flexplate question

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trudysduster

trudysduster

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I want to make sure I am right on this before I get into trouble here. I bought a 360/727 combo from a 79 RV to put in my sons car a week or so ago. The tailshaft as you know is different so I pulled the tranny and going to stick a 904 I have laying around to put behind the 360 just so he can drive this car until he can get the 340/4speed built. The question I have is when I looked at the flexplate, it looked like it was bent a little. I found a member here who has a flexplate for a 360 and he said it was straight so I am thinking about just getting it and replacing it to be sure. Also, Do I use the torque convertor from the 727 that came off of this 360. The 904 tranny and convertor I have is from a 318. Are they the same or will I be getting into a balance issue between the 360 convertor and the 318 convertor. The 904 and convertor is off of a 73 Dart Sport 318 car. I think I should stay with the convertor that came with the 360/727 combo and just switch the tranny but would like your guys opinion. Any help would be greatly appreciated. Bill
 

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bill you will need to get an aftermarket flexplate from summit...or change the transmission torque convertor the 360 is externally balanced,if he is going to use a 340 or 318 later down the line the aftermarket flexplate is the way to go....
 
Not positive, but I recall reading that the flexplate is different for 904 and 727. I think the aftermarket ones have multiple holes to fit both. I think that is what waggin refers to.

It sounds like you are contemplating using the torque converter from the 727 in the 904 but do they interchange? If so, that would fix your balance and tranny fit issues, assuming you have a driveshaft for the 904. However, I recall reading that 727 converters have a different number of ring teeth, meaning a bigger diameter, but maybe that is just the BB version.
 
there are three oem flexplates available, large, small and small with small center hole for early 273 and slant six. the torque convertors from 904 and 727 are NOT interchangeable...installing a externally balanced 360 in place of a 273 318 or 340 is going to cause a balance issue which is remedied in two ways.....buy a torque convertor with weights on it for a 360 or do it the easier, smarter more cost effective way and install the aftermarket flexplate
 
waggin, can you just swap the 727 out with a 904 tranny and just use the same torque convertor that was in the 727 behind the 360. Or would it be best to just find another SB 727 that has the right tail shaft for a car tranny mount. bear with me here I am new to this.
 
well, thats the good thing. He has no drivshaft right now. I was going to put the 904 in it and then find a driveshaft the length I need. He eventually has a 340/4 speed for it, which is another time down the road. I am just trying to get him a drivetrain that runs for now. So with a 360 and the convertor that came out of the 360/727 combo and a 904 tranny with a convertor that came from a 31/904 combo, which do I use to make this work for me. Never mind the driveshaft length for now.
 
...........use ur 904 trans from the 318 and get a B+M externally balanced flexplate for a 360 with a 904 trans.............kim.........
 
yeah Kimmer, I think that is the way I am gonna go. I have it in the works now. thanks Guys. I am new at this Mopar stuff. I was pretty much a Chevy man until I got my Duster and it is a whole new ballgame. BUT who said you cant teach an OLD dog new tricks.
 
I completed this match up last September. 318 swap for a 360. I used the torque converter from the 318 with the 904. I bought a weighted flexplate from the scrape yard {$50} . I had to wallow out one bolt hole on the flexplate, three holes will match up one will not by maybe 1/8 inch, have drill press will travel. Blue locktight and I have been driving it ever since. I tried to buy the B&M but they said they no longer make it for the external to internal balance match up. Maybe they do now. There is a string on this from my project on here. Good luck.
 
waggs, this is the torque convertor from the 318/904 combo. I dont see any weights on here. All I need is the B&M 10239 flexplate and I am good to go right.
 
the one on the very bottom of the pic in the link.....That's the one!!! you'll be good to go with that puppie :)
trudysduster said:
waggs, this is the torque convertor from the 318/904 combo. I dont see any weights on here. All I need is the B&M 10239 flexplate and I am good to go right.
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