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no reverse gear in 904
https://www.slantsix.org/forum/viewtopic.php?t=52037		 Page 1 of 1
Author:  Valleyant [ Sat May 11, 2013 5:51 pm ]
Post subject:  no reverse gear in 904
Hi,
After 66k miles I lost the reverse band in the transmission. I'm planning a rebuild. My concern is the torque converter. Here is the run down on the cars ('72 Plymouth Valiant) specs.
Super Six conversion
Head milled .085 for a calculated 9 to 1 comp ratio
Full 2 1/4" exhaust
Mopar electronic ignition
2.76 gears with plans for 3.23
stock cam now with the mopar perf p4529342 next upgrade
What torque converter do you recomend for a mostly daily/street driver with a few 1/4 mile drag strip runs a year? I guess most emphasis on the daily/street part....thanks!
Author:  WagonsRcool [ Tue May 14, 2013 11:02 am ]
Post subject: 
Have you dropped the pan to confirm band failure? I ask because I usually have seen the "link" between the servo lever & band fail more often than the band itself.

As far as your combo- it's a nice "pick-me-up" vs the original, but it's still fairly mild. Others will have their own opinions, but I wouldn't go more than a stock type converter that has higher stall, say 2200-2400. You might go a little higher, but you have to be realistic about when you think you're going to actually do the cam & gear swap (I'd personally run less stall with 3.23's on a driver unless I was going to a bigger tire at the same time, while the bigger cam might change the stall some vs stock cam) . I'd also put on a decent add-on cooler.
Author:  Valleyant [ Tue May 14, 2013 3:02 pm ]
Post subject: 
Thanks Wagons,
Just assuming its the reverse band. I was attempting to back up a slight incline and heard a clunk and suddenly no reverse. I have all forward gears. I also tested shifting into L at a low speed and the trans will not go into low/1st until the car is going slow enough for the trans to shift into 1st by itself. Hope that makes sense.
I did however confirm that the replacement trans I found was a 1979 built unit and is a non-lock up converter type so I should be ok for a swap. Before I do the swap I will drop the pan like you suggested and do some more snooping around incase its an easy fix.
Thanks for your advice!
Author:  Reed [ Tue May 14, 2013 3:17 pm ]
Post subject: 
I have found this diagram extremely useful in diagnosing what part of a 904 transmission has failed:

Image
Author:  bigslant6fan [ Tue May 14, 2013 4:46 pm ]
Post subject:  .
I agree with wagon 110%,72 and 79 model year 904s take a different adjustment for the rear band. It could have been adjusted wrong to start with,and caused the band strut to fall out.consider dropping the pan first.
Author:  hantayo13 [ Tue May 14, 2013 7:43 pm ]
Post subject: 
have fixed several by dropping pan and reinstalling band strut/adjusting rear band
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