transmissions slips until warmed up. How to replace?

[combat jump]

Some transmission questions:

So I drove 400 miles in my M1028 this weekend to visit my son in SoCal. Then, starting up in the morning, the truck revs, but hardly moves. I topped it up with a pint of Lucas no-slip, to no avail. Then, after driving it for a mile, it starts running fine - no slipping. Park it for a few hours, and the same thing.

I am making my way back up, spending the night in Lompoc. The truck still barley crawls while revving until a mile or two are driven, then all is well. I also got a "revvvvv-THUNK" as it shifted into second once.

I think my TH400 is toast, and I hope I make it home tomorrow - 240 miles to San Jose.

My question is this: Can a TH400 be replaced without removing the engine? I have seen some used ones for sale on Craigslist for $300. What should I look for in a used TH400? Has anyone replaced their own? Any "how-to" links you can share?

I also want to thank my friend Cucvfreek for being ready to call his SoCal buds on my behalf if I really got stranded (parking my truck at my ex's house was NOT an option!)

 

[Blood_of_Tyrants]

The TH400 is a basic tranny swap. You will need to remove the transfer case first and then lower the back of the tranny a bit to get to all the bolts around the case.

 

[combat jump]

The TH400 is a basic tranny swap. You will need to remove the transfer case first and then lower the back of the tranny a bit to get to all the bolts around the case.

Thanks for the reply. How high will I have to lift the truck to get it out? If I can do this with a Harbor Freight transmission jack, and welding up my own tall jackstands, I may give it a go.

 

[MrBouncer]

I changed mine in the driveway with it on a set of ramps and the jackstands high enough to level the truck. With the right tools and and help it should take a weekend. I had neither.

 

[combat jump]

I changed mine in the driveway with it on a set of ramps and the jackstands high enough to level the truck. With the right tools and and help it should take a weekend. I had neither.

That's good to know. Where did you get your other transmission? Any opinions on wrecking yard finds, as-is? Any tech manual recommendations? I have to keep this low-budget, so no $800 rebuilt transmission for me.

 

[Blood_of_Tyrants]

Well, if you can afford to have the tranny down for a period, this would be an excellent chance to get a rebuild kit and learn how to rebuild one.

 

[combat jump]

Well, if you can afford to have the tranny down for a period, this would be an excellent chance to get a rebuild kit and learn how to rebuild one.

I'm up for that, Blood. Looking online now for the kit, and to see what tools it takes. If this is something I could knock out in a 3 day weekend, I'll do it.

 

[ralbelt]

I have had mine out twice with the TC attached. I put the front tires on cement blocks and used a fork lift with 6' extensions. Had the assy on a pallet and slide it out. Plenty of room.
Mine hesitates when cold but after a few miles shifts fine.
You could put the TC in neutral and the trans in drive to warm it up.

 

[combat jump]

This guy rebuilt his without even changing his shirt, so I guess it means in one day?
https://picasaweb.google.com/branndon/TransmissionRebuild?authkey=Gv1sRgCMy9waWoisyYIw#

 

[Cucvnut]

We can pull it in your drive way I have some big jack stands its the t case cross member and the the linkage then the bellhousing bolts. We will talk when you get home

 

[japickar]

IMO I would drop the pan on your current transmission and give it an inspection before I concluded that it was toast. I know there was a guy where I live that had this happen to him and it turned out to be a clogged filter. It may not hurt to try this before swapping trannys.

 

[mtn man]

You can do it in a day if you find you must do the swap. I have had to do it on civ trucks and once on my CUCV to put on a new flywhee. It was a long day but with a pal and a import trans jack we got it done. I am a shadetree guy so all the shop we had was dirt driveway and HD jack stands...

pulled rear drive shaft, pulled transfer case (heavy mutha trucker) using the jack. unhook the linkage and reverse light, once cross member out the trans tilts down as if bowing down for you to get to the bolts around the bell. Mounted trans to the jack and with the use of several extensions and got the bolts out. ** dipstick can be tricky so get it out of way 1st**

I think the book puts it at 8 hours, but can't remember. Be ready to wear red cause you are going to see ATF... drain them 1st to make things easier. I had to make a gasket for the transfer case and the trans when I did the reinstall. I got lucky on splines since they seemed to line right up. Ohh and I took flexplate cover and starter off just to give a little extra room and visibility.

 

[combat jump]

Thanks, Cucvfreek!

Do torque converters go bad? Would I need to replace that along with rebuilding the trans? What "stall speed" does a CUCV use?

I'll see if I can rent a transmission jack from the tool yard. If not, I see that Harbor freight sells a couple different ones.

 

[wkbrdngsnw]

I would not try your first transmission rebuild without an experienced builder helping you if you want it to work the first time. I can speak from experience that the seals on the apply pistons are nearly impossible without one of the seal protector things. I had to have a trans shop install those on my first one after 3 hours of messing around with a feller gauge. Turns out I nicked them anyways and the truck burnt the clutches out in 3 blocks and had to be torn apart again and I considered that an achievement.

After the first one you know how things work and isn't that much harder than a carburetor. Its really just a pump that sends fluid through a metering system that applies pressure to clutches. The th-400 is about the simplest auto other than the power glide and requires very few special tools compared to modern ones. Snap ring pliers and a 12 point 3/8 are a must. A clean table and a friend to hold the case upright as you drop the drums in are helpful as well.

If you feel up to it and spare the time you can afford a few rebuild kits for the price of a rebuild and if you get it right the first time you've save a lot and learned something.

 

[combat jump]

Japickar, good idea - I'll drop the pan first. Since its worse when cold, and gets better as it warms up, Cucvfreek thinks that maybe its a clog that the ATF gets through once it warms up and thins out. The cost and work savings makes this worth trying.

Mtn man, good description of what I'd have to do to drop it. Thanks.

Wkbrdngsnw, there's wisdom in what you are saying. I've rebuild a valve body before, but never the whole thing.

 

[Cucvnut]

we can do it. were smart.

 

[DokWatson]

Getting the transmission out is the easy part. We always seem to forget the t-case shifter. You'll be wondering why the **** it isn't tilting down and notice the shifter all jammed up lol.

Don't forget to put the torque converter bolts back in, or you won't go anywhere and you'll think you rebuilt it wrong.

 

[SmokeyDod]

If you have not changed the filter and fluid in last year or so, I most certainly would change the fluid & filter and try it before you go to the major ordeal of removing and trying to rebuild the tranny. Fluid & filter kit will cost you about $30-$35 and about a hour of your time. Iv'e had cucv's that when get them home and running and they would barely pull. First thing I do is to change as above and they drive like new. A lot of these filters will form a solid like film over the filter and not let the fluid get thru it.

After you do this & it don't change way it pulls, then I would look into rebuild. My son does mine but to tackle this by yourself you are asking for a boatload of problems. Just one little thing, when putting the torque convertor back on, you got to make sure turn it until it "seat" all the way or else when you tighten your trans. bolts, you can break the pump.

A rebuild kit from "DACCO" costs approx. $85.00 . It includes all clutchs discs, gaskets, seals, filter etc. Another note is that probably about 1/4 of the pcs. in the kit you will not use. Hopefully that after the rebuild and all that money and mostly time and labor that it don't work after you get it back in. GOOD LUCK

 

[combat jump]

Thanks, Smokey.

I made it home ok, same problem starting it cold, though. Options are:
1. drop the pan, replace/look at the filter - $50 or so.
2. drop the trans, rebuild it in my garage over a long weekend - $200 or so.
3. shop Craiglsist for a used or "rebuilt" one, and swap it out - $?

 

[ranchhopper]

One thing to try is add a pint of DOT 3 brake fluid to the trans mine slipped a bit when cold too after adding the BF it worked great I got another year out of it. My friend who told me about adding the BF to it said the seals were bad adding the DOT 3 to it softens and swells the seals it worked in mine cheap fix if it helps yours out too.