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727 No reverse or 3rd gear

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Moffman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Moffman Quote  Post ReplyReply Direct Link To This Post Posted: Sep/02/2017 at 6:04pm
Originally posted by 1970390amx 1970390amx wrote:

http://theamcforum.com/forum/sick-727_topic38526.html

This might help you out.  It is fairly easy to pull the valve body and air check the direct drum, the service manual will call it the front drum I think. If you can apply low air pressure to it and hear a soft clunk the drum is probably ok. air hissing means you have an internal problem and trans needs to come out. If you changed the pump did you change or inspect the sealing rings on the back side of the stator support? They seal the passage from the pump int the front drum?

I didn't replace the front drum but I'll check it out.

Originally posted by 401MATCOUPE 401MATCOUPE wrote:

Just FYI, only the 73 TSM will be helpful, since the Torqueflights were introduced in 1972.  As 6PacBee and 1970390amx is saying, these things are very easy if you have mechanical skills......where are you at in New Jersey??  If you air check the servo's like the manual shows, that can give you some confidence that the seals are proper........not only look at the placement of the balls in the valve body, but there are two different diameters and I forgot to mention that a lot of shift kits have you remove the accumulator piston spring.  The key to working on automatics is CLEAN< CLEAN, CLEAN......clean work area, clean hands, avoid working in windy conditions outside, I probably use 20 cans of Brakleen during a rebuild.  One last thing, since you have driven it, how does the fluid smell?  Burnt?  If it does the apply servo seals probably have been compromised, but the basic air check will show up leaks.  Just another FYI, many automatic specialist say the 727 is one of the best trans ever built and as simple as it sounds, the filter is a primary key.  A lot of automatics from early days until today use more of a screen then a real fine particle filter...keeping the fine particles out of the valve body spools and frictions/bands, durable.  They can have a fatal problem if used in very abusive (high RPM and Drag Race) with front drum explosions......but they are rare and under those type conditions, there are billet drums, if you are running a 727 like that and are not aware of these limiting factors, you need to do more homework. For stock applications I will trade off the durability for the extra weight and horsepower it takes to spin it over the other smaller Torqueflights....but that is my personal opinion, every post 1972 AMC I own has a 727 in it.   I know of at least 4 Forum members that combined probably have rebuilt over 1000 of these 727 trans combined.......so plenty of help for you....and if you get really stuck I am not that far from New Jersey....was there last week for the Atlantic City Airshow.

I have driven it since, fluid looks and smells fine. I'm off exit 98, about a hour north from AC, very cool. I'll definitely be in contact if I get stuck, appreciate it. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote one bad rambler Quote  Post ReplyReply Direct Link To This Post Posted: Sep/02/2017 at 9:56pm
Been doing transmissions for over 30 years...Cleanliness is an understatement..At work i have stainless steel benches...at home i use Formica..A simple air test will tell you whats going on..also an elements in use chart will help you pin point the problem..A rear band(low/rev) is on in reverse and manual low(engine braking)front drum(clutches) is on drive high(3rd) and reverse...sounds like multiple problems....
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1970390amx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1970390amx Quote  Post ReplyReply Direct Link To This Post Posted: Sep/02/2017 at 10:46pm
I didn't replace the front drum but I'll check it out.

I said nothing about you replacing the front drum. You said you had to pull it and replace the pump. The rear of the pump has oil feed passages that feed the front drum. I suggested that the sealing rings on the back of the pump were left off.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Moffman Quote  Post ReplyReply Direct Link To This Post Posted: Sep/05/2017 at 10:53am
Originally posted by 1970390amx 1970390amx wrote:

I didn't replace the front drum but I'll check it out.

I said nothing about you replacing the front drum. You said you had to pull it and replace the pump. The rear of the pump has oil feed passages that feed the front drum. I suggested that the sealing rings on the back of the pump were left off.


Meant pump not drum.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote carnuck Quote  Post ReplyReply Direct Link To This Post Posted: Sep/08/2017 at 11:32am
If the front pump was damaged by shoddy installation then the bits from it will first go into the high/reverse clutch seals unless you were lucky and a check ball was just put in the wrong position. (I did that by accident with a Mopar 5 ton 727 trans with the extra low range that made it almost 6 speeds forward. It was the precursor to the modern 42RE but with lower gears rather than overdrive.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Moffman Quote  Post ReplyReply Direct Link To This Post Posted: Sep/10/2017 at 2:20pm
Haven't had a chance to pull the pan yet but noticed something interesting yesterday. First thing in the morning when the trans is cold I actually was pushing it out of my driveway, I put it in reverse instead of neutral like I usually do and reverse was working. I tested again when I got to work which was 10 mins away and nothing.

Does this give any hints into it being a front band/clutch issue? Still no third.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote carnuck Quote  Post ReplyReply Direct Link To This Post Posted: Sep/10/2017 at 2:54pm
Make sure it's not just a quart low on fluid and that the trans cooler in the rad isn't clogged with old clutch material. Make sure the pan isn't full of foreign materials as well. Drive is just both sets of clutches locking up. Low fluid pressure can do it too, but possibly it's two things. Passing gear set too tight won't let drive engage. Low fluid keeps reverse from working as soon as it warms up. Fluid needs checking in neutral warm. Wrong dipstick can give a false full reading. In 2wd 727s we would check by filling then pulling speedo drive plug out if it felt like too full. After it drained to its level, reinsert plug eccentric and add 1 quart of fluid. That's based on what I learned 30 some years ago.

Edited by carnuck - Sep/10/2017 at 3:02pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Moffman Quote  Post ReplyReply Direct Link To This Post Posted: Sep/10/2017 at 3:00pm
Originally posted by carnuck carnuck wrote:

Make sure it's not just a quart low on fluid and that the trans cooler in the rad isn't clogged with old clutch material. Make sure the pan isn't full of foreign materials as well.

Fluid level is good, fluid not burnt, new radiator, new lines. I guess the pan will tell.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote carnuck Quote  Post ReplyReply Direct Link To This Post Posted: Sep/10/2017 at 3:21pm
On this, I learned the hard way. Brand new rad in my Comanche when I converted to open system and I found out after driving to Ca border and came back towing an SX4 with dead and partially dismantled 998 auto. (So it was no use if we broke down) Hottest day in April recorded coming back but the floor was hot going down. I figured my cat was clogging but nope. Started down shifting of O/D on the highway at 55. Stopped and let it cool down while we ate lunch.
   Got home at dark and put the SX4 in driveway, then reverse went in my Comanche next AM. Added some Lucas to synthetic Ford fluid already in it. (Jug was mislabeled Mercon VII instead of dex/merc)
   If I nursed it in first a bit, reverse worked after warmup then all day until I drove highway and it went to neutral at 60 mph. Went to add external cooler for trans and top line had oil but nothing in the bottom return line. Turned out cooler in brand new three core brass XJ rad was clogged with factory sealer! Then trans was fine again until the cooler started losing antifreeze into trans and vice versa. I drove it a year like that before replacing the rad and trans. (Nowhere to work on it with access after work and my so-called friend I helped tow the car back turned out to be the loser people told me he was and I didn't believe them)
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