buy and change the bearings...

What are you doing for a TC? since your tranny has failed using the same TC is NOT a good idea...

These guys are "fair" on prices and have a good bit of info about what you can and or can not do with a 400... http://www.400raptor.com/

 

[gasser]

Thanks for the replies. The problem with the trans is that it "slides" into 3rd at a very high-rev, but doesn't hold ... it just right back down to 2nd. Shifting from 1st to 2nd is ok. This problem just started, out of the blue. Was driving for about 20 minutes before it started to occur. Based on that, I was thinking that the TC was OK. Thoughts?


The kit I ordered has everything, clutches, steel plates, bearings, seals. The shiftkit is a TransGo, and its listed for towing applications, which is good with me since I do some towing and what not.

-graham

 

[CUCVFAN]

The problem with the TC is that any junk from the tranny gets trapped in it and will contaminate the fluid in your rebuild and most probably shorten it's life. For this reason, most tranny shops will only warranty their work if they flush the converter or you buy a new.

 

[Blake]

turbi 400

Bring it to me G and Ill rebuild it.

 

[gasser]

RE: turbi 400

I would Blake if I was heading up that way. I think I am going to rebuilt it myself. I have rebuilt a TH350 in my '77 K5 I had back in high school (15 years ago). So it can't be that different, I hope.

-graham

 

[Zinlu]

Well I've never rebuilt an automatic before, had the 4-speed Rockcrusher from my Camaro apart a few times though. The biggest thing is Clean. Clean everything that touches anything that goes in the tranny.

TC replacement would be a good idea, as well as flushing the lines/cooler once the transmission is out.

Give me a shout if ya want a hand.

 

[gasser]

Give me a shout if ya want a hand.

Thanks Steve. I think I am going to take the trans out of the parts truck and rebuild it. Then do the R&R on my driver. I am going to try it this saturday, but I am not sure.
I will let you know though, thanks for the offer.

 

[85-m1028]

Shift kit is good, I would go for a low stall converter too. the lip seals in the clutch packs are the hardest to reasemble use caution not to tear them. there is a wave friction plate in each of the cluch packs remember the position they were in.

You will need to reuse the wave plate in each clutch pack, or you can replace the wave plate with a flat steel plate for a snappier shift. when you disassemble the clutch packs mic the plate thicknes and use the ones in the kit that are the same thicknes approximately. It helps to just do one clutch pack at a time.

The accumulator piston for the front band is made of ceramic there is an aluminum replacement for it because the ceramic ones are prone to breaking. You need to special order this part.

When you get the intermidiate and forward clutch assembly together that assembly has a splined hub that drops into the direct clutch pack already installed into the trans case "don't forget the large snap ring for this clutch pack, it comes with the shift kit" I found the easisest way to get it to line up was to drop the assembly in and twist the tail shaft so the "direct clutch" friction plates will line themselves up on the splined hub.

Ohh and remember to install the dipstick tube prior to bolting the trans to the engine, otherwise you won't be able to get it in. "don't ask me how I know this"

 

[CUCVFAN]

Ohh and remember to install the dipstick tube prior to bolting the trans to the engine, otherwise you won't be able to get it in. "don't ask me how I know this"

Oh, you can get it in, but it won't have the same shape as when you started trying to put it in... and don't ask me how I know this, either...

 

[ARMYMAN30YearsPlus]

Just a note about our M 1009 if the transmission fluid is still cherry red it is possible that this is a ten dollar fix like ours was. The M 1009 modulator needs a good vacum from the vacum pump on the deck of the engine since diesels do not have manifold vacum the pump needs to work and any dryrotted vacum hoses will cause poor shifting and really weird actions of the transmission. If you have not checked the vacum and color of the fluid do this and see what happens. It cost me less than $10 of hose to get ours running fine.

 

[gasser]

The fluid is still red, and doesn't smell burnt. I replaced some of the vacuum hoses, however I will give the truck a once-through again. I drove the truck last night after sitting for 9 hours, and the problem didn't occur. I only drove it for about 10 minutes. I am going to drive it for a longer period tonight to see if/when this problem shows up again.

 

[KD]

FYI on CUCV transmission shifting problems

To Gasser and other CUCV owners,

Regarding shifting problems with the CUCVs don't forget the vacumn regulator valve on the side of the injection pump. (black plastic with the two vacumn hoses) This regulates the vacumn pressure to the modulator valve on the tranny. This valve will regulate when your transmission will shift. I have a bad one right now. I get about 20 or so inches of vacumn from the pump to the valve and it drops off to about 1 inch out of the valve to the modulator. It should be around 8 inches. This causes my tranny to shift pretty late into third gear. If you have a vacumn gage it is very easy to check the pressure at the two hoses on the regulator. I hooked \the lines together to get me home, but it causes the tranny to shift way too quick and the transmission shop said it was too much vacumn and would eventually damage the tranny. Just a heads up, but you might want to give that a test before you pull your transmission. (check your manual, but its around 20 or so from the pump and 7or 8 from the valve to the modulator). Hope this helps.

Oh, and ditto on the tranny fill tube...what a super pain...Jeez. I even made up NEW curse words for that one.

Take care,

KD

 

[gasser]

RE: FYI on CUCV transmission shifting problems

Thanks KD. yeah, I am aware that you can change the overall shifting with the regulator at the IP. My issue however isn't that per-se; I believe with the kick down and apparently has only happened once (when I first started this post). It was only trying to get into 3rd, where it would drop back down to 2nd.... It hasn't occured again... Other than that, the truck shifts as it should.

Happy holidays,

-graham