Front clutch. Note the crack at 6:00.
Sprag
Overrunning clutch inner race
Low/reverse drum:
Drum bore:
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| Author: | slantvaliant [ Sun Dec 29, 2019 7:08 pm ] |
| Post subject: | A904 Disassembly Help Needed |
How do I get the low/reverse drum out of a cable-shift A904? It seems to be stuck. It does not move in relation to the output shaft or to the transmission case. I haven't been this deep into the transmission before. I'm using the ATSG guide and Tom Hand's book, which don't cover much on that year 904, and the '64 FSM which does. At this point the next step is, "remove the low/reverse drum". It don't wanna. Background: THIS HAPPENED last spring during a road trip. Basically, it went, "shhhhhBANGjerk...jerk.....jerk.....jerk.... " and stopped working. I've finally got it mostly apart. Autopsy notes so far: The transmission is not original to the car, and the number (2466118) decodes as a ’65 Plymouth. There is a rebuilder sticker on it, but I've put many thousands of miles on it with no real issues. ATF was dark, but no chunks. Very minor gray sludge in the pan. Internal parts are pretty clean. There is a crack in the pressure plate (I think that’s what it’s called) on the front clutch. The thicker plate on top of the stack. The low/reverse drum and output shaft seem to be frozen to the case. There is no play. I can’t tell anything about the overrunning clutch. All the rotating parts in front of the low/reverse drum and behind the rear pump housing are off. The rear pump looked clean, no issues noted. I loosened the low/reverse band, and it moves easily I don't see a C-clip or other retainer. What am I missing? |
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| Author: | GregCon [ Mon Dec 30, 2019 6:05 am ] |
| Post subject: | Re: A904 Disassembly Help Needed |
My 'gut reaction' is that the overrunning clutch is jammed up and preventing the drum from coming out. In other words, you need to pull and twist harder. But...I could be wrong. Does the drum move in and out at all? Does it rotate? I agree on your point...most books that cover the 904/727 spend too much time on the 727 and gloss over the differences that exist with the 904... |
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| Author: | slantvaliant [ Mon Dec 30, 2019 6:16 am ] |
| Post subject: | Re: A904 Disassembly Help Needed |
The drum and shaft do not move at all - no rotation, translation, or wiggle. |
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| Author: | Doctor Dodge [ Tue Dec 31, 2019 10:34 am ] |
| Post subject: | Re: A904 Disassembly Help Needed |
Vote #2 that there has been a "hard-part" failure and the broken stuff has jammed things together. Get a pry bar in there and see if you can get any side-to-side movement on the stuck drum. Re-install the nut on the rear of the output shaft to see if you can "force" any rotation, while wiggling the drum. Carefully and Lightly tap on the ends of the output shaft, (use a brass hammer or a "drift" between hammer & shaft) while doing all the above, to see if you can dislodge whatever is jammed in there. You are going to have to use more & more force... until something starts to move. DD |
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| Author: | slantvaliant [ Wed Jan 01, 2020 6:19 pm ] |
| Post subject: | Re: A904 Disassembly Help Needed |
Thanks, Doug. I've stepped up my efforts. Obviously, I'm concerned about damaging components - well, those that aren't already damaged. Couldn't get preceptable rocking from the drum, so I put the B&T flange on the output shaft. I made a spanner by drilling two 3/8" holes in a 3' piece of 1/4" X 1.5" hot rolled steel. The holes are spaced to let me bolt it across the flange. I had been putting PB Blaster on the parts to soak. It took some wrestling to hold the case and apply torque to the spanner, but it started to turn with a lot of resistance. By pulling, pushing down and tapping with a non-marring hammer, I got the shaft to move forward. Eventualy it came free - but only the shaft. Tapping with a slide hammer, I've managed to move the drum maybe 1/8" forward. It's slow work, as the only surface on the drum interior to pull on is angled, tending to make the hook cam out. The band keeps me from grabbing the back of the drum. I'll make a better tool in the next few days and keep working at it. |
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| Author: | GregCon [ Thu Jan 02, 2020 5:35 am ] |
| Post subject: | Re: A904 Disassembly Help Needed |
In all probability, if it's that trashed, you're not gonna salvage anything by carefully disassembling it. |
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| Author: | slantvaliant [ Thu Jan 02, 2020 10:13 am ] |
| Post subject: | Re: A904 Disassembly Help Needed |
I'd really like to rebuild this transmission. So far I haven't seem much actual damaged metal. I'd like avoid damaging anything else, but I'd also like to know what happened in there. If nothing else, it might be a good data point. Backup plan: I have been looking on various sites for a replacement transmission, but '63-'65 cable-shift A904's aren't as common as they used to be. Even if I find one, it might be good to have usable spares from the old transmission on hand. Changing to a newer transmission would mean setting up a completely different shifting mechanism. The '76 engine would, of course, work with an older or newer transmission. |
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| Author: | Doctor Dodge [ Thu Jan 02, 2020 5:35 pm ] |
| Post subject: | Re: A904 Disassembly Help Needed |
Keep at it but as already noted, there will likely be a number of hard parts that need replacing. The hope is that the case is OK so you just need some good used internal pieces. I had one where I arc welded threaded nuts onto the drum and then used a big slide hammer to get it apart. (replaced the drum afterwards) Once you "crack the nut", Send me a PM if you need some parts.. DD |
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| Author: | GregCon [ Thu Jan 02, 2020 6:53 pm ] |
| Post subject: | Re: A904 Disassembly Help Needed |
There was a nice core from a '63 or '64 here in Houston...a guy had it for sale for $100. I told Space Frank about it, not sure if he bought it or not. But if I wanted and early 904 I'd be all over it. |
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| Author: | Charrlie_S [ Fri Jan 03, 2020 3:48 am ] |
| Post subject: | Re: A904 Disassembly Help Needed |
I have some "CORE" cable shift 904's. |
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| Author: | slantvaliant [ Fri Jan 03, 2020 10:47 am ] |
| Post subject: | Re: A904 Disassembly Help Needed |
I'm making an attachment - kind of a crossbar - for my slide hammer that I hope will let me get the drum pulled. And I will be looking for parts once I figure out what is and is not usable. |
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| Author: | SpaceFrank [ Fri Jan 03, 2020 8:25 pm ] |
| Post subject: | Re: A904 Disassembly Help Needed |
Quote: There was a nice core from a '63 or '64 here in Houston...a guy had it for sale for $100. I told Space Frank about it, not sure if he bought it or not. But if I wanted and early 904 I'd be all over it.
Yeah, I bought that one. Still need to rebuild it so we have a known good spare. There's also a guy in Cedar Creek (about 30 min SE of Austin) who has a lot of early A-bodies that he's parting out. Not sure where he finds them. If you're on Facebook, go to Marketplace and search for "Doug Strom". That being said, if your case is fine but you just need a couple hard parts, I might have what you need. We had to disassemble 3 different transmissions to build one good one for the Lemons Dart (two of the bell housings were cracked), so we've got some guts left over. |
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| Author: | slantvaliant [ Fri Jan 03, 2020 9:29 pm ] |
| Post subject: | Re: A904 Disassembly Help Needed |
My home-made puller worked. The drum is off. As expected, the sprag is FUBAR'ed. Several of the rollers are chewed up. I'll try to post some photos tomorrow after I assess some of the damage. |
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| Author: | slantvaliant [ Sat Jan 04, 2020 2:04 pm ] |
| Post subject: | Re: A904 Disassembly Help Needed |
Front clutch. Note the crack at 6:00. Sprag Overrunning clutch inner race Low/reverse drum: Drum bore:
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| Author: | slantvaliant [ Sun Jan 05, 2020 8:45 am ] |
| Post subject: | Re: A904 Disassembly Help Needed |
I dug out another 904 I picked up some time in the dim, dark past. I have no idea of its condition. Per Hand's book, it's a 1965 6-cylinder 904 for a medium or large car - the same transmission number as on the one that I'm working on. It does, however, have the longer extension housing and output shaft. I'll disassemble it to see if some of the hard parts are useable, or if I can just rebuilt it instead. What is different on the "medium or large car" 904s vs "small car" versions? Is it just the extension housing and output shaft? In addition to the stuff in a rebuild kit (gaskets, seals, clutch plates, steels, etc) and a sprag, I think I need these parts: Rear pump housing Low/Reverse drum Output shaft (? - might polish out OK - I'll talk to a machinist at work) Pressure plate for the front clutch |
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