A904 complete rebuild.
- Thread starter CLAY72dart
- Start date
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j par
Well-hung Member
It should just be firm but not banging.. that's why I like the kit it just makes it shift correctly in my opinion. Plus it has optional shift command or you can put it down into second or first no matter... But be careful.,
Yes, firm, fast shifts are what is needed. I would also highly recommend a quality trans cooler. This is especially true if a high stall converter is used.
BillGrissom
Well-Known Member
I've only rebuilt my newer A413 and A604 Mopar transmissions, but the A413 is a 3-spd hydraulic "Torqueflite", basically a FWD version of the 904. In my 1965 727, I've only removed the valve body to install a shift-kit, but need to revisit with a Transgo kit I now have which is supposed to fix "morning sickness", which is overnight drainback from the torque converter requiring idling 15 sec in N to refill to get drive. Still exists after a "professional" rebuild by a Cottman shop after I told them the issue (didn't even open it up, just washed outside?). A modest shift kit is good for quick firm, but not harsh, shifts. The factory design is overly-slippy for "smooth shifts" which owners think means "good transmission" when actually causes faster clutch plate wear, as in slipping the clutch in a stick-shift. Also helps to lift off the throttle to encourage earlier shifts, and under less torque, for less wear in daily driving.
I don't understand the fuss about removing the front pump in a 904 since in my A413 and A604 I just screwed two long bolts in the tapped "pulling holes" until they bottomed out on the case and pushed the pump out. You replace that gasket anyway and didn't mar the aluminum behind it, but perhaps the 904/727 differs. Just working against a perhaps old stiff circumferential O-ring though mine were still resilient. I second Rusty's suggest to pick your own parts. A "Banner Kit" usually means with clutch plates but no steels. In my A413, the clutch plates were worn to bare steel in one pack (L/R, I recall with 3 clutch plates), making rpm flare between 1st and 2nd, which is why I "went in". I bought separate "racing" clutch plates with better friction material (dark brown, termed HEG or such, ~$6 each), so those plates in the Banner Kit went unused. A full kit includes steel plates, but I've never measured mine worn more than 1 mil (out of ~50 mil). You can buy a cheaper "Overhaul Kit" which is just rubber seals and gaskets and buy better clutch plates separately. Also note that some kits don't include a rubber -lipped piston(s) (stamped steel). You can buy most parts separately. For my A604, I went whole-hog and bought kits of brass bushings, thrust washers, lock rings, and sprags, which added ~$70 to the $120 kit with clutch and steel plates, since 250K miles and wife's vehicle (insurance against fussing at hubby). If a hobby car, you can wait until "in there" to see what you really need. In perhaps a bridge-too-far, I also replaced the two tapered roller bearings (like a wheel hub) at the output gear. Tricky because one bearing cone is recessed in a step on the gear, making tricky to pull out and designers weren't nice enough to provide openings in the step the outer race sits against to tap it out so had to grind it out w/ carbide mill in a hand drill (risky). Roller Bearings are standard PN's. I buy quality German or Japanese off ebay, rather than trust the usually-Chinese bearings you get at much higher price via auto parts sources.
Re manuals, for the A604 I bought the Chrysler manual on ebay which was strangely titled something like "Restoration and Improvements", instead of "Shop Manual". I also found the ATSG manual on the web (pdf free on Russian site, legal?). The ATSG manual was a direct copy of the factory manual, but missing the useful upgrade information for various years, like "use this instead of this", though only a few tips applied to my year which already had all the improvements. Anyway, better a used Chrysler manual than a pricier new ATSG one, in my experience. I will also buy the book mentioned here if/when I get into my 904 (have 3) and 727 (have 2), since won't trust an Aamco or Cottman again. Re Aamco, I first took my 727 there and the manager said, "nobody on staff who can rebuild a transmission". For real, in 2001 at Buford Hwy in Atlanta (or Chamblee). I was rushed since relocating for a job and had to get my 1965 Chrysler back together to ship, then found the rebuilt tranny I had in the garage didn't fit (for later years, from Oregon Transmission I recall). So wife proved wrong again with her, "just write a check" theory.
If never been in a transmission, the manual is very step-step, with a drawing for almost every step and even dimensions to check in the step (rather than thumbing thru specs table in back). Don't skip any step and bag all parts. To be safe, I kept all parts stacked in order. If you work on one clutch pack at a time, it isn't overwhelming. One issue is dealing with all the fluid which keeps draining out of parts. A table with "blood drain" like shops have is nice, but I used a lot of newspapers and kept refreshing them. Trickiest is reinstalling the clutch packs, by rotating and wiggling to get all the "teeth" aligned to drop in all the way. You'd think aligning the teeth ahead of time with screwdriver would make it just drop in, but never lucky. One thing I liked in the A604 is that you get a final check that all packs are fully in because you look thru the rpm sensor port and should see metal pickup teeth centered. I had to keep removing, inspecting, and trying again to get there. I recall I found an error in a pack with a snap ring or such (forget) so proved very useful. First, insure your pump sits flush against the step (without O-ring and gasket) before bolting it in. I doubt you need to force it like working against a spring. If it won't drop all the way to the step, you likely have a clutch plate not aligned so keep trying. Ditto for dropping in the torque converter. If the bolt pads don't sit at least 1/2" back from the bellhousing face, you don't have all splines aligned, so keep lifting slightly and rotating until it drops all the way in. If not, you could ruin the pump when bolting up to the engine.
BTW, the A604 doesn't have any bands, using additional clutch plates to "ground" the two planetaries to the case. I think the first such design, but most auto trannies are such today. That allowed them to fit 4-speeds into the same envelope. There are similar RWD Mopar versions. Somehow companies figured how to fit up to 11 speeds in the latest auto trannies, realizing almost a CVT. But, for drag-racers go the other way. Wheeler Dealers had an episode building a drag racer (Mopar I vaguely recall), where they used an early 2-speed 1960's GM transmission (ex. Corvette) since can't waste time shifting, and all the gears needed with a high torque engine.
For others with early-A's, be careful to get a filter with 2 holes. Those years (until 1966?) have a rear pump and need that second hole to not starve that pump and cause damage. An advantage is that those cars can actually be push-started (2nd gear at >30 mph I recall). True also in my 1984 M-B 300D and until 1986, exc 1985 CA (1986+ transmission). I think the rear pump was dropped to lower cost and perhaps liability from people push-starting. I think in 904/727 that correlates with having a shift cable and separate park cable (later an internal rod, as in my A413). Might be hard sourcing an early-A kit so might have to use a 1966+ kit and figure out what else you need and check every part. For one, those won't have the gasket for the parking cable housing.
I don't understand the fuss about removing the front pump in a 904 since in my A413 and A604 I just screwed two long bolts in the tapped "pulling holes" until they bottomed out on the case and pushed the pump out. You replace that gasket anyway and didn't mar the aluminum behind it, but perhaps the 904/727 differs. Just working against a perhaps old stiff circumferential O-ring though mine were still resilient. I second Rusty's suggest to pick your own parts. A "Banner Kit" usually means with clutch plates but no steels. In my A413, the clutch plates were worn to bare steel in one pack (L/R, I recall with 3 clutch plates), making rpm flare between 1st and 2nd, which is why I "went in". I bought separate "racing" clutch plates with better friction material (dark brown, termed HEG or such, ~$6 each), so those plates in the Banner Kit went unused. A full kit includes steel plates, but I've never measured mine worn more than 1 mil (out of ~50 mil). You can buy a cheaper "Overhaul Kit" which is just rubber seals and gaskets and buy better clutch plates separately. Also note that some kits don't include a rubber -lipped piston(s) (stamped steel). You can buy most parts separately. For my A604, I went whole-hog and bought kits of brass bushings, thrust washers, lock rings, and sprags, which added ~$70 to the $120 kit with clutch and steel plates, since 250K miles and wife's vehicle (insurance against fussing at hubby). If a hobby car, you can wait until "in there" to see what you really need. In perhaps a bridge-too-far, I also replaced the two tapered roller bearings (like a wheel hub) at the output gear. Tricky because one bearing cone is recessed in a step on the gear, making tricky to pull out and designers weren't nice enough to provide openings in the step the outer race sits against to tap it out so had to grind it out w/ carbide mill in a hand drill (risky). Roller Bearings are standard PN's. I buy quality German or Japanese off ebay, rather than trust the usually-Chinese bearings you get at much higher price via auto parts sources.
Re manuals, for the A604 I bought the Chrysler manual on ebay which was strangely titled something like "Restoration and Improvements", instead of "Shop Manual". I also found the ATSG manual on the web (pdf free on Russian site, legal?). The ATSG manual was a direct copy of the factory manual, but missing the useful upgrade information for various years, like "use this instead of this", though only a few tips applied to my year which already had all the improvements. Anyway, better a used Chrysler manual than a pricier new ATSG one, in my experience. I will also buy the book mentioned here if/when I get into my 904 (have 3) and 727 (have 2), since won't trust an Aamco or Cottman again. Re Aamco, I first took my 727 there and the manager said, "nobody on staff who can rebuild a transmission". For real, in 2001 at Buford Hwy in Atlanta (or Chamblee). I was rushed since relocating for a job and had to get my 1965 Chrysler back together to ship, then found the rebuilt tranny I had in the garage didn't fit (for later years, from Oregon Transmission I recall). So wife proved wrong again with her, "just write a check" theory.
If never been in a transmission, the manual is very step-step, with a drawing for almost every step and even dimensions to check in the step (rather than thumbing thru specs table in back). Don't skip any step and bag all parts. To be safe, I kept all parts stacked in order. If you work on one clutch pack at a time, it isn't overwhelming. One issue is dealing with all the fluid which keeps draining out of parts. A table with "blood drain" like shops have is nice, but I used a lot of newspapers and kept refreshing them. Trickiest is reinstalling the clutch packs, by rotating and wiggling to get all the "teeth" aligned to drop in all the way. You'd think aligning the teeth ahead of time with screwdriver would make it just drop in, but never lucky. One thing I liked in the A604 is that you get a final check that all packs are fully in because you look thru the rpm sensor port and should see metal pickup teeth centered. I had to keep removing, inspecting, and trying again to get there. I recall I found an error in a pack with a snap ring or such (forget) so proved very useful. First, insure your pump sits flush against the step (without O-ring and gasket) before bolting it in. I doubt you need to force it like working against a spring. If it won't drop all the way to the step, you likely have a clutch plate not aligned so keep trying. Ditto for dropping in the torque converter. If the bolt pads don't sit at least 1/2" back from the bellhousing face, you don't have all splines aligned, so keep lifting slightly and rotating until it drops all the way in. If not, you could ruin the pump when bolting up to the engine.
BTW, the A604 doesn't have any bands, using additional clutch plates to "ground" the two planetaries to the case. I think the first such design, but most auto trannies are such today. That allowed them to fit 4-speeds into the same envelope. There are similar RWD Mopar versions. Somehow companies figured how to fit up to 11 speeds in the latest auto trannies, realizing almost a CVT. But, for drag-racers go the other way. Wheeler Dealers had an episode building a drag racer (Mopar I vaguely recall), where they used an early 2-speed 1960's GM transmission (ex. Corvette) since can't waste time shifting, and all the gears needed with a high torque engine.
For others with early-A's, be careful to get a filter with 2 holes. Those years (until 1966?) have a rear pump and need that second hole to not starve that pump and cause damage. An advantage is that those cars can actually be push-started (2nd gear at >30 mph I recall). True also in my 1984 M-B 300D and until 1986, exc 1985 CA (1986+ transmission). I think the rear pump was dropped to lower cost and perhaps liability from people push-starting. I think in 904/727 that correlates with having a shift cable and separate park cable (later an internal rod, as in my A413). Might be hard sourcing an early-A kit so might have to use a 1966+ kit and figure out what else you need and check every part. For one, those won't have the gasket for the parking cable housing.
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j par
Well-hung Member
Holy smokes that's a read...
JDMopar
Well-Known Member
I backed up twice to look and see if it was AJ.....lol.
j par
Well-hung Member
I put that Yahoo on ignore years ago...
BillGrissom
Well-Known Member
Perhaps a "manager" who can only read a 2 sentence executive summary, and not even understand that. If details scare you, you definitely should not be getting inside a transmission.
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BillGrissom
Well-Known Member
Yes, us White Southern males are still ridiculed by you West Coasters, though I reside in CA now. Not my fault my ancestors lost the war (actually one grandpa was from Boston).
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j par
Well-hung Member
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