727 year interchanges

[robfxrs]

hey guys. I need to ask the masters, as I am grasshopper...
I bought 72 charger, 727 in it 400 big block. tranny was/ is. dead.
have not found the numbers on case yet
have chance to buy 727 from a 77 year vehicle, with t.c, says it drove good when came out
not lookin to swap innerrs. or parts
want to swap entire trans unit
think it will swap out?
anything to look for?

 

[Dave6T4]

Check to see if '77 transmission is a lock-up torque converter piece. I can't remember what year these came out. The input shaft will be drilled, and the splines do not come all the way down to the end of the shaft. Sometimes the lock-up converters fail, so I would avoid them. Otherwise, these Big Block transmissions are interchangeable.

 

[pnora]

77 should have a weighted converter for a cast crank. You need to know what crank is in your engine.

 

[CHGRSE74]

In my view it’s always best to keep it original numbers matching. The numbers are on the right side of the trans case just above the pan. This trans is fairly easy to rebuild, or substitute parts from a donor. If you have the shop manual refer to it and I’m sure you can do it, just take your time and keep things clean. If you do a swap do not dispose of the original trans providing its numbers matching to the vin.

 

[Rishi]

The numbers are on the right side of the trans case just above the pan.

If you don't know where to look, and your transmission is dirty/goopy with buildup, then these numbers can be hard to find. Follow the lip of the transmission, where it mates to the oil pan, along the outside. On the right side, there will be a flat machined area about 3 inches long by 1/4-inch high, and this is where the numbers are stamped. These numbers are less than 1/4-inch away from the oil pan.

Most of the time, the transmission number looks like "PKXXXXXXXX YYYY ZZZZ" where X, Y and Z are sets of numbers. Posting those numbers here, will help us identify the transmissions you have.

Unless your 400 engine was rebuilt and they decided to change the crankshaft, you have a cast crank in your 400 engine. The (balancing) weight on the torque converter is a little piece of flat steel, about an inch wide and 1/16-inch thick welded to the side of the torque convertor.

Around 1978, Chrysler Corp switched over to "locking" torque converters, to mechanically lock at highway speeds to improve fuel economy. These locking ones don't typically have a drain plug. There is normally a plug one can see from the front of the transmission torque converter. At 1977, you're right on the line, but if you can see the drain plug, you may not have a locking one.

Swap the transmissions, but save your older 1972-400 one. Swap the transmission and torque converter, together as a unit. If the 1977 transmission does not function to your satisfaction, you can have your 1972-400 one rebuilt, or do it yourself.

My first time rebuilding one, I was pretty intimidated and thought it would be more complex than an engine. Decades later, I have 6-7 of them under my belt, and agree they are pretty easy with a rebuild kit. If you're at all intimidated, watching a few YouTube videos will help. There are some decent books out there, too. I recommend the one by Tom Hand, although, it may have too many pictures, if you can believe it.

 

[dvw]

If your 400 has the original automatic cast crankshaft. This is how to tell if this trans will fit your application. Easy to check. First the bellhousing pattern has to match. Measure across the top bolt holes, this measurement has to be the same. Second the weight size and location on the front of the converter have to match. Third slide the converter out of the trans. The input shaft has to have splines all the way to the end. No smooth portion on the end of the shaft. This will assure you of it being a big block non lock up trans. If everything looks the same except the weights on the converter you could use your original converter if it's a known good piece. What is the issue with the current trans?
Doug

 

[Rebelrouser]

hey guys. I need to ask the masters, as I am grasshopper...
I bought 72 charger, 727 in it 400 big block. tranny was/ is. dead.
have not found the numbers on case yet
have chance to buy 727 from a 77 year vehicle, with t.c, says it drove good when came out
not lookin to swap innerrs. or parts
want to swap entire trans unit
think it will swap out?
anything to look for?

As mentioned, if it is not a lockup then it will swap. Make sure you use the kickdown lever and manual lever off the original transmission there are some differences in lengths and can cause shifting issues.

 

[Sam69sat]

Make sure you're buying a 727 for a car and not one from a motorhome, van, etc. with a short tail shaft.

 

[Voetom]

I just did one with the motor home swap. The one I used was a 76-78 440 18,000 GVH unit and it was a tough transmission. if you can find one, they have some HD stuff in them. Of course, you need to switch the output shaft and extension housing but when going through them anyway, that is not a big issue.

This is the book another person mentioned above. And thanks for the comment on it too Rishi.

 

[Trans Man #]

Check to see if '77 transmission is a lock-up torque converter piece. I can't remember what year these came out. The input shaft will be drilled, and the splines do not come all the way down to the end of the shaft. Sometimes the lock-up converters fail, so I would avoid them. Otherwise, these Big Block transmissions are interchangeable.

Lockup started in 1978.

 

[Trans Man #]

Here's some information on how to identify what crankshaft you've got. Also there is some other information on factory converter information members may find usefull.

 

[robfxrs]

I purchased and have been reading tom hands trans book like a bible, as well as purchased service manual.
thank you, for all replies. and info.

 

[Lefty71]

Lockup started in 1978.

Yep....but not all of them of course. I got a non-lockup one from a 78 newport fairly recently, and was surprised to find that it wasnt.... turned out to be a great trans (and would work find in the OP's application).

 

[dvw]

This stuff is old enough you never know whats been swapped in. Best to check.
Doug

 

[Thunderdan]

Yep....but not all of them of course. I got a non-lockup one from a 78 newport fairly recently, and was surprised to find that it wasnt.... turned out to be a great trans (and would work find in the OP's application).

This is true- all of the HD/Police 727's weren't lockup in '78 either. *Most* others were, but one has to check and verify.

 

[cudamark]

hey guys. I need to ask the masters, as I am grasshopper...
I bought 72 charger, 727 in it 400 big block. tranny was/ is. dead.
have not found the numbers on case yet
have chance to buy 727 from a 77 year vehicle, with t.c, says it drove good when came out
not lookin to swap innerrs. or parts
want to swap entire trans unit
think it will swap out?
anything to look for?

They will swap if: both are long tail shaft, slip yoke, big block 727's. Things to look for are: converter weights (400 and 440 use different ones) Lockup and non-lockup as already mentioned, bolt pattern on the converter to flex plate (there are two different ones) If I were you, I would have your original converter flushed and tested and re-used in the "new transmission....assuming of course that there's not a mismatch on lockup/non-lockup. Just pop in a new converter seal first. New yoke seal is a good idea too along with dip stick tube "O" ring. I always change the selector shaft seal too, but, that involves a bit more work, but, worth it IMO. I'd also check the speedometer gear too so it matches your rear end gear or your speedometer accuracy may be off.