Replacement transmission problem

[Bobert]

So I replaced my TH400 with a cucv TH400 and it went well. Last night I drove it around about 5 miles and it shifted great through all gears smoothly and did not slip at all.

It sat over night and now it slips in the forward gears. In drive, I can't feel it engage but I can in 2 and 1 but it slips alot and barely moves. Reverse is still strong.

Is this transmission junk or what? How could it go bad overnight? No fluid leaked out. Fluid level is at the bottom of the hot range when it is cold is that a problem?

Thanks guys.

 

[hovenga67]

Did you change the filter? Maybe the pickup tube fell off.
Brent

 

[Bobert]

Yes I changed it. I didn't think about that one.

Thanks, I will check that next.

 

[Bobert]

The pickup tube was still connected to the filter and I made sure it's on there good. That didn't fix it though.

Any other ideas? Or is this one just worn out?

If it acted like this first, I would just say it's dead but since it worked great before sitting over night I don't know.

 

[bowtiecrazy]

mine worked real good one day next mornining tried to get it to move i had to wait for it to move once it warmed up i drove it around the rest of the day changed fine. next morning same it just got worst. i got mine rebuilt with torque coverter for 400$ with a warranty.

 

[hovenga67]

I have a spare one that I think is good. If you are interested. Also I might be switching mine out for a 700r4 so it depends how soon you would need one. Mine in my truck works great.

 

[Ronbo]

It could be too much play in the pump gears or play in the converter , when it sits the fluid will drain back into the pan ( look over filled ) after it sits a few hours , then it has to pump all the extra fluid back into the torque converter.. How the vaccume at the modulator? check to make sure the line is connected .. Id bet since it worked and all the sudden NOT .It something simple. PS hows the rear seal ? is the fluid going into the transfer case causing the fluid to be low?

 

[Bobert]

mine worked real good one day next mornining tried to get it to move i had to wait for it to move once it warmed up i drove it around the rest of the day changed fine. next morning same it just got worst. i got mine rebuilt with torque coverter for 400$ with a warranty.

If I could find someone around here to do it for $400 that would be a good deal. I got my other one done for $650 6 month warantee and 3rd gear went bad about month 7.

I have a spare one that I think is good. If you are interested. Also I might be switching mine out for a 700r4 so it depends how soon you would need one. Mine in my truck works great.

I am not sure what I want to do yet, this was my spare so maybe i can take my 2 bad ones and make 1 good one. I am a jobless college student right now so I am poor. Maybe Obama will buy me a new transmission. Thanks for the offer, god to see another guy from Iowa one here.

It could be too much play in the pump gears or play in the converter , when it sits the fluid will drain back into the pan ( look over filled ) after it sits a few hours , then it has to pump all the extra fluid back into the torque converter.. How the vaccume at the modulator? check to make sure the line is connected .. Id bet since it worked and all the sudden NOT .It something simple. PS hows the rear seal ? is the fluid going into the transfer case causing the fluid to be low?

Vacuum is good, I just got a new vacuum pump. I has enough fluid in there, i dumped in a couple more quarts to be sure and no change. I havent checked the rear seal yet.

Thanks for the advice guys.

 

[Bobert]

I talked to a local transmission guy and here is his reply.

The fact that it worked and then quit overnight seems likely that something
broke, or stuck, not worn out. Possibly a servo sticking or a band not
releasing........... All of that stuff is internal, so it is going to have
to come out and apart.

Maybe if I whack it enough times with a hammer it will go.

 

[BISME03]

Never underestimate the power of the hammer. Just not too hard.

 

[Ronbo]

Man you can fix the trans yourself , just take your time. 400turbo is th easiest trans ever to work on.. very very simple.

 

[akonitony]

I worked as a transmission R&R man while I was an undergrad at The University of Florida (Go Gators). I eventually learned to rebuild them and opened my own shop on the side while I was doing post-graduate studies, and I do agree with Ronbo. You can build a TH400 in a box full of kitty litter and it will still work wonderfully.
The reason yours still works in reverse is probably due to the line pressure comes up in that gear to compensate for the fact you are turning the output shaft the opposite way of the input. In forward, there is no line pressure boost, so that is when it will slip. I would seriously doubt it has anything to do with the vacuum modulator. That would only keep it from shifting. What I would look at is your governor. Open up the cover on the side in the back that is held on by 4 bolts, and see if the governor has any wiggle room when you try and wiggle it from side to side or up and down. If it does, your case is bad, and you are losing line pressure at the governor bore. You can either replace the case, or buy a sleeve that will fix it after you ream it out.
You can buy an ATSG (Automatic Transmission Service Group) manual for a TH400 off of ebay for about $15. This will tell you everything from how to rebuild them to troubleshooting anything that can go wrong. It also gives specifications and tells you what bands and clutch packs engage for each gear. You can also buy rebuild kits from there very cheap as well. If you like, I can sell you a kit and manual from one of my vendors for my cost plus shipping. Just let me know.

Otherwise, I'm afraid you may be