904 flexplate alignment - no 1/8” hole. What should I do?

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azaustin

azaustin

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I’m getting ready to pull the cable-shift 904 in my ‘65 Dart GT 235HP. The old tranny is almost ready to come out. According to the factory manual, there should be 1/8” hole in the flexplate that you align with the arrow mark on the torque converter. My torque converter has the arrow mark, but the flex plate has no hole. I’ve marked it with a black sharpie so I can align it with the new torque converter going in. I’ve looked closely on every part of the flex plate web, and there is no 1/8” hole anywhere. Any advice on this from you 904 gurus our there? Pictures of my flex plate, TC, and FSM attached.

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IMG_1728.jpeg
 
Two of the ears have red paint on them. You can see it on the right one in this picture. I just wanted to make sure everything was where it should be. I figured if I put the new TC in the same place as the old one it would be ok. The new TC has the arrow mark, so I’ll just put it where the old one was. My old tranny works fine and had no issues other than leaking ATF out about as fast as you could put it in. I’ve swapped C6’s, E4OD’s, TH350 & 400’s, but this is my first Torqueflite, so I want to avoid any self-inflicted foot wounds. Thanks.
 
That’s kind of what I got from the FSM, but if that is the case, why does it need to be marked?
 
azaustin said:
That’s kind of what I got from the FSM, but if that is the case, why does it need to be marked?
Click to expand...
So you can figure it out a little quicker. Good lord man, just paint one leg of the flex plate white with a corresponding white mark on the converter. This ain't brain surgery.
 
azaustin said:
That’s kind of what I got from the FSM, but if that is the case, why does it need to be marked?
Click to expand...

Being marked saves you from putting bolts in it and turning the converter only to find out you have to turn the converter again to take them out again.
One of the bolt holes is offset.
 
Sorry for asking a dumb question. Just wanted to make there weren’t any balance issues, etc., since this is the first one of these I’ve worked on.
 
azaustin said:
Sorry for asking a dumb question. Just wanted to make there weren’t any balance issues, etc., since this is the first one of these I’ve worked on.
Click to expand...
It was not a dumb question. MANY guys don't know that, and to complicate, the later EFI Magnums had symmetrical bolt patterns on the flex.

The reason they are indexed, is that if the engine is externally balanced, the weighting on the LA engines is on the torque converter. On the later Magnums, the weighting is on the flex plate
 
That was my big concern. A section of the FSM discussed that very fact and I wasn’t sure if I interpreted it correctly. Thanks.
 
I guess I should have mentioned that the transmission had been rebuilt before I got the car and I was afraid the wrong flex plate (or torque converter) might have been installed. As I mentioned earlier, the transmission worked okay, but just leaked a lot. You never know when someone has tweaked something to get by, and I’m not at familiar with torqueflites.
 
azaustin said:
Sorry for asking a dumb question. Just wanted to make there weren’t any balance issues, etc., since this is the first one of these I’ve worked on.
Click to expand...
It wasn't dumb at all. Sometimes those of us who've done things for forty years or more are a little short sighted.
 
No. I’m replacing it with a rebuilt transmission I bought (off this web site) several years ago. The original owner had it rebuilt by a reputable shop in Phoenix, but decided to go with a 727 because he was installing a large displacement blown motor in his car. When I received the tranny it was complete with a rebuilt TQ and sealed in a large plastic bag. I may rebuild the original trans someday as a learning experience. It was leaking out of the front pump seal, output shaft seal and the pan when I got it, as well as the park cable oring and speedo cable. I I fixed the oring and pan leaks, but then it was pretty obvious the front seal was really the big one. When I bought he car the seller though the transmission was bad, but I was pretty sure it was the neutral safety switch, which it was. The car idled too fast, which made it jerk going into gear. Fixing the idle took care of that. The front seal leak wasn’t too bad when I got the car, but it got progressively worse.
 
So did u change the pump bushing. Cause it wears then the seal leaks. The shift shaft seal should also be changed while it’s out. Good luck 2 ya. Kim
 
What year is the replacement trans, is it a 65 cable shift also ?
If it's a later trans torque converter will have a larger diameter pilot going into crank and won't interchange without a special converter made-up. Old converter won't fit in later trans due to different split counts.
Lon
 
Here's how I would do it if it were mine. Take the 4 flex plate to converter bolts out, along with all the other stuff needed to get the old 904 out. Take it out, and before you start back with the new 904, take your new converter and stick it up in there and make sure the center hub fits into the crank register. If that's good, lay the converter down face up. Remove the flex plate from the end of the crank and lay it on the converter oriented like it will be when everything is all bolted up. Rotate the flex plate around until all 4 bolt holes line up and run the bolts in a few threads to be double dang sure! While it is laying there with all four flex plate to converter bolts in, pick a spray paint color of your choice and spray a little on 1 ear of the flex plate, and onto the converter in the same place. Let it dry, remove the flex plate and bolt it back to the crank flange, torquing it to 55 ft. lbs. Rotate the motor with a socket until that ear you painted on the flex plate is on the bottom, if it didn't end up there. Put your converter back in the new 904 and proceed with the install. Line the paint on the converter up with the painted ear on the flex plate and install a bolt. I leave that one finger tight and rotate the crank with the socket and install the other 3 bolts. I tighten them fully as I go, since after the second one lines up, the remaining 2 will also. Work back to the painted place and tighten that bolt and you're done with the flex plate/converter part.

Sorry for the book. Everybody said paint it....but didn't really tell you why. It only takes one time of doing it the hard way to learn that lesson, so I was just tryin to make it make sense so you didn't do just that. Good luck with it.

:thumbsup:
 
lkopaska said:
What year is the replacement trans, is it a 65 cable shift also ?
If it's a later trans torque converter will have a larger diameter pilot going into crank and won't interchange without a special converter made-up. Old converter won't fit in later trans due to different split counts.
Lon
Click to expand...
It is a cable shift taken from a ‘65 Dart. Converters are the same.
 
JDMopar said:
Here's how I would do it if it were mine. Take the 4 flex plate to converter bolts out, along with all the other stuff needed to get the old 904 out. Take it out, and before you start back with the new 904, take your new converter and stick it up in there and make sure the center hub fits into the crank register. If that's good, lay the converter down face up. Remove the flex plate from the end of the crank and lay it on the converter oriented like it will be when everything is all bolted up. Rotate the flex plate around until all 4 bolt holes line up and run the bolts in a few threads to be double dang sure! While it is laying there with all four flex plate to converter bolts in, pick a spray paint color of your choice and spray a little on 1 ear of the flex plate, and onto the converter in the same place. Let it dry, remove the flex plate and bolt it back to the crank flange, torquing it to 55 ft. lbs. Rotate the motor with a socket until that ear you painted on the flex plate is on the bottom, if it didn't end up there. Put your converter back in the new 904 and proceed with the install. Line the paint on the converter up with the painted ear on the flex plate and install a bolt. I leave that one finger tight and rotate the crank with the socket and install the other 3 bolts. I tighten them fully as I go, since after the second one lines up, the remaining 2 will also. Work back to the painted place and tighten that bolt and you're done with the flex plate/converter part.

Sorry for the book. Everybody said paint it....but didn't really tell you why. It only takes one time of doing it the hard way to learn that lesson, so I was just tryin to make it make sense so you didn't do just that. Good luck with it.

:thumbsup:
Click to expand...
Thanks for the great description of how to do it. This is the kind of advice I was hoping for.
 
You will probably have to have the pan off the 904 when you hook up the shifter cable. Take the pan off the old transmission while you're doing that so you can compare the rooster combs to make sure they are the same. From what I understand, there are different ones, depending on what type of shifter was in the car. Floor shifters had one, column shifters had another, and pushbutton shifters another. They aren't that hard to swap in the valve body if they appear to be different. Maybe you will get lucky and the one in the new 904 will be identical.
 
It should be the same. The transmission came out of a ‘65 cable shift Dart GT coupe with a 273 and a floor shifter. Basically the identical setup as what I have in this car, which is a ‘65 Dart GT convertible with a 235hp 273.
 
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