A-727 (T-407) Automatic Transmission Rebuild Dis-assembly
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As part of our revitalization of our 1972 IHC Scout II, we have to rebuild the T-407 (Chrysler A-727) automatic transmission. I will be adding pictures and notes to this as we go along. I have posted some articles about rebuilding resources on the front page. In addition, one of the best resources that you can find for information on rebuilding these transmissions is “Torqueflite A-727 Transmission Handbook” by Carl H. Munroe. It is a must have if you are going to tear one of these apart and put it back together.
Here is a picture of what we are starting with:
As you can see, we have removed it from the Scout and there is a lot of grease and grime on the unit. So the first order of business was to clean that off so we would have a clean working environment.
We took after it with a couple of putty knifes and a screw driver. I like to use the plastic disposable knifes since they tend to scratch less, but I must have used my supply up. The case is aluminum, so we carefully use a couple of makeshift metal ones and it didn’t cause too much noticeable damage.
In this next picture, you can see the amount of crime that came off the transmission and transfer case. We must have taken 5 to 10 pounds off of it. While that made a big improvement in the cleanliness of the transmission, we still had a long way to go before we could start to tear it down.
So the next step was power washing. We taped all of the holes up using duct tape or electrical tape. Then we put out a plastic drop cloth and moved the transmission and transfer case on top of the drop cloth. Next we sprayed some engine de-greaser on the units and waited a few minutes. After that we used our gas powered pressure washer and cleaned them off. We did this a few times while wire brushing between applications. After we were done, we let the plastic drop cloth dry and then rolled it up and threw it away. Below you can see the results of our efforts.
Now for dis-assembly. We went out to the local Menards and purchased a pan that goes under a washing machine to catch any leaks. It about 3′ square give or take a few inches and has sides on it about 3″ high. This will contain any fluid that is left in the transmission. We set that on the bench and moved the transmission up onto the bench.
The first mistake we made that I want to point out to you, is that we didn’t check the input shaft for end play. We will have to make that up when we re-assemble, it might slow us down a bit in that process.
In this first picture you can see the gear at the end of the output shaft. This turns the gears in the Dana 20 transfer case. It is held on by a single nut. In our case the nut was only hand tight. I will check that one re-assembly, seems to be kind of loose.
The next step in most A-727 transmission tear downs is to mark the speedometer adapter’s location on the housing so that you can put it back in the same way. On this particular unit, the speedometer actually is attached to the transfer case. So what we are actually removing is just a plug.
Now we removed the bolts that hold the extension housing to the case. Again, this is slightly different with the T-407 and the other A-727. There is no snap ring to remove. You just have to unbolt it and slide it off the shaft.
We did find out that on this unit we need to remove a couple of broken off bolts in the housing for the transmission mount. You can see them below. We will have to drill them and try to remove them with an easy out.
Then we remove the neutral safety switch from the case.
Next we remove the pan bolts and pan from the unit.
We found quite a lot of debris in the pan. You can see this in the next two pictures of the inside of the pan and the bottom of the filter. This is pretty normal, it accumulates under the filter in the pan. The oil was pretty dark, so some overheating must have occurred.
Now we take the three screws out holding the filter on and remove the filter.
Next we removed the selector controls.
Then we remove the ten hex bolts that secure the valve body to the case. Not the screws.
Some how I missed getting a picture of it, but in the following picture you will see a shot of the governor. In it you will remove a “E” clip and pull the governor valve and shaft out. Then you remove the snap ring from the tail shaft and pull the governor off the shaft.
Then we removed the Output Shaft Support from the back of the main housing.
Next we removed the bolts from the front pump and used a slide hame on the two highlighted bolts to pull the pump out.
Here you can see the front pump after it was removed.
In this picture you can see the front band.
We remove the front band adjustment screw.
Next we remove the front and rear clutch and the front band strut and band.
Now we slide out the output shaft, driving shell and planetary assemblies.
Then we loosen the rear band adjusting screw.
Then remove the rear band. Inspection of the rear band revels a pretty good surface.
The driving shell surface appears to be ok.
Then we remove the servos. You can see there is quite a bit of sludge. My guess is that some of the clutches got burned up and that is why all the metal shavings are in the pan.
Next step is the Disassembly of the unit assemblies.