Inspecting A727 Transmission

[Blowout]

I'll be getting my 727 transmission this week.  Any advise on what to look for to make sure it's going to be a good rebuild?  I thought about just sending it off to get rebuilt, but I don't see installing it back in the car anytime soon so it would just sit for now. Might be a year or two or even three by the time I get to that stage of the build.........unless you guys don't see an issue with it sitting for a while?  Thanks for any feedback.

[chargerdon]

Assuming it is a good rebuild, letting an automatic transmission sit for "a while" has the this simple problem.    Transmission fluid keeps the O-ring seals in the clutch packs from drying out and the friction material from drying out, and you get none on the top side when it isnt running.   When a transmission sits for a long time none of the fluid is on the "top" of the seals and the seals dry up.    How fast ?   In my opinion anything over 6 months is risky.   Two three years...you got bad issues...   i would have waited until is was ready to go in before having it rebuilt.   

When i bought my 74 Challenger in need of restoration i was told the 904 Automatic was in good running condition when parked.....8 years ago.  Before installing the freshly built engine, i pulled the front most seal and put in a new one...and patted myself on the back...who needs a leaking front seal. 

So, then i drained the transmission by dropping the pan, put in new filter and put in fresh fluid.   (note...a 904 takes about 7 quarts and about 2 in the TC but was only able to put in about 5 qts.   Once i got the new engine started up and allowed the engine to idle with the transmission in idle not park (the pump does not run on a torqueflite in park...thus the instructions to check in neutral idling).   Adjusted the fluid level and put it in reverse..voila right in, then into drive and was happy to feel it engage immediately.   Took it for a drive and it ran GREAT.    However, in as little as 25 miles, i started to notice the transmission "slipping" in first especially and then later in all of the forward gears.    It got so bad that it would barely drive.   Sigh

Took it out and tore it down and found the seals in the rear clutch pack in pieces and the clutches themselves with the friction material nearly completely gone.   

Cleaned it all out, put in new clutches and the O ring seals in the clutch packs and all good now !!    What happens is those o rings dont completly seal and so you dont get the amount of pressure on the clutch surfaces that is needed and then once it starts to slip it wears the friction material off quickly,  more slipping and the heat then tears those O-rings apart.   Funny thing was that the forward clutch pack clutches looked good, while the rear clutch pack the o seals were broken and the clutches had near zero friction material left. 

Simple answer is ...dont let it sit if you can help it and dont get it overhauled until your ready to use...   

[Blowout]

@chargerdon thanks for your response. I figured that was the case. So I'll waiting it's time.

Any tips on what to check for now. Was going to pull the pan off and see what things look like. Anything else?

Thanks again.

[chargerdon]

Like i said, check the wiring connector on the top near the selector.   Your E body needs a 3 wire system...take a look and see if your transmission has the 3 wires or just 2.   Difference is whether it handles the reverse light or not.   If its only two then it can be modified by changing out the valve body connector and rooster comb.   I just did a google search...  1967 and older mopars the reverse switch is on the steering column or on the floor shifter itself.   They moved it to inside the tranny for 68's so depending on the year of your transmission this is good to check before installing.   Simple check, 3 wires on the transmission connector or only 2 ??   You need the 3 in the transmission...   

Otherwise wait till you are close to needing the transmission before having it rebuilt...   And yes i recommend having a soft rebuilt (clutches and seals) before installing.   You can even do it yourself...i did it on my A904 on my 74 challenger and then on my A518 4 sp overdrive transmission.   I will say this...my A518 the clutches looked like new which is good...but having sat...i didn't trust the o-ring seals in the clutch packs.   You can't actually see the clutches and seals without disassembly of the clutch packs themselves. 

Regardless of this another thing which is easier to check with tranny out is the speedometer gear.   Take it out and see what the number of teeth on the big plastic sprocket is.   Its color coded and the number of teeth is stamped into it.   Now Measure the circumference of your rear tires and match that number with a chart that shows the number of teeth on the gear that is needed for that circumference.   If it is what you need great, otherwise buy the appropriate one (tci transmissions stocks them all or find the one you need on ebay) and install...   If you don't do this step then your speedometer wont be accurate.   

[Blowout]

@chargerdon sorry if I missed it but I didn't see anything regarding that connector in your earlier reply. I did however find a replay similar in someone else's post asking about their 1969 340 build?

[Blowout]

Very helpful @chargerdon Thanks for the feedback.

[7E-Bodies]

Great. I have my NM 727 sitting on a shelf over two years now and probably another year or two before it turns. I had told my transmission guy (famous in the area for muscle car restoration and race guys) that it'd be sitting and he said he'd use the right kind of lubricant and it'd be fine. He claimed he has several clients with similar wait times.