Transmission debacle

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I did buy that book months ago since i was planning to rebuild one or the other, just fely like rebuilding it was a little overwhelming compared to a engine lol
 
MoparMark91 said:
I did buy that book months ago since i was planning to rebuild one or the other, just fely like rebuilding it was a little overwhelming compared to a engine lol
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Rebuilding that transmission is ten times easier than rebuilding an engine..
I've been debunking that notion ever since I rebuilt my automatic.. what transmission gurus would have you thinking it's some kind of magical Act of God to rebuild an automatic transmission when it's just about the easiest thing you'll do on your car... Especially the 904 or 727 which are damn near alike... They are literally the easiest.. I rebuilt my friends 350 turbo for his Trans Am and had twice as many parts in it amd still not that difficult...
Once you take everything off the outside of the transmission all you do is tighten the front band from the outside, you pull out the pump or actually the trick is to push it out which took me a lot to learn but after that you can unloosen the band from the outside that's holding the front drum from coming out with the pump and then pull the front drum out and the rear drum as well and then the rear band just comes right out as well what the front Band. Behind that is just the rear shaft that's connected to the sun cluster gears which all comes out as one. At the bottom is the sprag which is just ball bearings and Springs... Oh yeah you first one to take off the tail shaft which is just a big c clip underneath the mounting pad and 4 bolts.. also first you would drop the valve body which is 3 bolts for the filter and 10 bolts for the valve body.... Once you've done it you can do it in your sleep... speaking of sleep it's easier than falling out of bed...
Each one of those drums is almost like a dirt bike clutch or there's a clutch and a ring in a clutch in a ring and a clutch in a ring and so on. Then there's is a bunch of seals that you just take out and put new ones in being careful not to damage them.. buy a large of generic Vaseline and use lots of it everywhere...
 
Also I didn't buy any books LOL I watched a couple YouTube videos lol...
Literally the best shifting transmission I ever in my life on and very much impressed my friends at its crisp shifts...
Do yourself a favor and install a transgo stage 2 shift kit... I personally did a stage 3 which is the same as a stage 2 except for it turns it into a full manual shift. which means you have to shift every gear up and down and start in the gear you want to start in which most people don't want...
 
install a Coen bolt in sprag in a 727. That is the weak link compared to the 904 from the factory. I don't see any 904's, 998's ,999'S behind big blocks. Wonder why they never used them in Big block cars? As I stated if you have a light weight race car, Use a 904. If your building a full interior all metal street car for passengers and packages in the trunk including a spare. Go with the 727.

Think of it this way. If your car was a heavy 4spd. would you install a 9 inch clutch or a 10 1/2 inch clutch. That's the difference. Shaft, Drum, and clutch diameter. The only thing the 904 has over the 727 is the riveted in sprag. And lighter recipricating weight plus ratio. Installing a bolt in sprag is a must on either for safety. Just that the 904 has the holes 727 you have to drill them.
 
Oldmanmopar said:
install a Coen bolt in sprag in a 727. That is the weak link compared to the 904 from the factory. I don't see any 904's, 998's ,999'S behind big blocks. Wonder why they never used them in Big block cars? As I stated if you have a light weight race car, Use a 904. If your building a full interior all metal street car for passengers and packages in the trunk including a spare. Go with the 727.

Think of it this way. If your car was a heavy 4spd. would you install a 9 inch clutch or a 10 1/2 inch clutch. That's the difference. Shaft, Drum, and clutch diameter. The only thing the 904 has over the 727 is the riveted in sprag. And lighter recipricating weight plus ratio. Installing a bolt in sprag is a must on either for safety. Just that the 904 has the holes 727 you have to drill them.
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Because they didn't make them for Big Block cars...
 
Also just as an FYI if you decide to do the 904 and later are able to get into a 4-speed they are the same length meaning you'll just need to change the slip yoke and not the length of your drive shaft...
 
I'd clean up the 727, replace the front, kickdown (external and internal), and rear seals, Flush the torque convertor, adjust the pressure up, adjust the bands, maybe install a 4.2 kickdown lever, replace the filter and fluid and run it. Get a balanced driveshaft and have at it.

The sprag problem occurs when doing water burnouts and and overrunning the sprag.
https://www.hotrod.com/articles/15-tips-improve-727-torqueflite-trans/

My 727's do not have the bolt in sprag. Not a drag racer warming the slicks in a water burnout.
 
j par said:
Also I didn't buy any books LOL I watched a couple YouTube videos lol...
Literally the best shifting transmission I ever in my life on and very much impressed my friends at its crisp shifts...
Do yourself a favor and install a transgo stage 2 shift kit... I personally did a stage 3 which is the same as a stage 2 except for it turns it into a full manual shift. which means you have to shift every gear up and down and start in the gear you want to start in which most people don't want...
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Thats what i want though is a manual shift or even a reverse manual valve body and i did want to make it a floor shift
 
j par said:
and as the person who encouraged me to do my first one said if the guy couldn't do three of those a day in his shop you wouldn't have a job very long.
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Hmmm. wonder who that was?:D

A buddy and I just pulled his 727 apart yesterday just to have a look at the clutches and bands because there were some blackish looking chunks in the pan.
It looked like something that got in there through the dipstick hole while sitting, but we wanted to be sure. (It looked perfect with very little wear and no discoloration on anything) so we are just going with a reseal kit.

I'll drill his separator plate in the valve body and mod the governor weights for him (quicky home shift kit):D
It's for his D100 and won't be beat on.
 
You can damage the sprag in either a 727 or 904. It's just that a 727 can explode. I've never seen a 904 come apart like a 727.

But also, make sure that neither transmission takes a lock-up converter, which would limit your converter and valve body options. In a lock-up trans, the input shaft tip is machined about 3/4". In a 904, the lock-up version may also have a 2.74 low gear, which you would be unnecessary with a high torque stroker.
 
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MoparMark91 said:
Thats what i want though is a manual shift or even a reverse manual valve body and i did want to make it a floor shift
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I used a stage 3 shift kit and Quicksilver
B & M ratchet shifter... I drove my buddies 10-second Cuda with a reverse valve body and it didn't really do anything for me as far as the way it shifted more confusing than anything....
 
I suggest upgrading and rebuilding the 904 . It is just as good as a 727 if built correctly . Especially with a 372 . don't cheap out on it or the converter .
 
383Scampman said:
I suggest upgrading and rebuilding the 904 . It is just as good as a 727 if built correctly . Especially with a 372 . don't cheap out on it or the converter .
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Yeah im not aire on what converter i need but i will probably call someome woth my specs
 
j par said:
I used a stage 3 shift kit and Quicksilver
B & M ratchet shifter... I drove my buddies 10-second Cuda with a reverse valve body and it didn't really do anything for me as far as the way it shifted more confusing than anything....
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Isnt it easier cause all it does is reverse the shift pattern of gears away from nuetral? Im been looking up trying to find a manual valve body thats good and all i have found on summit is the cheetah one
 
3650 lbs low to mid 10's. Stock 727 with cheata VB. 5500 ati converter. Foot braked for many yrs and street driven. A trans is only as good as the operator. You screw up they blow up. A 904 in this car the way it was driven with this HP would have fell out the bottom years ago.

Keep them cool with fresh fluid and watch when and how you shift they last a long time. I would recommend any car weighing more then 3100 with 500 plus HP use a 727 for the yearly street and track . A Track only car or under 2900 you can get away with a 904 for a couple years. The trans in my car was the original trans. Clutches, plates and bands once in 45 years. Its last day at the track it started flaring when shifting into 3rd at around 7900 when hot. you can hear it in this second video compared to the first video.

First video cool



Second video was a third time back to back pass. Listen to the difference on the third gear shift. A 904 wouldn't have held up to a hot flare like this all night pulling 0ver 3800 lbs. with driver it would have burned up. Been there.



904's are lighter , quicker and cheaper to build. Great for a racer. But no way are they as durable as a 727. Put a 904 behind my cummins and it wouldn't last one pull. I don't think it would make it out of low gear.
 
So i have the small 7 1/4 rear but plan on upgrading to a 8 3/4 what would be the difference on that with a 904?
 
Again my apologies as i am learning at the same time
 
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