Hawk's First 727 Transmission Rebuild

[HawkRod]

Background: This is for my 1973 Road Runner. It has a 416 small block stroker engine in it and a 727 with a Gear Vendors overdrive. I plan to drive this car across country and will do it "RoadKill" style. If you are interested the build and/or more pictures of the engine/car, look here:
https://www.forbbodiesonly.com/mopa...-hawk-rod-resurrection-roadkill-style.213411/

I figured I would start a separate thread for those simply interested in the transmission work. The current tranny in the car works fine, except it seeps a bit from the front pump.

Besides installing a shift kit in my original valve body in like 1982, I have never done any automatic transmission work. I appreciate any and all advice from the many transmission knowledgeable folks on the forum!

So the plan is this:
I have the transmission below which is for a big block. It was built to handle a 500 cubic inch stroker. It was freshened shortly before it was pulled out of the car, so this transmission should have good, beefy internals to handle the increased power of my 416 small block.

The internals from the big block 727 above will be put into my numbers matching small block 727 transmission below. This transmission worked fine when it was pulled out of the car years ago. It was swapped with another transmission (still in the car) to rule out transmission issues from a harmonic vibration the car has.

I have performed an initial cleaning to get the gunk off of the transmissions, and will now start to break down the small block 727. When done, I will clean the case again.

I am armed with a transmission manual and some seals, so now I know enough to be dangerous!

 

[eldubb440]

subscribed...... auto trans is about the only thing I've never had my hands in

 

[Durandal25]

Lord, do a vid on that.....I love the 727.

 

[zyzzyx]

Piece of cake Hawk! Just disassemble everything and lay it out in order from the front pump on back.
The trickiest part is the snap ring in the tail shaft. REALLY! Inspect all of the bushings and thrust washers
in the good trans, and check the clutch pack clearances. Put it together with new gaskets and seals and
you'll be good! Make sure you replace all of the seals for the selector shaft and the kickdown shaft. Now is
the time to change them. If the trans was built for a strong engine, it should have a heavy-duty front band
and a steel front planetary! The aluminum planetary female spline is not the strongest. I'm going through
my trans this winter and am doing about the same thing that you are. Taking two, and making one good one!
Four speed transmissions are harder in my opinion! All those damned needle bearings on the floor!!!!!

 

[HawkRod]

Tools:

I know I will need some special tools. I modified an axle puller to pull the front pump out of the car.

I also know I need a spring compressor, but don't yet know enough about what I need to see if I can either make one or make do with C clamps, etc. that I have now.

I'm sure some tools will become an issue as we move along. The book seems to state you can fabricate many of the needed tools, so I may try to do that as I go along.

 

[zyzzyx]

 

[HawkRod]

Piece of cake Hawk! Just disassemble everything and lay it out in order from the front pump on back.
The trickiest part is the snap ring in the tail shaft. REALLY! Inspect all of the bushings and thrust washers
in the good trans, and check the clutch pack clearances. Put it together with new gaskets and seals and
you'll be good! Make sure you replace all of the seals for the selector shaft and the kickdown shaft. Now is
the time to change them. If the trans was built for a strong engine, it should have a heavy-duty front band
and a steel front planetary! The aluminum planetary female spline is not the strongest. I'm going through
my trans this winter and am doing about the same thing that you are. Taking two, and making one good one!
Four speed transmissions are harder in my opinion! All those damned needle bearings on the floor!!!!!

Awesome! Heck, the snap ring in the tail shaft I have dealt with - that's easy - even I can do that!

Glad to have you along so you can let me know if I need to shift what I am doing!

 

[oldbee]

Check your shaft endplay before you start the tear down, gives you a reference point.

 

[Dave6T4]

I always take the spring off the accumulator piston. Some kits say to use a blocker rod under it, but I have found part throttle and off-the-gas shifts too harsh. I use engine assembly lube on lip seals, seal rings and bushings. I have a machinist friend modify non high performance governor weights to Hemi. spec, or just buy these from A&A Transmission. Be careful when installing the output shaft in the governor support. Lube up the seal rings and support cavity. A broken governor ring does not show up until the trans is assembled and back in the car. It happened to me once, early on. For high horsepower builds, a bolt in rear sprag is a consideration. I made a couple of alignment dowels for mounting the oil pump by grinding the heads off appropriate sized bolts and screwing them into the case. This also keeps the pump gasket from moving out of alignment. I also leave the outside seal off the oil pump when initially installing pump to check if clearances and input shaft drift are OK. This makes it easier to remove pump assembly. Once these clearances are fine, install the seal and bolt it all together. Lastly, carefully insert a thin screwdriver past the torque converter seal and turn the oil pump drive lugs to 12 and 6 o'clock position. This will make it easier to seat the torque converter. I hope this helps.

 

[Rockland71GTX]

When I did this years ago I used that same book, and also got a vhs tape on rebuilding the torqueflite. Nowadays they are all over YouTube.

 

[qkcuda]

Hawk, the trans had been modified to be a full manual forward pattern. The line pressure was not locked out though, so the throttle position lever still worked. I assume any mods were restricted to the valve body, so if you use the one from the 340 you should be OK. I still have contact with the fellow who built the trans if you need any more info.

 

[HawkRod]

Check your shaft endplay before you start the tear down, gives you a reference point.

Thanks! Done. End play on the tranny was .048"
By the way, this transmission was rebuilt by Aamco back in 1982. They obviously did a good job, because it has worked fine ever since. We'll see how it looks once I dig in to it though!

I always take the spring off the accumulator piston. Some kits say to use a blocker rod under it, but I have found part throttle and off-the-gas shifts too harsh. I use engine assembly lube on lip seals, seal rings and bushings. I have a machinist friend modify non high performance governor weights to Hemi. spec, or just buy these from A&A Transmission. Be careful when installing the output shaft in the governor support. Lube up the seal rings and support cavity. A broken governor ring does not show up until the trans is assembled and back in the car. It happened to me once, early on. For high horsepower builds, a bolt in rear sprag is a consideration. I made a couple of alignment dowels for mounting the oil pump by grinding the heads off appropriate sized bolts and screwing them into the case. This also keeps the pump gasket from moving out of alignment. I also leave the outside seal off the oil pump when initially installing pump to check if clearances and input shaft drift are OK. This makes it easier to remove pump assembly. Once these clearances are fine, install the seal and bolt it all together. Lastly, carefully insert a thin screwdriver past the torque converter seal and turn the oil pump drive lugs to 12 and 6 o'clock position. This will make it easier to seat the torque converter. I hope this helps.

Wow. An awesome amount of tips - much appreciated. I will have to absorb these as I go along.
This is for a street driven car that will go across country, so I do not want any shifts to be overly harsh. as a matter of fact, the way it was built and with the shift kit I thought it was about perfect. I plan to reuse this transmission's valve body, so hopefully that will work well.

When I did this years ago I used that same book, and also got a vhs tape on rebuilding the torqueflite. Nowadays they are all over YouTube.

I haven't done any YouTube video's yet, but I'm sure they are coming! There is so much information to absorb, so I am trying to take this one bit at a time. So yes, I do plan to watch some video's once I get into harder stuff that I am unfamiliar with.

Hawk, the trans had been modified to be a full manual forward pattern. The line pressure was not locked out though, so the throttle position lever still worked. I assume any mods were restricted to the valve body, so if you use the one from the 340 you should be OK. I still have contact with the fellow who built the trans if you need any more info.

Awesome - thank you! Yes, I did recall this was a full manual valve body, so I planned to use the valve body from my small block 727. It worked nicely and I like the way the transmission shifted with that one.
Honestly, I am ignorant on how to see or find any other modifications that may not be compatible with my intended use. Hopefully someone will see and/or have me check for these, but if you could ask the builder if the remaining parts can be used for my application, that would certainly give me piece of mind.

 

[HawkRod]

OK, so on to baby steps. This part I know how to do so it was easy.

First I removed the access plate to get to the tailshaft snap ring

Then I removed all the tailshaft bolts:

Then I removed the speedometer gear assembly

The above three steps can be done in any order. Then I used reverse pliers to expand the snap ring while pulling up on the tailshaft.

Bingo - It's out!

OK. There is the sum total of what I know how to do on a 727!

I now need to do some home projects. Next on the list will be to assure a CLEAN and orderly work place to put parts I take off, and then remove the valve body and front pump?

Now, at least for me, this will start to become interesting!

 

[QOTHL]

There's a complete video on how to do this on YouTube. It's about 2 1/2 hours and very detailed.

 

[Cranky]

Tools:

I know I will need some special tools. I modified an axle puller to pull the front pump out of the car.
View attachment 1195646

I also know I need a spring compressor, but don't yet know enough about what I need to see if I can either make one or make do with C clamps, etc. that I have now.

I'm sure some tools will become an issue as we move along. The book seems to state you can fabricate many of the needed tools, so I may try to do that as I go along.

OK, so on to baby steps. This part I know how to do so it was easy.

First I removed the access plate to get to the tailshaft snap ring
View attachment 1195747

Then I removed all the tailshaft bolts:
View attachment 1195748

Then I removed the speedometer gear assembly
View attachment 1195749

The above three steps can be done in any order. Then I used reverse pliers to expand the snap ring while pulling up on the tailshaft.
View attachment 1195750

Bingo - It's out!
View attachment 1195751

OK. There is the sum total of what I know how to do on a 727!

I now need to do some home projects. Next on the list will be to assure a CLEAN and orderly work place to put parts I take off, and then remove the valve body and front pump?

Now, at least for me, this will start to become interesting!

Your puller reminds me of mine. It's 100% homemade using mostly stainless steel and my crappy welding on ss really shows but it's held up since around the early 80's. Btw, a GOOD set of snap ring pliers are your friend.

The TF's are one of the most easy to rebuild and so far I've done a grand total of one and that was only because I tried to get the neutral safety switch out and when it popped loose, the case cracked. Dang it. A buddy that was a heavy equipment mechanic helped me do it. He just stood there and let me do it all but was guiding me along the way. He said everything looked good but I didn't know what bad looked like until I tore down a bad one lol

 

[66Satellite47]

Never used anything like an axel puller for the front pump, a couple of the right length bolts & washers with a pry bar works just fine, back & forth side to side with the front band tightened all the way down. I have my versions of internal components for different applications. Built my 1st 727 in '72.

 

[Cranky]

Never used anything like an axel puller for the front pump, a couple of the right length bolts & washers with a pry bar works just fine, back & forth side to side with the front band tightened all the way down. I have my versions of internal components for different applications. Built my 1st 727 in '72.

Did my first.....and only lol in 75. An axle puller is overkill but his puller doesn't look like one.....

 

[AR67GTX]

I rebuilt mine a few years ago and posted a long, blow by blow thread on it, if you can find it. Maybe more drama than you need and all the pictures have probably been wiped out by Photobucket. The Torqueflite book is a big help as is the heaviest duty set of snap ring pliers you can find. I made a short 2x4 ladder and roped the case to it so I could stand it leaning against my work table, holding the transmission case, face up and vertical. I could also walk it around and lay it down horizontally to work on the servos and valve body when that made sense.

Good luck - mine came out great and took care of the niggling problems I was dealing with - leaks, leak down of the converter, low gear whine.

 

[66Satellite47]

Did my first.....and only lol in 75. An axle puller is overkill but his puller doesn't look like one.....

I really should have also said that all the "special tools" shown in the FSM aren't really required. I made my front drum compressor, a little steel, welder, Oxy/Acet torch to bend the steel to the curve required. Been using it for least 45 years. 727's are fairly simple to rebuild and don't need many special tools. Planning the correct combination of internal components is very important.

 

[Ghostrider 67]

I did mine my friend and it was easier than I expected. I used the great book by Tom Hand and still have his phone number that he gave me if I needed help. The best advice has already been given, have a dedicated spot where you can lay put the many parts in strict order. This is paramount. Cleanliness is also paramount. It must be spotless going back together. Snap ring pliers are a good set of tools to have for this. I used Alto Red Eagle frictions and Black Kolene Racing steels in mine and 4 pinion planetaries. Yes, you can easily make the pullers and clamps to take the thing apart with and put it back together. It isn't rocket science. Close objective inspection for wear on everything is a must. Look for if you have hardened input and output shafts.

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Hope it helps. Ghost.