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Discussion Starter · #1 ·
We have a th400 in an RV manufactured by Chevy and Fireball Industries. It is 31 years old. It will not go in reverse. We checked with a pressure gauge and everything is within normal ranges. No problems going forward. We think the problem has to do with a broken band inside there. The trans fluid is clean & there was only a very small amount of metal shavings, barely noticeable to the eye, when we changed the trans fluid & filter.

We have to drop it in a gravel/dirt site with a bunch of flat wooden boards we can use as well as cinderblocks. We have an ATSG book and a Ruggles book. Together they show what to do once the trans is out. Can we do this with just one jack if we place blocks and boards under the engine? It's a 350 v8.

Any advice would be greatly appreciated. There are no Scotty Kilmer videos to help with this.
 

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Welcome to Hotrodders. I edited the thread title with information on your problem. That helps the members here.

If the trans is 31 yrs old, there maybe hard seals causing no reverse via pressure leakage internally

The low-reverse band functions with the direct clutch to produce reverse. If 3rd gear is good & solid, then likely the problem is with the band, band servo
 

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Discussion Starter · #3 ·
Ok, we're gonna drop the trans.
1. How important is it to support the engine during removal and while it's out, and of course during re-installation?

2. Should we buy just a soft rebuild kit? What is the best brand rebuild kit to buy? We found this on Amazon for 207 bucks: B&M 21041 Master Racing Automatic Transmission Overhaul Kit

(It copy/pasted in that format, sorry!) It claims to have only OEM parts. There's also another that claims to have all transbrake parts. We have no idea which is better.

3. Where do we find a hard rebuild kit if needed?

Currently we have most of the tools we need, including an air compressor and a 3 ton floor jack, sockets & combo wrenches, a torque wrench, punches, files, chisels, plenty of table space (with plastic tarping to keep rain out), pans, baggies, all that stuff. We know someone with a shop press, but don't know if we need a spring compressor.

We are also very lucky to have people around us who know us and will lend us pretty much anything we need. Word apparently got around that we fixed two heads and an LIM gasket in our sedan in a foot of snow while using a laptop for instructions. 2 months ago we would have thought a plenum was something like a gallbladder or spleen. We did an excellent job and have put over 400 miles on the car since. It's amazing what you can do with a little bit of cash and a lot of determination, and a bit of "nobody's gonna do this for me-I got no choice" old-school desperation.

Unfortunately most of the people offering to help are elderly farmers with more tools than transmission knowledge. There's also Angus 31, a strange bull that won't go away and is of no help at all.
 

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Why not drop the pan and pop the servo out?
Once the servo is out you can push up into the actuator hole and see if the band is working.

If it is broken at least the fluid will have been drained and you won't soak yourself to the nuts.:thumbup:
 

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Discussion Starter · #5 ·
Thanks: we'll be trying this after we get off our jobs this eve and let you know what we find. We didn't know we could do that! :)
 

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Discussion Starter · #7 ·
Okay, we got the pan off & the filter with it but one of the bolts on the servo cover is too close to the valve body to get either a socket or combo wrench on so we're thinking we'll have to take the valve body off to get at the bolt. We're gonna try that first thing in the morning. Any suggestions/warnings? Also, where are the best places to get the gaskets (valve body & core)? We have an Advance and an Auto Zone and there's a Napa and a Fischer too but they're further away. Is there a type (like OEM or Transbrake or just GM or whatever) that we should buy? Is there a particular sealant we're supposed to use? We didn't use any sealant when we changed the trans fluid & filter in a vain attempt to get reverse back. (Hey, ya can't blame us for hoping.)

Thank you guys for your help so far. If we can fix this without having to drop the trans here that would be a miracle :sweat:

Thanks,
Zach, Winter & Ange
 

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At 31 years of age you will tear or rip the gaskets.

There are several check balls that will fall out.
Remove the main valve body bolts first then drop the body.

Insert two guide studs after you remove the first two bolts.
There is a small kick down solenoid held with 2 - 7/16" bolts.

This can be removed later.

If you want to use sealant undo the cap of silicone glue and stick it in your pocket.:pimp:
 

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Discussion Starter · #9 ·
As long as we catch the check balls and clean them if they get dirty can we re-use them? Also, we really need to know which kind of gaskets are best. When we had to replace the LIM gasket in the sedan, we learned that the original, plastic gaskets were known to fail. We were told to use a metal gasket and we bought a Felt-Pro one. Does brand/type matter or do we just specify that we need a core gasket, etc, for a th400 transmission at the parts store? Do parts stores usually carry these things?

I know some of these questions are probably kind of stupid but this is our first transmission and we're pretty much learning as we go. I (Winter) had no idea there were so many parts in there. Those exploded views in the ATSG book are like...just wow. As I understand all those parts work together to transfer power made by the engine to the wheels. Together a strong engine and a strong transmission = a strong car. Both must be powerful, not just the engine. Oh, and the labyrinth part - all those passages and everything working at just the right moment- man that is both awesome and intimidating!

Anyway, thanks again, we are all grateful! :)
 

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Discussion Starter · #10 ·
We have removed the valve body and the servo. The separator plate and gaskets remained held in by the downshift solenoid. We could see the check balls poking down through the holes of the separator plate, but there were only 5. We weren't sure if one was stuck up there or what, so we popped off the solenoid and lowered the plate nice and slowly, keeping the 5 balls carefully balanced in the holes they sat in, and sure enough, only 5 are there. We are 100% positive the 6th did not fall when we lowered the others, but was it seated in the lower half of the valve body we took off or could it have slipped out with the servo?

Before we began, we laid a plastic sheet on the ground & lined boards along the edges to catch anything that rolled downhill. (We are on a slight incline but it helps keep the RV level with blocks under the front tires & leaves room to drop the trans if we have to.) We saw nothing fall and the boards are clear. We even purposefully dropped a few check balls from the separator plate to make sure the 6th couldn't have escaped. The boards caught every one. So our biggest question now is where is that check ball? If it dislodged when we were driving where would it have gone? Is it stuck somewhere? Could it be in the fluid we drained out and got rid of when we changed the filter & fluid several days ago?

Question 2: where do we get another one? We found ONE parts store of the 4 near us that has a th400 soft rebuild kit and even there we had to explain to the counter guy what we were looking for and had to go through the parts ordering book with him to pick out the right one. Btw we still aren't 100% sure what the right one is, because there are two on Amazon & the one at the parts store is only 107.00 but we don't want to purchase junk and have the repair fail. (To be honest we would like to never have to do this again, especially not in Southern Virginia with large frightening cows just walking wherever they please.)

Thanks to anyone who can advise us!! :welcome:
 

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If the trans was worked on previously, there may be only 5 check balls.

The trans will operate fine with 5.
 

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Since you have the VB off do an air check of the various circuits.

Three holes in the middle feed forward, intermediate and direct clutches.

The rear servo can also be applied by air.
 

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Discussion Starter · #13 ·
As soon as we're off work we'll try that Stuarta. Thanks! We weren't sure which step to take next. We'll fill you in more later. We also figured out that OEM means "original equipment manufacturer" or the parts used by the original manufacturer. We're going with the OEM gasket set.

We also wonder: if the trans has never been worked on before could that non-functional check ball have fallen into the servo and got thrown up somewhere into the trans? (The RV sat in a garage unregistered for almost 15 years & there's nothing we can find showing the trans was ever worked on, tho we have tons of records, some dating back to Sept of 1983, including a booklet about the "wonders" of the new, "advanced technology" of FM radio and how it differs from AM.)
 

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Discussion Starter · #15 ·
We looked at the witness marks and they all look clear and smooth. After a day of sitting under the Fireball getting covered in tranny fluid, we decided it has to come out. We began that process this afternoon. All we have left to pull are the supports on the crossmember and 5 of the 6 bellhousing bolts. And the dipstick, what's with that thing? I've (Zach) seen trannys dropped with the dipstick still attached (he saw it on Youtube) but ours is five feet long & stuck to the engine at 2 points for support, winding around to the hood. We'd rather take it off at the trans, but the rubber gasket might have to be destroyed. Is this a good or bad idea?

We also spoke with a group of teenagers with large old pickup trucks who were hanging around in the parking lot of the Peebles last night. They said we shouldn't prop the engine up while dropping the trans because the RV bounces and the engine will too. We don't have to remove any of the motor mounts, but the extended exhaust will be taking extra weight. We are considering putting a strap around the back of the engine to aid the exhaust while the tranny is out. Any suggestions or does this sound like a good idea?

We are from Baltimore. We just want to go home. This cannot happen without a transmission. There are scary cows all around, and now there are two goats. Deep, great, and awesome thanks to anyone who has any suggestions for us!!!
 

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Filler tube must be unbolted and pulled out of the trans and left hanging when the trans comes out.....Supporting the motor depends on how strong the motor mounts are..Weak mounts can cause 3 problems 1)The motor will drop too far,putting pressure on the exhaust and possibly cracking it,if its an older exhaust system 2)The motor will drop too much causing the distributor cap to hit the firewall,possibly cracking the cap 3) Both of the above....You will know all this when the crossmember is out and you start to lower the trans, before you pull the rest of the bell bolts.At the very least,disconnect the cap from the distributor (no need to pull any wires,just free the cap from the dist and lift it up out of the way.)That will avoid breaking the cap...Then start lowering the trans with the bell bolts still attached. If it drops more than you are comfortable with(like you think the motor is going to fall out,hehe),then put something under the corner of the motor pan,or some other means,to limit how far the motor drops.Then you can now pull the rest of the bell bolts,knowing the motor isn't going to drop any further when the trans is disconnected from it.
 

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Discussion Starter · #17 ·
The motor did not budge when we unbolted the bell. Unfortunately the torque converter is still bolted to the flywheel and we can't get the 3 bolts off. The flywheel just spins. We can't get the bell back far enough to clear the torque C because of the exhaust. We put the crossmember back and the tranny is balanced on that and the jack.

We tried using channel locks but neither me (Winter) nor Ange (even when she sat on my back) were able to hold the flywheel still enough that Zach could turn the bolts. Neither of us are big people tho. Then someone said we should use a prybar or crowbar. We're going to try to put a crowbar or prybar between the teeth of the flywheel tomorrow morning. If the teeth on the flywheel break is it hard to find another for a th400? The teeth seem pretty strong...

To all who've taken the time to help us, Thank You! We need all the help we can get and really appreciate all of your advice more than you guys know!:)
 

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Man, I feel for you guys. #1, please think SAFETY FIRST. Especially working under something as heavy as a motor home. TH-400 trans are heavy too, about 150# or more. Are you really planning to rebuild it in a field somewhere? If the only issue is no reverse, heck, drive that thing home as-is, and mess with it later? (My old van lost reverse, and I managed to drive it for over 3 months that way, with a lot of careful planning).
But if you are parked headfirst to a tree, in a place no 4x4 truck with a winch can get to your back end, then here goes:
Torque converter bolts. Most TC's I have removed, had bolts with nuts on them, requiring 2 box-end wrenches. If your bolts go into threaded holes in the TC, most parts stores have (or can get) a tool called a "Flywheel turning tool", with a handle that flexes and a couple "tooth-grabbers" that can be used to hold the flywheel. Napa stores almost always have them, others not so much. If not, I have used the handle of a large 1/2" drive breaker bar, or a hammer handle, wedged between either the flywheel or TC and the bell housing, to stop the FW from turning. Also, get a small can of "PB Blaster" from the parts store. It is unbelievably good for penetrating and loosening rusted old bolts. Then, the longest handled box-end wrench you can get that fits the bolt heads. And a hammer, preferably the mini-sledgehammer type (3-5#). With the flywheel locked using one of the above methods, use the hammer on the long wrench, as a sort of impact wrench, by tapping it firmly in the proper direction. Don't try to kill it, just whack it firmly, it may take 10-20 smacks to get the bolt broken loose. (The PB Blaster REALLY helps this part). When you get 1 bolt out, you can use the flywheel turner to rotate the engine to get at the next bolt. Or you can bump the starter, (if you have not removed it yet), in very short bursts, to get the next bolt accessible. Afterward, you may need to remove the starter in order to clear the trans/bellhousing for removal, some applications require it, others do not.
Now, after you get the 3rd/final bolt out, you'll need to slide the trans back with the converter in it. If you tilt the front of the trans down, that TC will want to slide right out! One way to prevent that, is to use 1 or 2 large zip-ties to hold it in. Run them through a bellhousing bolt hole, and a converter mounting lug. Or, if you have a small (approx. 1" by 3") flat piece of steel with a hole in it, you can put it on the end of a bellhousing bolt, then add a nut, and it will keep that thing in place.
REMEMBER - Safety First! Several components under there are heavy enough to badly injure or kill a person, so be careful where you put your head! A trans, a starter, or even a torque converter can be fatal if it lands on your coconut! Better to be off to the side then directly underneath any part that could drop, or even a tool, such as a hammer, etc.


Keep us posted, I wish you good luck!
 

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Put a pair of vice grips on the flexplate.
Let the grips move around so they get kind of jammed against the case.


Now remove a bolt.
Repeat two more times.

:pimp:
 

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Discussion Starter · #20 ·
Hi Ol'Jim. "Are you really planning to rebuild it in a field somewhere?" No, more of a mudhole really. We are near the trees. We try to stay away from the cows:)

Desperate times, desperate measures my friend. For now, home is where we park it. We like to park it in Baltimore but then this happened.
 
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